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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 /*
122  * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
123  */
124 static int __init init_zero_pfn(void)
125 {
126         zero_pfn = page_to_pfn(ZERO_PAGE(0));
127         return 0;
128 }
129 core_initcall(init_zero_pfn);
130 
131 
132 #if defined(SPLIT_RSS_COUNTING)
133 
134 void sync_mm_rss(struct mm_struct *mm)
135 {
136         int i;
137 
138         for (i = 0; i < NR_MM_COUNTERS; i++) {
139                 if (current->rss_stat.count[i]) {
140                         add_mm_counter(mm, i, current->rss_stat.count[i]);
141                         current->rss_stat.count[i] = 0;
142                 }
143         }
144         current->rss_stat.events = 0;
145 }
146 
147 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
148 {
149         struct task_struct *task = current;
150 
151         if (likely(task->mm == mm))
152                 task->rss_stat.count[member] += val;
153         else
154                 add_mm_counter(mm, member, val);
155 }
156 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
157 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
158 
159 /* sync counter once per 64 page faults */
160 #define TASK_RSS_EVENTS_THRESH  (64)
161 static void check_sync_rss_stat(struct task_struct *task)
162 {
163         if (unlikely(task != current))
164                 return;
165         if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
166                 sync_mm_rss(task->mm);
167 }
168 #else /* SPLIT_RSS_COUNTING */
169 
170 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
171 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
172 
173 static void check_sync_rss_stat(struct task_struct *task)
174 {
175 }
176 
177 #endif /* SPLIT_RSS_COUNTING */
178 
179 #ifdef HAVE_GENERIC_MMU_GATHER
180 
181 static int tlb_next_batch(struct mmu_gather *tlb)
182 {
183         struct mmu_gather_batch *batch;
184 
185         batch = tlb->active;
186         if (batch->next) {
187                 tlb->active = batch->next;
188                 return 1;
189         }
190 
191         if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
192                 return 0;
193 
194         batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
195         if (!batch)
196                 return 0;
197 
198         tlb->batch_count++;
199         batch->next = NULL;
200         batch->nr   = 0;
201         batch->max  = MAX_GATHER_BATCH;
202 
203         tlb->active->next = batch;
204         tlb->active = batch;
205 
206         return 1;
207 }
208 
209 /* tlb_gather_mmu
210  *      Called to initialize an (on-stack) mmu_gather structure for page-table
211  *      tear-down from @mm. The @fullmm argument is used when @mm is without
212  *      users and we're going to destroy the full address space (exit/execve).
213  */
214 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end)
215 {
216         tlb->mm = mm;
217 
218         /* Is it from 0 to ~0? */
219         tlb->fullmm     = !(start | (end+1));
220         tlb->need_flush_all = 0;
221         tlb->start      = start;
222         tlb->end        = end;
223         tlb->need_flush = 0;
224         tlb->local.next = NULL;
225         tlb->local.nr   = 0;
226         tlb->local.max  = ARRAY_SIZE(tlb->__pages);
227         tlb->active     = &tlb->local;
228         tlb->batch_count = 0;
229 
230 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
231         tlb->batch = NULL;
232 #endif
233 }
234 
235 static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
236 {
237         tlb->need_flush = 0;
238         tlb_flush(tlb);
239 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
240         tlb_table_flush(tlb);
241 #endif
242 }
243 
244 static void tlb_flush_mmu_free(struct mmu_gather *tlb)
245 {
246         struct mmu_gather_batch *batch;
247 
248         for (batch = &tlb->local; batch; batch = batch->next) {
249                 free_pages_and_swap_cache(batch->pages, batch->nr);
250                 batch->nr = 0;
251         }
252         tlb->active = &tlb->local;
253 }
254 
255 void tlb_flush_mmu(struct mmu_gather *tlb)
256 {
257         if (!tlb->need_flush)
258                 return;
259         tlb_flush_mmu_tlbonly(tlb);
260         tlb_flush_mmu_free(tlb);
261 }
262 
263 /* tlb_finish_mmu
264  *      Called at the end of the shootdown operation to free up any resources
265  *      that were required.
266  */
267 void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
268 {
269         struct mmu_gather_batch *batch, *next;
270 
271         tlb_flush_mmu(tlb);
272 
273         /* keep the page table cache within bounds */
274         check_pgt_cache();
275 
276         for (batch = tlb->local.next; batch; batch = next) {
277                 next = batch->next;
278                 free_pages((unsigned long)batch, 0);
279         }
280         tlb->local.next = NULL;
281 }
282 
283 /* __tlb_remove_page
284  *      Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
285  *      handling the additional races in SMP caused by other CPUs caching valid
286  *      mappings in their TLBs. Returns the number of free page slots left.
287  *      When out of page slots we must call tlb_flush_mmu().
288  */
289 int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
290 {
291         struct mmu_gather_batch *batch;
292 
293         VM_BUG_ON(!tlb->need_flush);
294 
295         batch = tlb->active;
296         batch->pages[batch->nr++] = page;
297         if (batch->nr == batch->max) {
298                 if (!tlb_next_batch(tlb))
299                         return 0;
300                 batch = tlb->active;
301         }
302         VM_BUG_ON_PAGE(batch->nr > batch->max, page);
303 
304         return batch->max - batch->nr;
305 }
306 
307 #endif /* HAVE_GENERIC_MMU_GATHER */
308 
309 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
310 
311 /*
312  * See the comment near struct mmu_table_batch.
313  */
314 
315 static void tlb_remove_table_smp_sync(void *arg)
316 {
317         /* Simply deliver the interrupt */
318 }
319 
320 static void tlb_remove_table_one(void *table)
321 {
322         /*
323          * This isn't an RCU grace period and hence the page-tables cannot be
324          * assumed to be actually RCU-freed.
325          *
326          * It is however sufficient for software page-table walkers that rely on
327          * IRQ disabling. See the comment near struct mmu_table_batch.
328          */
329         smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
330         __tlb_remove_table(table);
331 }
332 
333 static void tlb_remove_table_rcu(struct rcu_head *head)
334 {
335         struct mmu_table_batch *batch;
336         int i;
337 
338         batch = container_of(head, struct mmu_table_batch, rcu);
339 
340         for (i = 0; i < batch->nr; i++)
341                 __tlb_remove_table(batch->tables[i]);
342 
343         free_page((unsigned long)batch);
344 }
345 
346 void tlb_table_flush(struct mmu_gather *tlb)
347 {
348         struct mmu_table_batch **batch = &tlb->batch;
349 
350         if (*batch) {
351                 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
352                 *batch = NULL;
353         }
354 }
355 
356 void tlb_remove_table(struct mmu_gather *tlb, void *table)
357 {
358         struct mmu_table_batch **batch = &tlb->batch;
359 
360         tlb->need_flush = 1;
361 
362         /*
363          * When there's less then two users of this mm there cannot be a
364          * concurrent page-table walk.
365          */
366         if (atomic_read(&tlb->mm->mm_users) < 2) {
367                 __tlb_remove_table(table);
368                 return;
369         }
370 
371         if (*batch == NULL) {
372                 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
373                 if (*batch == NULL) {
374                         tlb_remove_table_one(table);
375                         return;
376                 }
377                 (*batch)->nr = 0;
378         }
379         (*batch)->tables[(*batch)->nr++] = table;
380         if ((*batch)->nr == MAX_TABLE_BATCH)
381                 tlb_table_flush(tlb);
382 }
383 
384 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */
385 
386 /*
387  * Note: this doesn't free the actual pages themselves. That
388  * has been handled earlier when unmapping all the memory regions.
389  */
390 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
391                            unsigned long addr)
392 {
393         pgtable_t token = pmd_pgtable(*pmd);
394         pmd_clear(pmd);
395         pte_free_tlb(tlb, token, addr);
396         atomic_long_dec(&tlb->mm->nr_ptes);
397 }
398 
399 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
400                                 unsigned long addr, unsigned long end,
401                                 unsigned long floor, unsigned long ceiling)
402 {
403         pmd_t *pmd;
404         unsigned long next;
405         unsigned long start;
406 
407         start = addr;
408         pmd = pmd_offset(pud, addr);
409         do {
410                 next = pmd_addr_end(addr, end);
411                 if (pmd_none_or_clear_bad(pmd))
412                         continue;
413                 free_pte_range(tlb, pmd, addr);
414         } while (pmd++, addr = next, addr != end);
415 
416         start &= PUD_MASK;
417         if (start < floor)
418                 return;
419         if (ceiling) {
420                 ceiling &= PUD_MASK;
421                 if (!ceiling)
422                         return;
423         }
424         if (end - 1 > ceiling - 1)
425                 return;
426 
427         pmd = pmd_offset(pud, start);
428         pud_clear(pud);
429         pmd_free_tlb(tlb, pmd, start);
430 }
431 
432 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
433                                 unsigned long addr, unsigned long end,
434                                 unsigned long floor, unsigned long ceiling)
435 {
436         pud_t *pud;
437         unsigned long next;
438         unsigned long start;
439 
440         start = addr;
441         pud = pud_offset(pgd, addr);
442         do {
443                 next = pud_addr_end(addr, end);
444                 if (pud_none_or_clear_bad(pud))
445                         continue;
446                 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
447         } while (pud++, addr = next, addr != end);
448 
449         start &= PGDIR_MASK;
450         if (start < floor)
451                 return;
452         if (ceiling) {
453                 ceiling &= PGDIR_MASK;
454                 if (!ceiling)
455                         return;
456         }
457         if (end - 1 > ceiling - 1)
458                 return;
459 
460         pud = pud_offset(pgd, start);
461         pgd_clear(pgd);
462         pud_free_tlb(tlb, pud, start);
463 }
464 
465 /*
466  * This function frees user-level page tables of a process.
467  */
468 void free_pgd_range(struct mmu_gather *tlb,
469                         unsigned long addr, unsigned long end,
470                         unsigned long floor, unsigned long ceiling)
471 {
472         pgd_t *pgd;
473         unsigned long next;
474 
475         /*
476          * The next few lines have given us lots of grief...
477          *
478          * Why are we testing PMD* at this top level?  Because often
479          * there will be no work to do at all, and we'd prefer not to
480          * go all the way down to the bottom just to discover that.
481          *
482          * Why all these "- 1"s?  Because 0 represents both the bottom
483          * of the address space and the top of it (using -1 for the
484          * top wouldn't help much: the masks would do the wrong thing).
485          * The rule is that addr 0 and floor 0 refer to the bottom of
486          * the address space, but end 0 and ceiling 0 refer to the top
487          * Comparisons need to use "end - 1" and "ceiling - 1" (though
488          * that end 0 case should be mythical).
489          *
490          * Wherever addr is brought up or ceiling brought down, we must
491          * be careful to reject "the opposite 0" before it confuses the
492          * subsequent tests.  But what about where end is brought down
493          * by PMD_SIZE below? no, end can't go down to 0 there.
494          *
495          * Whereas we round start (addr) and ceiling down, by different
496          * masks at different levels, in order to test whether a table
497          * now has no other vmas using it, so can be freed, we don't
498          * bother to round floor or end up - the tests don't need that.
499          */
500 
501         addr &= PMD_MASK;
502         if (addr < floor) {
503                 addr += PMD_SIZE;
504                 if (!addr)
505                         return;
506         }
507         if (ceiling) {
508                 ceiling &= PMD_MASK;
509                 if (!ceiling)
510                         return;
511         }
512         if (end - 1 > ceiling - 1)
513                 end -= PMD_SIZE;
514         if (addr > end - 1)
515                 return;
516 
517         pgd = pgd_offset(tlb->mm, addr);
518         do {
519                 next = pgd_addr_end(addr, end);
520                 if (pgd_none_or_clear_bad(pgd))
521                         continue;
522                 free_pud_range(tlb, pgd, addr, next, floor, ceiling);
523         } while (pgd++, addr = next, addr != end);
524 }
525 
526 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
527                 unsigned long floor, unsigned long ceiling)
528 {
529         while (vma) {
530                 struct vm_area_struct *next = vma->vm_next;
531                 unsigned long addr = vma->vm_start;
532 
533                 /*
534                  * Hide vma from rmap and truncate_pagecache before freeing
535                  * pgtables
536                  */
537                 unlink_anon_vmas(vma);
538                 unlink_file_vma(vma);
539 
540                 if (is_vm_hugetlb_page(vma)) {
541                         hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
542                                 floor, next? next->vm_start: ceiling);
543                 } else {
544                         /*
545                          * Optimization: gather nearby vmas into one call down
546                          */
547                         while (next && next->vm_start <= vma->vm_end + PMD_SIZE
548                                && !is_vm_hugetlb_page(next)) {
549                                 vma = next;
550                                 next = vma->vm_next;
551                                 unlink_anon_vmas(vma);
552                                 unlink_file_vma(vma);
553                         }
554                         free_pgd_range(tlb, addr, vma->vm_end,
555                                 floor, next? next->vm_start: ceiling);
556                 }
557                 vma = next;
558         }
559 }
560 
561 int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
562                 pmd_t *pmd, unsigned long address)
563 {
564         spinlock_t *ptl;
565         pgtable_t new = pte_alloc_one(mm, address);
566         int wait_split_huge_page;
567         if (!new)
568                 return -ENOMEM;
569 
570         /*
571          * Ensure all pte setup (eg. pte page lock and page clearing) are
572          * visible before the pte is made visible to other CPUs by being
573          * put into page tables.
574          *
575          * The other side of the story is the pointer chasing in the page
576          * table walking code (when walking the page table without locking;
577          * ie. most of the time). Fortunately, these data accesses consist
578          * of a chain of data-dependent loads, meaning most CPUs (alpha
579          * being the notable exception) will already guarantee loads are
580          * seen in-order. See the alpha page table accessors for the
581          * smp_read_barrier_depends() barriers in page table walking code.
582          */
583         smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
584 
585         ptl = pmd_lock(mm, pmd);
586         wait_split_huge_page = 0;
587         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
588                 atomic_long_inc(&mm->nr_ptes);
589                 pmd_populate(mm, pmd, new);
590                 new = NULL;
591         } else if (unlikely(pmd_trans_splitting(*pmd)))
592                 wait_split_huge_page = 1;
593         spin_unlock(ptl);
594         if (new)
595                 pte_free(mm, new);
596         if (wait_split_huge_page)
597                 wait_split_huge_page(vma->anon_vma, pmd);
598         return 0;
599 }
600 
601 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
602 {
603         pte_t *new = pte_alloc_one_kernel(&init_mm, address);
604         if (!new)
605                 return -ENOMEM;
606 
607         smp_wmb(); /* See comment in __pte_alloc */
608 
609         spin_lock(&init_mm.page_table_lock);
610         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
611                 pmd_populate_kernel(&init_mm, pmd, new);
612                 new = NULL;
613         } else
614                 VM_BUG_ON(pmd_trans_splitting(*pmd));
615         spin_unlock(&init_mm.page_table_lock);
616         if (new)
617                 pte_free_kernel(&init_mm, new);
618         return 0;
619 }
620 
621 static inline void init_rss_vec(int *rss)
622 {
623         memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
624 }
625 
626 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
627 {
628         int i;
629 
630         if (current->mm == mm)
631                 sync_mm_rss(mm);
632         for (i = 0; i < NR_MM_COUNTERS; i++)
633                 if (rss[i])
634                         add_mm_counter(mm, i, rss[i]);
635 }
636 
637 /*
638  * This function is called to print an error when a bad pte
639  * is found. For example, we might have a PFN-mapped pte in
640  * a region that doesn't allow it.
641  *
642  * The calling function must still handle the error.
643  */
644 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
645                           pte_t pte, struct page *page)
646 {
647         pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
648         pud_t *pud = pud_offset(pgd, addr);
649         pmd_t *pmd = pmd_offset(pud, addr);
650         struct address_space *mapping;
651         pgoff_t index;
652         static unsigned long resume;
653         static unsigned long nr_shown;
654         static unsigned long nr_unshown;
655 
656         /*
657          * Allow a burst of 60 reports, then keep quiet for that minute;
658          * or allow a steady drip of one report per second.
659          */
660         if (nr_shown == 60) {
661                 if (time_before(jiffies, resume)) {
662                         nr_unshown++;
663                         return;
664                 }
665                 if (nr_unshown) {
666                         printk(KERN_ALERT
667                                 "BUG: Bad page map: %lu messages suppressed\n",
668                                 nr_unshown);
669                         nr_unshown = 0;
670                 }
671                 nr_shown = 0;
672         }
673         if (nr_shown++ == 0)
674                 resume = jiffies + 60 * HZ;
675 
676         mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
677         index = linear_page_index(vma, addr);
678 
679         printk(KERN_ALERT
680                 "BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
681                 current->comm,
682                 (long long)pte_val(pte), (long long)pmd_val(*pmd));
683         if (page)
684                 dump_page(page, "bad pte");
685         printk(KERN_ALERT
686                 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
687                 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
688         /*
689          * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
690          */
691         if (vma->vm_ops)
692                 printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n",
693                        vma->vm_ops->fault);
694         if (vma->vm_file)
695                 printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n",
696                        vma->vm_file->f_op->mmap);
697         dump_stack();
698         add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
699 }
700 
701 /*
702  * vm_normal_page -- This function gets the "struct page" associated with a pte.
703  *
704  * "Special" mappings do not wish to be associated with a "struct page" (either
705  * it doesn't exist, or it exists but they don't want to touch it). In this
706  * case, NULL is returned here. "Normal" mappings do have a struct page.
707  *
708  * There are 2 broad cases. Firstly, an architecture may define a pte_special()
709  * pte bit, in which case this function is trivial. Secondly, an architecture
710  * may not have a spare pte bit, which requires a more complicated scheme,
711  * described below.
712  *
713  * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
714  * special mapping (even if there are underlying and valid "struct pages").
715  * COWed pages of a VM_PFNMAP are always normal.
716  *
717  * The way we recognize COWed pages within VM_PFNMAP mappings is through the
718  * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
719  * set, and the vm_pgoff will point to the first PFN mapped: thus every special
720  * mapping will always honor the rule
721  *
722  *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
723  *
724  * And for normal mappings this is false.
725  *
726  * This restricts such mappings to be a linear translation from virtual address
727  * to pfn. To get around this restriction, we allow arbitrary mappings so long
728  * as the vma is not a COW mapping; in that case, we know that all ptes are
729  * special (because none can have been COWed).
730  *
731  *
732  * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
733  *
734  * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
735  * page" backing, however the difference is that _all_ pages with a struct
736  * page (that is, those where pfn_valid is true) are refcounted and considered
737  * normal pages by the VM. The disadvantage is that pages are refcounted
738  * (which can be slower and simply not an option for some PFNMAP users). The
739  * advantage is that we don't have to follow the strict linearity rule of
740  * PFNMAP mappings in order to support COWable mappings.
741  *
742  */
743 #ifdef __HAVE_ARCH_PTE_SPECIAL
744 # define HAVE_PTE_SPECIAL 1
745 #else
746 # define HAVE_PTE_SPECIAL 0
747 #endif
748 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
749                                 pte_t pte)
750 {
751         unsigned long pfn = pte_pfn(pte);
752 
753         if (HAVE_PTE_SPECIAL) {
754                 if (likely(!pte_special(pte) || pte_numa(pte)))
755                         goto check_pfn;
756                 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
757                         return NULL;
758                 if (!is_zero_pfn(pfn))
759                         print_bad_pte(vma, addr, pte, NULL);
760                 return NULL;
761         }
762 
763         /* !HAVE_PTE_SPECIAL case follows: */
764 
765         if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
766                 if (vma->vm_flags & VM_MIXEDMAP) {
767                         if (!pfn_valid(pfn))
768                                 return NULL;
769                         goto out;
770                 } else {
771                         unsigned long off;
772                         off = (addr - vma->vm_start) >> PAGE_SHIFT;
773                         if (pfn == vma->vm_pgoff + off)
774                                 return NULL;
775                         if (!is_cow_mapping(vma->vm_flags))
776                                 return NULL;
777                 }
778         }
779 
780 check_pfn:
781         if (unlikely(pfn > highest_memmap_pfn)) {
782                 print_bad_pte(vma, addr, pte, NULL);
783                 return NULL;
784         }
785 
786         if (is_zero_pfn(pfn))
787                 return NULL;
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 (swap_duplicate(entry) < 0)
818                                 return entry.val;
819 
820                         /* make sure dst_mm is on swapoff's mmlist. */
821                         if (unlikely(list_empty(&dst_mm->mmlist))) {
822                                 spin_lock(&mmlist_lock);
823                                 if (list_empty(&dst_mm->mmlist))
824                                         list_add(&dst_mm->mmlist,
825                                                  &src_mm->mmlist);
826                                 spin_unlock(&mmlist_lock);
827                         }
828                         if (likely(!non_swap_entry(entry)))
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 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                                         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                                 break;
1150                         }
1151                         continue;
1152                 }
1153                 /*
1154                  * If details->check_mapping, we leave swap entries;
1155                  * if details->nonlinear_vma, we leave file entries.
1156                  */
1157                 if (unlikely(details))
1158                         continue;
1159                 if (pte_file(ptent)) {
1160                         if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
1161                                 print_bad_pte(vma, addr, ptent, NULL);
1162                 } else {
1163                         swp_entry_t entry = pte_to_swp_entry(ptent);
1164 
1165                         if (!non_swap_entry(entry))
1166                                 rss[MM_SWAPENTS]--;
1167                         else if (is_migration_entry(entry)) {
1168                                 struct page *page;
1169 
1170                                 page = migration_entry_to_page(entry);
1171 
1172                                 if (PageAnon(page))
1173                                         rss[MM_ANONPAGES]--;
1174                                 else
1175                                         rss[MM_FILEPAGES]--;
1176                         }
1177                         if (unlikely(!free_swap_and_cache(entry)))
1178                                 print_bad_pte(vma, addr, ptent, NULL);
1179                 }
1180                 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1181         } while (pte++, addr += PAGE_SIZE, addr != end);
1182 
1183         add_mm_rss_vec(mm, rss);
1184         arch_leave_lazy_mmu_mode();
1185 
1186         /* Do the actual TLB flush before dropping ptl */
1187         if (force_flush) {
1188                 unsigned long old_end;
1189 
1190                 /*
1191                  * Flush the TLB just for the previous segment,
1192                  * then update the range to be the remaining
1193                  * TLB range.
1194                  */
1195                 old_end = tlb->end;
1196                 tlb->end = addr;
1197                 tlb_flush_mmu_tlbonly(tlb);
1198                 tlb->start = addr;
1199                 tlb->end = old_end;
1200         }
1201         pte_unmap_unlock(start_pte, ptl);
1202 
1203         /*
1204          * If we forced a TLB flush (either due to running out of
1205          * batch buffers or because we needed to flush dirty TLB
1206          * entries before releasing the ptl), free the batched
1207          * memory too. Restart if we didn't do everything.
1208          */
1209         if (force_flush) {
1210                 force_flush = 0;
1211                 tlb_flush_mmu_free(tlb);
1212 
1213                 if (addr != end)
1214                         goto again;
1215         }
1216 
1217         return addr;
1218 }
1219 
1220 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1221                                 struct vm_area_struct *vma, pud_t *pud,
1222                                 unsigned long addr, unsigned long end,
1223                                 struct zap_details *details)
1224 {
1225         pmd_t *pmd;
1226         unsigned long next;
1227 
1228         pmd = pmd_offset(pud, addr);
1229         do {
1230                 next = pmd_addr_end(addr, end);
1231                 if (pmd_trans_huge(*pmd)) {
1232                         if (next - addr != HPAGE_PMD_SIZE) {
1233 #ifdef CONFIG_DEBUG_VM
1234                                 if (!rwsem_is_locked(&tlb->mm->mmap_sem)) {
1235                                         pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",
1236                                                 __func__, addr, end,
1237                                                 vma->vm_start,
1238                                                 vma->vm_end);
1239                                         BUG();
1240                                 }
1241 #endif
1242                                 split_huge_page_pmd(vma, addr, pmd);
1243                         } else if (zap_huge_pmd(tlb, vma, pmd, addr))
1244                                 goto next;
1245                         /* fall through */
1246                 }
1247                 /*
1248                  * Here there can be other concurrent MADV_DONTNEED or
1249                  * trans huge page faults running, and if the pmd is
1250                  * none or trans huge it can change under us. This is
1251                  * because MADV_DONTNEED holds the mmap_sem in read
1252                  * mode.
1253                  */
1254                 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1255                         goto next;
1256                 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1257 next:
1258                 cond_resched();
1259         } while (pmd++, addr = next, addr != end);
1260 
1261         return addr;
1262 }
1263 
1264 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1265                                 struct vm_area_struct *vma, pgd_t *pgd,
1266                                 unsigned long addr, unsigned long end,
1267                                 struct zap_details *details)
1268 {
1269         pud_t *pud;
1270         unsigned long next;
1271 
1272         pud = pud_offset(pgd, addr);
1273         do {
1274                 next = pud_addr_end(addr, end);
1275                 if (pud_none_or_clear_bad(pud))
1276                         continue;
1277                 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1278         } while (pud++, addr = next, addr != end);
1279 
1280         return addr;
1281 }
1282 
1283 static void unmap_page_range(struct mmu_gather *tlb,
1284                              struct vm_area_struct *vma,
1285                              unsigned long addr, unsigned long end,
1286                              struct zap_details *details)
1287 {
1288         pgd_t *pgd;
1289         unsigned long next;
1290 
1291         if (details && !details->check_mapping && !details->nonlinear_vma)
1292                 details = NULL;
1293 
1294         BUG_ON(addr >= end);
1295         mem_cgroup_uncharge_start();
1296         tlb_start_vma(tlb, vma);
1297         pgd = pgd_offset(vma->vm_mm, addr);
1298         do {
1299                 next = pgd_addr_end(addr, end);
1300                 if (pgd_none_or_clear_bad(pgd))
1301                         continue;
1302                 next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1303         } while (pgd++, addr = next, addr != end);
1304         tlb_end_vma(tlb, vma);
1305         mem_cgroup_uncharge_end();
1306 }
1307 
1308 
1309 static void unmap_single_vma(struct mmu_gather *tlb,
1310                 struct vm_area_struct *vma, unsigned long start_addr,
1311                 unsigned long end_addr,
1312                 struct zap_details *details)
1313 {
1314         unsigned long start = max(vma->vm_start, start_addr);
1315         unsigned long end;
1316 
1317         if (start >= vma->vm_end)
1318                 return;
1319         end = min(vma->vm_end, end_addr);
1320         if (end <= vma->vm_start)
1321                 return;
1322 
1323         if (vma->vm_file)
1324                 uprobe_munmap(vma, start, end);
1325 
1326         if (unlikely(vma->vm_flags & VM_PFNMAP))
1327                 untrack_pfn(vma, 0, 0);
1328 
1329         if (start != end) {
1330                 if (unlikely(is_vm_hugetlb_page(vma))) {
1331                         /*
1332                          * It is undesirable to test vma->vm_file as it
1333                          * should be non-null for valid hugetlb area.
1334                          * However, vm_file will be NULL in the error
1335                          * cleanup path of mmap_region. When
1336                          * hugetlbfs ->mmap method fails,
1337                          * mmap_region() nullifies vma->vm_file
1338                          * before calling this function to clean up.
1339                          * Since no pte has actually been setup, it is
1340                          * safe to do nothing in this case.
1341                          */
1342                         if (vma->vm_file) {
1343                                 mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
1344                                 __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1345                                 mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
1346                         }
1347                 } else
1348                         unmap_page_range(tlb, vma, start, end, details);
1349         }
1350 }
1351 
1352 /**
1353  * unmap_vmas - unmap a range of memory covered by a list of vma's
1354  * @tlb: address of the caller's struct mmu_gather
1355  * @vma: the starting vma
1356  * @start_addr: virtual address at which to start unmapping
1357  * @end_addr: virtual address at which to end unmapping
1358  *
1359  * Unmap all pages in the vma list.
1360  *
1361  * Only addresses between `start' and `end' will be unmapped.
1362  *
1363  * The VMA list must be sorted in ascending virtual address order.
1364  *
1365  * unmap_vmas() assumes that the caller will flush the whole unmapped address
1366  * range after unmap_vmas() returns.  So the only responsibility here is to
1367  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1368  * drops the lock and schedules.
1369  */
1370 void unmap_vmas(struct mmu_gather *tlb,
1371                 struct vm_area_struct *vma, unsigned long start_addr,
1372                 unsigned long end_addr)
1373 {
1374         struct mm_struct *mm = vma->vm_mm;
1375 
1376         mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1377         for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1378                 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1379         mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1380 }
1381 
1382 /**
1383  * zap_page_range - remove user pages in a given range
1384  * @vma: vm_area_struct holding the applicable pages
1385  * @start: starting address of pages to zap
1386  * @size: number of bytes to zap
1387  * @details: details of nonlinear truncation or shared cache invalidation
1388  *
1389  * Caller must protect the VMA list
1390  */
1391 void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1392                 unsigned long size, struct zap_details *details)
1393 {
1394         struct mm_struct *mm = vma->vm_mm;
1395         struct mmu_gather tlb;
1396         unsigned long end = start + size;
1397 
1398         lru_add_drain();
1399         tlb_gather_mmu(&tlb, mm, start, end);
1400         update_hiwater_rss(mm);
1401         mmu_notifier_invalidate_range_start(mm, start, end);
1402         for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1403                 unmap_single_vma(&tlb, vma, start, end, details);
1404         mmu_notifier_invalidate_range_end(mm, start, end);
1405         tlb_finish_mmu(&tlb, start, end);
1406 }
1407 
1408 /**
1409  * zap_page_range_single - remove user pages in a given range
1410  * @vma: vm_area_struct holding the applicable pages
1411  * @address: starting address of pages to zap
1412  * @size: number of bytes to zap
1413  * @details: details of nonlinear truncation or shared cache invalidation
1414  *
1415  * The range must fit into one VMA.
1416  */
1417 static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1418                 unsigned long size, struct zap_details *details)
1419 {
1420         struct mm_struct *mm = vma->vm_mm;
1421         struct mmu_gather tlb;
1422         unsigned long end = address + size;
1423 
1424         lru_add_drain();
1425         tlb_gather_mmu(&tlb, mm, address, end);
1426         update_hiwater_rss(mm);
1427         mmu_notifier_invalidate_range_start(mm, address, end);
1428         unmap_single_vma(&tlb, vma, address, end, details);
1429         mmu_notifier_invalidate_range_end(mm, address, end);
1430         tlb_finish_mmu(&tlb, address, end);
1431 }
1432 
1433 /**
1434  * zap_vma_ptes - remove ptes mapping the vma
1435  * @vma: vm_area_struct holding ptes to be zapped
1436  * @address: starting address of pages to zap
1437  * @size: number of bytes to zap
1438  *
1439  * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1440  *
1441  * The entire address range must be fully contained within the vma.
1442  *
1443  * Returns 0 if successful.
1444  */
1445 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1446                 unsigned long size)
1447 {
1448         if (address < vma->vm_start || address + size > vma->vm_end ||
1449                         !(vma->vm_flags & VM_PFNMAP))
1450                 return -1;
1451         zap_page_range_single(vma, address, size, NULL);
1452         return 0;
1453 }
1454 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1455 
1456 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1457                         spinlock_t **ptl)
1458 {
1459         pgd_t * pgd = pgd_offset(mm, addr);
1460         pud_t * pud = pud_alloc(mm, pgd, addr);
1461         if (pud) {
1462                 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1463                 if (pmd) {
1464                         VM_BUG_ON(pmd_trans_huge(*pmd));
1465                         return pte_alloc_map_lock(mm, pmd, addr, ptl);
1466                 }
1467         }
1468         return NULL;
1469 }
1470 
1471 /*
1472  * This is the old fallback for page remapping.
1473  *
1474  * For historical reasons, it only allows reserved pages. Only
1475  * old drivers should use this, and they needed to mark their
1476  * pages reserved for the old functions anyway.
1477  */
1478 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1479                         struct page *page, pgprot_t prot)
1480 {
1481         struct mm_struct *mm = vma->vm_mm;
1482         int retval;
1483         pte_t *pte;
1484         spinlock_t *ptl;
1485 
1486         retval = -EINVAL;
1487         if (PageAnon(page))
1488                 goto out;
1489         retval = -ENOMEM;
1490         flush_dcache_page(page);
1491         pte = get_locked_pte(mm, addr, &ptl);
1492         if (!pte)
1493                 goto out;
1494         retval = -EBUSY;
1495         if (!pte_none(*pte))
1496                 goto out_unlock;
1497 
1498         /* Ok, finally just insert the thing.. */
1499         get_page(page);
1500         inc_mm_counter_fast(mm, MM_FILEPAGES);
1501         page_add_file_rmap(page);
1502         set_pte_at(mm, addr, pte, mk_pte(page, prot));
1503 
1504         retval = 0;
1505         pte_unmap_unlock(pte, ptl);
1506         return retval;
1507 out_unlock:
1508         pte_unmap_unlock(pte, ptl);
1509 out:
1510         return retval;
1511 }
1512 
1513 /**
1514  * vm_insert_page - insert single page into user vma
1515  * @vma: user vma to map to
1516  * @addr: target user address of this page
1517  * @page: source kernel page
1518  *
1519  * This allows drivers to insert individual pages they've allocated
1520  * into a user vma.
1521  *
1522  * The page has to be a nice clean _individual_ kernel allocation.
1523  * If you allocate a compound page, you need to have marked it as
1524  * such (__GFP_COMP), or manually just split the page up yourself
1525  * (see split_page()).
1526  *
1527  * NOTE! Traditionally this was done with "remap_pfn_range()" which
1528  * took an arbitrary page protection parameter. This doesn't allow
1529  * that. Your vma protection will have to be set up correctly, which
1530  * means that if you want a shared writable mapping, you'd better
1531  * ask for a shared writable mapping!
1532  *
1533  * The page does not need to be reserved.
1534  *
1535  * Usually this function is called from f_op->mmap() handler
1536  * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
1537  * Caller must set VM_MIXEDMAP on vma if it wants to call this
1538  * function from other places, for example from page-fault handler.
1539  */
1540 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1541                         struct page *page)
1542 {
1543         if (addr < vma->vm_start || addr >= vma->vm_end)
1544                 return -EFAULT;
1545         if (!page_count(page))
1546                 return -EINVAL;
1547         if (!(vma->vm_flags & VM_MIXEDMAP)) {
1548                 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
1549                 BUG_ON(vma->vm_flags & VM_PFNMAP);
1550                 vma->vm_flags |= VM_MIXEDMAP;
1551         }
1552         return insert_page(vma, addr, page, vma->vm_page_prot);
1553 }
1554 EXPORT_SYMBOL(vm_insert_page);
1555 
1556 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1557                         unsigned long pfn, pgprot_t prot)
1558 {
1559         struct mm_struct *mm = vma->vm_mm;
1560         int retval;
1561         pte_t *pte, entry;
1562         spinlock_t *ptl;
1563 
1564         retval = -ENOMEM;
1565         pte = get_locked_pte(mm, addr, &ptl);
1566         if (!pte)
1567                 goto out;
1568         retval = -EBUSY;
1569         if (!pte_none(*pte))
1570                 goto out_unlock;
1571 
1572         /* Ok, finally just insert the thing.. */
1573         entry = pte_mkspecial(pfn_pte(pfn, prot));
1574         set_pte_at(mm, addr, pte, entry);
1575         update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1576 
1577         retval = 0;
1578 out_unlock:
1579         pte_unmap_unlock(pte, ptl);
1580 out:
1581         return retval;
1582 }
1583 
1584 /**
1585  * vm_insert_pfn - insert single pfn into user vma
1586  * @vma: user vma to map to
1587  * @addr: target user address of this page
1588  * @pfn: source kernel pfn
1589  *
1590  * Similar to vm_insert_page, this allows drivers to insert individual pages
1591  * they've allocated into a user vma. Same comments apply.
1592  *
1593  * This function should only be called from a vm_ops->fault handler, and
1594  * in that case the handler should return NULL.
1595  *
1596  * vma cannot be a COW mapping.
1597  *
1598  * As this is called only for pages that do not currently exist, we
1599  * do not need to flush old virtual caches or the TLB.
1600  */
1601 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1602                         unsigned long pfn)
1603 {
1604         int ret;
1605         pgprot_t pgprot = vma->vm_page_prot;
1606         /*
1607          * Technically, architectures with pte_special can avoid all these
1608          * restrictions (same for remap_pfn_range).  However we would like
1609          * consistency in testing and feature parity among all, so we should
1610          * try to keep these invariants in place for everybody.
1611          */
1612         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1613         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1614                                                 (VM_PFNMAP|VM_MIXEDMAP));
1615         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1616         BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1617 
1618         if (addr < vma->vm_start || addr >= vma->vm_end)
1619                 return -EFAULT;
1620         if (track_pfn_insert(vma, &pgprot, pfn))
1621                 return -EINVAL;
1622 
1623         ret = insert_pfn(vma, addr, pfn, pgprot);
1624 
1625         return ret;
1626 }
1627 EXPORT_SYMBOL(vm_insert_pfn);
1628 
1629 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1630                         unsigned long pfn)
1631 {
1632         BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1633 
1634         if (addr < vma->vm_start || addr >= vma->vm_end)
1635                 return -EFAULT;
1636 
1637         /*
1638          * If we don't have pte special, then we have to use the pfn_valid()
1639          * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1640          * refcount the page if pfn_valid is true (hence insert_page rather
1641          * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
1642          * without pte special, it would there be refcounted as a normal page.
1643          */
1644         if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
1645                 struct page *page;
1646 
1647                 page = pfn_to_page(pfn);
1648                 return insert_page(vma, addr, page, vma->vm_page_prot);
1649         }
1650         return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
1651 }
1652 EXPORT_SYMBOL(vm_insert_mixed);
1653 
1654 /*
1655  * maps a range of physical memory into the requested pages. the old
1656  * mappings are removed. any references to nonexistent pages results
1657  * in null mappings (currently treated as "copy-on-access")
1658  */
1659 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1660                         unsigned long addr, unsigned long end,
1661                         unsigned long pfn, pgprot_t prot)
1662 {
1663         pte_t *pte;
1664         spinlock_t *ptl;
1665 
1666         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1667         if (!pte)
1668                 return -ENOMEM;
1669         arch_enter_lazy_mmu_mode();
1670         do {
1671                 BUG_ON(!pte_none(*pte));
1672                 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1673                 pfn++;
1674         } while (pte++, addr += PAGE_SIZE, addr != end);
1675         arch_leave_lazy_mmu_mode();
1676         pte_unmap_unlock(pte - 1, ptl);
1677         return 0;
1678 }
1679 
1680 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1681                         unsigned long addr, unsigned long end,
1682                         unsigned long pfn, pgprot_t prot)
1683 {
1684         pmd_t *pmd;
1685         unsigned long next;
1686 
1687         pfn -= addr >> PAGE_SHIFT;
1688         pmd = pmd_alloc(mm, pud, addr);
1689         if (!pmd)
1690                 return -ENOMEM;
1691         VM_BUG_ON(pmd_trans_huge(*pmd));
1692         do {
1693                 next = pmd_addr_end(addr, end);
1694                 if (remap_pte_range(mm, pmd, addr, next,
1695                                 pfn + (addr >> PAGE_SHIFT), prot))
1696                         return -ENOMEM;
1697         } while (pmd++, addr = next, addr != end);
1698         return 0;
1699 }
1700 
1701 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1702                         unsigned long addr, unsigned long end,
1703                         unsigned long pfn, pgprot_t prot)
1704 {
1705         pud_t *pud;
1706         unsigned long next;
1707 
1708         pfn -= addr >> PAGE_SHIFT;
1709         pud = pud_alloc(mm, pgd, addr);
1710         if (!pud)
1711                 return -ENOMEM;
1712         do {
1713                 next = pud_addr_end(addr, end);
1714                 if (remap_pmd_range(mm, pud, addr, next,
1715                                 pfn + (addr >> PAGE_SHIFT), prot))
1716                         return -ENOMEM;
1717         } while (pud++, addr = next, addr != end);
1718         return 0;
1719 }
1720 
1721 /**
1722  * remap_pfn_range - remap kernel memory to userspace
1723  * @vma: user vma to map to
1724  * @addr: target user address to start at
1725  * @pfn: physical address of kernel memory
1726  * @size: size of map area
1727  * @prot: page protection flags for this mapping
1728  *
1729  *  Note: this is only safe if the mm semaphore is held when called.
1730  */
1731 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1732                     unsigned long pfn, unsigned long size, pgprot_t prot)
1733 {
1734         pgd_t *pgd;
1735         unsigned long next;
1736         unsigned long end = addr + PAGE_ALIGN(size);
1737         struct mm_struct *mm = vma->vm_mm;
1738         int err;
1739 
1740         /*
1741          * Physically remapped pages are special. Tell the
1742          * rest of the world about it:
1743          *   VM_IO tells people not to look at these pages
1744          *      (accesses can have side effects).
1745          *   VM_PFNMAP tells the core MM that the base pages are just
1746          *      raw PFN mappings, and do not have a "struct page" associated
1747          *      with them.
1748          *   VM_DONTEXPAND
1749          *      Disable vma merging and expanding with mremap().
1750          *   VM_DONTDUMP
1751          *      Omit vma from core dump, even when VM_IO turned off.
1752          *
1753          * There's a horrible special case to handle copy-on-write
1754          * behaviour that some programs depend on. We mark the "original"
1755          * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1756          * See vm_normal_page() for details.
1757          */
1758         if (is_cow_mapping(vma->vm_flags)) {
1759                 if (addr != vma->vm_start || end != vma->vm_end)
1760                         return -EINVAL;
1761                 vma->vm_pgoff = pfn;
1762         }
1763 
1764         err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
1765         if (err)
1766                 return -EINVAL;
1767 
1768         vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1769 
1770         BUG_ON(addr >= end);
1771         pfn -= addr >> PAGE_SHIFT;
1772         pgd = pgd_offset(mm, addr);
1773         flush_cache_range(vma, addr, end);
1774         do {
1775                 next = pgd_addr_end(addr, end);
1776                 err = remap_pud_range(mm, pgd, addr, next,
1777                                 pfn + (addr >> PAGE_SHIFT), prot);
1778                 if (err)
1779                         break;
1780         } while (pgd++, addr = next, addr != end);
1781 
1782         if (err)
1783                 untrack_pfn(vma, pfn, PAGE_ALIGN(size));
1784 
1785         return err;
1786 }
1787 EXPORT_SYMBOL(remap_pfn_range);
1788 
1789 /**
1790  * vm_iomap_memory - remap memory to userspace
1791  * @vma: user vma to map to
1792  * @start: start of area
1793  * @len: size of area
1794  *
1795  * This is a simplified io_remap_pfn_range() for common driver use. The
1796  * driver just needs to give us the physical memory range to be mapped,
1797  * we'll figure out the rest from the vma information.
1798  *
1799  * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
1800  * whatever write-combining details or similar.
1801  */
1802 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1803 {
1804         unsigned long vm_len, pfn, pages;
1805 
1806         /* Check that the physical memory area passed in looks valid */
1807         if (start + len < start)
1808                 return -EINVAL;
1809         /*
1810          * You *really* shouldn't map things that aren't page-aligned,
1811          * but we've historically allowed it because IO memory might
1812          * just have smaller alignment.
1813          */
1814         len += start & ~PAGE_MASK;
1815         pfn = start >> PAGE_SHIFT;
1816         pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
1817         if (pfn + pages < pfn)
1818                 return -EINVAL;
1819 
1820         /* We start the mapping 'vm_pgoff' pages into the area */
1821         if (vma->vm_pgoff > pages)
1822                 return -EINVAL;
1823         pfn += vma->vm_pgoff;
1824         pages -= vma->vm_pgoff;
1825 
1826         /* Can we fit all of the mapping? */
1827         vm_len = vma->vm_end - vma->vm_start;
1828         if (vm_len >> PAGE_SHIFT > pages)
1829                 return -EINVAL;
1830 
1831         /* Ok, let it rip */
1832         return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1833 }
1834 EXPORT_SYMBOL(vm_iomap_memory);
1835 
1836 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
1837                                      unsigned long addr, unsigned long end,
1838                                      pte_fn_t fn, void *data)
1839 {
1840         pte_t *pte;
1841         int err;
1842         pgtable_t token;
1843         spinlock_t *uninitialized_var(ptl);
1844 
1845         pte = (mm == &init_mm) ?
1846                 pte_alloc_kernel(pmd, addr) :
1847                 pte_alloc_map_lock(mm, pmd, addr, &ptl);
1848         if (!pte)
1849                 return -ENOMEM;
1850 
1851         BUG_ON(pmd_huge(*pmd));
1852 
1853         arch_enter_lazy_mmu_mode();
1854 
1855         token = pmd_pgtable(*pmd);
1856 
1857         do {
1858                 err = fn(pte++, token, addr, data);
1859                 if (err)
1860                         break;
1861         } while (addr += PAGE_SIZE, addr != end);
1862 
1863         arch_leave_lazy_mmu_mode();
1864 
1865         if (mm != &init_mm)
1866                 pte_unmap_unlock(pte-1, ptl);
1867         return err;
1868 }
1869 
1870 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
1871                                      unsigned long addr, unsigned long end,
1872                                      pte_fn_t fn, void *data)
1873 {
1874         pmd_t *pmd;
1875         unsigned long next;
1876         int err;
1877 
1878         BUG_ON(pud_huge(*pud));
1879 
1880         pmd = pmd_alloc(mm, pud, addr);
1881         if (!pmd)
1882                 return -ENOMEM;
1883         do {
1884                 next = pmd_addr_end(addr, end);
1885                 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
1886                 if (err)
1887                         break;
1888         } while (pmd++, addr = next, addr != end);
1889         return err;
1890 }
1891 
1892 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
1893                                      unsigned long addr, unsigned long end,
1894                                      pte_fn_t fn, void *data)
1895 {
1896         pud_t *pud;
1897         unsigned long next;
1898         int err;
1899 
1900         pud = pud_alloc(mm, pgd, addr);
1901         if (!pud)
1902                 return -ENOMEM;
1903         do {
1904                 next = pud_addr_end(addr, end);
1905                 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
1906                 if (err)
1907                         break;
1908         } while (pud++, addr = next, addr != end);
1909         return err;
1910 }
1911 
1912 /*
1913  * Scan a region of virtual memory, filling in page tables as necessary
1914  * and calling a provided function on each leaf page table.
1915  */
1916 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
1917                         unsigned long size, pte_fn_t fn, void *data)
1918 {
1919         pgd_t *pgd;
1920         unsigned long next;
1921         unsigned long end = addr + size;
1922         int err;
1923 
1924         BUG_ON(addr >= end);
1925         pgd = pgd_offset(mm, addr);
1926         do {
1927                 next = pgd_addr_end(addr, end);
1928                 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
1929                 if (err)
1930                         break;
1931         } while (pgd++, addr = next, addr != end);
1932 
1933         return err;
1934 }
1935 EXPORT_SYMBOL_GPL(apply_to_page_range);
1936 
1937 /*
1938  * handle_pte_fault chooses page fault handler according to an entry
1939  * which was read non-atomically.  Before making any commitment, on
1940  * those architectures or configurations (e.g. i386 with PAE) which
1941  * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
1942  * must check under lock before unmapping the pte and proceeding
1943  * (but do_wp_page is only called after already making such a check;
1944  * and do_anonymous_page can safely check later on).
1945  */
1946 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1947                                 pte_t *page_table, pte_t orig_pte)
1948 {
1949         int same = 1;
1950 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1951         if (sizeof(pte_t) > sizeof(unsigned long)) {
1952                 spinlock_t *ptl = pte_lockptr(mm, pmd);
1953                 spin_lock(ptl);
1954                 same = pte_same(*page_table, orig_pte);
1955                 spin_unlock(ptl);
1956         }
1957 #endif
1958         pte_unmap(page_table);
1959         return same;
1960 }
1961 
1962 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1963 {
1964         debug_dma_assert_idle(src);
1965 
1966         /*
1967          * If the source page was a PFN mapping, we don't have
1968          * a "struct page" for it. We do a best-effort copy by
1969          * just copying from the original user address. If that
1970          * fails, we just zero-fill it. Live with it.
1971          */
1972         if (unlikely(!src)) {
1973                 void *kaddr = kmap_atomic(dst);
1974                 void __user *uaddr = (void __user *)(va & PAGE_MASK);
1975 
1976                 /*
1977                  * This really shouldn't fail, because the page is there
1978                  * in the page tables. But it might just be unreadable,
1979                  * in which case we just give up and fill the result with
1980                  * zeroes.
1981                  */
1982                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1983                         clear_page(kaddr);
1984                 kunmap_atomic(kaddr);
1985                 flush_dcache_page(dst);
1986         } else
1987                 copy_user_highpage(dst, src, va, vma);
1988 }
1989 
1990 /*
1991  * Notify the address space that the page is about to become writable so that
1992  * it can prohibit this or wait for the page to get into an appropriate state.
1993  *
1994  * We do this without the lock held, so that it can sleep if it needs to.
1995  */
1996 static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page,
1997                unsigned long address)
1998 {
1999         struct vm_fault vmf;
2000         int ret;
2001 
2002         vmf.virtual_address = (void __user *)(address & PAGE_MASK);
2003         vmf.pgoff = page->index;
2004         vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2005         vmf.page = page;
2006 
2007         ret = vma->vm_ops->page_mkwrite(vma, &vmf);
2008         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2009                 return ret;
2010         if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2011                 lock_page(page);
2012                 if (!page->mapping) {
2013                         unlock_page(page);
2014                         return 0; /* retry */
2015                 }
2016                 ret |= VM_FAULT_LOCKED;
2017         } else
2018                 VM_BUG_ON_PAGE(!PageLocked(page), page);
2019         return ret;
2020 }
2021 
2022 /*
2023  * This routine handles present pages, when users try to write
2024  * to a shared page. It is done by copying the page to a new address
2025  * and decrementing the shared-page counter for the old page.
2026  *
2027  * Note that this routine assumes that the protection checks have been
2028  * done by the caller (the low-level page fault routine in most cases).
2029  * Thus we can safely just mark it writable once we've done any necessary
2030  * COW.
2031  *
2032  * We also mark the page dirty at this point even though the page will
2033  * change only once the write actually happens. This avoids a few races,
2034  * and potentially makes it more efficient.
2035  *
2036  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2037  * but allow concurrent faults), with pte both mapped and locked.
2038  * We return with mmap_sem still held, but pte unmapped and unlocked.
2039  */
2040 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2041                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2042                 spinlock_t *ptl, pte_t orig_pte)
2043         __releases(ptl)
2044 {
2045         struct page *old_page, *new_page = NULL;
2046         pte_t entry;
2047         int ret = 0;
2048         int page_mkwrite = 0;
2049         struct page *dirty_page = NULL;
2050         unsigned long mmun_start = 0;   /* For mmu_notifiers */
2051         unsigned long mmun_end = 0;     /* For mmu_notifiers */
2052 
2053         old_page = vm_normal_page(vma, address, orig_pte);
2054         if (!old_page) {
2055                 /*
2056                  * VM_MIXEDMAP !pfn_valid() case
2057                  *
2058                  * We should not cow pages in a shared writeable mapping.
2059                  * Just mark the pages writable as we can't do any dirty
2060                  * accounting on raw pfn maps.
2061                  */
2062                 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2063                                      (VM_WRITE|VM_SHARED))
2064                         goto reuse;
2065                 goto gotten;
2066         }
2067 
2068         /*
2069          * Take out anonymous pages first, anonymous shared vmas are
2070          * not dirty accountable.
2071          */
2072         if (PageAnon(old_page) && !PageKsm(old_page)) {
2073                 if (!trylock_page(old_page)) {
2074                         page_cache_get(old_page);
2075                         pte_unmap_unlock(page_table, ptl);
2076                         lock_page(old_page);
2077                         page_table = pte_offset_map_lock(mm, pmd, address,
2078                                                          &ptl);
2079                         if (!pte_same(*page_table, orig_pte)) {
2080                                 unlock_page(old_page);
2081                                 goto unlock;
2082                         }
2083                         page_cache_release(old_page);
2084                 }
2085                 if (reuse_swap_page(old_page)) {
2086                         /*
2087                          * The page is all ours.  Move it to our anon_vma so
2088                          * the rmap code will not search our parent or siblings.
2089                          * Protected against the rmap code by the page lock.
2090                          */
2091                         page_move_anon_rmap(old_page, vma, address);
2092                         unlock_page(old_page);
2093                         goto reuse;
2094                 }
2095                 unlock_page(old_page);
2096         } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2097                                         (VM_WRITE|VM_SHARED))) {
2098                 /*
2099                  * Only catch write-faults on shared writable pages,
2100                  * read-only shared pages can get COWed by
2101                  * get_user_pages(.write=1, .force=1).
2102                  */
2103                 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2104                         int tmp;
2105                         page_cache_get(old_page);
2106                         pte_unmap_unlock(page_table, ptl);
2107                         tmp = do_page_mkwrite(vma, old_page, address);
2108                         if (unlikely(!tmp || (tmp &
2109                                         (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2110                                 page_cache_release(old_page);
2111                                 return tmp;
2112                         }
2113                         /*
2114                          * Since we dropped the lock we need to revalidate
2115                          * the PTE as someone else may have changed it.  If
2116                          * they did, we just return, as we can count on the
2117                          * MMU to tell us if they didn't also make it writable.
2118                          */
2119                         page_table = pte_offset_map_lock(mm, pmd, address,
2120                                                          &ptl);
2121                         if (!pte_same(*page_table, orig_pte)) {
2122                                 unlock_page(old_page);
2123                                 goto unlock;
2124                         }
2125 
2126                         page_mkwrite = 1;
2127                 }
2128                 dirty_page = old_page;
2129                 get_page(dirty_page);
2130 
2131 reuse:
2132                 /*
2133                  * Clear the pages cpupid information as the existing
2134                  * information potentially belongs to a now completely
2135                  * unrelated process.
2136                  */
2137                 if (old_page)
2138                         page_cpupid_xchg_last(old_page, (1 << LAST_CPUPID_SHIFT) - 1);
2139 
2140                 flush_cache_page(vma, address, pte_pfn(orig_pte));
2141                 entry = pte_mkyoung(orig_pte);
2142                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2143                 if (ptep_set_access_flags(vma, address, page_table, entry,1))
2144                         update_mmu_cache(vma, address, page_table);
2145                 pte_unmap_unlock(page_table, ptl);
2146                 ret |= VM_FAULT_WRITE;
2147 
2148                 if (!dirty_page)
2149                         return ret;
2150 
2151                 /*
2152                  * Yes, Virginia, this is actually required to prevent a race
2153                  * with clear_page_dirty_for_io() from clearing the page dirty
2154                  * bit after it clear all dirty ptes, but before a racing
2155                  * do_wp_page installs a dirty pte.
2156                  *
2157                  * do_shared_fault is protected similarly.
2158                  */
2159                 if (!page_mkwrite) {
2160                         wait_on_page_locked(dirty_page);
2161                         set_page_dirty_balance(dirty_page);
2162                         /* file_update_time outside page_lock */
2163                         if (vma->vm_file)
2164                                 file_update_time(vma->vm_file);
2165                 }
2166                 put_page(dirty_page);
2167                 if (page_mkwrite) {
2168                         struct address_space *mapping = dirty_page->mapping;
2169 
2170                         set_page_dirty(dirty_page);
2171                         unlock_page(dirty_page);
2172                         page_cache_release(dirty_page);
2173                         if (mapping)    {
2174                                 /*
2175                                  * Some device drivers do not set page.mapping
2176                                  * but still dirty their pages
2177                                  */
2178                                 balance_dirty_pages_ratelimited(mapping);
2179                         }
2180                 }
2181 
2182                 return ret;
2183         }
2184 
2185         /*
2186          * Ok, we need to copy. Oh, well..
2187          */
2188         page_cache_get(old_page);
2189 gotten:
2190         pte_unmap_unlock(page_table, ptl);
2191 
2192         if (unlikely(anon_vma_prepare(vma)))
2193                 goto oom;
2194 
2195         if (is_zero_pfn(pte_pfn(orig_pte))) {
2196                 new_page = alloc_zeroed_user_highpage_movable(vma, address);
2197                 if (!new_page)
2198                         goto oom;
2199         } else {
2200                 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2201                 if (!new_page)
2202                         goto oom;
2203                 cow_user_page(new_page, old_page, address, vma);
2204         }
2205         __SetPageUptodate(new_page);
2206 
2207         if (mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL))
2208                 goto oom_free_new;
2209 
2210         mmun_start  = address & PAGE_MASK;
2211         mmun_end    = mmun_start + PAGE_SIZE;
2212         mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2213 
2214         /*
2215          * Re-check the pte - we dropped the lock
2216          */
2217         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2218         if (likely(pte_same(*page_table, orig_pte))) {
2219                 if (old_page) {
2220                         if (!PageAnon(old_page)) {
2221                                 dec_mm_counter_fast(mm, MM_FILEPAGES);
2222                                 inc_mm_counter_fast(mm, MM_ANONPAGES);
2223                         }
2224                 } else
2225                         inc_mm_counter_fast(mm, MM_ANONPAGES);
2226                 flush_cache_page(vma, address, pte_pfn(orig_pte));
2227                 entry = mk_pte(new_page, vma->vm_page_prot);
2228                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2229                 /*
2230                  * Clear the pte entry and flush it first, before updating the
2231                  * pte with the new entry. This will avoid a race condition
2232                  * seen in the presence of one thread doing SMC and another
2233                  * thread doing COW.
2234                  */
2235                 ptep_clear_flush(vma, address, page_table);
2236                 page_add_new_anon_rmap(new_page, vma, address);
2237                 /*
2238                  * We call the notify macro here because, when using secondary
2239                  * mmu page tables (such as kvm shadow page tables), we want the
2240                  * new page to be mapped directly into the secondary page table.
2241                  */
2242                 set_pte_at_notify(mm, address, page_table, entry);
2243                 update_mmu_cache(vma, address, page_table);
2244                 if (old_page) {
2245                         /*
2246                          * Only after switching the pte to the new page may
2247                          * we remove the mapcount here. Otherwise another
2248                          * process may come and find the rmap count decremented
2249                          * before the pte is switched to the new page, and
2250                          * "reuse" the old page writing into it while our pte
2251                          * here still points into it and can be read by other
2252                          * threads.
2253                          *
2254                          * The critical issue is to order this
2255                          * page_remove_rmap with the ptp_clear_flush above.
2256                          * Those stores are ordered by (if nothing else,)
2257                          * the barrier present in the atomic_add_negative
2258                          * in page_remove_rmap.
2259                          *
2260                          * Then the TLB flush in ptep_clear_flush ensures that
2261                          * no process can access the old page before the
2262                          * decremented mapcount is visible. And the old page
2263                          * cannot be reused until after the decremented
2264                          * mapcount is visible. So transitively, TLBs to
2265                          * old page will be flushed before it can be reused.
2266                          */
2267                         page_remove_rmap(old_page);
2268                 }
2269 
2270                 /* Free the old page.. */
2271                 new_page = old_page;
2272                 ret |= VM_FAULT_WRITE;
2273         } else
2274                 mem_cgroup_uncharge_page(new_page);
2275 
2276         if (new_page)
2277                 page_cache_release(new_page);
2278 unlock:
2279         pte_unmap_unlock(page_table, ptl);
2280         if (mmun_end > mmun_start)
2281                 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2282         if (old_page) {
2283                 /*
2284                  * Don't let another task, with possibly unlocked vma,
2285                  * keep the mlocked page.
2286                  */
2287                 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
2288                         lock_page(old_page);    /* LRU manipulation */
2289                         munlock_vma_page(old_page);
2290                         unlock_page(old_page);
2291                 }
2292                 page_cache_release(old_page);
2293         }
2294         return ret;
2295 oom_free_new:
2296         page_cache_release(new_page);
2297 oom:
2298         if (old_page)
2299                 page_cache_release(old_page);
2300         return VM_FAULT_OOM;
2301 }
2302 
2303 static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2304                 unsigned long start_addr, unsigned long end_addr,
2305                 struct zap_details *details)
2306 {
2307         zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2308 }
2309 
2310 static inline void unmap_mapping_range_tree(struct rb_root *root,
2311                                             struct zap_details *details)
2312 {
2313         struct vm_area_struct *vma;
2314         pgoff_t vba, vea, zba, zea;
2315 
2316         vma_interval_tree_foreach(vma, root,
2317                         details->first_index, details->last_index) {
2318 
2319                 vba = vma->vm_pgoff;
2320                 vea = vba + vma_pages(vma) - 1;
2321                 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2322                 zba = details->first_index;
2323                 if (zba < vba)
2324                         zba = vba;
2325                 zea = details->last_index;
2326                 if (zea > vea)
2327                         zea = vea;
2328 
2329                 unmap_mapping_range_vma(vma,
2330                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2331                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2332                                 details);
2333         }
2334 }
2335 
2336 static inline void unmap_mapping_range_list(struct list_head *head,
2337                                             struct zap_details *details)
2338 {
2339         struct vm_area_struct *vma;
2340 
2341         /*
2342          * In nonlinear VMAs there is no correspondence between virtual address
2343          * offset and file offset.  So we must perform an exhaustive search
2344          * across *all* the pages in each nonlinear VMA, not just the pages
2345          * whose virtual address lies outside the file truncation point.
2346          */
2347         list_for_each_entry(vma, head, shared.nonlinear) {
2348                 details->nonlinear_vma = vma;
2349                 unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
2350         }
2351 }
2352 
2353 /**
2354  * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2355  * @mapping: the address space containing mmaps to be unmapped.
2356  * @holebegin: byte in first page to unmap, relative to the start of
2357  * the underlying file.  This will be rounded down to a PAGE_SIZE
2358  * boundary.  Note that this is different from truncate_pagecache(), which
2359  * must keep the partial page.  In contrast, we must get rid of
2360  * partial pages.
2361  * @holelen: size of prospective hole in bytes.  This will be rounded
2362  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
2363  * end of the file.
2364  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2365  * but 0 when invalidating pagecache, don't throw away private data.
2366  */
2367 void unmap_mapping_range(struct address_space *mapping,
2368                 loff_t const holebegin, loff_t const holelen, int even_cows)
2369 {
2370         struct zap_details details;
2371         pgoff_t hba = holebegin >> PAGE_SHIFT;
2372         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2373 
2374         /* Check for overflow. */
2375         if (sizeof(holelen) > sizeof(hlen)) {
2376                 long long holeend =
2377                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2378                 if (holeend & ~(long long)ULONG_MAX)
2379                         hlen = ULONG_MAX - hba + 1;
2380         }
2381 
2382         details.check_mapping = even_cows? NULL: mapping;
2383         details.nonlinear_vma = NULL;
2384         details.first_index = hba;
2385         details.last_index = hba + hlen - 1;
2386         if (details.last_index < details.first_index)
2387                 details.last_index = ULONG_MAX;
2388 
2389 
2390         mutex_lock(&mapping->i_mmap_mutex);
2391         if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
2392                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2393         if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2394                 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2395         mutex_unlock(&mapping->i_mmap_mutex);
2396 }
2397 EXPORT_SYMBOL(unmap_mapping_range);
2398 
2399 /*
2400  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2401  * but allow concurrent faults), and pte mapped but not yet locked.
2402  * We return with mmap_sem still held, but pte unmapped and unlocked.
2403  */
2404 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2405                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2406                 unsigned int flags, pte_t orig_pte)
2407 {
2408         spinlock_t *ptl;
2409         struct page *page, *swapcache;
2410         swp_entry_t entry;
2411         pte_t pte;
2412         int locked;
2413         struct mem_cgroup *ptr;
2414         int exclusive = 0;
2415         int ret = 0;
2416 
2417         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2418                 goto out;
2419 
2420         entry = pte_to_swp_entry(orig_pte);
2421         if (unlikely(non_swap_entry(entry))) {
2422                 if (is_migration_entry(entry)) {
2423                         migration_entry_wait(mm, pmd, address);
2424                 } else if (is_hwpoison_entry(entry)) {
2425                         ret = VM_FAULT_HWPOISON;
2426                 } else {
2427                         print_bad_pte(vma, address, orig_pte, NULL);
2428                         ret = VM_FAULT_SIGBUS;
2429                 }
2430                 goto out;
2431         }
2432         delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2433         page = lookup_swap_cache(entry);
2434         if (!page) {
2435                 page = swapin_readahead(entry,
2436                                         GFP_HIGHUSER_MOVABLE, vma, address);
2437                 if (!page) {
2438                         /*
2439                          * Back out if somebody else faulted in this pte
2440                          * while we released the pte lock.
2441                          */
2442                         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2443                         if (likely(pte_same(*page_table, orig_pte)))
2444                                 ret = VM_FAULT_OOM;
2445                         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2446                         goto unlock;
2447                 }
2448 
2449                 /* Had to read the page from swap area: Major fault */
2450                 ret = VM_FAULT_MAJOR;
2451                 count_vm_event(PGMAJFAULT);
2452                 mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2453         } else if (PageHWPoison(page)) {
2454                 /*
2455                  * hwpoisoned dirty swapcache pages are kept for killing
2456                  * owner processes (which may be unknown at hwpoison time)
2457                  */
2458                 ret = VM_FAULT_HWPOISON;
2459                 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2460                 swapcache = page;
2461                 goto out_release;
2462         }
2463 
2464         swapcache = page;
2465         locked = lock_page_or_retry(page, mm, flags);
2466 
2467         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2468         if (!locked) {
2469                 ret |= VM_FAULT_RETRY;
2470                 goto out_release;
2471         }
2472 
2473         /*
2474          * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2475          * release the swapcache from under us.  The page pin, and pte_same
2476          * test below, are not enough to exclude that.  Even if it is still
2477          * swapcache, we need to check that the page's swap has not changed.
2478          */
2479         if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
2480                 goto out_page;
2481 
2482         page = ksm_might_need_to_copy(page, vma, address);
2483         if (unlikely(!page)) {
2484                 ret = VM_FAULT_OOM;
2485                 page = swapcache;
2486                 goto out_page;
2487         }
2488 
2489         if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2490                 ret = VM_FAULT_OOM;
2491                 goto out_page;
2492         }
2493 
2494         /*
2495          * Back out if somebody else already faulted in this pte.
2496          */
2497         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2498         if (unlikely(!pte_same(*page_table, orig_pte)))
2499                 goto out_nomap;
2500 
2501         if (unlikely(!PageUptodate(page))) {
2502                 ret = VM_FAULT_SIGBUS;
2503                 goto out_nomap;
2504         }
2505 
2506         /*
2507          * The page isn't present yet, go ahead with the fault.
2508          *
2509          * Be careful about the sequence of operations here.
2510          * To get its accounting right, reuse_swap_page() must be called
2511          * while the page is counted on swap but not yet in mapcount i.e.
2512          * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2513          * must be called after the swap_free(), or it will never succeed.
2514          * Because delete_from_swap_page() may be called by reuse_swap_page(),
2515          * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
2516          * in page->private. In this case, a record in swap_cgroup  is silently
2517          * discarded at swap_free().
2518          */
2519 
2520         inc_mm_counter_fast(mm, MM_ANONPAGES);
2521         dec_mm_counter_fast(mm, MM_SWAPENTS);
2522         pte = mk_pte(page, vma->vm_page_prot);
2523         if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
2524                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2525                 flags &= ~FAULT_FLAG_WRITE;
2526                 ret |= VM_FAULT_WRITE;
2527                 exclusive = 1;
2528         }
2529         flush_icache_page(vma, page);
2530         if (pte_swp_soft_dirty(orig_pte))
2531                 pte = pte_mksoft_dirty(pte);
2532         set_pte_at(mm, address, page_table, pte);
2533         if (page == swapcache)
2534                 do_page_add_anon_rmap(page, vma, address, exclusive);
2535         else /* ksm created a completely new copy */
2536                 page_add_new_anon_rmap(page, vma, address);
2537         /* It's better to call commit-charge after rmap is established */
2538         mem_cgroup_commit_charge_swapin(page, ptr);
2539 
2540         swap_free(entry);
2541         if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2542                 try_to_free_swap(page);
2543         unlock_page(page);
2544         if (page != swapcache) {
2545                 /*
2546                  * Hold the lock to avoid the swap entry to be reused
2547                  * until we take the PT lock for the pte_same() check
2548                  * (to avoid false positives from pte_same). For
2549                  * further safety release the lock after the swap_free
2550                  * so that the swap count won't change under a
2551                  * parallel locked swapcache.
2552                  */
2553                 unlock_page(swapcache);
2554                 page_cache_release(swapcache);
2555         }
2556 
2557         if (flags & FAULT_FLAG_WRITE) {
2558                 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
2559                 if (ret & VM_FAULT_ERROR)
2560                         ret &= VM_FAULT_ERROR;
2561                 goto out;
2562         }
2563 
2564         /* No need to invalidate - it was non-present before */
2565         update_mmu_cache(vma, address, page_table);
2566 unlock:
2567         pte_unmap_unlock(page_table, ptl);
2568 out:
2569         return ret;
2570 out_nomap:
2571         mem_cgroup_cancel_charge_swapin(ptr);
2572         pte_unmap_unlock(page_table, ptl);
2573 out_page:
2574         unlock_page(page);
2575 out_release:
2576         page_cache_release(page);
2577         if (page != swapcache) {
2578                 unlock_page(swapcache);
2579                 page_cache_release(swapcache);
2580         }
2581         return ret;
2582 }
2583 
2584 /*
2585  * This is like a special single-page "expand_{down|up}wards()",
2586  * except we must first make sure that 'address{-|+}PAGE_SIZE'
2587  * doesn't hit another vma.
2588  */
2589 static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
2590 {
2591         address &= PAGE_MASK;
2592         if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
2593                 struct vm_area_struct *prev = vma->vm_prev;
2594 
2595                 /*
2596                  * Is there a mapping abutting this one below?
2597                  *
2598                  * That's only ok if it's the same stack mapping
2599                  * that has gotten split..
2600                  */
2601                 if (prev && prev->vm_end == address)
2602                         return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
2603 
2604                 expand_downwards(vma, address - PAGE_SIZE);
2605         }
2606         if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
2607                 struct vm_area_struct *next = vma->vm_next;
2608 
2609                 /* As VM_GROWSDOWN but s/below/above/ */
2610                 if (next && next->vm_start == address + PAGE_SIZE)
2611                         return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
2612 
2613                 expand_upwards(vma, address + PAGE_SIZE);
2614         }
2615         return 0;
2616 }
2617 
2618 /*
2619  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2620  * but allow concurrent faults), and pte mapped but not yet locked.
2621  * We return with mmap_sem still held, but pte unmapped and unlocked.
2622  */
2623 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
2624                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2625                 unsigned int flags)
2626 {
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_SIGBUS;
2636 
2637         /* Use the zero-page for reads */
2638         if (!(flags & FAULT_FLAG_WRITE)) {
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_charge_anon(page, mm, GFP_KERNEL))
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 setpte:
2674         set_pte_at(mm, address, page_table, entry);
2675 
2676         /* No need to invalidate - it was non-present before */
2677         update_mmu_cache(vma, address, page_table);
2678 unlock:
2679         pte_unmap_unlock(page_table, ptl);
2680         return 0;
2681 release:
2682         mem_cgroup_uncharge_page(page);
2683         page_cache_release(page);
2684         goto unlock;
2685 oom_free_page:
2686         page_cache_release(page);
2687 oom:
2688         return VM_FAULT_OOM;
2689 }
2690 
2691 static int __do_fault(struct vm_area_struct *vma, unsigned long address,
2692                 pgoff_t pgoff, unsigned int flags, struct page **page)
2693 {
2694         struct vm_fault vmf;
2695         int ret;
2696 
2697         vmf.virtual_address = (void __user *)(address & PAGE_MASK);
2698         vmf.pgoff = pgoff;
2699         vmf.flags = flags;
2700         vmf.page = NULL;
2701 
2702         ret = vma->vm_ops->fault(vma, &vmf);
2703         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
2704                 return ret;
2705 
2706         if (unlikely(PageHWPoison(vmf.page))) {
2707                 if (ret & VM_FAULT_LOCKED)
2708                         unlock_page(vmf.page);
2709                 page_cache_release(vmf.page);
2710                 return VM_FAULT_HWPOISON;
2711         }
2712 
2713         if (unlikely(!(ret & VM_FAULT_LOCKED)))
2714                 lock_page(vmf.page);
2715         else
2716                 VM_BUG_ON_PAGE(!PageLocked(vmf.page), vmf.page);
2717 
2718         *page = vmf.page;
2719         return ret;
2720 }
2721 
2722 /**
2723  * do_set_pte - setup new PTE entry for given page and add reverse page mapping.
2724  *
2725  * @vma: virtual memory area
2726  * @address: user virtual address
2727  * @page: page to map
2728  * @pte: pointer to target page table entry
2729  * @write: true, if new entry is writable
2730  * @anon: true, if it's anonymous page
2731  *
2732  * Caller must hold page table lock relevant for @pte.
2733  *
2734  * Target users are page handler itself and implementations of
2735  * vm_ops->map_pages.
2736  */
2737 void do_set_pte(struct vm_area_struct *vma, unsigned long address,
2738                 struct page *page, pte_t *pte, bool write, bool anon)
2739 {
2740         pte_t entry;
2741 
2742         flush_icache_page(vma, page);
2743         entry = mk_pte(page, vma->vm_page_prot);
2744         if (write)
2745                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2746         else if (pte_file(*pte) && pte_file_soft_dirty(*pte))
2747                 pte_mksoft_dirty(entry);
2748         if (anon) {
2749                 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
2750                 page_add_new_anon_rmap(page, vma, address);
2751         } else {
2752                 inc_mm_counter_fast(vma->vm_mm, MM_FILEPAGES);
2753                 page_add_file_rmap(page);
2754         }
2755         set_pte_at(vma->vm_mm, address, pte, entry);
2756 
2757         /* no need to invalidate: a not-present page won't be cached */
2758         update_mmu_cache(vma, address, pte);
2759 }
2760 
2761 static unsigned long fault_around_bytes = rounddown_pow_of_two(65536);
2762 
2763 static inline unsigned long fault_around_pages(void)
2764 {
2765         return fault_around_bytes >> PAGE_SHIFT;
2766 }
2767 
2768 static inline unsigned long fault_around_mask(void)
2769 {
2770         return ~(fault_around_bytes - 1) & PAGE_MASK;
2771 }
2772 
2773 #ifdef CONFIG_DEBUG_FS
2774 static int fault_around_bytes_get(void *data, u64 *val)
2775 {
2776         *val = fault_around_bytes;
2777         return 0;
2778 }
2779 
2780 /*
2781  * fault_around_pages() and fault_around_mask() expects fault_around_bytes
2782  * rounded down to nearest page order. It's what do_fault_around() expects to
2783  * see.
2784  */
2785 static int fault_around_bytes_set(void *data, u64 val)
2786 {
2787         if (val / PAGE_SIZE > PTRS_PER_PTE)
2788                 return -EINVAL;
2789         if (val > PAGE_SIZE)
2790                 fault_around_bytes = rounddown_pow_of_two(val);
2791         else
2792                 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
2793         return 0;
2794 }
2795 DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops,
2796                 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
2797 
2798 static int __init fault_around_debugfs(void)
2799 {
2800         void *ret;
2801 
2802         ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL,
2803                         &fault_around_bytes_fops);
2804         if (!ret)
2805                 pr_warn("Failed to create fault_around_bytes in debugfs");
2806         return 0;
2807 }
2808 late_initcall(fault_around_debugfs);
2809 #endif
2810 
2811 /*
2812  * do_fault_around() tries to map few pages around the fault address. The hope
2813  * is that the pages will be needed soon and this will lower the number of
2814  * faults to handle.
2815  *
2816  * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
2817  * not ready to be mapped: not up-to-date, locked, etc.
2818  *
2819  * This function is called with the page table lock taken. In the split ptlock
2820  * case the page table lock only protects only those entries which belong to
2821  * the page table corresponding to the fault address.
2822  *
2823  * This function doesn't cross the VMA boundaries, in order to call map_pages()
2824  * only once.
2825  *
2826  * fault_around_pages() defines how many pages we'll try to map.
2827  * do_fault_around() expects it to return a power of two less than or equal to
2828  * PTRS_PER_PTE.
2829  *
2830  * The virtual address of the area that we map is naturally aligned to the
2831  * fault_around_pages() value (and therefore to page order).  This way it's
2832  * easier to guarantee that we don't cross page table boundaries.
2833  */
2834 static void do_fault_around(struct vm_area_struct *vma, unsigned long address,
2835                 pte_t *pte, pgoff_t pgoff, unsigned int flags)
2836 {
2837         unsigned long start_addr;
2838         pgoff_t max_pgoff;
2839         struct vm_fault vmf;
2840         int off;
2841 
2842         start_addr = max(address & fault_around_mask(), vma->vm_start);
2843         off = ((address - start_addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
2844         pte -= off;
2845         pgoff -= off;
2846 
2847         /*
2848          *  max_pgoff is either end of page table or end of vma
2849          *  or fault_around_pages() from pgoff, depending what is nearest.
2850          */
2851         max_pgoff = pgoff - ((start_addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
2852                 PTRS_PER_PTE - 1;
2853         max_pgoff = min3(max_pgoff, vma_pages(vma) + vma->vm_pgoff - 1,
2854                         pgoff + fault_around_pages() - 1);
2855 
2856         /* Check if it makes any sense to call ->map_pages */
2857         while (!pte_none(*pte)) {
2858                 if (++pgoff > max_pgoff)
2859                         return;
2860                 start_addr += PAGE_SIZE;
2861                 if (start_addr >= vma->vm_end)
2862                         return;
2863                 pte++;
2864         }
2865 
2866         vmf.virtual_address = (void __user *) start_addr;
2867         vmf.pte = pte;
2868         vmf.pgoff = pgoff;
2869         vmf.max_pgoff = max_pgoff;
2870         vmf.flags = flags;
2871         vma->vm_ops->map_pages(vma, &vmf);
2872 }
2873 
2874 static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2875                 unsigned long address, pmd_t *pmd,
2876                 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
2877 {
2878         struct page *fault_page;
2879         spinlock_t *ptl;
2880         pte_t *pte;
2881         int ret = 0;
2882 
2883         /*
2884          * Let's call ->map_pages() first and use ->fault() as fallback
2885          * if page by the offset is not ready to be mapped (cold cache or
2886          * something).
2887          */
2888         if (vma->vm_ops->map_pages && !(flags & FAULT_FLAG_NONLINEAR) &&
2889             fault_around_pages() > 1) {
2890                 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2891                 do_fault_around(vma, address, pte, pgoff, flags);
2892                 if (!pte_same(*pte, orig_pte))
2893                         goto unlock_out;
2894                 pte_unmap_unlock(pte, ptl);
2895         }
2896 
2897         ret = __do_fault(vma, address, pgoff, flags, &fault_page);
2898         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
2899                 return ret;
2900 
2901         pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2902         if (unlikely(!pte_same(*pte, orig_pte))) {
2903                 pte_unmap_unlock(pte, ptl);
2904                 unlock_page(fault_page);
2905                 page_cache_release(fault_page);
2906                 return ret;
2907         }
2908         do_set_pte(vma, address, fault_page, pte, false, false);
2909         unlock_page(fault_page);
2910 unlock_out:
2911         pte_unmap_unlock(pte, ptl);
2912         return ret;
2913 }
2914 
2915 static int do_cow_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2916                 unsigned long address, pmd_t *pmd,
2917                 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
2918 {
2919         struct page *fault_page, *new_page;
2920         spinlock_t *ptl;
2921         pte_t *pte;
2922         int ret;
2923 
2924         if (unlikely(anon_vma_prepare(vma)))
2925                 return VM_FAULT_OOM;
2926 
2927         new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2928         if (!new_page)
2929                 return VM_FAULT_OOM;
2930 
2931         if (mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL)) {
2932                 page_cache_release(new_page);
2933                 return VM_FAULT_OOM;
2934         }
2935 
2936         ret = __do_fault(vma, address, pgoff, flags, &fault_page);
2937         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
2938                 goto uncharge_out;
2939 
2940         copy_user_highpage(new_page, fault_page, address, vma);
2941         __SetPageUptodate(new_page);
2942 
2943         pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2944         if (unlikely(!pte_same(*pte, orig_pte))) {
2945                 pte_unmap_unlock(pte, ptl);
2946                 unlock_page(fault_page);
2947                 page_cache_release(fault_page);
2948                 goto uncharge_out;
2949         }
2950         do_set_pte(vma, address, new_page, pte, true, true);
2951         pte_unmap_unlock(pte, ptl);
2952         unlock_page(fault_page);
2953         page_cache_release(fault_page);
2954         return ret;
2955 uncharge_out:
2956         mem_cgroup_uncharge_page(new_page);
2957         page_cache_release(new_page);
2958         return ret;
2959 }
2960 
2961 static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2962                 unsigned long address, pmd_t *pmd,
2963                 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
2964 {
2965         struct page *fault_page;
2966         struct address_space *mapping;
2967         spinlock_t *ptl;
2968         pte_t *pte;
2969         int dirtied = 0;
2970         int ret, tmp;
2971 
2972         ret = __do_fault(vma, address, pgoff, flags, &fault_page);
2973         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
2974                 return ret;
2975 
2976         /*
2977          * Check if the backing address space wants to know that the page is
2978          * about to become writable
2979          */
2980         if (vma->vm_ops->page_mkwrite) {
2981                 unlock_page(fault_page);
2982                 tmp = do_page_mkwrite(vma, fault_page, address);
2983                 if (unlikely(!tmp ||
2984                                 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2985                         page_cache_release(fault_page);
2986                         return tmp;
2987                 }
2988         }
2989 
2990         pte = pte_offset_map_lock(mm, pmd, address, &ptl);
2991         if (unlikely(!pte_same(*pte, orig_pte))) {
2992                 pte_unmap_unlock(pte, ptl);
2993                 unlock_page(fault_page);
2994                 page_cache_release(fault_page);
2995                 return ret;
2996         }
2997         do_set_pte(vma, address, fault_page, pte, true, false);
2998         pte_unmap_unlock(pte, ptl);
2999 
3000         if (set_page_dirty(fault_page))
3001                 dirtied = 1;
3002         mapping = fault_page->mapping;
3003         unlock_page(fault_page);
3004         if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) {
3005                 /*
3006                  * Some device drivers do not set page.mapping but still
3007                  * dirty their pages
3008                  */
3009                 balance_dirty_pages_ratelimited(mapping);
3010         }
3011 
3012         /* file_update_time outside page_lock */
3013         if (vma->vm_file && !vma->vm_ops->page_mkwrite)
3014                 file_update_time(vma->vm_file);
3015 
3016         return ret;
3017 }
3018 
3019 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3020                 unsigned long address, pte_t *page_table, pmd_t *pmd,
3021                 unsigned int flags, pte_t orig_pte)
3022 {
3023         pgoff_t pgoff = (((address & PAGE_MASK)
3024                         - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3025 
3026         pte_unmap(page_table);
3027         if (!(flags & FAULT_FLAG_WRITE))
3028                 return do_read_fault(mm, vma, address, pmd, pgoff, flags,
3029                                 orig_pte);
3030         if (!(vma->vm_flags & VM_SHARED))
3031                 return do_cow_fault(mm, vma, address, pmd, pgoff, flags,
3032                                 orig_pte);
3033         return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3034 }
3035 
3036 /*
3037  * Fault of a previously existing named mapping. Repopulate the pte
3038  * from the encoded file_pte if possible. This enables swappable
3039  * nonlinear vmas.
3040  *
3041  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3042  * but allow concurrent faults), and pte mapped but not yet locked.
3043  * We return with mmap_sem still held, but pte unmapped and unlocked.
3044  */
3045 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3046                 unsigned long address, pte_t *page_table, pmd_t *pmd,
3047                 unsigned int flags, pte_t orig_pte)
3048 {
3049         pgoff_t pgoff;
3050 
3051         flags |= FAULT_FLAG_NONLINEAR;
3052 
3053         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3054                 return 0;
3055 
3056         if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3057                 /*
3058                  * Page table corrupted: show pte and kill process.
3059                  */
3060                 print_bad_pte(vma, address, orig_pte, NULL);
3061                 return VM_FAULT_SIGBUS;
3062         }
3063 
3064         pgoff = pte_to_pgoff(orig_pte);
3065         if (!(flags & FAULT_FLAG_WRITE))
3066                 return do_read_fault(mm, vma, address, pmd, pgoff, flags,
3067                                 orig_pte);
3068         if (!(vma->vm_flags & VM_SHARED))
3069                 return do_cow_fault(mm, vma, address, pmd, pgoff, flags,
3070                                 orig_pte);
3071         return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3072 }
3073 
3074 static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3075                                 unsigned long addr, int page_nid,
3076                                 int *flags)
3077 {
3078         get_page(page);
3079 
3080         count_vm_numa_event(NUMA_HINT_FAULTS);
3081         if (page_nid == numa_node_id()) {
3082                 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3083                 *flags |= TNF_FAULT_LOCAL;
3084         }
3085 
3086         return mpol_misplaced(page, vma, addr);
3087 }
3088 
3089 static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
3090                    unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd)
3091 {
3092         struct page *page = NULL;
3093         spinlock_t *ptl;
3094         int page_nid = -1;
3095         int last_cpupid;
3096         int target_nid;
3097         bool migrated = false;
3098         int flags = 0;
3099 
3100         /*
3101         * The "pte" at this point cannot be used safely without
3102         * validation through pte_unmap_same(). It's of NUMA type but
3103         * the pfn may be screwed if the read is non atomic.
3104         *
3105         * ptep_modify_prot_start is not called as this is clearing
3106         * the _PAGE_NUMA bit and it is not really expected that there
3107         * would be concurrent hardware modifications to the PTE.
3108         */
3109         ptl = pte_lockptr(mm, pmd);
3110         spin_lock(ptl);
3111         if (unlikely(!pte_same(*ptep, pte))) {
3112                 pte_unmap_unlock(ptep, ptl);
3113                 goto out;
3114         }
3115 
3116         pte = pte_mknonnuma(pte);
3117         set_pte_at(mm, addr, ptep, pte);
3118         update_mmu_cache(vma, addr, ptep);
3119 
3120         page = vm_normal_page(vma, addr, pte);
3121         if (!page) {
3122                 pte_unmap_unlock(ptep, ptl);
3123                 return 0;
3124         }
3125         BUG_ON(is_zero_pfn(page_to_pfn(page)));
3126 
3127         /*
3128          * Avoid grouping on DSO/COW pages in specific and RO pages
3129          * in general, RO pages shouldn't hurt as much anyway since
3130          * they can be in shared cache state.
3131          */
3132         if (!pte_write(pte))
3133                 flags |= TNF_NO_GROUP;
3134 
3135         /*
3136          * Flag if the page is shared between multiple address spaces. This
3137          * is later used when determining whether to group tasks together
3138          */
3139         if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
3140                 flags |= TNF_SHARED;
3141 
3142         last_cpupid = page_cpupid_last(page);
3143         page_nid = page_to_nid(page);
3144         target_nid = numa_migrate_prep(page, vma, addr, page_nid, &flags);
3145         pte_unmap_unlock(ptep, ptl);
3146         if (target_nid == -1) {
3147                 put_page(page);
3148                 goto out;
3149         }
3150 
3151         /* Migrate to the requested node */
3152         migrated = migrate_misplaced_page(page, vma, target_nid);
3153         if (migrated) {
3154                 page_nid = target_nid;
3155                 flags |= TNF_MIGRATED;
3156         }
3157 
3158 out:
3159         if (page_nid != -1)
3160                 task_numa_fault(last_cpupid, page_nid, 1, flags);
3161         return 0;
3162 }
3163 
3164 /*
3165  * These routines also need to handle stuff like marking pages dirty
3166  * and/or accessed for architectures that don't do it in hardware (most
3167  * RISC architectures).  The early dirtying is also good on the i386.
3168  *
3169  * There is also a hook called "update_mmu_cache()" that architectures
3170  * with external mmu caches can use to update those (ie the Sparc or
3171  * PowerPC hashed page tables that act as extended TLBs).
3172  *
3173  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3174  * but allow concurrent faults), and pte mapped but not yet locked.
3175  * We return with mmap_sem still held, but pte unmapped and unlocked.
3176  */
3177 static int handle_pte_fault(struct mm_struct *mm,
3178                      struct vm_area_struct *vma, unsigned long address,
3179                      pte_t *pte, pmd_t *pmd, unsigned int flags)
3180 {
3181         pte_t entry;
3182         spinlock_t *ptl;
3183 
3184         entry = *pte;
3185         if (!pte_present(entry)) {
3186                 if (pte_none(entry)) {
3187                         if (vma->vm_ops) {
3188                                 if (likely(vma->vm_ops->fault))
3189                                         return do_linear_fault(mm, vma, address,
3190                                                 pte, pmd, flags, entry);
3191                         }
3192                         return do_anonymous_page(mm, vma, address,
3193                                                  pte, pmd, flags);
3194                 }
3195                 if (pte_file(entry))
3196                         return do_nonlinear_fault(mm, vma, address,
3197                                         pte, pmd, flags, entry);
3198                 return do_swap_page(mm, vma, address,
3199                                         pte, pmd, flags, entry);
3200         }
3201 
3202         if (pte_numa(entry))
3203                 return do_numa_page(mm, vma, address, entry, pte, pmd);
3204 
3205         ptl = pte_lockptr(mm, pmd);
3206         spin_lock(ptl);
3207         if (unlikely(!pte_same(*pte, entry)))
3208                 goto unlock;
3209         if (flags & FAULT_FLAG_WRITE) {
3210                 if (!pte_write(entry))
3211                         return do_wp_page(mm, vma, address,
3212                                         pte, pmd, ptl, entry);
3213                 entry = pte_mkdirty(entry);
3214         }
3215         entry = pte_mkyoung(entry);
3216         if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3217                 update_mmu_cache(vma, address, pte);
3218         } else {
3219                 /*
3220                  * This is needed only for protection faults but the arch code
3221                  * is not yet telling us if this is a protection fault or not.
3222                  * This still avoids useless tlb flushes for .text page faults
3223                  * with threads.
3224                  */
3225                 if (flags & FAULT_FLAG_WRITE)
3226                         flush_tlb_fix_spurious_fault(vma, address);
3227         }
3228 unlock:
3229         pte_unmap_unlock(pte, ptl);
3230         return 0;
3231 }
3232 
3233 /*
3234  * By the time we get here, we already hold the mm semaphore
3235  */
3236 static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3237                              unsigned long address, unsigned int flags)
3238 {
3239         pgd_t *pgd;
3240         pud_t *pud;
3241         pmd_t *pmd;
3242         pte_t *pte;
3243 
3244         if (unlikely(is_vm_hugetlb_page(vma)))
3245                 return hugetlb_fault(mm, vma, address, flags);
3246 
3247         pgd = pgd_offset(mm, address);
3248         pud = pud_alloc(mm, pgd, address);
3249         if (!pud)
3250                 return VM_FAULT_OOM;
3251         pmd = pmd_alloc(mm, pud, address);
3252         if (!pmd)
3253                 return VM_FAULT_OOM;
3254         if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3255                 int ret = VM_FAULT_FALLBACK;
3256                 if (!vma->vm_ops)
3257                         ret = do_huge_pmd_anonymous_page(mm, vma, address,
3258                                         pmd, flags);
3259                 if (!(ret & VM_FAULT_FALLBACK))
3260                         return ret;
3261         } else {
3262                 pmd_t orig_pmd = *pmd;
3263                 int ret;
3264 
3265                 barrier();
3266                 if (pmd_trans_huge(orig_pmd)) {
3267                         unsigned int dirty = flags & FAULT_FLAG_WRITE;
3268 
3269                         /*
3270                          * If the pmd is splitting, return and retry the
3271                          * the fault.  Alternative: wait until the split
3272                          * is done, and goto retry.
3273                          */
3274                         if (pmd_trans_splitting(orig_pmd))
3275                                 return 0;
3276 
3277                         if (pmd_numa(orig_pmd))
3278                                 return do_huge_pmd_numa_page(mm, vma, address,
3279                                                              orig_pmd, pmd);
3280 
3281                         if (dirty && !pmd_write(orig_pmd)) {
3282                                 ret = do_huge_pmd_wp_page(mm, vma, address, pmd,
3283                                                           orig_pmd);
3284                                 if (!(ret & VM_FAULT_FALLBACK))
3285                                         return ret;
3286                         } else {
3287                                 huge_pmd_set_accessed(mm, vma, address, pmd,
3288                                                       orig_pmd, dirty);
3289                                 return 0;
3290                         }
3291                 }
3292         }
3293 
3294         /*
3295          * Use __pte_alloc instead of pte_alloc_map, because we can't
3296          * run pte_offset_map on the pmd, if an huge pmd could
3297          * materialize from under us from a different thread.
3298          */
3299         if (unlikely(pmd_none(*pmd)) &&
3300             unlikely(__pte_alloc(mm, vma, pmd, address)))
3301                 return VM_FAULT_OOM;
3302         /* if an huge pmd materialized from under us just retry later */
3303         if (unlikely(pmd_trans_huge(*pmd)))
3304                 return 0;
3305         /*
3306          * A regular pmd is established and it can't morph into a huge pmd
3307          * from under us anymore at this point because we hold the mmap_sem
3308          * read mode and khugepaged takes it in write mode. So now it's
3309          * safe to run pte_offset_map().
3310          */
3311         pte = pte_offset_map(pmd, address);
3312 
3313         return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3314 }
3315 
3316 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3317                     unsigned long address, unsigned int flags)
3318 {
3319         int ret;
3320 
3321         __set_current_state(TASK_RUNNING);
3322 
3323         count_vm_event(PGFAULT);
3324         mem_cgroup_count_vm_event(mm, PGFAULT);
3325 
3326         /* do counter updates before entering really critical section. */
3327         check_sync_rss_stat(current);
3328 
3329         /*
3330          * Enable the memcg OOM handling for faults triggered in user
3331          * space.  Kernel faults are handled more gracefully.
3332          */
3333         if (flags & FAULT_FLAG_USER)
3334                 mem_cgroup_oom_enable();
3335 
3336         ret = __handle_mm_fault(mm, vma, address, flags);
3337 
3338         if (flags & FAULT_FLAG_USER) {
3339                 mem_cgroup_oom_disable();
3340                 /*
3341                  * The task may have entered a memcg OOM situation but
3342                  * if the allocation error was handled gracefully (no
3343                  * VM_FAULT_OOM), there is no need to kill anything.
3344                  * Just clean up the OOM state peacefully.
3345                  */
3346                 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
3347                         mem_cgroup_oom_synchronize(false);
3348         }
3349 
3350         return ret;
3351 }
3352 
3353 #ifndef __PAGETABLE_PUD_FOLDED
3354 /*
3355  * Allocate page upper directory.
3356  * We've already handled the fast-path in-line.
3357  */
3358 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3359 {
3360         pud_t *new = pud_alloc_one(mm, address);
3361         if (!new)
3362                 return -ENOMEM;
3363 
3364         smp_wmb(); /* See comment in __pte_alloc */
3365 
3366         spin_lock(&mm->page_table_lock);
3367         if (pgd_present(*pgd))          /* Another has populated it */
3368                 pud_free(mm, new);
3369         else
3370                 pgd_populate(mm, pgd, new);
3371         spin_unlock(&mm->page_table_lock);
3372         return 0;
3373 }
3374 #endif /* __PAGETABLE_PUD_FOLDED */
3375 
3376 #ifndef __PAGETABLE_PMD_FOLDED
3377 /*
3378  * Allocate page middle directory.
3379  * We've already handled the fast-path in-line.
3380  */
3381 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3382 {
3383         pmd_t *new = pmd_alloc_one(mm, address);
3384         if (!new)
3385                 return -ENOMEM;
3386 
3387         smp_wmb(); /* See comment in __pte_alloc */
3388 
3389         spin_lock(&mm->page_table_lock);
3390 #ifndef __ARCH_HAS_4LEVEL_HACK
3391         if (pud_present(*pud))          /* Another has populated it */
3392                 pmd_free(mm, new);
3393         else
3394                 pud_populate(mm, pud, new);
3395 #else
3396         if (pgd_present(*pud))          /* Another has populated it */
3397                 pmd_free(mm, new);
3398         else
3399                 pgd_populate(mm, pud, new);
3400 #endif /* __ARCH_HAS_4LEVEL_HACK */
3401         spin_unlock(&mm->page_table_lock);
3402         return 0;
3403 }
3404 #endif /* __PAGETABLE_PMD_FOLDED */
3405 
3406 #if !defined(__HAVE_ARCH_GATE_AREA)
3407 
3408 #if defined(AT_SYSINFO_EHDR)
3409 static struct vm_area_struct gate_vma;
3410 
3411 static int __init gate_vma_init(void)
3412 {
3413         gate_vma.vm_mm = NULL;
3414         gate_vma.vm_start = FIXADDR_USER_START;
3415         gate_vma.vm_end = FIXADDR_USER_END;
3416         gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
3417         gate_vma.vm_page_prot = __P101;
3418 
3419         return 0;
3420 }
3421 __initcall(gate_vma_init);
3422 #endif
3423 
3424 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
3425 {
3426 #ifdef AT_SYSINFO_EHDR
3427         return &gate_vma;
3428 #else
3429         return NULL;
3430 #endif
3431 }
3432 
3433 int in_gate_area_no_mm(unsigned long addr)
3434 {
3435 #ifdef AT_SYSINFO_EHDR
3436         if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3437                 return 1;
3438 #endif
3439         return 0;
3440 }
3441 
3442 #endif  /* __HAVE_ARCH_GATE_AREA */
3443 
3444 static int __follow_pte(struct mm_struct *mm, unsigned long address,
3445                 pte_t **ptepp, spinlock_t **ptlp)
3446 {
3447         pgd_t *pgd;
3448         pud_t *pud;
3449         pmd_t *pmd;
3450         pte_t *ptep;
3451 
3452         pgd = pgd_offset(mm, address);
3453         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3454                 goto out;
3455 
3456         pud = pud_offset(pgd, address);
3457         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3458                 goto out;
3459 
3460         pmd = pmd_offset(pud, address);
3461         VM_BUG_ON(pmd_trans_huge(*pmd));
3462         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3463                 goto out;
3464 
3465         /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3466         if (pmd_huge(*pmd))
3467                 goto out;
3468 
3469         ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3470         if (!ptep)
3471                 goto out;
3472         if (!pte_present(*ptep))
3473                 goto unlock;
3474         *ptepp = ptep;
3475         return 0;
3476 unlock:
3477         pte_unmap_unlock(ptep, *ptlp);
3478 out:
3479         return -EINVAL;
3480 }
3481 
3482 static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3483                              pte_t **ptepp, spinlock_t **ptlp)
3484 {
3485         int res;
3486 
3487         /* (void) is needed to make gcc happy */
3488         (void) __cond_lock(*ptlp,
3489                            !(res = __follow_pte(mm, address, ptepp, ptlp)));
3490         return res;
3491 }
3492 
3493 /**
3494  * follow_pfn - look up PFN at a user virtual address
3495  * @vma: memory mapping
3496  * @address: user virtual address
3497  * @pfn: location to store found PFN
3498  *
3499  * Only IO mappings and raw PFN mappings are allowed.
3500  *
3501  * Returns zero and the pfn at @pfn on success, -ve otherwise.
3502  */
3503 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3504         unsigned long *pfn)
3505 {
3506         int ret = -EINVAL;
3507         spinlock_t *ptl;
3508         pte_t *ptep;
3509 
3510         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3511                 return ret;
3512 
3513         ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3514         if (ret)
3515                 return ret;
3516         *pfn = pte_pfn(*ptep);
3517         pte_unmap_unlock(ptep, ptl);
3518         return 0;
3519 }
3520 EXPORT_SYMBOL(follow_pfn);
3521 
3522 #ifdef CONFIG_HAVE_IOREMAP_PROT
3523 int follow_phys(struct vm_area_struct *vma,
3524                 unsigned long address, unsigned int flags,
3525                 unsigned long *prot, resource_size_t *phys)
3526 {
3527         int ret = -EINVAL;
3528         pte_t *ptep, pte;
3529         spinlock_t *ptl;
3530 
3531         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3532                 goto out;
3533 
3534         if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3535                 goto out;
3536         pte = *ptep;
3537 
3538         if ((flags & FOLL_WRITE) && !pte_write(pte))
3539                 goto unlock;
3540 
3541         *prot = pgprot_val(pte_pgprot(pte));
3542         *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3543 
3544         ret = 0;
3545 unlock:
3546         pte_unmap_unlock(ptep, ptl);
3547 out:
3548         return ret;
3549 }
3550 
3551 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3552                         void *buf, int len, int write)
3553 {
3554         resource_size_t phys_addr;
3555         unsigned long prot = 0;
3556         void __iomem *maddr;
3557         int offset = addr & (PAGE_SIZE-1);
3558 
3559         if (follow_phys(vma, addr, write, &prot, &phys_addr))
3560                 return -EINVAL;
3561 
3562         maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
3563         if (write)
3564                 memcpy_toio(maddr + offset, buf, len);
3565         else
3566                 memcpy_fromio(buf, maddr + offset, len);
3567         iounmap(maddr);
3568 
3569         return len;
3570 }
3571 EXPORT_SYMBOL_GPL(generic_access_phys);
3572 #endif
3573 
3574 /*
3575  * Access another process' address space as given in mm.  If non-NULL, use the
3576  * given task for page fault accounting.
3577  */
3578 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
3579                 unsigned long addr, void *buf, int len, int write)
3580 {
3581         struct vm_area_struct *vma;
3582         void *old_buf = buf;
3583 
3584         down_read(&mm->mmap_sem);
3585         /* ignore errors, just check how much was successfully transferred */
3586         while (len) {
3587                 int bytes, ret, offset;
3588                 void *maddr;
3589                 struct page *page = NULL;
3590 
3591                 ret = get_user_pages(tsk, mm, addr, 1,
3592                                 write, 1, &page, &vma);
3593                 if (ret <= 0) {
3594                         /*
3595                          * Check if this is a VM_IO | VM_PFNMAP VMA, which
3596                          * we can access using slightly different code.
3597                          */
3598 #ifdef CONFIG_HAVE_IOREMAP_PROT
3599                         vma = find_vma(mm, addr);
3600                         if (!vma || vma->vm_start > addr)
3601                                 break;
3602                         if (vma->vm_ops && vma->vm_ops->access)
3603                                 ret = vma->vm_ops->access(vma, addr, buf,
3604                                                           len, write);
3605                         if (ret <= 0)
3606 #endif
3607                                 break;
3608                         bytes = ret;
3609                 } else {
3610                         bytes = len;
3611                         offset = addr & (PAGE_SIZE-1);
3612                         if (bytes > PAGE_SIZE-offset)
3613                                 bytes = PAGE_SIZE-offset;
3614 
3615                         maddr = kmap(page);
3616                         if (write) {
3617                                 copy_to_user_page(vma, page, addr,
3618                                                   maddr + offset, buf, bytes);
3619                                 set_page_dirty_lock(page);
3620                         } else {
3621                                 copy_from_user_page(vma, page, addr,
3622                                                     buf, maddr + offset, bytes);
3623                         }
3624                         kunmap(page);
3625                         page_cache_release(page);
3626                 }
3627                 len -= bytes;
3628                 buf += bytes;
3629                 addr += bytes;
3630         }
3631         up_read(&mm->mmap_sem);
3632 
3633         return buf - old_buf;
3634 }
3635 
3636 /**
3637  * access_remote_vm - access another process' address space
3638  * @mm:         the mm_struct of the target address space
3639  * @addr:       start address to access
3640  * @buf:        source or destination buffer
3641  * @len:        number of bytes to transfer
3642  * @write:      whether the access is a write
3643  *
3644  * The caller must hold a reference on @mm.
3645  */
3646 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
3647                 void *buf, int len, int write)
3648 {
3649         return __access_remote_vm(NULL, mm, addr, buf, len, write);
3650 }
3651 
3652 /*
3653  * Access another process' address space.
3654  * Source/target buffer must be kernel space,
3655  * Do not walk the page table directly, use get_user_pages
3656  */
3657 int access_process_vm(struct task_struct *tsk, unsigned long addr,
3658                 void *buf, int len, int write)
3659 {
3660         struct mm_struct *mm;
3661         int ret;
3662 
3663         mm = get_task_mm(tsk);
3664         if (!mm)
3665                 return 0;
3666 
3667         ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
3668         mmput(mm);
3669 
3670         return ret;
3671 }
3672 
3673 /*
3674  * Print the name of a VMA.
3675  */
3676 void print_vma_addr(char *prefix, unsigned long ip)
3677 {
3678         struct mm_struct *mm = current->mm;
3679         struct vm_area_struct *vma;
3680 
3681         /*
3682          * Do not print if we are in atomic
3683          * contexts (in exception stacks, etc.):
3684          */
3685         if (preempt_count())
3686                 return;
3687 
3688         down_read(&mm->mmap_sem);
3689         vma = find_vma(mm, ip);
3690         if (vma && vma->vm_file) {
3691                 struct file *f = vma->vm_file;
3692                 char *buf = (char *)__get_free_page(GFP_KERNEL);
3693                 if (buf) {
3694                         char *p;
3695 
3696                         p = d_path(&f->f_path, buf, PAGE_SIZE);
3697                         if (IS_ERR(p))
3698                                 p = "?";
3699                         printk("%s%s[%lx+%lx]", prefix, kbasename(p),
3700                                         vma->vm_start,
3701                                         vma->vm_end - vma->vm_start);
3702                         free_page((unsigned long)buf);
3703                 }
3704         }
3705         up_read(&mm->mmap_sem);
3706 }
3707 
3708 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
3709 void might_fault(void)
3710 {
3711         /*
3712          * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3713          * holding the mmap_sem, this is safe because kernel memory doesn't
3714          * get paged out, therefore we'll never actually fault, and the
3715          * below annotations will generate false positives.
3716          */
3717         if (segment_eq(get_fs(), KERNEL_DS))
3718                 return;
3719 
3720         /*
3721          * it would be nicer only to annotate paths which are not under
3722          * pagefault_disable, however that requires a larger audit and
3723          * providing helpers like get_user_atomic.
3724          */
3725         if (in_atomic())
3726                 return;
3727 
3728         __might_sleep(__FILE__, __LINE__, 0);
3729 
3730         if (current->mm)
3731                 might_lock_read(&current->mm->mmap_sem);
3732 }
3733 EXPORT_SYMBOL(might_fault);
3734 #endif
3735 
3736 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
3737 static void clear_gigantic_page(struct page *page,
3738                                 unsigned long addr,
3739                                 unsigned int pages_per_huge_page)
3740 {
3741         int i;
3742         struct page *p = page;
3743 
3744         might_sleep();
3745         for (i = 0; i < pages_per_huge_page;
3746              i++, p = mem_map_next(p, page, i)) {
3747                 cond_resched();
3748                 clear_user_highpage(p, addr + i * PAGE_SIZE);
3749         }
3750 }
3751 void clear_huge_page(struct page *page,
3752                      unsigned long addr, unsigned int pages_per_huge_page)
3753 {
3754         int i;
3755 
3756         if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3757                 clear_gigantic_page(page, addr, pages_per_huge_page);
3758                 return;
3759         }
3760 
3761         might_sleep();
3762         for (i = 0; i < pages_per_huge_page; i++) {
3763                 cond_resched();
3764                 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
3765         }
3766 }
3767 
3768 static void copy_user_gigantic_page(struct page *dst, struct page *src,
3769                                     unsigned long addr,
3770                                     struct vm_area_struct *vma,
3771                                     unsigned int pages_per_huge_page)
3772 {
3773         int i;
3774         struct page *dst_base = dst;
3775         struct page *src_base = src;
3776 
3777         for (i = 0; i < pages_per_huge_page; ) {
3778                 cond_resched();
3779                 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
3780 
3781                 i++;
3782                 dst = mem_map_next(dst, dst_base, i);
3783                 src = mem_map_next(src, src_base, i);
3784         }
3785 }
3786 
3787 void copy_user_huge_page(struct page *dst, struct page *src,
3788                          unsigned long addr, struct vm_area_struct *vma,
3789                          unsigned int pages_per_huge_page)
3790 {
3791         int i;
3792 
3793         if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3794                 copy_user_gigantic_page(dst, src, addr, vma,
3795                                         pages_per_huge_page);
3796                 return;
3797         }
3798 
3799         might_sleep();
3800         for (i = 0; i < pages_per_huge_page; i++) {
3801                 cond_resched();
3802                 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
3803         }
3804 }
3805 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
3806 
3807 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
3808 
3809 static struct kmem_cache *page_ptl_cachep;
3810 
3811 void __init ptlock_cache_init(void)
3812 {
3813         page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
3814                         SLAB_PANIC, NULL);
3815 }
3816 
3817 bool ptlock_alloc(struct page *page)
3818 {
3819         spinlock_t *ptl;
3820 
3821         ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
3822         if (!ptl)
3823                 return false;
3824         page->ptl = ptl;
3825         return true;
3826 }
3827 
3828 void ptlock_free(struct page *page)
3829 {
3830         kmem_cache_free(page_ptl_cachep, page->ptl);
3831 }
3832 #endif
3833 

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