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Linux/mm/memory.c

  1 /*
  2  *  linux/mm/memory.c
  3  *
  4  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  5  */
  6 
  7 /*
  8  * demand-loading started 01.12.91 - seems it is high on the list of
  9  * things wanted, and it should be easy to implement. - Linus
 10  */
 11 
 12 /*
 13  * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
 14  * pages started 02.12.91, seems to work. - Linus.
 15  *
 16  * Tested sharing by executing about 30 /bin/sh: under the old kernel it
 17  * would have taken more than the 6M I have free, but it worked well as
 18  * far as I could see.
 19  *
 20  * Also corrected some "invalidate()"s - I wasn't doing enough of them.
 21  */
 22 
 23 /*
 24  * Real VM (paging to/from disk) started 18.12.91. Much more work and
 25  * thought has to go into this. Oh, well..
 26  * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
 27  *              Found it. Everything seems to work now.
 28  * 20.12.91  -  Ok, making the swap-device changeable like the root.
 29  */
 30 
 31 /*
 32  * 05.04.94  -  Multi-page memory management added for v1.1.
 33  *              Idea by Alex Bligh (alex@cconcepts.co.uk)
 34  *
 35  * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
 36  *              (Gerhard.Wichert@pdb.siemens.de)
 37  *
 38  * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
 39  */
 40 
 41 #include <linux/kernel_stat.h>
 42 #include <linux/mm.h>
 43 #include <linux/hugetlb.h>
 44 #include <linux/mman.h>
 45 #include <linux/swap.h>
 46 #include <linux/highmem.h>
 47 #include <linux/pagemap.h>
 48 #include <linux/ksm.h>
 49 #include <linux/rmap.h>
 50 #include <linux/export.h>
 51 #include <linux/delayacct.h>
 52 #include <linux/init.h>
 53 #include <linux/writeback.h>
 54 #include <linux/memcontrol.h>
 55 #include <linux/mmu_notifier.h>
 56 #include <linux/kallsyms.h>
 57 #include <linux/swapops.h>
 58 #include <linux/elf.h>
 59 #include <linux/gfp.h>
 60 #include <linux/migrate.h>
 61 #include <linux/string.h>
 62 #include <linux/dma-debug.h>
 63 #include <linux/debugfs.h>
 64 
 65 #include <asm/io.h>
 66 #include <asm/pgalloc.h>
 67 #include <asm/uaccess.h>
 68 #include <asm/tlb.h>
 69 #include <asm/tlbflush.h>
 70 #include <asm/pgtable.h>
 71 
 72 #include "internal.h"
 73 
 74 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
 75 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
 76 #endif
 77 
 78 #ifndef CONFIG_NEED_MULTIPLE_NODES
 79 /* use the per-pgdat data instead for discontigmem - mbligh */
 80 unsigned long max_mapnr;
 81 struct page *mem_map;
 82 
 83 EXPORT_SYMBOL(max_mapnr);
 84 EXPORT_SYMBOL(mem_map);
 85 #endif
 86 
 87 /*
 88  * A number of key systems in x86 including ioremap() rely on the assumption
 89  * that high_memory defines the upper bound on direct map memory, then end
 90  * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
 91  * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
 92  * and ZONE_HIGHMEM.
 93  */
 94 void * high_memory;
 95 
 96 EXPORT_SYMBOL(high_memory);
 97 
 98 /*
 99  * Randomize the address space (stacks, mmaps, brk, etc.).
100  *
101  * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
102  *   as ancient (libc5 based) binaries can segfault. )
103  */
104 int randomize_va_space __read_mostly =
105 #ifdef CONFIG_COMPAT_BRK
106                                         1;
107 #else
108                                         2;
109 #endif
110 
111 static int __init disable_randmaps(char *s)
112 {
113         randomize_va_space = 0;
114         return 1;
115 }
116 __setup("norandmaps", disable_randmaps);
117 
118 unsigned long zero_pfn __read_mostly;
119 unsigned long highest_memmap_pfn __read_mostly;
120 
121 EXPORT_SYMBOL(zero_pfn);
122 
123 /*
124  * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
125  */
126 static int __init init_zero_pfn(void)
127 {
128         zero_pfn = page_to_pfn(ZERO_PAGE(0));
129         return 0;
130 }
131 core_initcall(init_zero_pfn);
132 
133 
134 #if defined(SPLIT_RSS_COUNTING)
135 
136 void sync_mm_rss(struct mm_struct *mm)
137 {
138         int i;
139 
140         for (i = 0; i < NR_MM_COUNTERS; i++) {
141                 if (current->rss_stat.count[i]) {
142                         add_mm_counter(mm, i, current->rss_stat.count[i]);
143                         current->rss_stat.count[i] = 0;
144                 }
145         }
146         current->rss_stat.events = 0;
147 }
148 
149 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
150 {
151         struct task_struct *task = current;
152 
153         if (likely(task->mm == mm))
154                 task->rss_stat.count[member] += val;
155         else
156                 add_mm_counter(mm, member, val);
157 }
158 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
159 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
160 
161 /* sync counter once per 64 page faults */
162 #define TASK_RSS_EVENTS_THRESH  (64)
163 static void check_sync_rss_stat(struct task_struct *task)
164 {
165         if (unlikely(task != current))
166                 return;
167         if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
168                 sync_mm_rss(task->mm);
169 }
170 #else /* SPLIT_RSS_COUNTING */
171 
172 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
173 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
174 
175 static void check_sync_rss_stat(struct task_struct *task)
176 {
177 }
178 
179 #endif /* SPLIT_RSS_COUNTING */
180 
181 #ifdef HAVE_GENERIC_MMU_GATHER
182 
183 static int tlb_next_batch(struct mmu_gather *tlb)
184 {
185         struct mmu_gather_batch *batch;
186 
187         batch = tlb->active;
188         if (batch->next) {
189                 tlb->active = batch->next;
190                 return 1;
191         }
192 
193         if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
194                 return 0;
195 
196         batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
197         if (!batch)
198                 return 0;
199 
200         tlb->batch_count++;
201         batch->next = NULL;
202         batch->nr   = 0;
203         batch->max  = MAX_GATHER_BATCH;
204 
205         tlb->active->next = batch;
206         tlb->active = batch;
207 
208         return 1;
209 }
210 
211 /* tlb_gather_mmu
212  *      Called to initialize an (on-stack) mmu_gather structure for page-table
213  *      tear-down from @mm. The @fullmm argument is used when @mm is without
214  *      users and we're going to destroy the full address space (exit/execve).
215  */
216 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end)
217 {
218         tlb->mm = mm;
219 
220         /* Is it from 0 to ~0? */
221         tlb->fullmm     = !(start | (end+1));
222         tlb->need_flush_all = 0;
223         tlb->local.next = NULL;
224         tlb->local.nr   = 0;
225         tlb->local.max  = ARRAY_SIZE(tlb->__pages);
226         tlb->active     = &tlb->local;
227         tlb->batch_count = 0;
228 
229 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
230         tlb->batch = NULL;
231 #endif
232 
233         __tlb_reset_range(tlb);
234 }
235 
236 static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
237 {
238         if (!tlb->end)
239                 return;
240 
241         tlb_flush(tlb);
242         mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
243 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
244         tlb_table_flush(tlb);
245 #endif
246         __tlb_reset_range(tlb);
247 }
248 
249 static void tlb_flush_mmu_free(struct mmu_gather *tlb)
250 {
251         struct mmu_gather_batch *batch;
252 
253         for (batch = &tlb->local; batch && batch->nr; batch = batch->next) {
254                 free_pages_and_swap_cache(batch->pages, batch->nr);
255                 batch->nr = 0;
256         }
257         tlb->active = &tlb->local;
258 }
259 
260 void tlb_flush_mmu(struct mmu_gather *tlb)
261 {
262         tlb_flush_mmu_tlbonly(tlb);
263         tlb_flush_mmu_free(tlb);
264 }
265 
266 /* tlb_finish_mmu
267  *      Called at the end of the shootdown operation to free up any resources
268  *      that were required.
269  */
270 void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
271 {
272         struct mmu_gather_batch *batch, *next;
273 
274         tlb_flush_mmu(tlb);
275 
276         /* keep the page table cache within bounds */
277         check_pgt_cache();
278 
279         for (batch = tlb->local.next; batch; batch = next) {
280                 next = batch->next;
281                 free_pages((unsigned long)batch, 0);
282         }
283         tlb->local.next = NULL;
284 }
285 
286 /* __tlb_remove_page
287  *      Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
288  *      handling the additional races in SMP caused by other CPUs caching valid
289  *      mappings in their TLBs. Returns the number of free page slots left.
290  *      When out of page slots we must call tlb_flush_mmu().
291  */
292 int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
293 {
294         struct mmu_gather_batch *batch;
295 
296         VM_BUG_ON(!tlb->end);
297 
298         batch = tlb->active;
299         batch->pages[batch->nr++] = page;
300         if (batch->nr == batch->max) {
301                 if (!tlb_next_batch(tlb))
302                         return 0;
303                 batch = tlb->active;
304         }
305         VM_BUG_ON_PAGE(batch->nr > batch->max, page);
306 
307         return batch->max - batch->nr;
308 }
309 
310 #endif /* HAVE_GENERIC_MMU_GATHER */
311 
312 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
313 
314 /*
315  * See the comment near struct mmu_table_batch.
316  */
317 
318 static void tlb_remove_table_smp_sync(void *arg)
319 {
320         /* Simply deliver the interrupt */
321 }
322 
323 static void tlb_remove_table_one(void *table)
324 {
325         /*
326          * This isn't an RCU grace period and hence the page-tables cannot be
327          * assumed to be actually RCU-freed.
328          *
329          * It is however sufficient for software page-table walkers that rely on
330          * IRQ disabling. See the comment near struct mmu_table_batch.
331          */
332         smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
333         __tlb_remove_table(table);
334 }
335 
336 static void tlb_remove_table_rcu(struct rcu_head *head)
337 {
338         struct mmu_table_batch *batch;
339         int i;
340 
341         batch = container_of(head, struct mmu_table_batch, rcu);
342 
343         for (i = 0; i < batch->nr; i++)
344                 __tlb_remove_table(batch->tables[i]);
345 
346         free_page((unsigned long)batch);
347 }
348 
349 void tlb_table_flush(struct mmu_gather *tlb)
350 {
351         struct mmu_table_batch **batch = &tlb->batch;
352 
353         if (*batch) {
354                 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
355                 *batch = NULL;
356         }
357 }
358 
359 void tlb_remove_table(struct mmu_gather *tlb, void *table)
360 {
361         struct mmu_table_batch **batch = &tlb->batch;
362 
363         /*
364          * When there's less then two users of this mm there cannot be a
365          * concurrent page-table walk.
366          */
367         if (atomic_read(&tlb->mm->mm_users) < 2) {
368                 __tlb_remove_table(table);
369                 return;
370         }
371 
372         if (*batch == NULL) {
373                 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
374                 if (*batch == NULL) {
375                         tlb_remove_table_one(table);
376                         return;
377                 }
378                 (*batch)->nr = 0;
379         }
380         (*batch)->tables[(*batch)->nr++] = table;
381         if ((*batch)->nr == MAX_TABLE_BATCH)
382                 tlb_table_flush(tlb);
383 }
384 
385 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */
386 
387 /*
388  * Note: this doesn't free the actual pages themselves. That
389  * has been handled earlier when unmapping all the memory regions.
390  */
391 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
392                            unsigned long addr)
393 {
394         pgtable_t token = pmd_pgtable(*pmd);
395         pmd_clear(pmd);
396         pte_free_tlb(tlb, token, addr);
397         atomic_long_dec(&tlb->mm->nr_ptes);
398 }
399 
400 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
401                                 unsigned long addr, unsigned long end,
402                                 unsigned long floor, unsigned long ceiling)
403 {
404         pmd_t *pmd;
405         unsigned long next;
406         unsigned long start;
407 
408         start = addr;
409         pmd = pmd_offset(pud, addr);
410         do {
411                 next = pmd_addr_end(addr, end);
412                 if (pmd_none_or_clear_bad(pmd))
413                         continue;
414                 free_pte_range(tlb, pmd, addr);
415         } while (pmd++, addr = next, addr != end);
416 
417         start &= PUD_MASK;
418         if (start < floor)
419                 return;
420         if (ceiling) {
421                 ceiling &= PUD_MASK;
422                 if (!ceiling)
423                         return;
424         }
425         if (end - 1 > ceiling - 1)
426                 return;
427 
428         pmd = pmd_offset(pud, start);
429         pud_clear(pud);
430         pmd_free_tlb(tlb, pmd, start);
431 }
432 
433 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
434                                 unsigned long addr, unsigned long end,
435                                 unsigned long floor, unsigned long ceiling)
436 {
437         pud_t *pud;
438         unsigned long next;
439         unsigned long start;
440 
441         start = addr;
442         pud = pud_offset(pgd, addr);
443         do {
444                 next = pud_addr_end(addr, end);
445                 if (pud_none_or_clear_bad(pud))
446                         continue;
447                 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
448         } while (pud++, addr = next, addr != end);
449 
450         start &= PGDIR_MASK;
451         if (start < floor)
452                 return;
453         if (ceiling) {
454                 ceiling &= PGDIR_MASK;
455                 if (!ceiling)
456                         return;
457         }
458         if (end - 1 > ceiling - 1)
459                 return;
460 
461         pud = pud_offset(pgd, start);
462         pgd_clear(pgd);
463         pud_free_tlb(tlb, pud, start);
464 }
465 
466 /*
467  * This function frees user-level page tables of a process.
468  */
469 void free_pgd_range(struct mmu_gather *tlb,
470                         unsigned long addr, unsigned long end,
471                         unsigned long floor, unsigned long ceiling)
472 {
473         pgd_t *pgd;
474         unsigned long next;
475 
476         /*
477          * The next few lines have given us lots of grief...
478          *
479          * Why are we testing PMD* at this top level?  Because often
480          * there will be no work to do at all, and we'd prefer not to
481          * go all the way down to the bottom just to discover that.
482          *
483          * Why all these "- 1"s?  Because 0 represents both the bottom
484          * of the address space and the top of it (using -1 for the
485          * top wouldn't help much: the masks would do the wrong thing).
486          * The rule is that addr 0 and floor 0 refer to the bottom of
487          * the address space, but end 0 and ceiling 0 refer to the top
488          * Comparisons need to use "end - 1" and "ceiling - 1" (though
489          * that end 0 case should be mythical).
490          *
491          * Wherever addr is brought up or ceiling brought down, we must
492          * be careful to reject "the opposite 0" before it confuses the
493          * subsequent tests.  But what about where end is brought down
494          * by PMD_SIZE below? no, end can't go down to 0 there.
495          *
496          * Whereas we round start (addr) and ceiling down, by different
497          * masks at different levels, in order to test whether a table
498          * now has no other vmas using it, so can be freed, we don't
499          * bother to round floor or end up - the tests don't need that.
500          */
501 
502         addr &= PMD_MASK;
503         if (addr < floor) {
504                 addr += PMD_SIZE;
505                 if (!addr)
506                         return;
507         }
508         if (ceiling) {
509                 ceiling &= PMD_MASK;
510                 if (!ceiling)
511                         return;
512         }
513         if (end - 1 > ceiling - 1)
514                 end -= PMD_SIZE;
515         if (addr > end - 1)
516                 return;
517 
518         pgd = pgd_offset(tlb->mm, addr);
519         do {
520                 next = pgd_addr_end(addr, end);
521                 if (pgd_none_or_clear_bad(pgd))
522                         continue;
523                 free_pud_range(tlb, pgd, addr, next, floor, ceiling);
524         } while (pgd++, addr = next, addr != end);
525 }
526 
527 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
528                 unsigned long floor, unsigned long ceiling)
529 {
530         while (vma) {
531                 struct vm_area_struct *next = vma->vm_next;
532                 unsigned long addr = vma->vm_start;
533 
534                 /*
535                  * Hide vma from rmap and truncate_pagecache before freeing
536                  * pgtables
537                  */
538                 unlink_anon_vmas(vma);
539                 unlink_file_vma(vma);
540 
541                 if (is_vm_hugetlb_page(vma)) {
542                         hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
543                                 floor, next? next->vm_start: ceiling);
544                 } else {
545                         /*
546                          * Optimization: gather nearby vmas into one call down
547                          */
548                         while (next && next->vm_start <= vma->vm_end + PMD_SIZE
549                                && !is_vm_hugetlb_page(next)) {
550                                 vma = next;
551                                 next = vma->vm_next;
552                                 unlink_anon_vmas(vma);
553                                 unlink_file_vma(vma);
554                         }
555                         free_pgd_range(tlb, addr, vma->vm_end,
556                                 floor, next? next->vm_start: ceiling);
557                 }
558                 vma = next;
559         }
560 }
561 
562 int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
563                 pmd_t *pmd, unsigned long address)
564 {
565         spinlock_t *ptl;
566         pgtable_t new = pte_alloc_one(mm, address);
567         int wait_split_huge_page;
568         if (!new)
569                 return -ENOMEM;
570 
571         /*
572          * Ensure all pte setup (eg. pte page lock and page clearing) are
573          * visible before the pte is made visible to other CPUs by being
574          * put into page tables.
575          *
576          * The other side of the story is the pointer chasing in the page
577          * table walking code (when walking the page table without locking;
578          * ie. most of the time). Fortunately, these data accesses consist
579          * of a chain of data-dependent loads, meaning most CPUs (alpha
580          * being the notable exception) will already guarantee loads are
581          * seen in-order. See the alpha page table accessors for the
582          * smp_read_barrier_depends() barriers in page table walking code.
583          */
584         smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
585 
586         ptl = pmd_lock(mm, pmd);
587         wait_split_huge_page = 0;
588         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
589                 atomic_long_inc(&mm->nr_ptes);
590                 pmd_populate(mm, pmd, new);
591                 new = NULL;
592         } else if (unlikely(pmd_trans_splitting(*pmd)))
593                 wait_split_huge_page = 1;
594         spin_unlock(ptl);
595         if (new)
596                 pte_free(mm, new);
597         if (wait_split_huge_page)
598                 wait_split_huge_page(vma->anon_vma, pmd);
599         return 0;
600 }
601 
602 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
603 {
604         pte_t *new = pte_alloc_one_kernel(&init_mm, address);
605         if (!new)
606                 return -ENOMEM;
607 
608         smp_wmb(); /* See comment in __pte_alloc */
609 
610         spin_lock(&init_mm.page_table_lock);
611         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
612                 pmd_populate_kernel(&init_mm, pmd, new);
613                 new = NULL;
614         } else
615                 VM_BUG_ON(pmd_trans_splitting(*pmd));
616         spin_unlock(&init_mm.page_table_lock);
617         if (new)
618                 pte_free_kernel(&init_mm, new);
619         return 0;
620 }
621 
622 static inline void init_rss_vec(int *rss)
623 {
624         memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
625 }
626 
627 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
628 {
629         int i;
630 
631         if (current->mm == mm)
632                 sync_mm_rss(mm);
633         for (i = 0; i < NR_MM_COUNTERS; i++)
634                 if (rss[i])
635                         add_mm_counter(mm, i, rss[i]);
636 }
637 
638 /*
639  * This function is called to print an error when a bad pte
640  * is found. For example, we might have a PFN-mapped pte in
641  * a region that doesn't allow it.
642  *
643  * The calling function must still handle the error.
644  */
645 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
646                           pte_t pte, struct page *page)
647 {
648         pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
649         pud_t *pud = pud_offset(pgd, addr);
650         pmd_t *pmd = pmd_offset(pud, addr);
651         struct address_space *mapping;
652         pgoff_t index;
653         static unsigned long resume;
654         static unsigned long nr_shown;
655         static unsigned long nr_unshown;
656 
657         /*
658          * Allow a burst of 60 reports, then keep quiet for that minute;
659          * or allow a steady drip of one report per second.
660          */
661         if (nr_shown == 60) {
662                 if (time_before(jiffies, resume)) {
663                         nr_unshown++;
664                         return;
665                 }
666                 if (nr_unshown) {
667                         printk(KERN_ALERT
668                                 "BUG: Bad page map: %lu messages suppressed\n",
669                                 nr_unshown);
670                         nr_unshown = 0;
671                 }
672                 nr_shown = 0;
673         }
674         if (nr_shown++ == 0)
675                 resume = jiffies + 60 * HZ;
676 
677         mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
678         index = linear_page_index(vma, addr);
679 
680         printk(KERN_ALERT
681                 "BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
682                 current->comm,
683                 (long long)pte_val(pte), (long long)pmd_val(*pmd));
684         if (page)
685                 dump_page(page, "bad pte");
686         printk(KERN_ALERT
687                 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
688                 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
689         /*
690          * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
691          */
692         if (vma->vm_ops)
693                 printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n",
694                        vma->vm_ops->fault);
695         if (vma->vm_file)
696                 printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n",
697                        vma->vm_file->f_op->mmap);
698         dump_stack();
699         add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
700 }
701 
702 /*
703  * vm_normal_page -- This function gets the "struct page" associated with a pte.
704  *
705  * "Special" mappings do not wish to be associated with a "struct page" (either
706  * it doesn't exist, or it exists but they don't want to touch it). In this
707  * case, NULL is returned here. "Normal" mappings do have a struct page.
708  *
709  * There are 2 broad cases. Firstly, an architecture may define a pte_special()
710  * pte bit, in which case this function is trivial. Secondly, an architecture
711  * may not have a spare pte bit, which requires a more complicated scheme,
712  * described below.
713  *
714  * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
715  * special mapping (even if there are underlying and valid "struct pages").
716  * COWed pages of a VM_PFNMAP are always normal.
717  *
718  * The way we recognize COWed pages within VM_PFNMAP mappings is through the
719  * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
720  * set, and the vm_pgoff will point to the first PFN mapped: thus every special
721  * mapping will always honor the rule
722  *
723  *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
724  *
725  * And for normal mappings this is false.
726  *
727  * This restricts such mappings to be a linear translation from virtual address
728  * to pfn. To get around this restriction, we allow arbitrary mappings so long
729  * as the vma is not a COW mapping; in that case, we know that all ptes are
730  * special (because none can have been COWed).
731  *
732  *
733  * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
734  *
735  * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
736  * page" backing, however the difference is that _all_ pages with a struct
737  * page (that is, those where pfn_valid is true) are refcounted and considered
738  * normal pages by the VM. The disadvantage is that pages are refcounted
739  * (which can be slower and simply not an option for some PFNMAP users). The
740  * advantage is that we don't have to follow the strict linearity rule of
741  * PFNMAP mappings in order to support COWable mappings.
742  *
743  */
744 #ifdef __HAVE_ARCH_PTE_SPECIAL
745 # define HAVE_PTE_SPECIAL 1
746 #else
747 # define HAVE_PTE_SPECIAL 0
748 #endif
749 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
750                                 pte_t pte)
751 {
752         unsigned long pfn = pte_pfn(pte);
753 
754         if (HAVE_PTE_SPECIAL) {
755                 if (likely(!pte_special(pte)))
756                         goto check_pfn;
757                 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
758                         return NULL;
759                 if (!is_zero_pfn(pfn))
760                         print_bad_pte(vma, addr, pte, NULL);
761                 return NULL;
762         }
763 
764         /* !HAVE_PTE_SPECIAL case follows: */
765 
766         if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
767                 if (vma->vm_flags & VM_MIXEDMAP) {
768                         if (!pfn_valid(pfn))
769                                 return NULL;
770                         goto out;
771                 } else {
772                         unsigned long off;
773                         off = (addr - vma->vm_start) >> PAGE_SHIFT;
774                         if (pfn == vma->vm_pgoff + off)
775                                 return NULL;
776                         if (!is_cow_mapping(vma->vm_flags))
777                                 return NULL;
778                 }
779         }
780 
781         if (is_zero_pfn(pfn))
782                 return NULL;
783 check_pfn:
784         if (unlikely(pfn > highest_memmap_pfn)) {
785                 print_bad_pte(vma, addr, pte, NULL);
786                 return NULL;
787         }
788 
789         /*
790          * NOTE! We still have PageReserved() pages in the page tables.
791          * eg. VDSO mappings can cause them to exist.
792          */
793 out:
794         return pfn_to_page(pfn);
795 }
796 
797 /*
798  * copy one vm_area from one task to the other. Assumes the page tables
799  * already present in the new task to be cleared in the whole range
800  * covered by this vma.
801  */
802 
803 static inline unsigned long
804 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
805                 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
806                 unsigned long addr, int *rss)
807 {
808         unsigned long vm_flags = vma->vm_flags;
809         pte_t pte = *src_pte;
810         struct page *page;
811 
812         /* pte contains position in swap or file, so copy. */
813         if (unlikely(!pte_present(pte))) {
814                 if (!pte_file(pte)) {
815                         swp_entry_t entry = pte_to_swp_entry(pte);
816 
817                         if (likely(!non_swap_entry(entry))) {
818                                 if (swap_duplicate(entry) < 0)
819                                         return entry.val;
820 
821                                 /* make sure dst_mm is on swapoff's mmlist. */
822                                 if (unlikely(list_empty(&dst_mm->mmlist))) {
823                                         spin_lock(&mmlist_lock);
824                                         if (list_empty(&dst_mm->mmlist))
825                                                 list_add(&dst_mm->mmlist,
826                                                          &src_mm->mmlist);
827                                         spin_unlock(&mmlist_lock);
828                                 }
829                                 rss[MM_SWAPENTS]++;
830                         } else if (is_migration_entry(entry)) {
831                                 page = migration_entry_to_page(entry);
832 
833                                 if (PageAnon(page))
834                                         rss[MM_ANONPAGES]++;
835                                 else
836                                         rss[MM_FILEPAGES]++;
837 
838                                 if (is_write_migration_entry(entry) &&
839                                     is_cow_mapping(vm_flags)) {
840                                         /*
841                                          * COW mappings require pages in both
842                                          * parent and child to be set to read.
843                                          */
844                                         make_migration_entry_read(&entry);
845                                         pte = swp_entry_to_pte(entry);
846                                         if (pte_swp_soft_dirty(*src_pte))
847                                                 pte = pte_swp_mksoft_dirty(pte);
848                                         set_pte_at(src_mm, addr, src_pte, pte);
849                                 }
850                         }
851                 }
852                 goto out_set_pte;
853         }
854 
855         /*
856          * If it's a COW mapping, write protect it both
857          * in the parent and the child
858          */
859         if (is_cow_mapping(vm_flags)) {
860                 ptep_set_wrprotect(src_mm, addr, src_pte);
861                 pte = pte_wrprotect(pte);
862         }
863 
864         /*
865          * If it's a shared mapping, mark it clean in
866          * the child
867          */
868         if (vm_flags & VM_SHARED)
869                 pte = pte_mkclean(pte);
870         pte = pte_mkold(pte);
871 
872         page = vm_normal_page(vma, addr, pte);
873         if (page) {
874                 get_page(page);
875                 page_dup_rmap(page);
876                 if (PageAnon(page))
877                         rss[MM_ANONPAGES]++;
878                 else
879                         rss[MM_FILEPAGES]++;
880         }
881 
882 out_set_pte:
883         set_pte_at(dst_mm, addr, dst_pte, pte);
884         return 0;
885 }
886 
887 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
888                    pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
889                    unsigned long addr, unsigned long end)
890 {
891         pte_t *orig_src_pte, *orig_dst_pte;
892         pte_t *src_pte, *dst_pte;
893         spinlock_t *src_ptl, *dst_ptl;
894         int progress = 0;
895         int rss[NR_MM_COUNTERS];
896         swp_entry_t entry = (swp_entry_t){0};
897 
898 again:
899         init_rss_vec(rss);
900 
901         dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
902         if (!dst_pte)
903                 return -ENOMEM;
904         src_pte = pte_offset_map(src_pmd, addr);
905         src_ptl = pte_lockptr(src_mm, src_pmd);
906         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
907         orig_src_pte = src_pte;
908         orig_dst_pte = dst_pte;
909         arch_enter_lazy_mmu_mode();
910 
911         do {
912                 /*
913                  * We are holding two locks at this point - either of them
914                  * could generate latencies in another task on another CPU.
915                  */
916                 if (progress >= 32) {
917                         progress = 0;
918                         if (need_resched() ||
919                             spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
920                                 break;
921                 }
922                 if (pte_none(*src_pte)) {
923                         progress++;
924                         continue;
925                 }
926                 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
927                                                         vma, addr, rss);
928                 if (entry.val)
929                         break;
930                 progress += 8;
931         } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
932 
933         arch_leave_lazy_mmu_mode();
934         spin_unlock(src_ptl);
935         pte_unmap(orig_src_pte);
936         add_mm_rss_vec(dst_mm, rss);
937         pte_unmap_unlock(orig_dst_pte, dst_ptl);
938         cond_resched();
939 
940         if (entry.val) {
941                 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
942                         return -ENOMEM;
943                 progress = 0;
944         }
945         if (addr != end)
946                 goto again;
947         return 0;
948 }
949 
950 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
951                 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
952                 unsigned long addr, unsigned long end)
953 {
954         pmd_t *src_pmd, *dst_pmd;
955         unsigned long next;
956 
957         dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
958         if (!dst_pmd)
959                 return -ENOMEM;
960         src_pmd = pmd_offset(src_pud, addr);
961         do {
962                 next = pmd_addr_end(addr, end);
963                 if (pmd_trans_huge(*src_pmd)) {
964                         int err;
965                         VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
966                         err = copy_huge_pmd(dst_mm, src_mm,
967                                             dst_pmd, src_pmd, addr, vma);
968                         if (err == -ENOMEM)
969                                 return -ENOMEM;
970                         if (!err)
971                                 continue;
972                         /* fall through */
973                 }
974                 if (pmd_none_or_clear_bad(src_pmd))
975                         continue;
976                 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
977                                                 vma, addr, next))
978                         return -ENOMEM;
979         } while (dst_pmd++, src_pmd++, addr = next, addr != end);
980         return 0;
981 }
982 
983 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
984                 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
985                 unsigned long addr, unsigned long end)
986 {
987         pud_t *src_pud, *dst_pud;
988         unsigned long next;
989 
990         dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
991         if (!dst_pud)
992                 return -ENOMEM;
993         src_pud = pud_offset(src_pgd, addr);
994         do {
995                 next = pud_addr_end(addr, end);
996                 if (pud_none_or_clear_bad(src_pud))
997                         continue;
998                 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
999                                                 vma, addr, next))
1000                         return -ENOMEM;
1001         } while (dst_pud++, src_pud++, addr = next, addr != end);
1002         return 0;
1003 }
1004 
1005 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1006                 struct vm_area_struct *vma)
1007 {
1008         pgd_t *src_pgd, *dst_pgd;
1009         unsigned long next;
1010         unsigned long addr = vma->vm_start;
1011         unsigned long end = vma->vm_end;
1012         unsigned long mmun_start;       /* For mmu_notifiers */
1013         unsigned long mmun_end;         /* For mmu_notifiers */
1014         bool is_cow;
1015         int ret;
1016 
1017         /*
1018          * Don't copy ptes where a page fault will fill them correctly.
1019          * Fork becomes much lighter when there are big shared or private
1020          * readonly mappings. The tradeoff is that copy_page_range is more
1021          * efficient than faulting.
1022          */
1023         if (!(vma->vm_flags & (VM_HUGETLB | VM_NONLINEAR |
1024                                VM_PFNMAP | VM_MIXEDMAP))) {
1025                 if (!vma->anon_vma)
1026                         return 0;
1027         }
1028 
1029         if (is_vm_hugetlb_page(vma))
1030                 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1031 
1032         if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1033                 /*
1034                  * We do not free on error cases below as remove_vma
1035                  * gets called on error from higher level routine
1036                  */
1037                 ret = track_pfn_copy(vma);
1038                 if (ret)
1039                         return ret;
1040         }
1041 
1042         /*
1043          * We need to invalidate the secondary MMU mappings only when
1044          * there could be a permission downgrade on the ptes of the
1045          * parent mm. And a permission downgrade will only happen if
1046          * is_cow_mapping() returns true.
1047          */
1048         is_cow = is_cow_mapping(vma->vm_flags);
1049         mmun_start = addr;
1050         mmun_end   = end;
1051         if (is_cow)
1052                 mmu_notifier_invalidate_range_start(src_mm, mmun_start,
1053                                                     mmun_end);
1054 
1055         ret = 0;
1056         dst_pgd = pgd_offset(dst_mm, addr);
1057         src_pgd = pgd_offset(src_mm, addr);
1058         do {
1059                 next = pgd_addr_end(addr, end);
1060                 if (pgd_none_or_clear_bad(src_pgd))
1061                         continue;
1062                 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
1063                                             vma, addr, next))) {
1064                         ret = -ENOMEM;
1065                         break;
1066                 }
1067         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1068 
1069         if (is_cow)
1070                 mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
1071         return ret;
1072 }
1073 
1074 static unsigned long zap_pte_range(struct mmu_gather *tlb,
1075                                 struct vm_area_struct *vma, pmd_t *pmd,
1076                                 unsigned long addr, unsigned long end,
1077                                 struct zap_details *details)
1078 {
1079         struct mm_struct *mm = tlb->mm;
1080         int force_flush = 0;
1081         int rss[NR_MM_COUNTERS];
1082         spinlock_t *ptl;
1083         pte_t *start_pte;
1084         pte_t *pte;
1085 
1086 again:
1087         init_rss_vec(rss);
1088         start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1089         pte = start_pte;
1090         arch_enter_lazy_mmu_mode();
1091         do {
1092                 pte_t ptent = *pte;
1093                 if (pte_none(ptent)) {
1094                         continue;
1095                 }
1096 
1097                 if (pte_present(ptent)) {
1098                         struct page *page;
1099 
1100                         page = vm_normal_page(vma, addr, ptent);
1101                         if (unlikely(details) && page) {
1102                                 /*
1103                                  * unmap_shared_mapping_pages() wants to
1104                                  * invalidate cache without truncating:
1105                                  * unmap shared but keep private pages.
1106                                  */
1107                                 if (details->check_mapping &&
1108                                     details->check_mapping != page->mapping)
1109                                         continue;
1110                                 /*
1111                                  * Each page->index must be checked when
1112                                  * invalidating or truncating nonlinear.
1113                                  */
1114                                 if (details->nonlinear_vma &&
1115                                     (page->index < details->first_index ||
1116                                      page->index > details->last_index))
1117                                         continue;
1118                         }
1119                         ptent = ptep_get_and_clear_full(mm, addr, pte,
1120                                                         tlb->fullmm);
1121                         tlb_remove_tlb_entry(tlb, pte, addr);
1122                         if (unlikely(!page))
1123                                 continue;
1124                         if (unlikely(details) && details->nonlinear_vma
1125                             && linear_page_index(details->nonlinear_vma,
1126                                                 addr) != page->index) {
1127                                 pte_t ptfile = pgoff_to_pte(page->index);
1128                                 if (pte_soft_dirty(ptent))
1129                                         ptfile = pte_file_mksoft_dirty(ptfile);
1130                                 set_pte_at(mm, addr, pte, ptfile);
1131                         }
1132                         if (PageAnon(page))
1133                                 rss[MM_ANONPAGES]--;
1134                         else {
1135                                 if (pte_dirty(ptent)) {
1136                                         force_flush = 1;
1137                                         set_page_dirty(page);
1138                                 }
1139                                 if (pte_young(ptent) &&
1140                                     likely(!(vma->vm_flags & VM_SEQ_READ)))
1141                                         mark_page_accessed(page);
1142                                 rss[MM_FILEPAGES]--;
1143                         }
1144                         page_remove_rmap(page);
1145                         if (unlikely(page_mapcount(page) < 0))
1146                                 print_bad_pte(vma, addr, ptent, page);
1147                         if (unlikely(!__tlb_remove_page(tlb, page))) {
1148                                 force_flush = 1;
1149                                 addr += PAGE_SIZE;
1150                                 break;
1151                         }
1152                         continue;
1153                 }
1154                 /*
1155                  * If details->check_mapping, we leave swap entries;
1156                  * if details->nonlinear_vma, we leave file entries.
1157                  */
1158                 if (unlikely(details))
1159                         continue;
1160                 if (pte_file(ptent)) {
1161                         if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
1162                                 print_bad_pte(vma, addr, ptent, NULL);
1163                 } else {
1164                         swp_entry_t entry = pte_to_swp_entry(ptent);
1165 
1166                         if (!non_swap_entry(entry))
1167                                 rss[MM_SWAPENTS]--;
1168                         else if (is_migration_entry(entry)) {
1169                                 struct page *page;
1170 
1171                                 page = migration_entry_to_page(entry);
1172 
1173                                 if (PageAnon(page))
1174                                         rss[MM_ANONPAGES]--;
1175                                 else
1176                                         rss[MM_FILEPAGES]--;
1177                         }
1178                         if (unlikely(!free_swap_and_cache(entry)))
1179                                 print_bad_pte(vma, addr, ptent, NULL);
1180                 }
1181                 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1182         } while (pte++, addr += PAGE_SIZE, addr != end);
1183 
1184         add_mm_rss_vec(mm, rss);
1185         arch_leave_lazy_mmu_mode();
1186 
1187         /* Do the actual TLB flush before dropping ptl */
1188         if (force_flush)
1189                 tlb_flush_mmu_tlbonly(tlb);
1190         pte_unmap_unlock(start_pte, ptl);
1191 
1192         /*
1193          * If we forced a TLB flush (either due to running out of
1194          * batch buffers or because we needed to flush dirty TLB
1195          * entries before releasing the ptl), free the batched
1196          * memory too. Restart if we didn't do everything.
1197          */
1198         if (force_flush) {
1199                 force_flush = 0;
1200                 tlb_flush_mmu_free(tlb);
1201 
1202                 if (addr != end)
1203                         goto again;
1204         }
1205 
1206         return addr;
1207 }
1208 
1209 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1210                                 struct vm_area_struct *vma, pud_t *pud,
1211                                 unsigned long addr, unsigned long end,
1212                                 struct zap_details *details)
1213 {
1214         pmd_t *pmd;
1215         unsigned long next;
1216 
1217         pmd = pmd_offset(pud, addr);
1218         do {
1219                 next = pmd_addr_end(addr, end);
1220                 if (pmd_trans_huge(*pmd)) {
1221                         if (next - addr != HPAGE_PMD_SIZE) {
1222 #ifdef CONFIG_DEBUG_VM
1223                                 if (!rwsem_is_locked(&tlb->mm->mmap_sem)) {
1224                                         pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",
1225                                                 __func__, addr, end,
1226                                                 vma->vm_start,
1227                                                 vma->vm_end);
1228                                         BUG();
1229                                 }
1230 #endif
1231                                 split_huge_page_pmd(vma, addr, pmd);
1232                         } else if (zap_huge_pmd(tlb, vma, pmd, addr))
1233                                 goto next;
1234                         /* fall through */
1235                 }
1236                 /*
1237                  * Here there can be other concurrent MADV_DONTNEED or
1238                  * trans huge page faults running, and if the pmd is
1239                  * none or trans huge it can change under us. This is
1240                  * because MADV_DONTNEED holds the mmap_sem in read
1241                  * mode.
1242                  */
1243                 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1244                         goto next;
1245                 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1246 next:
1247                 cond_resched();
1248         } while (pmd++, addr = next, addr != end);
1249 
1250         return addr;
1251 }
1252 
1253 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1254                                 struct vm_area_struct *vma, pgd_t *pgd,
1255                                 unsigned long addr, unsigned long end,
1256                                 struct zap_details *details)
1257 {
1258         pud_t *pud;
1259         unsigned long next;
1260 
1261         pud = pud_offset(pgd, addr);
1262         do {
1263                 next = pud_addr_end(addr, end);
1264                 if (pud_none_or_clear_bad(pud))
1265                         continue;
1266                 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1267         } while (pud++, addr = next, addr != end);
1268 
1269         return addr;
1270 }
1271 
1272 static void unmap_page_range(struct mmu_gather *tlb,
1273                              struct vm_area_struct *vma,
1274                              unsigned long addr, unsigned long end,
1275                              struct zap_details *details)
1276 {
1277         pgd_t *pgd;
1278         unsigned long next;
1279 
1280         if (details && !details->check_mapping && !details->nonlinear_vma)
1281                 details = NULL;
1282 
1283         BUG_ON(addr >= end);
1284         tlb_start_vma(tlb, vma);
1285         pgd = pgd_offset(vma->vm_mm, addr);
1286         do {
1287                 next = pgd_addr_end(addr, end);
1288                 if (pgd_none_or_clear_bad(pgd))
1289                         continue;
1290                 next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1291         } while (pgd++, addr = next, addr != end);
1292         tlb_end_vma(tlb, vma);
1293 }
1294 
1295 
1296 static void unmap_single_vma(struct mmu_gather *tlb,
1297                 struct vm_area_struct *vma, unsigned long start_addr,
1298                 unsigned long end_addr,
1299                 struct zap_details *details)
1300 {
1301         unsigned long start = max(vma->vm_start, start_addr);
1302         unsigned long end;
1303 
1304         if (start >= vma->vm_end)
1305                 return;
1306         end = min(vma->vm_end, end_addr);
1307         if (end <= vma->vm_start)
1308                 return;
1309 
1310         if (vma->vm_file)
1311                 uprobe_munmap(vma, start, end);
1312 
1313         if (unlikely(vma->vm_flags & VM_PFNMAP))
1314                 untrack_pfn(vma, 0, 0);
1315 
1316         if (start != end) {
1317                 if (unlikely(is_vm_hugetlb_page(vma))) {
1318                         /*
1319                          * It is undesirable to test vma->vm_file as it
1320                          * should be non-null for valid hugetlb area.
1321                          * However, vm_file will be NULL in the error
1322                          * cleanup path of mmap_region. When
1323                          * hugetlbfs ->mmap method fails,
1324                          * mmap_region() nullifies vma->vm_file
1325                          * before calling this function to clean up.
1326                          * Since no pte has actually been setup, it is
1327                          * safe to do nothing in this case.
1328                          */
1329                         if (vma->vm_file) {
1330                                 i_mmap_lock_write(vma->vm_file->f_mapping);
1331                                 __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1332                                 i_mmap_unlock_write(vma->vm_file->f_mapping);
1333                         }
1334                 } else
1335                         unmap_page_range(tlb, vma, start, end, details);
1336         }
1337 }
1338 
1339 /**
1340  * unmap_vmas - unmap a range of memory covered by a list of vma's
1341  * @tlb: address of the caller's struct mmu_gather
1342  * @vma: the starting vma
1343  * @start_addr: virtual address at which to start unmapping
1344  * @end_addr: virtual address at which to end unmapping
1345  *
1346  * Unmap all pages in the vma list.
1347  *
1348  * Only addresses between `start' and `end' will be unmapped.
1349  *
1350  * The VMA list must be sorted in ascending virtual address order.
1351  *
1352  * unmap_vmas() assumes that the caller will flush the whole unmapped address
1353  * range after unmap_vmas() returns.  So the only responsibility here is to
1354  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1355  * drops the lock and schedules.
1356  */
1357 void unmap_vmas(struct mmu_gather *tlb,
1358                 struct vm_area_struct *vma, unsigned long start_addr,
1359                 unsigned long end_addr)
1360 {
1361         struct mm_struct *mm = vma->vm_mm;
1362 
1363         mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1364         for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1365                 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1366         mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1367 }
1368 
1369 /**
1370  * zap_page_range - remove user pages in a given range
1371  * @vma: vm_area_struct holding the applicable pages
1372  * @start: starting address of pages to zap
1373  * @size: number of bytes to zap
1374  * @details: details of nonlinear truncation or shared cache invalidation
1375  *
1376  * Caller must protect the VMA list
1377  */
1378 void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1379                 unsigned long size, struct zap_details *details)
1380 {
1381         struct mm_struct *mm = vma->vm_mm;
1382         struct mmu_gather tlb;
1383         unsigned long end = start + size;
1384 
1385         lru_add_drain();
1386         tlb_gather_mmu(&tlb, mm, start, end);
1387         update_hiwater_rss(mm);
1388         mmu_notifier_invalidate_range_start(mm, start, end);
1389         for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1390                 unmap_single_vma(&tlb, vma, start, end, details);
1391         mmu_notifier_invalidate_range_end(mm, start, end);
1392         tlb_finish_mmu(&tlb, start, end);
1393 }
1394 
1395 /**
1396  * zap_page_range_single - remove user pages in a given range
1397  * @vma: vm_area_struct holding the applicable pages
1398  * @address: starting address of pages to zap
1399  * @size: number of bytes to zap
1400  * @details: details of nonlinear truncation or shared cache invalidation
1401  *
1402  * The range must fit into one VMA.
1403  */
1404 static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1405                 unsigned long size, struct zap_details *details)
1406 {
1407         struct mm_struct *mm = vma->vm_mm;
1408         struct mmu_gather tlb;
1409         unsigned long end = address + size;
1410 
1411         lru_add_drain();
1412         tlb_gather_mmu(&tlb, mm, address, end);
1413         update_hiwater_rss(mm);
1414         mmu_notifier_invalidate_range_start(mm, address, end);
1415         unmap_single_vma(&tlb, vma, address, end, details);
1416         mmu_notifier_invalidate_range_end(mm, address, end);
1417         tlb_finish_mmu(&tlb, address, end);
1418 }
1419 
1420 /**
1421  * zap_vma_ptes - remove ptes mapping the vma
1422  * @vma: vm_area_struct holding ptes to be zapped
1423  * @address: starting address of pages to zap
1424  * @size: number of bytes to zap
1425  *
1426  * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1427  *
1428  * The entire address range must be fully contained within the vma.
1429  *
1430  * Returns 0 if successful.
1431  */
1432 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1433                 unsigned long size)
1434 {
1435         if (address < vma->vm_start || address + size > vma->vm_end ||
1436                         !(vma->vm_flags & VM_PFNMAP))
1437                 return -1;
1438         zap_page_range_single(vma, address, size, NULL);
1439         return 0;
1440 }
1441 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1442 
1443 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1444                         spinlock_t **ptl)
1445 {
1446         pgd_t * pgd = pgd_offset(mm, addr);
1447         pud_t * pud = pud_alloc(mm, pgd, addr);
1448         if (pud) {
1449                 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1450                 if (pmd) {
1451                         VM_BUG_ON(pmd_trans_huge(*pmd));
1452                         return pte_alloc_map_lock(mm, pmd, addr, ptl);
1453                 }
1454         }
1455         return NULL;
1456 }
1457 
1458 /*
1459  * This is the old fallback for page remapping.
1460  *
1461  * For historical reasons, it only allows reserved pages. Only
1462  * old drivers should use this, and they needed to mark their
1463  * pages reserved for the old functions anyway.
1464  */
1465 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1466                         struct page *page, pgprot_t prot)
1467 {
1468         struct mm_struct *mm = vma->vm_mm;
1469         int retval;
1470         pte_t *pte;
1471         spinlock_t *ptl;
1472 
1473         retval = -EINVAL;
1474         if (PageAnon(page))
1475                 goto out;
1476         retval = -ENOMEM;
1477         flush_dcache_page(page);
1478         pte = get_locked_pte(mm, addr, &ptl);
1479         if (!pte)
1480                 goto out;
1481         retval = -EBUSY;
1482         if (!pte_none(*pte))
1483                 goto out_unlock;
1484 
1485         /* Ok, finally just insert the thing.. */
1486         get_page(page);
1487         inc_mm_counter_fast(mm, MM_FILEPAGES);
1488         page_add_file_rmap(page);
1489         set_pte_at(mm, addr, pte, mk_pte(page, prot));
1490 
1491         retval = 0;
1492         pte_unmap_unlock(pte, ptl);
1493         return retval;
1494 out_unlock:
1495         pte_unmap_unlock(pte, ptl);
1496 out:
1497         return retval;
1498 }
1499 
1500 /**
1501  * vm_insert_page - insert single page into user vma
1502  * @vma: user vma to map to
1503  * @addr: target user address of this page
1504  * @page: source kernel page
1505  *
1506  * This allows drivers to insert individual pages they've allocated
1507  * into a user vma.
1508  *
1509  * The page has to be a nice clean _individual_ kernel allocation.
1510  * If you allocate a compound page, you need to have marked it as
1511  * such (__GFP_COMP), or manually just split the page up yourself
1512  * (see split_page()).
1513  *
1514  * NOTE! Traditionally this was done with "remap_pfn_range()" which
1515  * took an arbitrary page protection parameter. This doesn't allow
1516  * that. Your vma protection will have to be set up correctly, which
1517  * means that if you want a shared writable mapping, you'd better
1518  * ask for a shared writable mapping!
1519  *
1520  * The page does not need to be reserved.
1521  *
1522  * Usually this function is called from f_op->mmap() handler
1523  * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
1524  * Caller must set VM_MIXEDMAP on vma if it wants to call this
1525  * function from other places, for example from page-fault handler.
1526  */
1527 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1528                         struct page *page)
1529 {
1530         if (addr < vma->vm_start || addr >= vma->vm_end)
1531                 return -EFAULT;
1532         if (!page_count(page))
1533                 return -EINVAL;
1534         if (!(vma->vm_flags & VM_MIXEDMAP)) {
1535                 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
1536                 BUG_ON(vma->vm_flags & VM_PFNMAP);
1537                 vma->vm_flags |= VM_MIXEDMAP;
1538         }
1539         return insert_page(vma, addr, page, vma->vm_page_prot);
1540 }
1541 EXPORT_SYMBOL(vm_insert_page);
1542 
1543 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1544                         unsigned long pfn, pgprot_t prot)
1545 {
1546         struct mm_struct *mm = vma->vm_mm;
1547         int retval;
1548         pte_t *pte, entry;
1549         spinlock_t *ptl;
1550 
1551         retval = -ENOMEM;
1552         pte = get_locked_pte(mm, addr, &ptl);
1553         if (!pte)
1554                 goto out;
1555         retval = -EBUSY;
1556         if (!pte_none(*pte))
1557                 goto out_unlock;
1558 
1559         /* Ok, finally just insert the thing.. */
1560         entry = pte_mkspecial(pfn_pte(pfn, prot));
1561         set_pte_at(mm, addr, pte, entry);
1562         update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1563 
1564         retval = 0;
1565 out_unlock:
1566         pte_unmap_unlock(pte, ptl);
1567 out:
1568         return retval;
1569 }
1570 
1571 /**
1572  * vm_insert_pfn - insert single pfn into user vma
1573  * @vma: user vma to map to
1574  * @addr: target user address of this page
1575  * @pfn: source kernel pfn
1576  *
1577  * Similar to vm_insert_page, this allows drivers to insert individual pages
1578  * they've allocated into a user vma. Same comments apply.
1579  *
1580  * This function should only be called from a vm_ops->fault handler, and
1581  * in that case the handler should return NULL.
1582  *
1583  * vma cannot be a COW mapping.
1584  *
1585  * As this is called only for pages that do not currently exist, we
1586  * do not need to flush old virtual caches or the TLB.
1587  */
1588 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1589                         unsigned long pfn)
1590 {
1591         int ret;
1592         pgprot_t pgprot = vma->vm_page_prot;
1593         /*
1594          * Technically, architectures with pte_special can avoid all these
1595          * restrictions (same for remap_pfn_range).  However we would like
1596          * consistency in testing and feature parity among all, so we should
1597          * try to keep these invariants in place for everybody.
1598          */
1599         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1600         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1601                                                 (VM_PFNMAP|VM_MIXEDMAP));
1602         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1603         BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1604 
1605         if (addr < vma->vm_start || addr >= vma->vm_end)
1606                 return -EFAULT;
1607         if (track_pfn_insert(vma, &pgprot, pfn))
1608                 return -EINVAL;
1609 
1610         ret = insert_pfn(vma, addr, pfn, pgprot);
1611 
1612         return ret;
1613 }
1614 EXPORT_SYMBOL(vm_insert_pfn);
1615 
1616 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1617                         unsigned long pfn)
1618 {
1619         BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1620 
1621         if (addr < vma->vm_start || addr >= vma->vm_end)
1622                 return -EFAULT;
1623 
1624         /*
1625          * If we don't have pte special, then we have to use the pfn_valid()
1626          * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1627          * refcount the page if pfn_valid is true (hence insert_page rather
1628          * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
1629          * without pte special, it would there be refcounted as a normal page.
1630          */
1631         if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
1632                 struct page *page;
1633 
1634                 page = pfn_to_page(pfn);
1635                 return insert_page(vma, addr, page, vma->vm_page_prot);
1636         }
1637         return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
1638 }
1639 EXPORT_SYMBOL(vm_insert_mixed);
1640 
1641 /*
1642  * maps a range of physical memory into the requested pages. the old
1643  * mappings are removed. any references to nonexistent pages results
1644  * in null mappings (currently treated as "copy-on-access")
1645  */
1646 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1647                         unsigned long addr, unsigned long end,
1648                         unsigned long pfn, pgprot_t prot)
1649 {
1650         pte_t *pte;
1651         spinlock_t *ptl;
1652 
1653         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1654         if (!pte)
1655                 return -ENOMEM;
1656         arch_enter_lazy_mmu_mode();
1657         do {
1658                 BUG_ON(!pte_none(*pte));
1659                 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1660                 pfn++;
1661         } while (pte++, addr += PAGE_SIZE, addr != end);
1662         arch_leave_lazy_mmu_mode();
1663         pte_unmap_unlock(pte - 1, ptl);
1664         return 0;
1665 }
1666 
1667 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1668                         unsigned long addr, unsigned long end,
1669                         unsigned long pfn, pgprot_t prot)
1670 {
1671         pmd_t *pmd;
1672         unsigned long next;
1673 
1674         pfn -= addr >> PAGE_SHIFT;
1675         pmd = pmd_alloc(mm, pud, addr);
1676         if (!pmd)
1677                 return -ENOMEM;
1678         VM_BUG_ON(pmd_trans_huge(*pmd));
1679         do {
1680                 next = pmd_addr_end(addr, end);
1681                 if (remap_pte_range(mm, pmd, addr, next,
1682                                 pfn + (addr >> PAGE_SHIFT), prot))
1683                         return -ENOMEM;
1684         } while (pmd++, addr = next, addr != end);
1685         return 0;
1686 }
1687 
1688 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1689                         unsigned long addr, unsigned long end,
1690                         unsigned long pfn, pgprot_t prot)
1691 {
1692         pud_t *pud;
1693         unsigned long next;
1694 
1695         pfn -= addr >> PAGE_SHIFT;
1696         pud = pud_alloc(mm, pgd, addr);
1697         if (!pud)
1698                 return -ENOMEM;
1699         do {
1700                 next = pud_addr_end(addr, end);
1701                 if (remap_pmd_range(mm, pud, addr, next,
1702                                 pfn + (addr >> PAGE_SHIFT), prot))
1703                         return -ENOMEM;
1704         } while (pud++, addr = next, addr != end);
1705         return 0;
1706 }
1707 
1708 /**
1709  * remap_pfn_range - remap kernel memory to userspace
1710  * @vma: user vma to map to
1711  * @addr: target user address to start at
1712  * @pfn: physical address of kernel memory
1713  * @size: size of map area
1714  * @prot: page protection flags for this mapping
1715  *
1716  *  Note: this is only safe if the mm semaphore is held when called.
1717  */
1718 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1719                     unsigned long pfn, unsigned long size, pgprot_t prot)
1720 {
1721         pgd_t *pgd;
1722         unsigned long next;
1723         unsigned long end = addr + PAGE_ALIGN(size);
1724         struct mm_struct *mm = vma->vm_mm;
1725         int err;
1726 
1727         /*
1728          * Physically remapped pages are special. Tell the
1729          * rest of the world about it:
1730          *   VM_IO tells people not to look at these pages
1731          *      (accesses can have side effects).
1732          *   VM_PFNMAP tells the core MM that the base pages are just
1733          *      raw PFN mappings, and do not have a "struct page" associated
1734          *      with them.
1735          *   VM_DONTEXPAND
1736          *      Disable vma merging and expanding with mremap().
1737          *   VM_DONTDUMP
1738          *      Omit vma from core dump, even when VM_IO turned off.
1739          *
1740          * There's a horrible special case to handle copy-on-write
1741          * behaviour that some programs depend on. We mark the "original"
1742          * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1743          * See vm_normal_page() for details.
1744          */
1745         if (is_cow_mapping(vma->vm_flags)) {
1746                 if (addr != vma->vm_start || end != vma->vm_end)
1747                         return -EINVAL;
1748                 vma->vm_pgoff = pfn;
1749         }
1750 
1751         err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
1752         if (err)
1753                 return -EINVAL;
1754 
1755         vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1756 
1757         BUG_ON(addr >= end);
1758         pfn -= addr >> PAGE_SHIFT;
1759         pgd = pgd_offset(mm, addr);
1760         flush_cache_range(vma, addr, end);
1761         do {
1762                 next = pgd_addr_end(addr, end);
1763                 err = remap_pud_range(mm, pgd, addr, next,
1764                                 pfn + (addr >> PAGE_SHIFT), prot);
1765                 if (err)
1766                         break;
1767         } while (pgd++, addr = next, addr != end);
1768 
1769         if (err)
1770                 untrack_pfn(vma, pfn, PAGE_ALIGN(size));
1771 
1772         return err;
1773 }
1774 EXPORT_SYMBOL(remap_pfn_range);
1775 
1776 /**
1777  * vm_iomap_memory - remap memory to userspace
1778  * @vma: user vma to map to
1779  * @start: start of area
1780  * @len: size of area
1781  *
1782  * This is a simplified io_remap_pfn_range() for common driver use. The
1783  * driver just needs to give us the physical memory range to be mapped,
1784  * we'll figure out the rest from the vma information.
1785  *
1786  * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
1787  * whatever write-combining details or similar.
1788  */
1789 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1790 {
1791         unsigned long vm_len, pfn, pages;
1792 
1793         /* Check that the physical memory area passed in looks valid */
1794         if (start + len < start)
1795                 return -EINVAL;
1796         /*
1797          * You *really* shouldn't map things that aren't page-aligned,
1798          * but we've historically allowed it because IO memory might
1799          * just have smaller alignment.
1800          */
1801         len += start & ~PAGE_MASK;
1802         pfn = start >> PAGE_SHIFT;
1803         pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
1804         if (pfn + pages < pfn)
1805                 return -EINVAL;
1806 
1807         /* We start the mapping 'vm_pgoff' pages into the area */
1808         if (vma->vm_pgoff > pages)
1809                 return -EINVAL;
1810         pfn += vma->vm_pgoff;
1811         pages -= vma->vm_pgoff;
1812 
1813         /* Can we fit all of the mapping? */
1814         vm_len = vma->vm_end - vma->vm_start;
1815         if (vm_len >> PAGE_SHIFT > pages)
1816                 return -EINVAL;
1817 
1818         /* Ok, let it rip */
1819         return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1820 }
1821 EXPORT_SYMBOL(vm_iomap_memory);
1822 
1823 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
1824                                      unsigned long addr, unsigned long end,
1825                                      pte_fn_t fn, void *data)
1826 {
1827         pte_t *pte;
1828         int err;
1829         pgtable_t token;
1830         spinlock_t *uninitialized_var(ptl);
1831 
1832         pte = (mm == &init_mm) ?
1833                 pte_alloc_kernel(pmd, addr) :
1834                 pte_alloc_map_lock(mm, pmd, addr, &ptl);
1835         if (!pte)
1836                 return -ENOMEM;
1837 
1838         BUG_ON(pmd_huge(*pmd));
1839 
1840         arch_enter_lazy_mmu_mode();
1841 
1842         token = pmd_pgtable(*pmd);
1843 
1844         do {
1845                 err = fn(pte++, token, addr, data);
1846                 if (err)
1847                         break;
1848         } while (addr += PAGE_SIZE, addr != end);
1849 
1850         arch_leave_lazy_mmu_mode();
1851 
1852         if (mm != &init_mm)
1853                 pte_unmap_unlock(pte-1, ptl);
1854         return err;
1855 }
1856 
1857 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
1858                                      unsigned long addr, unsigned long end,
1859                                      pte_fn_t fn, void *data)
1860 {
1861         pmd_t *pmd;
1862         unsigned long next;
1863         int err;
1864 
1865         BUG_ON(pud_huge(*pud));
1866 
1867         pmd = pmd_alloc(mm, pud, addr);
1868         if (!pmd)
1869                 return -ENOMEM;
1870         do {
1871                 next = pmd_addr_end(addr, end);
1872                 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
1873                 if (err)
1874                         break;
1875         } while (pmd++, addr = next, addr != end);
1876         return err;
1877 }
1878 
1879 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
1880                                      unsigned long addr, unsigned long end,
1881                                      pte_fn_t fn, void *data)
1882 {
1883         pud_t *pud;
1884         unsigned long next;
1885         int err;
1886 
1887         pud = pud_alloc(mm, pgd, addr);
1888         if (!pud)
1889                 return -ENOMEM;
1890         do {
1891                 next = pud_addr_end(addr, end);
1892                 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
1893                 if (err)
1894                         break;
1895         } while (pud++, addr = next, addr != end);
1896         return err;
1897 }
1898 
1899 /*
1900  * Scan a region of virtual memory, filling in page tables as necessary
1901  * and calling a provided function on each leaf page table.
1902  */
1903 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
1904                         unsigned long size, pte_fn_t fn, void *data)
1905 {
1906         pgd_t *pgd;
1907         unsigned long next;
1908         unsigned long end = addr + size;
1909         int err;
1910 
1911         BUG_ON(addr >= end);
1912         pgd = pgd_offset(mm, addr);
1913         do {
1914                 next = pgd_addr_end(addr, end);
1915                 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
1916                 if (err)
1917                         break;
1918         } while (pgd++, addr = next, addr != end);
1919 
1920         return err;
1921 }
1922 EXPORT_SYMBOL_GPL(apply_to_page_range);
1923 
1924 /*
1925  * handle_pte_fault chooses page fault handler according to an entry
1926  * which was read non-atomically.  Before making any commitment, on
1927  * those architectures or configurations (e.g. i386 with PAE) which
1928  * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
1929  * must check under lock before unmapping the pte and proceeding
1930  * (but do_wp_page is only called after already making such a check;
1931  * and do_anonymous_page can safely check later on).
1932  */
1933 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1934                                 pte_t *page_table, pte_t orig_pte)
1935 {
1936         int same = 1;
1937 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1938         if (sizeof(pte_t) > sizeof(unsigned long)) {
1939                 spinlock_t *ptl = pte_lockptr(mm, pmd);
1940                 spin_lock(ptl);
1941                 same = pte_same(*page_table, orig_pte);
1942                 spin_unlock(ptl);
1943         }
1944 #endif
1945         pte_unmap(page_table);
1946         return same;
1947 }
1948 
1949 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1950 {
1951         debug_dma_assert_idle(src);
1952 
1953         /*
1954          * If the source page was a PFN mapping, we don't have
1955          * a "struct page" for it. We do a best-effort copy by
1956          * just copying from the original user address. If that
1957          * fails, we just zero-fill it. Live with it.
1958          */
1959         if (unlikely(!src)) {
1960                 void *kaddr = kmap_atomic(dst);
1961                 void __user *uaddr = (void __user *)(va & PAGE_MASK);
1962 
1963                 /*
1964                  * This really shouldn't fail, because the page is there
1965                  * in the page tables. But it might just be unreadable,
1966                  * in which case we just give up and fill the result with
1967                  * zeroes.
1968                  */
1969                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1970                         clear_page(kaddr);
1971                 kunmap_atomic(kaddr);
1972                 flush_dcache_page(dst);
1973         } else
1974                 copy_user_highpage(dst, src, va, vma);
1975 }
1976 
1977 /*
1978  * Notify the address space that the page is about to become writable so that
1979  * it can prohibit this or wait for the page to get into an appropriate state.
1980  *
1981  * We do this without the lock held, so that it can sleep if it needs to.
1982  */
1983 static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page,
1984                unsigned long address)
1985 {
1986         struct vm_fault vmf;
1987         int ret;
1988 
1989         vmf.virtual_address = (void __user *)(address & PAGE_MASK);
1990         vmf.pgoff = page->index;
1991         vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
1992         vmf.page = page;
1993 
1994         ret = vma->vm_ops->page_mkwrite(vma, &vmf);
1995         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
1996                 return ret;
1997         if (unlikely(!(ret & VM_FAULT_LOCKED))) {
1998                 lock_page(page);
1999                 if (!page->mapping) {
2000                         unlock_page(page);
2001                         return 0; /* retry */
2002                 }
2003                 ret |= VM_FAULT_LOCKED;
2004         } else
2005                 VM_BUG_ON_PAGE(!PageLocked(page), page);
2006         return ret;
2007 }
2008 
2009 /*
2010  * This routine handles present pages, when users try to write
2011  * to a shared page. It is done by copying the page to a new address
2012  * and decrementing the shared-page counter for the old page.
2013  *
2014  * Note that this routine assumes that the protection checks have been
2015  * done by the caller (the low-level page fault routine in most cases).
2016  * Thus we can safely just mark it writable once we've done any necessary
2017  * COW.
2018  *
2019  * We also mark the page dirty at this point even though the page will
2020  * change only once the write actually happens. This avoids a few races,
2021  * and potentially makes it more efficient.
2022  *
2023  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2024  * but allow concurrent faults), with pte both mapped and locked.
2025  * We return with mmap_sem still held, but pte unmapped and unlocked.
2026  */
2027 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2028                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2029                 spinlock_t *ptl, pte_t orig_pte)
2030         __releases(ptl)
2031 {
2032         struct page *old_page, *new_page = NULL;
2033         pte_t entry;
2034         int ret = 0;
2035         int page_mkwrite = 0;
2036         struct page *dirty_page = NULL;
2037         unsigned long mmun_start = 0;   /* For mmu_notifiers */
2038         unsigned long mmun_end = 0;     /* For mmu_notifiers */
2039         struct mem_cgroup *memcg;
2040 
2041         old_page = vm_normal_page(vma, address, orig_pte);
2042         if (!old_page) {
2043                 /*
2044                  * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
2045                  * VM_PFNMAP VMA.
2046                  *
2047                  * We should not cow pages in a shared writeable mapping.
2048                  * Just mark the pages writable as we can't do any dirty
2049                  * accounting on raw pfn maps.
2050                  */
2051                 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2052                                      (VM_WRITE|VM_SHARED))
2053                         goto reuse;
2054                 goto gotten;
2055         }
2056 
2057         /*
2058          * Take out anonymous pages first, anonymous shared vmas are
2059          * not dirty accountable.
2060          */
2061         if (PageAnon(old_page) && !PageKsm(old_page)) {
2062                 if (!trylock_page(old_page)) {
2063                         page_cache_get(old_page);
2064                         pte_unmap_unlock(page_table, ptl);
2065                         lock_page(old_page);
2066                         page_table = pte_offset_map_lock(mm, pmd, address,
2067                                                          &ptl);
2068                         if (!pte_same(*page_table, orig_pte)) {
2069                                 unlock_page(old_page);
2070                                 goto unlock;
2071                         }
2072                         page_cache_release(old_page);
2073                 }
2074                 if (reuse_swap_page(old_page)) {
2075                         /*
2076                          * The page is all ours.  Move it to our anon_vma so
2077                          * the rmap code will not search our parent or siblings.
2078                          * Protected against the rmap code by the page lock.
2079                          */
2080                         page_move_anon_rmap(old_page, vma, address);
2081                         unlock_page(old_page);
2082                         goto reuse;
2083                 }
2084                 unlock_page(old_page);
2085         } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2086                                         (VM_WRITE|VM_SHARED))) {
2087                 /*
2088                  * Only catch write-faults on shared writable pages,
2089                  * read-only shared pages can get COWed by
2090                  * get_user_pages(.write=1, .force=1).
2091                  */
2092                 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2093                         int tmp;
2094                         page_cache_get(old_page);
2095                         pte_unmap_unlock(page_table, ptl);
2096                         tmp = do_page_mkwrite(vma, old_page, address);
2097                         if (unlikely(!tmp || (tmp &
2098                                         (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2099                                 page_cache_release(old_page);
2100                                 return tmp;
2101                         }
2102                         /*
2103                          * Since we dropped the lock we need to revalidate
2104                          * the PTE as someone else may have changed it.  If
2105                          * they did, we just return, as we can count on the
2106                          * MMU to tell us if they didn't also make it writable.
2107                          */
2108                         page_table = pte_offset_map_lock(mm, pmd, address,
2109                                                          &ptl);
2110                         if (!pte_same(*page_table, orig_pte)) {
2111                                 unlock_page(old_page);
2112                                 goto unlock;
2113                         }
2114 
2115                         page_mkwrite = 1;
2116                 }
2117                 dirty_page = old_page;
2118                 get_page(dirty_page);
2119 
2120 reuse:
2121                 /*
2122                  * Clear the pages cpupid information as the existing
2123                  * information potentially belongs to a now completely
2124                  * unrelated process.
2125                  */
2126                 if (old_page)
2127                         page_cpupid_xchg_last(old_page, (1 << LAST_CPUPID_SHIFT) - 1);
2128 
2129                 flush_cache_page(vma, address, pte_pfn(orig_pte));
2130                 entry = pte_mkyoung(orig_pte);
2131                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2132                 if (ptep_set_access_flags(vma, address, page_table, entry,1))
2133                         update_mmu_cache(vma, address, page_table);
2134                 pte_unmap_unlock(page_table, ptl);
2135                 ret |= VM_FAULT_WRITE;
2136 
2137                 if (!dirty_page)
2138                         return ret;
2139 
2140                 if (!page_mkwrite) {
2141                         struct address_space *mapping;
2142                         int dirtied;
2143 
2144                         lock_page(dirty_page);
2145                         dirtied = set_page_dirty(dirty_page);
2146                         VM_BUG_ON_PAGE(PageAnon(dirty_page), dirty_page);
2147                         mapping = dirty_page->mapping;
2148                         unlock_page(dirty_page);
2149 
2150                         if (dirtied && mapping) {
2151                                 /*
2152                                  * Some device drivers do not set page.mapping
2153                                  * but still dirty their pages
2154                                  */
2155                                 balance_dirty_pages_ratelimited(mapping);
2156                         }
2157 
2158                         /* file_update_time outside page_lock */
2159                         if (vma->vm_file)
2160                                 file_update_time(vma->vm_file);
2161                 }
2162                 put_page(dirty_page);
2163                 if (page_mkwrite) {
2164                         struct address_space *mapping = dirty_page->mapping;
2165 
2166                         set_page_dirty(dirty_page);
2167                         unlock_page(dirty_page);
2168                         page_cache_release(dirty_page);
2169                         if (mapping)    {
2170                                 /*
2171                                  * Some device drivers do not set page.mapping
2172                                  * but still dirty their pages
2173                                  */
2174                                 balance_dirty_pages_ratelimited(mapping);
2175                         }
2176                 }
2177 
2178                 return ret;
2179         }
2180 
2181         /*
2182          * Ok, we need to copy. Oh, well..
2183          */
2184         page_cache_get(old_page);
2185 gotten:
2186         pte_unmap_unlock(page_table, ptl);
2187 
2188         if (unlikely(anon_vma_prepare(vma)))
2189                 goto oom;
2190 
2191         if (is_zero_pfn(pte_pfn(orig_pte))) {
2192                 new_page = alloc_zeroed_user_highpage_movable(vma, address);
2193                 if (!new_page)
2194                         goto oom;
2195         } else {
2196                 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2197                 if (!new_page)
2198                         goto oom;
2199                 cow_user_page(new_page, old_page, address, vma);
2200         }
2201         __SetPageUptodate(new_page);
2202 
2203         if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg))
2204                 goto oom_free_new;
2205 
2206         mmun_start  = address & PAGE_MASK;
2207         mmun_end    = mmun_start + PAGE_SIZE;
2208         mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2209 
2210         /*
2211          * Re-check the pte - we dropped the lock
2212          */
2213         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2214         if (likely(pte_same(*page_table, orig_pte))) {
2215                 if (old_page) {
2216                         if (!PageAnon(old_page)) {
2217                                 dec_mm_counter_fast(mm, MM_FILEPAGES);
2218                                 inc_mm_counter_fast(mm, MM_ANONPAGES);
2219                         }
2220                 } else
2221                         inc_mm_counter_fast(mm, MM_ANONPAGES);
2222                 flush_cache_page(vma, address, pte_pfn(orig_pte));
2223                 entry = mk_pte(new_page, vma->vm_page_prot);
2224                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2225                 /*
2226                  * Clear the pte entry and flush it first, before updating the
2227                  * pte with the new entry. This will avoid a race condition
2228                  * seen in the presence of one thread doing SMC and another
2229                  * thread doing COW.
2230                  */
2231                 ptep_clear_flush_notify(vma, address, page_table);
2232                 page_add_new_anon_rmap(new_page, vma, address);
2233                 mem_cgroup_commit_charge(new_page, memcg, false);
2234                 lru_cache_add_active_or_unevictable(new_page, vma);
2235                 /*
2236                  * We call the notify macro here because, when using secondary
2237                  * mmu page tables (such as kvm shadow page tables), we want the
2238                  * new page to be mapped directly into the secondary page table.
2239                  */
2240                 set_pte_at_notify(mm, address, page_table, entry);
2241                 update_mmu_cache(vma, address, page_table);
2242                 if (old_page) {
2243                         /*
2244                          * Only after switching the pte to the new page may
2245                          * we remove the mapcount here. Otherwise another
2246                          * process may come and find the rmap count decremented
2247                          * before the pte is switched to the new page, and
2248                          * "reuse" the old page writing into it while our pte
2249                          * here still points into it and can be read by other
2250                          * threads.
2251                          *
2252                          * The critical issue is to order this
2253                          * page_remove_rmap with the ptp_clear_flush above.
2254                          * Those stores are ordered by (if nothing else,)
2255                          * the barrier present in the atomic_add_negative
2256                          * in page_remove_rmap.
2257                          *
2258                          * Then the TLB flush in ptep_clear_flush ensures that
2259                          * no process can access the old page before the
2260                          * decremented mapcount is visible. And the old page
2261                          * cannot be reused until after the decremented
2262                          * mapcount is visible. So transitively, TLBs to
2263                          * old page will be flushed before it can be reused.
2264                          */
2265                         page_remove_rmap(old_page);
2266                 }
2267 
2268                 /* Free the old page.. */
2269                 new_page = old_page;
2270                 ret |= VM_FAULT_WRITE;
2271         } else
2272                 mem_cgroup_cancel_charge(new_page, memcg);
2273 
2274         if (new_page)
2275                 page_cache_release(new_page);
2276 unlock:
2277         pte_unmap_unlock(page_table, ptl);
2278         if (mmun_end > mmun_start)
2279                 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2280         if (old_page) {
2281                 /*
2282                  * Don't let another task, with possibly unlocked vma,
2283                  * keep the mlocked page.
2284                  */
2285                 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
2286                         lock_page(old_page);    /* LRU manipulation */
2287                         munlock_vma_page(old_page);
2288                         unlock_page(old_page);
2289                 }
2290                 page_cache_release(old_page);
2291         }
2292         return ret;
2293 oom_free_new:
2294         page_cache_release(new_page);
2295 oom:
2296         if (old_page)
2297                 page_cache_release(old_page);
2298         return VM_FAULT_OOM;
2299 }
2300 
2301 static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2302                 unsigned long start_addr, unsigned long end_addr,
2303                 struct zap_details *details)
2304 {
2305         zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2306 }
2307 
2308 static inline void unmap_mapping_range_tree(struct rb_root *root,
2309                                             struct zap_details *details)
2310 {
2311         struct vm_area_struct *vma;
2312         pgoff_t vba, vea, zba, zea;
2313 
2314         vma_interval_tree_foreach(vma, root,
2315                         details->first_index, details->last_index) {
2316 
2317                 vba = vma->vm_pgoff;
2318                 vea = vba + vma_pages(vma) - 1;
2319                 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2320                 zba = details->first_index;
2321                 if (zba < vba)
2322                         zba = vba;
2323                 zea = details->last_index;
2324                 if (zea > vea)
2325                         zea = vea;
2326 
2327                 unmap_mapping_range_vma(vma,
2328                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2329                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2330                                 details);
2331         }
2332 }
2333 
2334 static inline void unmap_mapping_range_list(struct list_head *head,
2335                                             struct zap_details *details)
2336 {
2337         struct vm_area_struct *vma;
2338 
2339         /*
2340          * In nonlinear VMAs there is no correspondence between virtual address
2341          * offset and file offset.  So we must perform an exhaustive search
2342          * across *all* the pages in each nonlinear VMA, not just the pages
2343          * whose virtual address lies outside the file truncation point.
2344          */
2345         list_for_each_entry(vma, head, shared.nonlinear) {
2346                 details->nonlinear_vma = vma;
2347                 unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
2348         }
2349 }
2350 
2351 /**
2352  * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2353  * @mapping: the address space containing mmaps to be unmapped.
2354  * @holebegin: byte in first page to unmap, relative to the start of
2355  * the underlying file.  This will be rounded down to a PAGE_SIZE
2356  * boundary.  Note that this is different from truncate_pagecache(), which
2357  * must keep the partial page.  In contrast, we must get rid of
2358  * partial pages.
2359  * @holelen: size of prospective hole in bytes.  This will be rounded
2360  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
2361  * end of the file.
2362  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2363  * but 0 when invalidating pagecache, don't throw away private data.
2364  */
2365 void unmap_mapping_range(struct address_space *mapping,
2366                 loff_t const holebegin, loff_t const holelen, int even_cows)
2367 {
2368         struct zap_details details;
2369         pgoff_t hba = holebegin >> PAGE_SHIFT;
2370         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2371 
2372         /* Check for overflow. */
2373         if (sizeof(holelen) > sizeof(hlen)) {
2374                 long long holeend =
2375                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2376                 if (holeend & ~(long long)ULONG_MAX)
2377                         hlen = ULONG_MAX - hba + 1;
2378         }
2379 
2380         details.check_mapping = even_cows? NULL: mapping;
2381         details.nonlinear_vma = NULL;
2382         details.first_index = hba;
2383         details.last_index = hba + hlen - 1;
2384         if (details.last_index < details.first_index)
2385                 details.last_index = ULONG_MAX;
2386 
2387 
2388         i_mmap_lock_write(mapping);
2389         if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
2390                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2391         if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2392                 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2393         i_mmap_unlock_write(mapping);
2394 }
2395 EXPORT_SYMBOL(unmap_mapping_range);
2396 
2397 /*
2398  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2399  * but allow concurrent faults), and pte mapped but not yet locked.
2400  * We return with pte unmapped and unlocked.
2401  *
2402  * We return with the mmap_sem locked or unlocked in the same cases
2403  * as does filemap_fault().
2404  */
2405 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2406                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2407                 unsigned int flags, pte_t orig_pte)
2408 {
2409         spinlock_t *ptl;
2410         struct page *page, *swapcache;
2411         struct mem_cgroup *memcg;
2412         swp_entry_t entry;
2413         pte_t pte;
2414         int locked;
2415         int exclusive = 0;
2416         int ret = 0;
2417 
2418         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2419                 goto out;
2420 
2421         entry = pte_to_swp_entry(orig_pte);
2422         if (unlikely(non_swap_entry(entry))) {
2423                 if (is_migration_entry(entry)) {
2424                         migration_entry_wait(mm, pmd, address);
2425                 } else if (is_hwpoison_entry(entry)) {
2426                         ret = VM_FAULT_HWPOISON;
2427                 } else {
2428                         print_bad_pte(vma, address, orig_pte, NULL);
2429                         ret = VM_FAULT_SIGBUS;
2430                 }
2431                 goto out;
2432         }
2433         delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2434         page = lookup_swap_cache(entry);
2435         if (!page) {
2436                 page = swapin_readahead(entry,
2437                                         GFP_HIGHUSER_MOVABLE, vma, address);
2438                 if (!page) {
2439                         /*
2440                          * Back out if somebody else faulted in this pte
2441                          * while we released the pte lock.
2442                          */
2443                         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2444                         if (likely(pte_same(*page_table, orig_pte)))
2445                                 ret = VM_FAULT_OOM;
2446                         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2447                         goto unlock;
2448                 }
2449 
2450                 /* Had to read the page from swap area: Major fault */
2451                 ret = VM_FAULT_MAJOR;
2452                 count_vm_event(PGMAJFAULT);
2453                 mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2454         } else if (PageHWPoison(page)) {
2455                 /*
2456                  * hwpoisoned dirty swapcache pages are kept for killing
2457                  * owner processes (which may be unknown at hwpoison time)
2458                  */
2459                 ret = VM_FAULT_HWPOISON;
2460                 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2461                 swapcache = page;
2462                 goto out_release;
2463         }
2464 
2465         swapcache = page;
2466         locked = lock_page_or_retry(page, mm, flags);
2467 
2468         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2469         if (!locked) {
2470                 ret |= VM_FAULT_RETRY;
2471                 goto out_release;
2472         }
2473 
2474         /*
2475          * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2476          * release the swapcache from under us.  The page pin, and pte_same
2477          * test below, are not enough to exclude that.  Even if it is still
2478          * swapcache, we need to check that the page's swap has not changed.
2479          */
2480         if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
2481                 goto out_page;
2482 
2483         page = ksm_might_need_to_copy(page, vma, address);
2484         if (unlikely(!page)) {
2485                 ret = VM_FAULT_OOM;
2486                 page = swapcache;
2487                 goto out_page;
2488         }
2489 
2490         if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg)) {
2491                 ret = VM_FAULT_OOM;
2492                 goto out_page;
2493         }
2494 
2495         /*
2496          * Back out if somebody else already faulted in this pte.
2497          */
2498         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2499         if (unlikely(!pte_same(*page_table, orig_pte)))
2500                 goto out_nomap;
2501 
2502         if (unlikely(!PageUptodate(page))) {
2503                 ret = VM_FAULT_SIGBUS;
2504                 goto out_nomap;
2505         }
2506 
2507         /*
2508          * The page isn't present yet, go ahead with the fault.
2509          *
2510          * Be careful about the sequence of operations here.
2511          * To get its accounting right, reuse_swap_page() must be called
2512          * while the page is counted on swap but not yet in mapcount i.e.
2513          * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2514          * must be called after the swap_free(), or it will never succeed.
2515          */
2516 
2517         inc_mm_counter_fast(mm, MM_ANONPAGES);
2518         dec_mm_counter_fast(mm, MM_SWAPENTS);
2519         pte = mk_pte(page, vma->vm_page_prot);
2520         if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
2521                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2522                 flags &= ~FAULT_FLAG_WRITE;
2523                 ret |= VM_FAULT_WRITE;
2524                 exclusive = 1;
2525         }
2526         flush_icache_page(vma, page);
2527         if (pte_swp_soft_dirty(orig_pte))
2528                 pte = pte_mksoft_dirty(pte);
2529         set_pte_at(mm, address, page_table, pte);
2530         if (page == swapcache) {
2531                 do_page_add_anon_rmap(page, vma, address, exclusive);
2532                 mem_cgroup_commit_charge(page, memcg, true);
2533         } else { /* ksm created a completely new copy */
2534                 page_add_new_anon_rmap(page, vma, address);
2535                 mem_cgroup_commit_charge(page, memcg, false);
2536                 lru_cache_add_active_or_unevictable(page, vma);
2537         }
2538 
2539         swap_free(entry);
2540         if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2541                 try_to_free_swap(page);
2542         unlock_page(page);
2543         if (page != swapcache) {
2544                 /*
2545                  * Hold the lock to avoid the swap entry to be reused
2546                  * until we take the PT lock for the pte_same() check
2547                  * (to avoid false positives from pte_same). For
2548                  * further safety release the lock after the swap_free
2549                  * so that the swap count won't change under a
2550                  * parallel locked swapcache.
2551                  */
2552                 unlock_page(swapcache);
2553                 page_cache_release(swapcache);
2554         }
2555 
2556         if (flags & FAULT_FLAG_WRITE) {
2557                 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
2558                 if (ret & VM_FAULT_ERROR)
2559                         ret &= VM_FAULT_ERROR;
2560                 goto out;
2561         }
2562 
2563         /* No need to invalidate - it was non-present before */
2564         update_mmu_cache(vma, address, page_table);
2565 unlock:
2566         pte_unmap_unlock(page_table, ptl);
2567 out:
2568         return ret;
2569 out_nomap:
2570         mem_cgroup_cancel_charge(page, memcg);
2571         pte_unmap_unlock(page_table, ptl);
2572 out_page:
2573         unlock_page(page);
2574 out_release:
2575         page_cache_release(page);
2576         if (page != swapcache) {
2577                 unlock_page(swapcache);
2578                 page_cache_release(swapcache);
2579         }
2580         return ret;
2581 }
2582 
2583 /*
2584  * This is like a special single-page "expand_{down|up}wards()",
2585  * except we must first make sure that 'address{-|+}PAGE_SIZE'
2586  * doesn't hit another vma.
2587  */
2588 static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
2589 {
2590         address &= PAGE_MASK;
2591         if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
2592                 struct vm_area_struct *prev = vma->vm_prev;
2593 
2594                 /*
2595                  * Is there a mapping abutting this one below?
2596                  *
2597                  * That's only ok if it's the same stack mapping
2598                  * that has gotten split..
2599                  */
2600                 if (prev && prev->vm_end == address)
2601                         return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
2602 
2603                 return expand_downwards(vma, address - PAGE_SIZE);
2604         }
2605         if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
2606                 struct vm_area_struct *next = vma->vm_next;
2607 
2608                 /* As VM_GROWSDOWN but s/below/above/ */
2609                 if (next && next->vm_start == address + PAGE_SIZE)
2610                         return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
2611 
2612                 return expand_upwards(vma, address + PAGE_SIZE);
2613         }
2614         return 0;
2615 }
2616 
2617 /*
2618  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2619  * but allow concurrent faults), and pte mapped but not yet locked.
2620  * We return with mmap_sem still held, but pte unmapped and unlocked.
2621  */
2622 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
2623                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2624                 unsigned int flags)
2625 {
2626         struct mem_cgroup *memcg;
2627         struct page *page;
2628         spinlock_t *ptl;
2629         pte_t entry;
2630 
2631         pte_unmap(page_table);
2632 
2633         /* Check if we need to add a guard page to the stack */
2634         if (check_stack_guard_page(vma, address) < 0)
2635                 return VM_FAULT_SIGSEGV;
2636 
2637         /* Use the zero-page for reads */
2638         if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm)) {
2639                 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
2640                                                 vma->vm_page_prot));
2641                 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2642                 if (!pte_none(*page_table))
2643                         goto unlock;
2644                 goto setpte;
2645         }
2646 
2647         /* Allocate our own private page. */
2648         if (unlikely(anon_vma_prepare(vma)))
2649                 goto oom;
2650         page = alloc_zeroed_user_highpage_movable(vma, address);
2651         if (!page)
2652                 goto oom;
2653         /*
2654          * The memory barrier inside __SetPageUptodate makes sure that
2655          * preceeding stores to the page contents become visible before
2656          * the set_pte_at() write.
2657          */
2658         __SetPageUptodate(page);
2659 
2660         if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg))
2661                 goto oom_free_page;
2662 
2663         entry = mk_pte(page, vma->vm_page_prot);
2664         if (vma->vm_flags & VM_WRITE)
2665                 entry = pte_mkwrite(pte_mkdirty(entry));
2666 
2667         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2668         if (!pte_none(*page_table))
2669                 goto release;
2670 
2671         inc_mm_counter_fast(mm, MM_ANONPAGES);
2672         page_add_new_anon_rmap(page, vma, address);
2673         mem_cgroup_commit_charge(page, memcg, false);
2674         lru_cache_add_active_or_unevictable(page, vma);
2675 setpte:
2676         set_pte_at(mm, address, page_table, entry);
2677 
2678         /* No need to invalidate - it was non-present before */
2679         update_mmu_cache(vma, address, page_table);
2680 unlock:
2681         pte_unmap_unlock(page_table, ptl);
2682         return 0;
2683 release:
2684         mem_cgroup_cancel_charge(page, memcg);
2685         page_cache_release(page);
2686         goto unlock;
2687 oom_free_page:
2688         page_cache_release(page);
2689 oom:
2690         return VM_FAULT_OOM;
2691 }
2692 
2693 /*
2694  * The mmap_sem must have been held on entry, and may have been
2695  * released depending on flags and vma->vm_ops->fault() return value.
2696  * See filemap_fault() and __lock_page_retry().
2697  */
2698 static int __do_fault(struct vm_area_struct *vma, unsigned long address,
2699                 pgoff_t pgoff, unsigned int flags, struct page **page)
2700 {
2701         struct vm_fault vmf;
2702         int ret;
2703 
2704         vmf.virtual_address = (void __user *)(address & PAGE_MASK);
2705         vmf.pgoff = pgoff;
2706         vmf.flags = flags;
2707         vmf.page = NULL;
2708 
2709         ret = vma->vm_ops->fault(vma, &vmf);
2710         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
2711                 return ret;
2712 
2713         if (unlikely(PageHWPoison(vmf.page))) {
2714                 if (ret & VM_FAULT_LOCKED)
2715                         unlock_page(vmf.page);
2716                 page_cache_release(vmf.page);
2717                 return VM_FAULT_HWPOISON;
2718         }
2719 
2720         if (unlikely(!(ret & VM_FAULT_LOCKED)))
2721                 lock_page(vmf.page);
2722         else
2723                 VM_BUG_ON_PAGE(!PageLocked(vmf.page), vmf.page);
2724 
2725         *page = vmf.page;
2726         return ret;
2727 }
2728 
2729 /**
2730  * do_set_pte - setup new PTE entry for given page and add reverse page mapping.
2731  *
2732  * @vma: virtual memory area
2733  * @address: user virtual address
2734  * @page: page to map
2735  * @pte: pointer to target page table entry
2736  * @write: true, if new entry is writable
2737  * @anon: true, if it's anonymous page
2738  *
2739  * Caller must hold page table lock relevant for @pte.
2740  *
2741  * Target users are page handler itself and implementations of
2742  * vm_ops->map_pages.
2743  */
2744 void do_set_pte(struct vm_area_struct *vma, unsigned long address,
2745                 struct page *page, pte_t *pte, bool write, bool anon)
2746 {
2747         pte_t entry;
2748 
2749         flush_icache_page(vma, page);
2750         entry = mk_pte(page, vma->vm_page_prot);
2751         if (write)
2752                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2753         else if (pte_file(*pte) && pte_file_soft_dirty(*pte))
2754                 entry = pte_mksoft_dirty(entry);
2755         if (anon) {
2756                 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
2757                 page_add_new_anon_rmap(page, vma, address);
2758         } else {
2759                 inc_mm_counter_fast(vma->vm_mm, MM_FILEPAGES);
2760                 page_add_file_rmap(page);
2761         }
2762         set_pte_at(vma->vm_mm, address, pte, entry);
2763 
2764         /* no need to invalidate: a not-present page won't be cached */
2765         update_mmu_cache(vma, address, pte);
2766 }
2767 
2768 static unsigned long fault_around_bytes __read_mostly =
2769         rounddown_pow_of_two(65536);
2770 
2771 #ifdef CONFIG_DEBUG_FS
2772 static int fault_around_bytes_get(void *data, u64 *val)
2773 {
2774         *val = fault_around_bytes;
2775         return 0;
2776 }
2777 
2778 /*
2779  * fault_around_pages() and fault_around_mask() expects fault_around_bytes
2780  * rounded down to nearest page order. It's what do_fault_around() expects to
2781  * see.
2782  */
2783 static int fault_around_bytes_set(void *data, u64 val)
2784 {
2785         if (val / PAGE_SIZE > PTRS_PER_PTE)
2786                 return -EINVAL;
2787         if (val > PAGE_SIZE)
2788                 fault_around_bytes = rounddown_pow_of_two(val);
2789         else
2790                 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
2791         return 0;
2792 }
2793 DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops,
2794                 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
2795 
2796 static int __init fault_around_debugfs(void)
2797 {
2798         void *ret;
2799 
2800         ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL,
2801                         &fault_around_bytes_fops);
2802         if (!ret)
2803                 pr_warn("Failed to create fault_around_bytes in debugfs");
2804         return 0;
2805 }
2806 late_initcall(fault_around_debugfs);
2807 #endif
2808 
2809 /*
2810  * do_fault_around() tries to map few pages around the fault address. The hope
2811  * is that the pages will be needed soon and this will lower the number of
2812  * faults to handle.
2813  *
2814  * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
2815  * not ready to be mapped: not up-to-date, locked, etc.
2816  *
2817  * This function is called with the page table lock taken. In the split ptlock
2818  * case the page table lock only protects only those entries which belong to
2819  * the page table corresponding to the fault address.
2820  *
2821  * This function doesn't cross the VMA boundaries, in order to call map_pages()
2822  * only once.
2823  *
2824  * fault_around_pages() defines how many pages we'll try to map.
2825  * do_fault_around() expects it to return a power of two less than or equal to
2826  * PTRS_PER_PTE.
2827  *
2828  * The virtual address of the area that we map is naturally aligned to the
2829  * fault_around_pages() value (and therefore to page order).  This way it's
2830  * easier to guarantee that we don't cross page table boundaries.
2831  */
2832 static void do_fault_around(struct vm_area_struct *vma, unsigned long address,
2833                 pte_t *pte, pgoff_t pgoff, unsigned int flags)
2834 {
2835         unsigned long start_addr, nr_pages, mask;
2836         pgoff_t max_pgoff;
2837         struct vm_fault vmf;
2838         int off;
2839 
2840         nr_pages = ACCESS_ONCE(fault_around_bytes) >> PAGE_SHIFT;
2841         mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
2842 
2843         start_addr = max(address & mask, vma->vm_start);
2844         off = ((address - start_addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
2845         pte -= off;
2846         pgoff -= off;
2847 
2848         /*
2849          *  max_pgoff is either end of page table or end of vma
2850          *  or fault_around_pages() from pgoff, depending what is nearest.
2851          */
2852         max_pgoff = pgoff - ((start_addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
2853                 PTRS_PER_PTE - 1;
2854         max_pgoff = min3(max_pgoff, vma_pages(vma) + vma->vm_pgoff - 1,
2855                         pgoff + nr_pages - 1);
2856 
2857         /* Check if it makes any sense to call ->map_pages */
2858         while (!pte_none(*pte)) {
2859                 if (++pgoff > max_pgoff)
2860                         return;
2861                 start_addr += PAGE_SIZE;
2862                 if (start_addr >= vma->vm_end)
2863                         return;
2864                 pte++;
2865         }
2866 
2867         vmf.virtual_address = (void __user *) start_addr;
2868         vmf.pte = pte;
2869         vmf.pgoff = pgoff;
2870         vmf.max_pgoff = max_pgoff;
2871         vmf.flags = flags;
2872         vma->vm_ops->map_pages(vma, &vmf);
2873 }
2874 
2875 static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2876                 unsigned long address, pmd_t *pmd,
2877                 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
2878 {
2879         struct page *fault_page;
2880         spinlock_t *ptl;
2881         pte_t *pte;
2882         int ret = 0;
2883 
2884         /*
2885          * Let's call ->map_pages() first and use ->fault() as fallback
2886          * if page by the offset is not ready to be mapped (cold cache or
2887          * something).
2888          */
2889         if (vma->vm_ops->map_pages && !(flags & FAULT_FLAG_NONLINEAR) &&
2890             fault_around_bytes >> PAGE_SHIFT > 1) {
2891                 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2892                 do_fault_around(vma, address, pte, pgoff, flags);
2893                 if (!pte_same(*pte, orig_pte))
2894                         goto unlock_out;
2895                 pte_unmap_unlock(pte, ptl);
2896         }
2897 
2898         ret = __do_fault(vma, address, pgoff, flags, &fault_page);
2899         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
2900                 return ret;
2901 
2902         pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2903         if (unlikely(!pte_same(*pte, orig_pte))) {
2904                 pte_unmap_unlock(pte, ptl);
2905                 unlock_page(fault_page);
2906                 page_cache_release(fault_page);
2907                 return ret;
2908         }
2909         do_set_pte(vma, address, fault_page, pte, false, false);
2910         unlock_page(fault_page);
2911 unlock_out:
2912         pte_unmap_unlock(pte, ptl);
2913         return ret;
2914 }
2915 
2916 static int do_cow_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2917                 unsigned long address, pmd_t *pmd,
2918                 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
2919 {
2920         struct page *fault_page, *new_page;
2921         struct mem_cgroup *memcg;
2922         spinlock_t *ptl;
2923         pte_t *pte;
2924         int ret;
2925 
2926         if (unlikely(anon_vma_prepare(vma)))
2927                 return VM_FAULT_OOM;
2928 
2929         new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2930         if (!new_page)
2931                 return VM_FAULT_OOM;
2932 
2933         if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg)) {
2934                 page_cache_release(new_page);
2935                 return VM_FAULT_OOM;
2936         }
2937 
2938         ret = __do_fault(vma, address, pgoff, flags, &fault_page);
2939         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
2940                 goto uncharge_out;
2941 
2942         copy_user_highpage(new_page, fault_page, address, vma);
2943         __SetPageUptodate(new_page);
2944 
2945         pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2946         if (unlikely(!pte_same(*pte, orig_pte))) {
2947                 pte_unmap_unlock(pte, ptl);
2948                 unlock_page(fault_page);
2949                 page_cache_release(fault_page);
2950                 goto uncharge_out;
2951         }
2952         do_set_pte(vma, address, new_page, pte, true, true);
2953         mem_cgroup_commit_charge(new_page, memcg, false);
2954         lru_cache_add_active_or_unevictable(new_page, vma);
2955         pte_unmap_unlock(pte, ptl);
2956         unlock_page(fault_page);
2957         page_cache_release(fault_page);
2958         return ret;
2959 uncharge_out:
2960         mem_cgroup_cancel_charge(new_page, memcg);
2961         page_cache_release(new_page);
2962         return ret;
2963 }
2964 
2965 static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2966                 unsigned long address, pmd_t *pmd,
2967                 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
2968 {
2969         struct page *fault_page;
2970         struct address_space *mapping;
2971         spinlock_t *ptl;
2972         pte_t *pte;
2973         int dirtied = 0;
2974         int ret, tmp;
2975 
2976         ret = __do_fault(vma, address, pgoff, flags, &fault_page);
2977         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
2978                 return ret;
2979 
2980         /*
2981          * Check if the backing address space wants to know that the page is
2982          * about to become writable
2983          */
2984         if (vma->vm_ops->page_mkwrite) {
2985                 unlock_page(fault_page);
2986                 tmp = do_page_mkwrite(vma, fault_page, address);
2987                 if (unlikely(!tmp ||
2988                                 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2989                         page_cache_release(fault_page);
2990                         return tmp;
2991                 }
2992         }
2993 
2994         pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2995         if (unlikely(!pte_same(*pte, orig_pte))) {
2996                 pte_unmap_unlock(pte, ptl);
2997                 unlock_page(fault_page);
2998                 page_cache_release(fault_page);
2999                 return ret;
3000         }
3001         do_set_pte(vma, address, fault_page, pte, true, false);
3002         pte_unmap_unlock(pte, ptl);
3003 
3004         if (set_page_dirty(fault_page))
3005                 dirtied = 1;
3006         /*
3007          * Take a local copy of the address_space - page.mapping may be zeroed
3008          * by truncate after unlock_page().   The address_space itself remains
3009          * pinned by vma->vm_file's reference.  We rely on unlock_page()'s
3010          * release semantics to prevent the compiler from undoing this copying.
3011          */
3012         mapping = fault_page->mapping;
3013         unlock_page(fault_page);
3014         if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) {
3015                 /*
3016                  * Some device drivers do not set page.mapping but still
3017                  * dirty their pages
3018                  */
3019                 balance_dirty_pages_ratelimited(mapping);
3020         }
3021 
3022         /* file_update_time outside page_lock */
3023         if (vma->vm_file && !vma->vm_ops->page_mkwrite)
3024                 file_update_time(vma->vm_file);
3025 
3026         return ret;
3027 }
3028 
3029 /*
3030  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3031  * but allow concurrent faults).
3032  * The mmap_sem may have been released depending on flags and our
3033  * return value.  See filemap_fault() and __lock_page_or_retry().
3034  */
3035 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3036                 unsigned long address, pte_t *page_table, pmd_t *pmd,
3037                 unsigned int flags, pte_t orig_pte)
3038 {
3039         pgoff_t pgoff = (((address & PAGE_MASK)
3040                         - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3041 
3042         pte_unmap(page_table);
3043         if (!(flags & FAULT_FLAG_WRITE))
3044                 return do_read_fault(mm, vma, address, pmd, pgoff, flags,
3045                                 orig_pte);
3046         if (!(vma->vm_flags & VM_SHARED))
3047                 return do_cow_fault(mm, vma, address, pmd, pgoff, flags,
3048                                 orig_pte);
3049         return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3050 }
3051 
3052 /*
3053  * Fault of a previously existing named mapping. Repopulate the pte
3054  * from the encoded file_pte if possible. This enables swappable
3055  * nonlinear vmas.
3056  *
3057  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3058  * but allow concurrent faults), and pte mapped but not yet locked.
3059  * We return with pte unmapped and unlocked.
3060  * The mmap_sem may have been released depending on flags and our
3061  * return value.  See filemap_fault() and __lock_page_or_retry().
3062  */
3063 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3064                 unsigned long address, pte_t *page_table, pmd_t *pmd,
3065                 unsigned int flags, pte_t orig_pte)
3066 {
3067         pgoff_t pgoff;
3068 
3069         flags |= FAULT_FLAG_NONLINEAR;
3070 
3071         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3072                 return 0;
3073 
3074         if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3075                 /*
3076                  * Page table corrupted: show pte and kill process.
3077                  */
3078                 print_bad_pte(vma, address, orig_pte, NULL);
3079                 return VM_FAULT_SIGBUS;
3080         }
3081 
3082         pgoff = pte_to_pgoff(orig_pte);
3083         if (!(flags & FAULT_FLAG_WRITE))
3084                 return do_read_fault(mm, vma, address, pmd, pgoff, flags,
3085                                 orig_pte);
3086         if (!(vma->vm_flags & VM_SHARED))
3087                 return do_cow_fault(mm, vma, address, pmd, pgoff, flags,
3088                                 orig_pte);
3089         return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3090 }
3091 
3092 static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3093                                 unsigned long addr, int page_nid,
3094                                 int *flags)
3095 {
3096         get_page(page);
3097 
3098         count_vm_numa_event(NUMA_HINT_FAULTS);
3099         if (page_nid == numa_node_id()) {
3100                 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3101                 *flags |= TNF_FAULT_LOCAL;
3102         }
3103 
3104         return mpol_misplaced(page, vma, addr);
3105 }
3106 
3107 static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
3108                    unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd)
3109 {
3110         struct page *page = NULL;
3111         spinlock_t *ptl;
3112         int page_nid = -1;
3113         int last_cpupid;
3114         int target_nid;
3115         bool migrated = false;
3116         int flags = 0;
3117 
3118         /*
3119         * The "pte" at this point cannot be used safely without
3120         * validation through pte_unmap_same(). It's of NUMA type but
3121         * the pfn may be screwed if the read is non atomic.
3122         *
3123         * ptep_modify_prot_start is not called as this is clearing
3124         * the _PAGE_NUMA bit and it is not really expected that there
3125         * would be concurrent hardware modifications to the PTE.
3126         */
3127         ptl = pte_lockptr(mm, pmd);
3128         spin_lock(ptl);
3129         if (unlikely(!pte_same(*ptep, pte))) {
3130                 pte_unmap_unlock(ptep, ptl);
3131                 goto out;
3132         }
3133 
3134         pte = pte_mknonnuma(pte);
3135         set_pte_at(mm, addr, ptep, pte);
3136         update_mmu_cache(vma, addr, ptep);
3137 
3138         page = vm_normal_page(vma, addr, pte);
3139         if (!page) {
3140                 pte_unmap_unlock(ptep, ptl);
3141                 return 0;
3142         }
3143         BUG_ON(is_zero_pfn(page_to_pfn(page)));
3144 
3145         /*
3146          * Avoid grouping on DSO/COW pages in specific and RO pages
3147          * in general, RO pages shouldn't hurt as much anyway since
3148          * they can be in shared cache state.
3149          */
3150         if (!pte_write(pte))
3151                 flags |= TNF_NO_GROUP;
3152 
3153         /*
3154          * Flag if the page is shared between multiple address spaces. This
3155          * is later used when determining whether to group tasks together
3156          */
3157         if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
3158                 flags |= TNF_SHARED;
3159 
3160         last_cpupid = page_cpupid_last(page);
3161         page_nid = page_to_nid(page);
3162         target_nid = numa_migrate_prep(page, vma, addr, page_nid, &flags);
3163         pte_unmap_unlock(ptep, ptl);
3164         if (target_nid == -1) {
3165                 put_page(page);
3166                 goto out;
3167         }
3168 
3169         /* Migrate to the requested node */
3170         migrated = migrate_misplaced_page(page, vma, target_nid);
3171         if (migrated) {
3172                 page_nid = target_nid;
3173                 flags |= TNF_MIGRATED;
3174         }
3175 
3176 out:
3177         if (page_nid != -1)
3178                 task_numa_fault(last_cpupid, page_nid, 1, flags);
3179         return 0;
3180 }
3181 
3182 /*
3183  * These routines also need to handle stuff like marking pages dirty
3184  * and/or accessed for architectures that don't do it in hardware (most
3185  * RISC architectures).  The early dirtying is also good on the i386.
3186  *
3187  * There is also a hook called "update_mmu_cache()" that architectures
3188  * with external mmu caches can use to update those (ie the Sparc or
3189  * PowerPC hashed page tables that act as extended TLBs).
3190  *
3191  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3192  * but allow concurrent faults), and pte mapped but not yet locked.
3193  * We return with pte unmapped and unlocked.
3194  *
3195  * The mmap_sem may have been released depending on flags and our
3196  * return value.  See filemap_fault() and __lock_page_or_retry().
3197  */
3198 static int handle_pte_fault(struct mm_struct *mm,
3199                      struct vm_area_struct *vma, unsigned long address,
3200                      pte_t *pte, pmd_t *pmd, unsigned int flags)
3201 {
3202         pte_t entry;
3203         spinlock_t *ptl;
3204 
3205         /*
3206          * some architectures can have larger ptes than wordsize,
3207          * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and CONFIG_32BIT=y,
3208          * so READ_ONCE or ACCESS_ONCE cannot guarantee atomic accesses.
3209          * The code below just needs a consistent view for the ifs and
3210          * we later double check anyway with the ptl lock held. So here
3211          * a barrier will do.
3212          */
3213         entry = *pte;
3214         barrier();
3215         if (!pte_present(entry)) {
3216                 if (pte_none(entry)) {
3217                         if (vma->vm_ops) {
3218                                 if (likely(vma->vm_ops->fault))
3219                                         return do_linear_fault(mm, vma, address,
3220                                                 pte, pmd, flags, entry);
3221                         }
3222                         return do_anonymous_page(mm, vma, address,
3223                                                  pte, pmd, flags);
3224                 }
3225                 if (pte_file(entry))
3226                         return do_nonlinear_fault(mm, vma, address,
3227                                         pte, pmd, flags, entry);
3228                 return do_swap_page(mm, vma, address,
3229                                         pte, pmd, flags, entry);
3230         }
3231 
3232         if (pte_numa(entry))
3233                 return do_numa_page(mm, vma, address, entry, pte, pmd);
3234 
3235         ptl = pte_lockptr(mm, pmd);
3236         spin_lock(ptl);
3237         if (unlikely(!pte_same(*pte, entry)))
3238                 goto unlock;
3239         if (flags & FAULT_FLAG_WRITE) {
3240                 if (!pte_write(entry))
3241                         return do_wp_page(mm, vma, address,
3242                                         pte, pmd, ptl, entry);
3243                 entry = pte_mkdirty(entry);
3244         }
3245         entry = pte_mkyoung(entry);
3246         if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3247                 update_mmu_cache(vma, address, pte);
3248         } else {
3249                 /*
3250                  * This is needed only for protection faults but the arch code
3251                  * is not yet telling us if this is a protection fault or not.
3252                  * This still avoids useless tlb flushes for .text page faults
3253                  * with threads.
3254                  */
3255                 if (flags & FAULT_FLAG_WRITE)
3256                         flush_tlb_fix_spurious_fault(vma, address);
3257         }
3258 unlock:
3259         pte_unmap_unlock(pte, ptl);
3260         return 0;
3261 }
3262 
3263 /*
3264  * By the time we get here, we already hold the mm semaphore
3265  *
3266  * The mmap_sem may have been released depending on flags and our
3267  * return value.  See filemap_fault() and __lock_page_or_retry().
3268  */
3269 static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3270                              unsigned long address, unsigned int flags)
3271 {
3272         pgd_t *pgd;
3273         pud_t *pud;
3274         pmd_t *pmd;
3275         pte_t *pte;
3276 
3277         if (unlikely(is_vm_hugetlb_page(vma)))
3278                 return hugetlb_fault(mm, vma, address, flags);
3279 
3280         pgd = pgd_offset(mm, address);
3281         pud = pud_alloc(mm, pgd, address);
3282         if (!pud)
3283                 return VM_FAULT_OOM;
3284         pmd = pmd_alloc(mm, pud, address);
3285         if (!pmd)
3286                 return VM_FAULT_OOM;
3287         if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3288                 int ret = VM_FAULT_FALLBACK;
3289                 if (!vma->vm_ops)
3290                         ret = do_huge_pmd_anonymous_page(mm, vma, address,
3291                                         pmd, flags);
3292                 if (!(ret & VM_FAULT_FALLBACK))
3293                         return ret;
3294         } else {
3295                 pmd_t orig_pmd = *pmd;
3296                 int ret;
3297 
3298                 barrier();
3299                 if (pmd_trans_huge(orig_pmd)) {
3300                         unsigned int dirty = flags & FAULT_FLAG_WRITE;
3301 
3302                         /*
3303                          * If the pmd is splitting, return and retry the
3304                          * the fault.  Alternative: wait until the split
3305                          * is done, and goto retry.
3306                          */
3307                         if (pmd_trans_splitting(orig_pmd))
3308                                 return 0;
3309 
3310                         if (pmd_numa(orig_pmd))
3311                                 return do_huge_pmd_numa_page(mm, vma, address,
3312                                                              orig_pmd, pmd);
3313 
3314                         if (dirty && !pmd_write(orig_pmd)) {
3315                                 ret = do_huge_pmd_wp_page(mm, vma, address, pmd,
3316                                                           orig_pmd);
3317                                 if (!(ret & VM_FAULT_FALLBACK))
3318                                         return ret;
3319                         } else {
3320                                 huge_pmd_set_accessed(mm, vma, address, pmd,
3321                                                       orig_pmd, dirty);
3322                                 return 0;
3323                         }
3324                 }
3325         }
3326 
3327         /*
3328          * Use __pte_alloc instead of pte_alloc_map, because we can't
3329          * run pte_offset_map on the pmd, if an huge pmd could
3330          * materialize from under us from a different thread.
3331          */
3332         if (unlikely(pmd_none(*pmd)) &&
3333             unlikely(__pte_alloc(mm, vma, pmd, address)))
3334                 return VM_FAULT_OOM;
3335         /* if an huge pmd materialized from under us just retry later */
3336         if (unlikely(pmd_trans_huge(*pmd)))
3337                 return 0;
3338         /*
3339          * A regular pmd is established and it can't morph into a huge pmd
3340          * from under us anymore at this point because we hold the mmap_sem
3341          * read mode and khugepaged takes it in write mode. So now it's
3342          * safe to run pte_offset_map().
3343          */
3344         pte = pte_offset_map(pmd, address);
3345 
3346         return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3347 }
3348 
3349 /*
3350  * By the time we get here, we already hold the mm semaphore
3351  *
3352  * The mmap_sem may have been released depending on flags and our
3353  * return value.  See filemap_fault() and __lock_page_or_retry().
3354  */
3355 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3356                     unsigned long address, unsigned int flags)
3357 {
3358         int ret;
3359 
3360         __set_current_state(TASK_RUNNING);
3361 
3362         count_vm_event(PGFAULT);
3363         mem_cgroup_count_vm_event(mm, PGFAULT);
3364 
3365         /* do counter updates before entering really critical section. */
3366         check_sync_rss_stat(current);
3367 
3368         /*
3369          * Enable the memcg OOM handling for faults triggered in user
3370          * space.  Kernel faults are handled more gracefully.
3371          */
3372         if (flags & FAULT_FLAG_USER)
3373                 mem_cgroup_oom_enable();
3374 
3375         ret = __handle_mm_fault(mm, vma, address, flags);
3376 
3377         if (flags & FAULT_FLAG_USER) {
3378                 mem_cgroup_oom_disable();
3379                 /*
3380                  * The task may have entered a memcg OOM situation but
3381                  * if the allocation error was handled gracefully (no
3382                  * VM_FAULT_OOM), there is no need to kill anything.
3383                  * Just clean up the OOM state peacefully.
3384                  */
3385                 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
3386                         mem_cgroup_oom_synchronize(false);
3387         }
3388 
3389         return ret;
3390 }
3391 EXPORT_SYMBOL_GPL(handle_mm_fault);
3392 
3393 #ifndef __PAGETABLE_PUD_FOLDED
3394 /*
3395  * Allocate page upper directory.
3396  * We've already handled the fast-path in-line.
3397  */
3398 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3399 {
3400         pud_t *new = pud_alloc_one(mm, address);
3401         if (!new)
3402                 return -ENOMEM;
3403 
3404         smp_wmb(); /* See comment in __pte_alloc */
3405 
3406         spin_lock(&mm->page_table_lock);
3407         if (pgd_present(*pgd))          /* Another has populated it */
3408                 pud_free(mm, new);
3409         else
3410                 pgd_populate(mm, pgd, new);
3411         spin_unlock(&mm->page_table_lock);
3412         return 0;
3413 }
3414 #endif /* __PAGETABLE_PUD_FOLDED */
3415 
3416 #ifndef __PAGETABLE_PMD_FOLDED
3417 /*
3418  * Allocate page middle directory.
3419  * We've already handled the fast-path in-line.
3420  */
3421 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3422 {
3423         pmd_t *new = pmd_alloc_one(mm, address);
3424         if (!new)
3425                 return -ENOMEM;
3426 
3427         smp_wmb(); /* See comment in __pte_alloc */
3428 
3429         spin_lock(&mm->page_table_lock);
3430 #ifndef __ARCH_HAS_4LEVEL_HACK
3431         if (pud_present(*pud))          /* Another has populated it */
3432                 pmd_free(mm, new);
3433         else
3434                 pud_populate(mm, pud, new);
3435 #else
3436         if (pgd_present(*pud))          /* Another has populated it */
3437                 pmd_free(mm, new);
3438         else
3439                 pgd_populate(mm, pud, new);
3440 #endif /* __ARCH_HAS_4LEVEL_HACK */
3441         spin_unlock(&mm->page_table_lock);
3442         return 0;
3443 }
3444 #endif /* __PAGETABLE_PMD_FOLDED */
3445 
3446 static int __follow_pte(struct mm_struct *mm, unsigned long address,
3447                 pte_t **ptepp, spinlock_t **ptlp)
3448 {
3449         pgd_t *pgd;
3450         pud_t *pud;
3451         pmd_t *pmd;
3452         pte_t *ptep;
3453 
3454         pgd = pgd_offset(mm, address);
3455         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3456                 goto out;
3457 
3458         pud = pud_offset(pgd, address);
3459         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3460                 goto out;
3461 
3462         pmd = pmd_offset(pud, address);
3463         VM_BUG_ON(pmd_trans_huge(*pmd));
3464         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3465                 goto out;
3466 
3467         /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3468         if (pmd_huge(*pmd))
3469                 goto out;
3470 
3471         ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3472         if (!ptep)
3473                 goto out;
3474         if (!pte_present(*ptep))
3475                 goto unlock;
3476         *ptepp = ptep;
3477         return 0;
3478 unlock:
3479         pte_unmap_unlock(ptep, *ptlp);
3480 out:
3481         return -EINVAL;
3482 }
3483 
3484 static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3485                              pte_t **ptepp, spinlock_t **ptlp)
3486 {
3487         int res;
3488 
3489         /* (void) is needed to make gcc happy */
3490         (void) __cond_lock(*ptlp,
3491                            !(res = __follow_pte(mm, address, ptepp, ptlp)));
3492         return res;
3493 }
3494 
3495 /**
3496  * follow_pfn - look up PFN at a user virtual address
3497  * @vma: memory mapping
3498  * @address: user virtual address
3499  * @pfn: location to store found PFN
3500  *
3501  * Only IO mappings and raw PFN mappings are allowed.
3502  *
3503  * Returns zero and the pfn at @pfn on success, -ve otherwise.
3504  */
3505 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3506         unsigned long *pfn)
3507 {
3508         int ret = -EINVAL;
3509         spinlock_t *ptl;
3510         pte_t *ptep;
3511 
3512         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3513                 return ret;
3514 
3515         ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3516         if (ret)
3517                 return ret;
3518         *pfn = pte_pfn(*ptep);
3519         pte_unmap_unlock(ptep, ptl);
3520         return 0;
3521 }
3522 EXPORT_SYMBOL(follow_pfn);
3523 
3524 #ifdef CONFIG_HAVE_IOREMAP_PROT
3525 int follow_phys(struct vm_area_struct *vma,
3526                 unsigned long address, unsigned int flags,
3527                 unsigned long *prot, resource_size_t *phys)
3528 {
3529         int ret = -EINVAL;
3530         pte_t *ptep, pte;
3531         spinlock_t *ptl;
3532 
3533         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3534                 goto out;
3535 
3536         if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3537                 goto out;
3538         pte = *ptep;
3539 
3540         if ((flags & FOLL_WRITE) && !pte_write(pte))
3541                 goto unlock;
3542 
3543         *prot = pgprot_val(pte_pgprot(pte));
3544         *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3545 
3546         ret = 0;
3547 unlock:
3548         pte_unmap_unlock(ptep, ptl);
3549 out:
3550         return ret;
3551 }
3552 
3553 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3554                         void *buf, int len, int write)
3555 {
3556         resource_size_t phys_addr;
3557         unsigned long prot = 0;
3558         void __iomem *maddr;
3559         int offset = addr & (PAGE_SIZE-1);
3560 
3561         if (follow_phys(vma, addr, write, &prot, &phys_addr))
3562                 return -EINVAL;
3563 
3564         maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
3565         if (write)
3566                 memcpy_toio(maddr + offset, buf, len);
3567         else
3568                 memcpy_fromio(buf, maddr + offset, len);
3569         iounmap(maddr);
3570 
3571         return len;
3572 }
3573 EXPORT_SYMBOL_GPL(generic_access_phys);
3574 #endif
3575 
3576 /*
3577  * Access another process' address space as given in mm.  If non-NULL, use the
3578  * given task for page fault accounting.
3579  */
3580 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
3581                 unsigned long addr, void *buf, int len, int write)
3582 {
3583         struct vm_area_struct *vma;
3584         void *old_buf = buf;
3585 
3586         down_read(&mm->mmap_sem);
3587         /* ignore errors, just check how much was successfully transferred */
3588         while (len) {
3589                 int bytes, ret, offset;
3590                 void *maddr;
3591                 struct page *page = NULL;
3592 
3593                 ret = get_user_pages(tsk, mm, addr, 1,
3594                                 write, 1, &page, &vma);
3595                 if (ret <= 0) {
3596 #ifndef CONFIG_HAVE_IOREMAP_PROT
3597                         break;
3598 #else
3599                         /*
3600                          * Check if this is a VM_IO | VM_PFNMAP VMA, which
3601                          * we can access using slightly different code.
3602                          */
3603                         vma = find_vma(mm, addr);
3604                         if (!vma || vma->vm_start > addr)
3605                                 break;
3606                         if (vma->vm_ops && vma->vm_ops->access)
3607                                 ret = vma->vm_ops->access(vma, addr, buf,
3608                                                           len, write);
3609                         if (ret <= 0)
3610                                 break;
3611                         bytes = ret;
3612 #endif
3613                 } else {
3614                         bytes = len;
3615                         offset = addr & (PAGE_SIZE-1);
3616                         if (bytes > PAGE_SIZE-offset)
3617                                 bytes = PAGE_SIZE-offset;
3618 
3619                         maddr = kmap(page);
3620                         if (write) {
3621                                 copy_to_user_page(vma, page, addr,
3622                                                   maddr + offset, buf, bytes);
3623                                 set_page_dirty_lock(page);
3624                         } else {
3625                                 copy_from_user_page(vma, page, addr,
3626                                                     buf, maddr + offset, bytes);
3627                         }
3628                         kunmap(page);
3629                         page_cache_release(page);
3630                 }
3631                 len -= bytes;
3632                 buf += bytes;
3633                 addr += bytes;
3634         }
3635         up_read(&mm->mmap_sem);
3636 
3637         return buf - old_buf;
3638 }
3639 
3640 /**
3641  * access_remote_vm - access another process' address space
3642  * @mm:         the mm_struct of the target address space
3643  * @addr:       start address to access
3644  * @buf:        source or destination buffer
3645  * @len:        number of bytes to transfer
3646  * @write:      whether the access is a write
3647  *
3648  * The caller must hold a reference on @mm.
3649  */
3650 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
3651                 void *buf, int len, int write)
3652 {
3653         return __access_remote_vm(NULL, mm, addr, buf, len, write);
3654 }
3655 
3656 /*
3657  * Access another process' address space.
3658  * Source/target buffer must be kernel space,
3659  * Do not walk the page table directly, use get_user_pages
3660  */
3661 int access_process_vm(struct task_struct *tsk, unsigned long addr,
3662                 void *buf, int len, int write)
3663 {
3664         struct mm_struct *mm;
3665         int ret;
3666 
3667         mm = get_task_mm(tsk);
3668         if (!mm)
3669                 return 0;
3670 
3671         ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
3672         mmput(mm);
3673 
3674         return ret;
3675 }
3676 
3677 /*
3678  * Print the name of a VMA.
3679  */
3680 void print_vma_addr(char *prefix, unsigned long ip)
3681 {
3682         struct mm_struct *mm = current->mm;
3683         struct vm_area_struct *vma;
3684 
3685         /*
3686          * Do not print if we are in atomic
3687          * contexts (in exception stacks, etc.):
3688          */
3689         if (preempt_count())
3690                 return;
3691 
3692         down_read(&mm->mmap_sem);
3693         vma = find_vma(mm, ip);
3694         if (vma && vma->vm_file) {
3695                 struct file *f = vma->vm_file;
3696                 char *buf = (char *)__get_free_page(GFP_KERNEL);
3697                 if (buf) {
3698                         char *p;
3699 
3700                         p = d_path(&f->f_path, buf, PAGE_SIZE);
3701                         if (IS_ERR(p))
3702                                 p = "?";
3703                         printk("%s%s[%lx+%lx]", prefix, kbasename(p),
3704                                         vma->vm_start,
3705                                         vma->vm_end - vma->vm_start);
3706                         free_page((unsigned long)buf);
3707                 }
3708         }
3709         up_read(&mm->mmap_sem);
3710 }
3711 
3712 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
3713 void might_fault(void)
3714 {
3715         /*
3716          * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3717          * holding the mmap_sem, this is safe because kernel memory doesn't
3718          * get paged out, therefore we'll never actually fault, and the
3719          * below annotations will generate false positives.
3720          */
3721         if (segment_eq(get_fs(), KERNEL_DS))
3722                 return;
3723 
3724         /*
3725          * it would be nicer only to annotate paths which are not under
3726          * pagefault_disable, however that requires a larger audit and
3727          * providing helpers like get_user_atomic.
3728          */
3729         if (in_atomic())
3730                 return;
3731 
3732         __might_sleep(__FILE__, __LINE__, 0);
3733 
3734         if (current->mm)
3735                 might_lock_read(&current->mm->mmap_sem);
3736 }
3737 EXPORT_SYMBOL(might_fault);
3738 #endif
3739 
3740 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
3741 static void clear_gigantic_page(struct page *page,
3742                                 unsigned long addr,
3743                                 unsigned int pages_per_huge_page)
3744 {
3745         int i;
3746         struct page *p = page;
3747 
3748         might_sleep();
3749         for (i = 0; i < pages_per_huge_page;
3750              i++, p = mem_map_next(p, page, i)) {
3751                 cond_resched();
3752                 clear_user_highpage(p, addr + i * PAGE_SIZE);
3753         }
3754 }
3755 void clear_huge_page(struct page *page,
3756                      unsigned long addr, unsigned int pages_per_huge_page)
3757 {
3758         int i;
3759 
3760         if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3761                 clear_gigantic_page(page, addr, pages_per_huge_page);
3762                 return;
3763         }
3764 
3765         might_sleep();
3766         for (i = 0; i < pages_per_huge_page; i++) {
3767                 cond_resched();
3768                 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
3769         }
3770 }
3771 
3772 static void copy_user_gigantic_page(struct page *dst, struct page *src,
3773                                     unsigned long addr,
3774                                     struct vm_area_struct *vma,
3775                                     unsigned int pages_per_huge_page)
3776 {
3777         int i;
3778         struct page *dst_base = dst;
3779         struct page *src_base = src;
3780 
3781         for (i = 0; i < pages_per_huge_page; ) {
3782                 cond_resched();
3783                 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
3784 
3785                 i++;
3786                 dst = mem_map_next(dst, dst_base, i);
3787                 src = mem_map_next(src, src_base, i);
3788         }
3789 }
3790 
3791 void copy_user_huge_page(struct page *dst, struct page *src,
3792                          unsigned long addr, struct vm_area_struct *vma,
3793                          unsigned int pages_per_huge_page)
3794 {
3795         int i;
3796 
3797         if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3798                 copy_user_gigantic_page(dst, src, addr, vma,
3799                                         pages_per_huge_page);
3800                 return;
3801         }
3802 
3803         might_sleep();
3804         for (i = 0; i < pages_per_huge_page; i++) {
3805                 cond_resched();
3806                 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
3807         }
3808 }
3809 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
3810 
3811 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
3812 
3813 static struct kmem_cache *page_ptl_cachep;
3814 
3815 void __init ptlock_cache_init(void)
3816 {
3817         page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
3818                         SLAB_PANIC, NULL);
3819 }
3820 
3821 bool ptlock_alloc(struct page *page)
3822 {
3823         spinlock_t *ptl;
3824 
3825         ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
3826         if (!ptl)
3827                 return false;
3828         page->ptl = ptl;
3829         return true;
3830 }
3831 
3832 void ptlock_free(struct page *page)
3833 {
3834         kmem_cache_free(page_ptl_cachep, page->ptl);
3835 }
3836 #endif
3837 

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