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Linux/include/linux/mm.h

  1 #ifndef _LINUX_MM_H
  2 #define _LINUX_MM_H
  3 
  4 #include <linux/errno.h>
  5 
  6 #ifdef __KERNEL__
  7 
  8 #include <linux/mmdebug.h>
  9 #include <linux/gfp.h>
 10 #include <linux/bug.h>
 11 #include <linux/list.h>
 12 #include <linux/mmzone.h>
 13 #include <linux/rbtree.h>
 14 #include <linux/atomic.h>
 15 #include <linux/debug_locks.h>
 16 #include <linux/mm_types.h>
 17 #include <linux/range.h>
 18 #include <linux/pfn.h>
 19 #include <linux/percpu-refcount.h>
 20 #include <linux/bit_spinlock.h>
 21 #include <linux/shrinker.h>
 22 #include <linux/resource.h>
 23 #include <linux/page_ext.h>
 24 #include <linux/err.h>
 25 
 26 struct mempolicy;
 27 struct anon_vma;
 28 struct anon_vma_chain;
 29 struct file_ra_state;
 30 struct user_struct;
 31 struct writeback_control;
 32 struct bdi_writeback;
 33 
 34 #ifndef CONFIG_NEED_MULTIPLE_NODES      /* Don't use mapnrs, do it properly */
 35 extern unsigned long max_mapnr;
 36 
 37 static inline void set_max_mapnr(unsigned long limit)
 38 {
 39         max_mapnr = limit;
 40 }
 41 #else
 42 static inline void set_max_mapnr(unsigned long limit) { }
 43 #endif
 44 
 45 extern unsigned long totalram_pages;
 46 extern void * high_memory;
 47 extern int page_cluster;
 48 
 49 #ifdef CONFIG_SYSCTL
 50 extern int sysctl_legacy_va_layout;
 51 #else
 52 #define sysctl_legacy_va_layout 0
 53 #endif
 54 
 55 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
 56 extern const int mmap_rnd_bits_min;
 57 extern const int mmap_rnd_bits_max;
 58 extern int mmap_rnd_bits __read_mostly;
 59 #endif
 60 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
 61 extern const int mmap_rnd_compat_bits_min;
 62 extern const int mmap_rnd_compat_bits_max;
 63 extern int mmap_rnd_compat_bits __read_mostly;
 64 #endif
 65 
 66 #include <asm/page.h>
 67 #include <asm/pgtable.h>
 68 #include <asm/processor.h>
 69 
 70 #ifndef __pa_symbol
 71 #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
 72 #endif
 73 
 74 /*
 75  * To prevent common memory management code establishing
 76  * a zero page mapping on a read fault.
 77  * This macro should be defined within <asm/pgtable.h>.
 78  * s390 does this to prevent multiplexing of hardware bits
 79  * related to the physical page in case of virtualization.
 80  */
 81 #ifndef mm_forbids_zeropage
 82 #define mm_forbids_zeropage(X)  (0)
 83 #endif
 84 
 85 extern unsigned long sysctl_user_reserve_kbytes;
 86 extern unsigned long sysctl_admin_reserve_kbytes;
 87 
 88 extern int sysctl_overcommit_memory;
 89 extern int sysctl_overcommit_ratio;
 90 extern unsigned long sysctl_overcommit_kbytes;
 91 
 92 extern int overcommit_ratio_handler(struct ctl_table *, int, void __user *,
 93                                     size_t *, loff_t *);
 94 extern int overcommit_kbytes_handler(struct ctl_table *, int, void __user *,
 95                                     size_t *, loff_t *);
 96 
 97 #define nth_page(page,n) pfn_to_page(page_to_pfn((page)) + (n))
 98 
 99 /* to align the pointer to the (next) page boundary */
100 #define PAGE_ALIGN(addr) ALIGN(addr, PAGE_SIZE)
101 
102 /* test whether an address (unsigned long or pointer) is aligned to PAGE_SIZE */
103 #define PAGE_ALIGNED(addr)      IS_ALIGNED((unsigned long)addr, PAGE_SIZE)
104 
105 /*
106  * Linux kernel virtual memory manager primitives.
107  * The idea being to have a "virtual" mm in the same way
108  * we have a virtual fs - giving a cleaner interface to the
109  * mm details, and allowing different kinds of memory mappings
110  * (from shared memory to executable loading to arbitrary
111  * mmap() functions).
112  */
113 
114 extern struct kmem_cache *vm_area_cachep;
115 
116 #ifndef CONFIG_MMU
117 extern struct rb_root nommu_region_tree;
118 extern struct rw_semaphore nommu_region_sem;
119 
120 extern unsigned int kobjsize(const void *objp);
121 #endif
122 
123 /*
124  * vm_flags in vm_area_struct, see mm_types.h.
125  */
126 #define VM_NONE         0x00000000
127 
128 #define VM_READ         0x00000001      /* currently active flags */
129 #define VM_WRITE        0x00000002
130 #define VM_EXEC         0x00000004
131 #define VM_SHARED       0x00000008
132 
133 /* mprotect() hardcodes VM_MAYREAD >> 4 == VM_READ, and so for r/w/x bits. */
134 #define VM_MAYREAD      0x00000010      /* limits for mprotect() etc */
135 #define VM_MAYWRITE     0x00000020
136 #define VM_MAYEXEC      0x00000040
137 #define VM_MAYSHARE     0x00000080
138 
139 #define VM_GROWSDOWN    0x00000100      /* general info on the segment */
140 #define VM_UFFD_MISSING 0x00000200      /* missing pages tracking */
141 #define VM_PFNMAP       0x00000400      /* Page-ranges managed without "struct page", just pure PFN */
142 #define VM_DENYWRITE    0x00000800      /* ETXTBSY on write attempts.. */
143 #define VM_UFFD_WP      0x00001000      /* wrprotect pages tracking */
144 
145 #define VM_LOCKED       0x00002000
146 #define VM_IO           0x00004000      /* Memory mapped I/O or similar */
147 
148                                         /* Used by sys_madvise() */
149 #define VM_SEQ_READ     0x00008000      /* App will access data sequentially */
150 #define VM_RAND_READ    0x00010000      /* App will not benefit from clustered reads */
151 
152 #define VM_DONTCOPY     0x00020000      /* Do not copy this vma on fork */
153 #define VM_DONTEXPAND   0x00040000      /* Cannot expand with mremap() */
154 #define VM_LOCKONFAULT  0x00080000      /* Lock the pages covered when they are faulted in */
155 #define VM_ACCOUNT      0x00100000      /* Is a VM accounted object */
156 #define VM_NORESERVE    0x00200000      /* should the VM suppress accounting */
157 #define VM_HUGETLB      0x00400000      /* Huge TLB Page VM */
158 #define VM_ARCH_1       0x01000000      /* Architecture-specific flag */
159 #define VM_ARCH_2       0x02000000
160 #define VM_DONTDUMP     0x04000000      /* Do not include in the core dump */
161 
162 #ifdef CONFIG_MEM_SOFT_DIRTY
163 # define VM_SOFTDIRTY   0x08000000      /* Not soft dirty clean area */
164 #else
165 # define VM_SOFTDIRTY   0
166 #endif
167 
168 #define VM_MIXEDMAP     0x10000000      /* Can contain "struct page" and pure PFN pages */
169 #define VM_HUGEPAGE     0x20000000      /* MADV_HUGEPAGE marked this vma */
170 #define VM_NOHUGEPAGE   0x40000000      /* MADV_NOHUGEPAGE marked this vma */
171 #define VM_MERGEABLE    0x80000000      /* KSM may merge identical pages */
172 
173 #if defined(CONFIG_X86)
174 # define VM_PAT         VM_ARCH_1       /* PAT reserves whole VMA at once (x86) */
175 #elif defined(CONFIG_PPC)
176 # define VM_SAO         VM_ARCH_1       /* Strong Access Ordering (powerpc) */
177 #elif defined(CONFIG_PARISC)
178 # define VM_GROWSUP     VM_ARCH_1
179 #elif defined(CONFIG_METAG)
180 # define VM_GROWSUP     VM_ARCH_1
181 #elif defined(CONFIG_IA64)
182 # define VM_GROWSUP     VM_ARCH_1
183 #elif !defined(CONFIG_MMU)
184 # define VM_MAPPED_COPY VM_ARCH_1       /* T if mapped copy of data (nommu mmap) */
185 #endif
186 
187 #if defined(CONFIG_X86)
188 /* MPX specific bounds table or bounds directory */
189 # define VM_MPX         VM_ARCH_2
190 #endif
191 
192 #ifndef VM_GROWSUP
193 # define VM_GROWSUP     VM_NONE
194 #endif
195 
196 /* Bits set in the VMA until the stack is in its final location */
197 #define VM_STACK_INCOMPLETE_SETUP       (VM_RAND_READ | VM_SEQ_READ)
198 
199 #ifndef VM_STACK_DEFAULT_FLAGS          /* arch can override this */
200 #define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
201 #endif
202 
203 #ifdef CONFIG_STACK_GROWSUP
204 #define VM_STACK        VM_GROWSUP
205 #else
206 #define VM_STACK        VM_GROWSDOWN
207 #endif
208 
209 #define VM_STACK_FLAGS  (VM_STACK | VM_STACK_DEFAULT_FLAGS | VM_ACCOUNT)
210 
211 /*
212  * Special vmas that are non-mergable, non-mlock()able.
213  * Note: mm/huge_memory.c VM_NO_THP depends on this definition.
214  */
215 #define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_PFNMAP | VM_MIXEDMAP)
216 
217 /* This mask defines which mm->def_flags a process can inherit its parent */
218 #define VM_INIT_DEF_MASK        VM_NOHUGEPAGE
219 
220 /* This mask is used to clear all the VMA flags used by mlock */
221 #define VM_LOCKED_CLEAR_MASK    (~(VM_LOCKED | VM_LOCKONFAULT))
222 
223 /*
224  * mapping from the currently active vm_flags protection bits (the
225  * low four bits) to a page protection mask..
226  */
227 extern pgprot_t protection_map[16];
228 
229 #define FAULT_FLAG_WRITE        0x01    /* Fault was a write access */
230 #define FAULT_FLAG_MKWRITE      0x02    /* Fault was mkwrite of existing pte */
231 #define FAULT_FLAG_ALLOW_RETRY  0x04    /* Retry fault if blocking */
232 #define FAULT_FLAG_RETRY_NOWAIT 0x08    /* Don't drop mmap_sem and wait when retrying */
233 #define FAULT_FLAG_KILLABLE     0x10    /* The fault task is in SIGKILL killable region */
234 #define FAULT_FLAG_TRIED        0x20    /* Second try */
235 #define FAULT_FLAG_USER         0x40    /* The fault originated in userspace */
236 
237 /*
238  * vm_fault is filled by the the pagefault handler and passed to the vma's
239  * ->fault function. The vma's ->fault is responsible for returning a bitmask
240  * of VM_FAULT_xxx flags that give details about how the fault was handled.
241  *
242  * MM layer fills up gfp_mask for page allocations but fault handler might
243  * alter it if its implementation requires a different allocation context.
244  *
245  * pgoff should be used in favour of virtual_address, if possible.
246  */
247 struct vm_fault {
248         unsigned int flags;             /* FAULT_FLAG_xxx flags */
249         gfp_t gfp_mask;                 /* gfp mask to be used for allocations */
250         pgoff_t pgoff;                  /* Logical page offset based on vma */
251         void __user *virtual_address;   /* Faulting virtual address */
252 
253         struct page *cow_page;          /* Handler may choose to COW */
254         struct page *page;              /* ->fault handlers should return a
255                                          * page here, unless VM_FAULT_NOPAGE
256                                          * is set (which is also implied by
257                                          * VM_FAULT_ERROR).
258                                          */
259         /* for ->map_pages() only */
260         pgoff_t max_pgoff;              /* map pages for offset from pgoff till
261                                          * max_pgoff inclusive */
262         pte_t *pte;                     /* pte entry associated with ->pgoff */
263 };
264 
265 /*
266  * These are the virtual MM functions - opening of an area, closing and
267  * unmapping it (needed to keep files on disk up-to-date etc), pointer
268  * to the functions called when a no-page or a wp-page exception occurs. 
269  */
270 struct vm_operations_struct {
271         void (*open)(struct vm_area_struct * area);
272         void (*close)(struct vm_area_struct * area);
273         int (*mremap)(struct vm_area_struct * area);
274         int (*fault)(struct vm_area_struct *vma, struct vm_fault *vmf);
275         int (*pmd_fault)(struct vm_area_struct *, unsigned long address,
276                                                 pmd_t *, unsigned int flags);
277         void (*map_pages)(struct vm_area_struct *vma, struct vm_fault *vmf);
278 
279         /* notification that a previously read-only page is about to become
280          * writable, if an error is returned it will cause a SIGBUS */
281         int (*page_mkwrite)(struct vm_area_struct *vma, struct vm_fault *vmf);
282 
283         /* same as page_mkwrite when using VM_PFNMAP|VM_MIXEDMAP */
284         int (*pfn_mkwrite)(struct vm_area_struct *vma, struct vm_fault *vmf);
285 
286         /* called by access_process_vm when get_user_pages() fails, typically
287          * for use by special VMAs that can switch between memory and hardware
288          */
289         int (*access)(struct vm_area_struct *vma, unsigned long addr,
290                       void *buf, int len, int write);
291 
292         /* Called by the /proc/PID/maps code to ask the vma whether it
293          * has a special name.  Returning non-NULL will also cause this
294          * vma to be dumped unconditionally. */
295         const char *(*name)(struct vm_area_struct *vma);
296 
297 #ifdef CONFIG_NUMA
298         /*
299          * set_policy() op must add a reference to any non-NULL @new mempolicy
300          * to hold the policy upon return.  Caller should pass NULL @new to
301          * remove a policy and fall back to surrounding context--i.e. do not
302          * install a MPOL_DEFAULT policy, nor the task or system default
303          * mempolicy.
304          */
305         int (*set_policy)(struct vm_area_struct *vma, struct mempolicy *new);
306 
307         /*
308          * get_policy() op must add reference [mpol_get()] to any policy at
309          * (vma,addr) marked as MPOL_SHARED.  The shared policy infrastructure
310          * in mm/mempolicy.c will do this automatically.
311          * get_policy() must NOT add a ref if the policy at (vma,addr) is not
312          * marked as MPOL_SHARED. vma policies are protected by the mmap_sem.
313          * If no [shared/vma] mempolicy exists at the addr, get_policy() op
314          * must return NULL--i.e., do not "fallback" to task or system default
315          * policy.
316          */
317         struct mempolicy *(*get_policy)(struct vm_area_struct *vma,
318                                         unsigned long addr);
319 #endif
320         /*
321          * Called by vm_normal_page() for special PTEs to find the
322          * page for @addr.  This is useful if the default behavior
323          * (using pte_page()) would not find the correct page.
324          */
325         struct page *(*find_special_page)(struct vm_area_struct *vma,
326                                           unsigned long addr);
327 };
328 
329 struct mmu_gather;
330 struct inode;
331 
332 #define page_private(page)              ((page)->private)
333 #define set_page_private(page, v)       ((page)->private = (v))
334 
335 #if !defined(__HAVE_ARCH_PTE_DEVMAP) || !defined(CONFIG_TRANSPARENT_HUGEPAGE)
336 static inline int pmd_devmap(pmd_t pmd)
337 {
338         return 0;
339 }
340 #endif
341 
342 /*
343  * FIXME: take this include out, include page-flags.h in
344  * files which need it (119 of them)
345  */
346 #include <linux/page-flags.h>
347 #include <linux/huge_mm.h>
348 
349 /*
350  * Methods to modify the page usage count.
351  *
352  * What counts for a page usage:
353  * - cache mapping   (page->mapping)
354  * - private data    (page->private)
355  * - page mapped in a task's page tables, each mapping
356  *   is counted separately
357  *
358  * Also, many kernel routines increase the page count before a critical
359  * routine so they can be sure the page doesn't go away from under them.
360  */
361 
362 /*
363  * Drop a ref, return true if the refcount fell to zero (the page has no users)
364  */
365 static inline int put_page_testzero(struct page *page)
366 {
367         VM_BUG_ON_PAGE(atomic_read(&page->_count) == 0, page);
368         return atomic_dec_and_test(&page->_count);
369 }
370 
371 /*
372  * Try to grab a ref unless the page has a refcount of zero, return false if
373  * that is the case.
374  * This can be called when MMU is off so it must not access
375  * any of the virtual mappings.
376  */
377 static inline int get_page_unless_zero(struct page *page)
378 {
379         return atomic_inc_not_zero(&page->_count);
380 }
381 
382 extern int page_is_ram(unsigned long pfn);
383 
384 enum {
385         REGION_INTERSECTS,
386         REGION_DISJOINT,
387         REGION_MIXED,
388 };
389 
390 int region_intersects(resource_size_t offset, size_t size, const char *type);
391 
392 /* Support for virtually mapped pages */
393 struct page *vmalloc_to_page(const void *addr);
394 unsigned long vmalloc_to_pfn(const void *addr);
395 
396 /*
397  * Determine if an address is within the vmalloc range
398  *
399  * On nommu, vmalloc/vfree wrap through kmalloc/kfree directly, so there
400  * is no special casing required.
401  */
402 static inline int is_vmalloc_addr(const void *x)
403 {
404 #ifdef CONFIG_MMU
405         unsigned long addr = (unsigned long)x;
406 
407         return addr >= VMALLOC_START && addr < VMALLOC_END;
408 #else
409         return 0;
410 #endif
411 }
412 #ifdef CONFIG_MMU
413 extern int is_vmalloc_or_module_addr(const void *x);
414 #else
415 static inline int is_vmalloc_or_module_addr(const void *x)
416 {
417         return 0;
418 }
419 #endif
420 
421 extern void kvfree(const void *addr);
422 
423 static inline atomic_t *compound_mapcount_ptr(struct page *page)
424 {
425         return &page[1].compound_mapcount;
426 }
427 
428 static inline int compound_mapcount(struct page *page)
429 {
430         if (!PageCompound(page))
431                 return 0;
432         page = compound_head(page);
433         return atomic_read(compound_mapcount_ptr(page)) + 1;
434 }
435 
436 /*
437  * The atomic page->_mapcount, starts from -1: so that transitions
438  * both from it and to it can be tracked, using atomic_inc_and_test
439  * and atomic_add_negative(-1).
440  */
441 static inline void page_mapcount_reset(struct page *page)
442 {
443         atomic_set(&(page)->_mapcount, -1);
444 }
445 
446 int __page_mapcount(struct page *page);
447 
448 static inline int page_mapcount(struct page *page)
449 {
450         VM_BUG_ON_PAGE(PageSlab(page), page);
451 
452         if (unlikely(PageCompound(page)))
453                 return __page_mapcount(page);
454         return atomic_read(&page->_mapcount) + 1;
455 }
456 
457 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
458 int total_mapcount(struct page *page);
459 #else
460 static inline int total_mapcount(struct page *page)
461 {
462         return page_mapcount(page);
463 }
464 #endif
465 
466 static inline int page_count(struct page *page)
467 {
468         return atomic_read(&compound_head(page)->_count);
469 }
470 
471 static inline struct page *virt_to_head_page(const void *x)
472 {
473         struct page *page = virt_to_page(x);
474 
475         return compound_head(page);
476 }
477 
478 /*
479  * Setup the page count before being freed into the page allocator for
480  * the first time (boot or memory hotplug)
481  */
482 static inline void init_page_count(struct page *page)
483 {
484         atomic_set(&page->_count, 1);
485 }
486 
487 void __put_page(struct page *page);
488 
489 void put_pages_list(struct list_head *pages);
490 
491 void split_page(struct page *page, unsigned int order);
492 int split_free_page(struct page *page);
493 
494 /*
495  * Compound pages have a destructor function.  Provide a
496  * prototype for that function and accessor functions.
497  * These are _only_ valid on the head of a compound page.
498  */
499 typedef void compound_page_dtor(struct page *);
500 
501 /* Keep the enum in sync with compound_page_dtors array in mm/page_alloc.c */
502 enum compound_dtor_id {
503         NULL_COMPOUND_DTOR,
504         COMPOUND_PAGE_DTOR,
505 #ifdef CONFIG_HUGETLB_PAGE
506         HUGETLB_PAGE_DTOR,
507 #endif
508 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
509         TRANSHUGE_PAGE_DTOR,
510 #endif
511         NR_COMPOUND_DTORS,
512 };
513 extern compound_page_dtor * const compound_page_dtors[];
514 
515 static inline void set_compound_page_dtor(struct page *page,
516                 enum compound_dtor_id compound_dtor)
517 {
518         VM_BUG_ON_PAGE(compound_dtor >= NR_COMPOUND_DTORS, page);
519         page[1].compound_dtor = compound_dtor;
520 }
521 
522 static inline compound_page_dtor *get_compound_page_dtor(struct page *page)
523 {
524         VM_BUG_ON_PAGE(page[1].compound_dtor >= NR_COMPOUND_DTORS, page);
525         return compound_page_dtors[page[1].compound_dtor];
526 }
527 
528 static inline unsigned int compound_order(struct page *page)
529 {
530         if (!PageHead(page))
531                 return 0;
532         return page[1].compound_order;
533 }
534 
535 static inline void set_compound_order(struct page *page, unsigned int order)
536 {
537         page[1].compound_order = order;
538 }
539 
540 void free_compound_page(struct page *page);
541 
542 #ifdef CONFIG_MMU
543 /*
544  * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
545  * servicing faults for write access.  In the normal case, do always want
546  * pte_mkwrite.  But get_user_pages can cause write faults for mappings
547  * that do not have writing enabled, when used by access_process_vm.
548  */
549 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
550 {
551         if (likely(vma->vm_flags & VM_WRITE))
552                 pte = pte_mkwrite(pte);
553         return pte;
554 }
555 
556 void do_set_pte(struct vm_area_struct *vma, unsigned long address,
557                 struct page *page, pte_t *pte, bool write, bool anon);
558 #endif
559 
560 /*
561  * Multiple processes may "see" the same page. E.g. for untouched
562  * mappings of /dev/null, all processes see the same page full of
563  * zeroes, and text pages of executables and shared libraries have
564  * only one copy in memory, at most, normally.
565  *
566  * For the non-reserved pages, page_count(page) denotes a reference count.
567  *   page_count() == 0 means the page is free. page->lru is then used for
568  *   freelist management in the buddy allocator.
569  *   page_count() > 0  means the page has been allocated.
570  *
571  * Pages are allocated by the slab allocator in order to provide memory
572  * to kmalloc and kmem_cache_alloc. In this case, the management of the
573  * page, and the fields in 'struct page' are the responsibility of mm/slab.c
574  * unless a particular usage is carefully commented. (the responsibility of
575  * freeing the kmalloc memory is the caller's, of course).
576  *
577  * A page may be used by anyone else who does a __get_free_page().
578  * In this case, page_count still tracks the references, and should only
579  * be used through the normal accessor functions. The top bits of page->flags
580  * and page->virtual store page management information, but all other fields
581  * are unused and could be used privately, carefully. The management of this
582  * page is the responsibility of the one who allocated it, and those who have
583  * subsequently been given references to it.
584  *
585  * The other pages (we may call them "pagecache pages") are completely
586  * managed by the Linux memory manager: I/O, buffers, swapping etc.
587  * The following discussion applies only to them.
588  *
589  * A pagecache page contains an opaque `private' member, which belongs to the
590  * page's address_space. Usually, this is the address of a circular list of
591  * the page's disk buffers. PG_private must be set to tell the VM to call
592  * into the filesystem to release these pages.
593  *
594  * A page may belong to an inode's memory mapping. In this case, page->mapping
595  * is the pointer to the inode, and page->index is the file offset of the page,
596  * in units of PAGE_CACHE_SIZE.
597  *
598  * If pagecache pages are not associated with an inode, they are said to be
599  * anonymous pages. These may become associated with the swapcache, and in that
600  * case PG_swapcache is set, and page->private is an offset into the swapcache.
601  *
602  * In either case (swapcache or inode backed), the pagecache itself holds one
603  * reference to the page. Setting PG_private should also increment the
604  * refcount. The each user mapping also has a reference to the page.
605  *
606  * The pagecache pages are stored in a per-mapping radix tree, which is
607  * rooted at mapping->page_tree, and indexed by offset.
608  * Where 2.4 and early 2.6 kernels kept dirty/clean pages in per-address_space
609  * lists, we instead now tag pages as dirty/writeback in the radix tree.
610  *
611  * All pagecache pages may be subject to I/O:
612  * - inode pages may need to be read from disk,
613  * - inode pages which have been modified and are MAP_SHARED may need
614  *   to be written back to the inode on disk,
615  * - anonymous pages (including MAP_PRIVATE file mappings) which have been
616  *   modified may need to be swapped out to swap space and (later) to be read
617  *   back into memory.
618  */
619 
620 /*
621  * The zone field is never updated after free_area_init_core()
622  * sets it, so none of the operations on it need to be atomic.
623  */
624 
625 /* Page flags: | [SECTION] | [NODE] | ZONE | [LAST_CPUPID] | ... | FLAGS | */
626 #define SECTIONS_PGOFF          ((sizeof(unsigned long)*8) - SECTIONS_WIDTH)
627 #define NODES_PGOFF             (SECTIONS_PGOFF - NODES_WIDTH)
628 #define ZONES_PGOFF             (NODES_PGOFF - ZONES_WIDTH)
629 #define LAST_CPUPID_PGOFF       (ZONES_PGOFF - LAST_CPUPID_WIDTH)
630 
631 /*
632  * Define the bit shifts to access each section.  For non-existent
633  * sections we define the shift as 0; that plus a 0 mask ensures
634  * the compiler will optimise away reference to them.
635  */
636 #define SECTIONS_PGSHIFT        (SECTIONS_PGOFF * (SECTIONS_WIDTH != 0))
637 #define NODES_PGSHIFT           (NODES_PGOFF * (NODES_WIDTH != 0))
638 #define ZONES_PGSHIFT           (ZONES_PGOFF * (ZONES_WIDTH != 0))
639 #define LAST_CPUPID_PGSHIFT     (LAST_CPUPID_PGOFF * (LAST_CPUPID_WIDTH != 0))
640 
641 /* NODE:ZONE or SECTION:ZONE is used to ID a zone for the buddy allocator */
642 #ifdef NODE_NOT_IN_PAGE_FLAGS
643 #define ZONEID_SHIFT            (SECTIONS_SHIFT + ZONES_SHIFT)
644 #define ZONEID_PGOFF            ((SECTIONS_PGOFF < ZONES_PGOFF)? \
645                                                 SECTIONS_PGOFF : ZONES_PGOFF)
646 #else
647 #define ZONEID_SHIFT            (NODES_SHIFT + ZONES_SHIFT)
648 #define ZONEID_PGOFF            ((NODES_PGOFF < ZONES_PGOFF)? \
649                                                 NODES_PGOFF : ZONES_PGOFF)
650 #endif
651 
652 #define ZONEID_PGSHIFT          (ZONEID_PGOFF * (ZONEID_SHIFT != 0))
653 
654 #if SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS
655 #error SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS
656 #endif
657 
658 #define ZONES_MASK              ((1UL << ZONES_WIDTH) - 1)
659 #define NODES_MASK              ((1UL << NODES_WIDTH) - 1)
660 #define SECTIONS_MASK           ((1UL << SECTIONS_WIDTH) - 1)
661 #define LAST_CPUPID_MASK        ((1UL << LAST_CPUPID_SHIFT) - 1)
662 #define ZONEID_MASK             ((1UL << ZONEID_SHIFT) - 1)
663 
664 static inline enum zone_type page_zonenum(const struct page *page)
665 {
666         return (page->flags >> ZONES_PGSHIFT) & ZONES_MASK;
667 }
668 
669 #ifdef CONFIG_ZONE_DEVICE
670 void get_zone_device_page(struct page *page);
671 void put_zone_device_page(struct page *page);
672 static inline bool is_zone_device_page(const struct page *page)
673 {
674         return page_zonenum(page) == ZONE_DEVICE;
675 }
676 #else
677 static inline void get_zone_device_page(struct page *page)
678 {
679 }
680 static inline void put_zone_device_page(struct page *page)
681 {
682 }
683 static inline bool is_zone_device_page(const struct page *page)
684 {
685         return false;
686 }
687 #endif
688 
689 static inline void get_page(struct page *page)
690 {
691         page = compound_head(page);
692         /*
693          * Getting a normal page or the head of a compound page
694          * requires to already have an elevated page->_count.
695          */
696         VM_BUG_ON_PAGE(atomic_read(&page->_count) <= 0, page);
697         atomic_inc(&page->_count);
698 
699         if (unlikely(is_zone_device_page(page)))
700                 get_zone_device_page(page);
701 }
702 
703 static inline void put_page(struct page *page)
704 {
705         page = compound_head(page);
706 
707         if (put_page_testzero(page))
708                 __put_page(page);
709 
710         if (unlikely(is_zone_device_page(page)))
711                 put_zone_device_page(page);
712 }
713 
714 #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
715 #define SECTION_IN_PAGE_FLAGS
716 #endif
717 
718 /*
719  * The identification function is mainly used by the buddy allocator for
720  * determining if two pages could be buddies. We are not really identifying
721  * the zone since we could be using the section number id if we do not have
722  * node id available in page flags.
723  * We only guarantee that it will return the same value for two combinable
724  * pages in a zone.
725  */
726 static inline int page_zone_id(struct page *page)
727 {
728         return (page->flags >> ZONEID_PGSHIFT) & ZONEID_MASK;
729 }
730 
731 static inline int zone_to_nid(struct zone *zone)
732 {
733 #ifdef CONFIG_NUMA
734         return zone->node;
735 #else
736         return 0;
737 #endif
738 }
739 
740 #ifdef NODE_NOT_IN_PAGE_FLAGS
741 extern int page_to_nid(const struct page *page);
742 #else
743 static inline int page_to_nid(const struct page *page)
744 {
745         return (page->flags >> NODES_PGSHIFT) & NODES_MASK;
746 }
747 #endif
748 
749 #ifdef CONFIG_NUMA_BALANCING
750 static inline int cpu_pid_to_cpupid(int cpu, int pid)
751 {
752         return ((cpu & LAST__CPU_MASK) << LAST__PID_SHIFT) | (pid & LAST__PID_MASK);
753 }
754 
755 static inline int cpupid_to_pid(int cpupid)
756 {
757         return cpupid & LAST__PID_MASK;
758 }
759 
760 static inline int cpupid_to_cpu(int cpupid)
761 {
762         return (cpupid >> LAST__PID_SHIFT) & LAST__CPU_MASK;
763 }
764 
765 static inline int cpupid_to_nid(int cpupid)
766 {
767         return cpu_to_node(cpupid_to_cpu(cpupid));
768 }
769 
770 static inline bool cpupid_pid_unset(int cpupid)
771 {
772         return cpupid_to_pid(cpupid) == (-1 & LAST__PID_MASK);
773 }
774 
775 static inline bool cpupid_cpu_unset(int cpupid)
776 {
777         return cpupid_to_cpu(cpupid) == (-1 & LAST__CPU_MASK);
778 }
779 
780 static inline bool __cpupid_match_pid(pid_t task_pid, int cpupid)
781 {
782         return (task_pid & LAST__PID_MASK) == cpupid_to_pid(cpupid);
783 }
784 
785 #define cpupid_match_pid(task, cpupid) __cpupid_match_pid(task->pid, cpupid)
786 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
787 static inline int page_cpupid_xchg_last(struct page *page, int cpupid)
788 {
789         return xchg(&page->_last_cpupid, cpupid & LAST_CPUPID_MASK);
790 }
791 
792 static inline int page_cpupid_last(struct page *page)
793 {
794         return page->_last_cpupid;
795 }
796 static inline void page_cpupid_reset_last(struct page *page)
797 {
798         page->_last_cpupid = -1 & LAST_CPUPID_MASK;
799 }
800 #else
801 static inline int page_cpupid_last(struct page *page)
802 {
803         return (page->flags >> LAST_CPUPID_PGSHIFT) & LAST_CPUPID_MASK;
804 }
805 
806 extern int page_cpupid_xchg_last(struct page *page, int cpupid);
807 
808 static inline void page_cpupid_reset_last(struct page *page)
809 {
810         int cpupid = (1 << LAST_CPUPID_SHIFT) - 1;
811 
812         page->flags &= ~(LAST_CPUPID_MASK << LAST_CPUPID_PGSHIFT);
813         page->flags |= (cpupid & LAST_CPUPID_MASK) << LAST_CPUPID_PGSHIFT;
814 }
815 #endif /* LAST_CPUPID_NOT_IN_PAGE_FLAGS */
816 #else /* !CONFIG_NUMA_BALANCING */
817 static inline int page_cpupid_xchg_last(struct page *page, int cpupid)
818 {
819         return page_to_nid(page); /* XXX */
820 }
821 
822 static inline int page_cpupid_last(struct page *page)
823 {
824         return page_to_nid(page); /* XXX */
825 }
826 
827 static inline int cpupid_to_nid(int cpupid)
828 {
829         return -1;
830 }
831 
832 static inline int cpupid_to_pid(int cpupid)
833 {
834         return -1;
835 }
836 
837 static inline int cpupid_to_cpu(int cpupid)
838 {
839         return -1;
840 }
841 
842 static inline int cpu_pid_to_cpupid(int nid, int pid)
843 {
844         return -1;
845 }
846 
847 static inline bool cpupid_pid_unset(int cpupid)
848 {
849         return 1;
850 }
851 
852 static inline void page_cpupid_reset_last(struct page *page)
853 {
854 }
855 
856 static inline bool cpupid_match_pid(struct task_struct *task, int cpupid)
857 {
858         return false;
859 }
860 #endif /* CONFIG_NUMA_BALANCING */
861 
862 static inline struct zone *page_zone(const struct page *page)
863 {
864         return &NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)];
865 }
866 
867 #ifdef SECTION_IN_PAGE_FLAGS
868 static inline void set_page_section(struct page *page, unsigned long section)
869 {
870         page->flags &= ~(SECTIONS_MASK << SECTIONS_PGSHIFT);
871         page->flags |= (section & SECTIONS_MASK) << SECTIONS_PGSHIFT;
872 }
873 
874 static inline unsigned long page_to_section(const struct page *page)
875 {
876         return (page->flags >> SECTIONS_PGSHIFT) & SECTIONS_MASK;
877 }
878 #endif
879 
880 static inline void set_page_zone(struct page *page, enum zone_type zone)
881 {
882         page->flags &= ~(ZONES_MASK << ZONES_PGSHIFT);
883         page->flags |= (zone & ZONES_MASK) << ZONES_PGSHIFT;
884 }
885 
886 static inline void set_page_node(struct page *page, unsigned long node)
887 {
888         page->flags &= ~(NODES_MASK << NODES_PGSHIFT);
889         page->flags |= (node & NODES_MASK) << NODES_PGSHIFT;
890 }
891 
892 static inline void set_page_links(struct page *page, enum zone_type zone,
893         unsigned long node, unsigned long pfn)
894 {
895         set_page_zone(page, zone);
896         set_page_node(page, node);
897 #ifdef SECTION_IN_PAGE_FLAGS
898         set_page_section(page, pfn_to_section_nr(pfn));
899 #endif
900 }
901 
902 #ifdef CONFIG_MEMCG
903 static inline struct mem_cgroup *page_memcg(struct page *page)
904 {
905         return page->mem_cgroup;
906 }
907 
908 static inline void set_page_memcg(struct page *page, struct mem_cgroup *memcg)
909 {
910         page->mem_cgroup = memcg;
911 }
912 #else
913 static inline struct mem_cgroup *page_memcg(struct page *page)
914 {
915         return NULL;
916 }
917 
918 static inline void set_page_memcg(struct page *page, struct mem_cgroup *memcg)
919 {
920 }
921 #endif
922 
923 /*
924  * Some inline functions in vmstat.h depend on page_zone()
925  */
926 #include <linux/vmstat.h>
927 
928 static __always_inline void *lowmem_page_address(const struct page *page)
929 {
930         return __va(PFN_PHYS(page_to_pfn(page)));
931 }
932 
933 #if defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL)
934 #define HASHED_PAGE_VIRTUAL
935 #endif
936 
937 #if defined(WANT_PAGE_VIRTUAL)
938 static inline void *page_address(const struct page *page)
939 {
940         return page->virtual;
941 }
942 static inline void set_page_address(struct page *page, void *address)
943 {
944         page->virtual = address;
945 }
946 #define page_address_init()  do { } while(0)
947 #endif
948 
949 #if defined(HASHED_PAGE_VIRTUAL)
950 void *page_address(const struct page *page);
951 void set_page_address(struct page *page, void *virtual);
952 void page_address_init(void);
953 #endif
954 
955 #if !defined(HASHED_PAGE_VIRTUAL) && !defined(WANT_PAGE_VIRTUAL)
956 #define page_address(page) lowmem_page_address(page)
957 #define set_page_address(page, address)  do { } while(0)
958 #define page_address_init()  do { } while(0)
959 #endif
960 
961 extern void *page_rmapping(struct page *page);
962 extern struct anon_vma *page_anon_vma(struct page *page);
963 extern struct address_space *page_mapping(struct page *page);
964 
965 extern struct address_space *__page_file_mapping(struct page *);
966 
967 static inline
968 struct address_space *page_file_mapping(struct page *page)
969 {
970         if (unlikely(PageSwapCache(page)))
971                 return __page_file_mapping(page);
972 
973         return page->mapping;
974 }
975 
976 /*
977  * Return the pagecache index of the passed page.  Regular pagecache pages
978  * use ->index whereas swapcache pages use ->private
979  */
980 static inline pgoff_t page_index(struct page *page)
981 {
982         if (unlikely(PageSwapCache(page)))
983                 return page_private(page);
984         return page->index;
985 }
986 
987 extern pgoff_t __page_file_index(struct page *page);
988 
989 /*
990  * Return the file index of the page. Regular pagecache pages use ->index
991  * whereas swapcache pages use swp_offset(->private)
992  */
993 static inline pgoff_t page_file_index(struct page *page)
994 {
995         if (unlikely(PageSwapCache(page)))
996                 return __page_file_index(page);
997 
998         return page->index;
999 }
1000 
1001 /*
1002  * Return true if this page is mapped into pagetables.
1003  * For compound page it returns true if any subpage of compound page is mapped.
1004  */
1005 static inline bool page_mapped(struct page *page)
1006 {
1007         int i;
1008         if (likely(!PageCompound(page)))
1009                 return atomic_read(&page->_mapcount) >= 0;
1010         page = compound_head(page);
1011         if (atomic_read(compound_mapcount_ptr(page)) >= 0)
1012                 return true;
1013         for (i = 0; i < hpage_nr_pages(page); i++) {
1014                 if (atomic_read(&page[i]._mapcount) >= 0)
1015                         return true;
1016         }
1017         return false;
1018 }
1019 
1020 /*
1021  * Return true only if the page has been allocated with
1022  * ALLOC_NO_WATERMARKS and the low watermark was not
1023  * met implying that the system is under some pressure.
1024  */
1025 static inline bool page_is_pfmemalloc(struct page *page)
1026 {
1027         /*
1028          * Page index cannot be this large so this must be
1029          * a pfmemalloc page.
1030          */
1031         return page->index == -1UL;
1032 }
1033 
1034 /*
1035  * Only to be called by the page allocator on a freshly allocated
1036  * page.
1037  */
1038 static inline void set_page_pfmemalloc(struct page *page)
1039 {
1040         page->index = -1UL;
1041 }
1042 
1043 static inline void clear_page_pfmemalloc(struct page *page)
1044 {
1045         page->index = 0;
1046 }
1047 
1048 /*
1049  * Different kinds of faults, as returned by handle_mm_fault().
1050  * Used to decide whether a process gets delivered SIGBUS or
1051  * just gets major/minor fault counters bumped up.
1052  */
1053 
1054 #define VM_FAULT_MINOR  0 /* For backwards compat. Remove me quickly. */
1055 
1056 #define VM_FAULT_OOM    0x0001
1057 #define VM_FAULT_SIGBUS 0x0002
1058 #define VM_FAULT_MAJOR  0x0004
1059 #define VM_FAULT_WRITE  0x0008  /* Special case for get_user_pages */
1060 #define VM_FAULT_HWPOISON 0x0010        /* Hit poisoned small page */
1061 #define VM_FAULT_HWPOISON_LARGE 0x0020  /* Hit poisoned large page. Index encoded in upper bits */
1062 #define VM_FAULT_SIGSEGV 0x0040
1063 
1064 #define VM_FAULT_NOPAGE 0x0100  /* ->fault installed the pte, not return page */
1065 #define VM_FAULT_LOCKED 0x0200  /* ->fault locked the returned page */
1066 #define VM_FAULT_RETRY  0x0400  /* ->fault blocked, must retry */
1067 #define VM_FAULT_FALLBACK 0x0800        /* huge page fault failed, fall back to small */
1068 
1069 #define VM_FAULT_HWPOISON_LARGE_MASK 0xf000 /* encodes hpage index for large hwpoison */
1070 
1071 #define VM_FAULT_ERROR  (VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV | \
1072                          VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE | \
1073                          VM_FAULT_FALLBACK)
1074 
1075 /* Encode hstate index for a hwpoisoned large page */
1076 #define VM_FAULT_SET_HINDEX(x) ((x) << 12)
1077 #define VM_FAULT_GET_HINDEX(x) (((x) >> 12) & 0xf)
1078 
1079 /*
1080  * Can be called by the pagefault handler when it gets a VM_FAULT_OOM.
1081  */
1082 extern void pagefault_out_of_memory(void);
1083 
1084 #define offset_in_page(p)       ((unsigned long)(p) & ~PAGE_MASK)
1085 
1086 /*
1087  * Flags passed to show_mem() and show_free_areas() to suppress output in
1088  * various contexts.
1089  */
1090 #define SHOW_MEM_FILTER_NODES           (0x0001u)       /* disallowed nodes */
1091 
1092 extern void show_free_areas(unsigned int flags);
1093 extern bool skip_free_areas_node(unsigned int flags, int nid);
1094 
1095 int shmem_zero_setup(struct vm_area_struct *);
1096 #ifdef CONFIG_SHMEM
1097 bool shmem_mapping(struct address_space *mapping);
1098 #else
1099 static inline bool shmem_mapping(struct address_space *mapping)
1100 {
1101         return false;
1102 }
1103 #endif
1104 
1105 extern bool can_do_mlock(void);
1106 extern int user_shm_lock(size_t, struct user_struct *);
1107 extern void user_shm_unlock(size_t, struct user_struct *);
1108 
1109 /*
1110  * Parameter block passed down to zap_pte_range in exceptional cases.
1111  */
1112 struct zap_details {
1113         struct address_space *check_mapping;    /* Check page->mapping if set */
1114         pgoff_t first_index;                    /* Lowest page->index to unmap */
1115         pgoff_t last_index;                     /* Highest page->index to unmap */
1116 };
1117 
1118 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
1119                 pte_t pte);
1120 
1121 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1122                 unsigned long size);
1123 void zap_page_range(struct vm_area_struct *vma, unsigned long address,
1124                 unsigned long size, struct zap_details *);
1125 void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
1126                 unsigned long start, unsigned long end);
1127 
1128 /**
1129  * mm_walk - callbacks for walk_page_range
1130  * @pmd_entry: if set, called for each non-empty PMD (3rd-level) entry
1131  *             this handler is required to be able to handle
1132  *             pmd_trans_huge() pmds.  They may simply choose to
1133  *             split_huge_page() instead of handling it explicitly.
1134  * @pte_entry: if set, called for each non-empty PTE (4th-level) entry
1135  * @pte_hole: if set, called for each hole at all levels
1136  * @hugetlb_entry: if set, called for each hugetlb entry
1137  * @test_walk: caller specific callback function to determine whether
1138  *             we walk over the current vma or not. A positive returned
1139  *             value means "do page table walk over the current vma,"
1140  *             and a negative one means "abort current page table walk
1141  *             right now." 0 means "skip the current vma."
1142  * @mm:        mm_struct representing the target process of page table walk
1143  * @vma:       vma currently walked (NULL if walking outside vmas)
1144  * @private:   private data for callbacks' usage
1145  *
1146  * (see the comment on walk_page_range() for more details)
1147  */
1148 struct mm_walk {
1149         int (*pmd_entry)(pmd_t *pmd, unsigned long addr,
1150                          unsigned long next, struct mm_walk *walk);
1151         int (*pte_entry)(pte_t *pte, unsigned long addr,
1152                          unsigned long next, struct mm_walk *walk);
1153         int (*pte_hole)(unsigned long addr, unsigned long next,
1154                         struct mm_walk *walk);
1155         int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
1156                              unsigned long addr, unsigned long next,
1157                              struct mm_walk *walk);
1158         int (*test_walk)(unsigned long addr, unsigned long next,
1159                         struct mm_walk *walk);
1160         struct mm_struct *mm;
1161         struct vm_area_struct *vma;
1162         void *private;
1163 };
1164 
1165 int walk_page_range(unsigned long addr, unsigned long end,
1166                 struct mm_walk *walk);
1167 int walk_page_vma(struct vm_area_struct *vma, struct mm_walk *walk);
1168 void free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
1169                 unsigned long end, unsigned long floor, unsigned long ceiling);
1170 int copy_page_range(struct mm_struct *dst, struct mm_struct *src,
1171                         struct vm_area_struct *vma);
1172 void unmap_mapping_range(struct address_space *mapping,
1173                 loff_t const holebegin, loff_t const holelen, int even_cows);
1174 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
1175         unsigned long *pfn);
1176 int follow_phys(struct vm_area_struct *vma, unsigned long address,
1177                 unsigned int flags, unsigned long *prot, resource_size_t *phys);
1178 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
1179                         void *buf, int len, int write);
1180 
1181 static inline void unmap_shared_mapping_range(struct address_space *mapping,
1182                 loff_t const holebegin, loff_t const holelen)
1183 {
1184         unmap_mapping_range(mapping, holebegin, holelen, 0);
1185 }
1186 
1187 extern void truncate_pagecache(struct inode *inode, loff_t new);
1188 extern void truncate_setsize(struct inode *inode, loff_t newsize);
1189 void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to);
1190 void truncate_pagecache_range(struct inode *inode, loff_t offset, loff_t end);
1191 int truncate_inode_page(struct address_space *mapping, struct page *page);
1192 int generic_error_remove_page(struct address_space *mapping, struct page *page);
1193 int invalidate_inode_page(struct page *page);
1194 
1195 #ifdef CONFIG_MMU
1196 extern int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
1197                         unsigned long address, unsigned int flags);
1198 extern int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
1199                             unsigned long address, unsigned int fault_flags,
1200                             bool *unlocked);
1201 #else
1202 static inline int handle_mm_fault(struct mm_struct *mm,
1203                         struct vm_area_struct *vma, unsigned long address,
1204                         unsigned int flags)
1205 {
1206         /* should never happen if there's no MMU */
1207         BUG();
1208         return VM_FAULT_SIGBUS;
1209 }
1210 static inline int fixup_user_fault(struct task_struct *tsk,
1211                 struct mm_struct *mm, unsigned long address,
1212                 unsigned int fault_flags, bool *unlocked)
1213 {
1214         /* should never happen if there's no MMU */
1215         BUG();
1216         return -EFAULT;
1217 }
1218 #endif
1219 
1220 extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write);
1221 extern int access_remote_vm(struct mm_struct *mm, unsigned long addr,
1222                 void *buf, int len, int write);
1223 
1224 long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1225                       unsigned long start, unsigned long nr_pages,
1226                       unsigned int foll_flags, struct page **pages,
1227                       struct vm_area_struct **vmas, int *nonblocking);
1228 long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1229                     unsigned long start, unsigned long nr_pages,
1230                     int write, int force, struct page **pages,
1231                     struct vm_area_struct **vmas);
1232 long get_user_pages_locked(struct task_struct *tsk, struct mm_struct *mm,
1233                     unsigned long start, unsigned long nr_pages,
1234                     int write, int force, struct page **pages,
1235                     int *locked);
1236 long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
1237                                unsigned long start, unsigned long nr_pages,
1238                                int write, int force, struct page **pages,
1239                                unsigned int gup_flags);
1240 long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
1241                     unsigned long start, unsigned long nr_pages,
1242                     int write, int force, struct page **pages);
1243 int get_user_pages_fast(unsigned long start, int nr_pages, int write,
1244                         struct page **pages);
1245 
1246 /* Container for pinned pfns / pages */
1247 struct frame_vector {
1248         unsigned int nr_allocated;      /* Number of frames we have space for */
1249         unsigned int nr_frames; /* Number of frames stored in ptrs array */
1250         bool got_ref;           /* Did we pin pages by getting page ref? */
1251         bool is_pfns;           /* Does array contain pages or pfns? */
1252         void *ptrs[0];          /* Array of pinned pfns / pages. Use
1253                                  * pfns_vector_pages() or pfns_vector_pfns()
1254                                  * for access */
1255 };
1256 
1257 struct frame_vector *frame_vector_create(unsigned int nr_frames);
1258 void frame_vector_destroy(struct frame_vector *vec);
1259 int get_vaddr_frames(unsigned long start, unsigned int nr_pfns,
1260                      bool write, bool force, struct frame_vector *vec);
1261 void put_vaddr_frames(struct frame_vector *vec);
1262 int frame_vector_to_pages(struct frame_vector *vec);
1263 void frame_vector_to_pfns(struct frame_vector *vec);
1264 
1265 static inline unsigned int frame_vector_count(struct frame_vector *vec)
1266 {
1267         return vec->nr_frames;
1268 }
1269 
1270 static inline struct page **frame_vector_pages(struct frame_vector *vec)
1271 {
1272         if (vec->is_pfns) {
1273                 int err = frame_vector_to_pages(vec);
1274 
1275                 if (err)
1276                         return ERR_PTR(err);
1277         }
1278         return (struct page **)(vec->ptrs);
1279 }
1280 
1281 static inline unsigned long *frame_vector_pfns(struct frame_vector *vec)
1282 {
1283         if (!vec->is_pfns)
1284                 frame_vector_to_pfns(vec);
1285         return (unsigned long *)(vec->ptrs);
1286 }
1287 
1288 struct kvec;
1289 int get_kernel_pages(const struct kvec *iov, int nr_pages, int write,
1290                         struct page **pages);
1291 int get_kernel_page(unsigned long start, int write, struct page **pages);
1292 struct page *get_dump_page(unsigned long addr);
1293 
1294 extern int try_to_release_page(struct page * page, gfp_t gfp_mask);
1295 extern void do_invalidatepage(struct page *page, unsigned int offset,
1296                               unsigned int length);
1297 
1298 int __set_page_dirty_nobuffers(struct page *page);
1299 int __set_page_dirty_no_writeback(struct page *page);
1300 int redirty_page_for_writepage(struct writeback_control *wbc,
1301                                 struct page *page);
1302 void account_page_dirtied(struct page *page, struct address_space *mapping,
1303                           struct mem_cgroup *memcg);
1304 void account_page_cleaned(struct page *page, struct address_space *mapping,
1305                           struct mem_cgroup *memcg, struct bdi_writeback *wb);
1306 int set_page_dirty(struct page *page);
1307 int set_page_dirty_lock(struct page *page);
1308 void cancel_dirty_page(struct page *page);
1309 int clear_page_dirty_for_io(struct page *page);
1310 
1311 int get_cmdline(struct task_struct *task, char *buffer, int buflen);
1312 
1313 /* Is the vma a continuation of the stack vma above it? */
1314 static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr)
1315 {
1316         return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN);
1317 }
1318 
1319 static inline bool vma_is_anonymous(struct vm_area_struct *vma)
1320 {
1321         return !vma->vm_ops;
1322 }
1323 
1324 static inline int stack_guard_page_start(struct vm_area_struct *vma,
1325                                              unsigned long addr)
1326 {
1327         return (vma->vm_flags & VM_GROWSDOWN) &&
1328                 (vma->vm_start == addr) &&
1329                 !vma_growsdown(vma->vm_prev, addr);
1330 }
1331 
1332 /* Is the vma a continuation of the stack vma below it? */
1333 static inline int vma_growsup(struct vm_area_struct *vma, unsigned long addr)
1334 {
1335         return vma && (vma->vm_start == addr) && (vma->vm_flags & VM_GROWSUP);
1336 }
1337 
1338 static inline int stack_guard_page_end(struct vm_area_struct *vma,
1339                                            unsigned long addr)
1340 {
1341         return (vma->vm_flags & VM_GROWSUP) &&
1342                 (vma->vm_end == addr) &&
1343                 !vma_growsup(vma->vm_next, addr);
1344 }
1345 
1346 int vma_is_stack_for_task(struct vm_area_struct *vma, struct task_struct *t);
1347 
1348 extern unsigned long move_page_tables(struct vm_area_struct *vma,
1349                 unsigned long old_addr, struct vm_area_struct *new_vma,
1350                 unsigned long new_addr, unsigned long len,
1351                 bool need_rmap_locks);
1352 extern unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
1353                               unsigned long end, pgprot_t newprot,
1354                               int dirty_accountable, int prot_numa);
1355 extern int mprotect_fixup(struct vm_area_struct *vma,
1356                           struct vm_area_struct **pprev, unsigned long start,
1357                           unsigned long end, unsigned long newflags);
1358 
1359 /*
1360  * doesn't attempt to fault and will return short.
1361  */
1362 int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
1363                           struct page **pages);
1364 /*
1365  * per-process(per-mm_struct) statistics.
1366  */
1367 static inline unsigned long get_mm_counter(struct mm_struct *mm, int member)
1368 {
1369         long val = atomic_long_read(&mm->rss_stat.count[member]);
1370 
1371 #ifdef SPLIT_RSS_COUNTING
1372         /*
1373          * counter is updated in asynchronous manner and may go to minus.
1374          * But it's never be expected number for users.
1375          */
1376         if (val < 0)
1377                 val = 0;
1378 #endif
1379         return (unsigned long)val;
1380 }
1381 
1382 static inline void add_mm_counter(struct mm_struct *mm, int member, long value)
1383 {
1384         atomic_long_add(value, &mm->rss_stat.count[member]);
1385 }
1386 
1387 static inline void inc_mm_counter(struct mm_struct *mm, int member)
1388 {
1389         atomic_long_inc(&mm->rss_stat.count[member]);
1390 }
1391 
1392 static inline void dec_mm_counter(struct mm_struct *mm, int member)
1393 {
1394         atomic_long_dec(&mm->rss_stat.count[member]);
1395 }
1396 
1397 /* Optimized variant when page is already known not to be PageAnon */
1398 static inline int mm_counter_file(struct page *page)
1399 {
1400         if (PageSwapBacked(page))
1401                 return MM_SHMEMPAGES;
1402         return MM_FILEPAGES;
1403 }
1404 
1405 static inline int mm_counter(struct page *page)
1406 {
1407         if (PageAnon(page))
1408                 return MM_ANONPAGES;
1409         return mm_counter_file(page);
1410 }
1411 
1412 static inline unsigned long get_mm_rss(struct mm_struct *mm)
1413 {
1414         return get_mm_counter(mm, MM_FILEPAGES) +
1415                 get_mm_counter(mm, MM_ANONPAGES) +
1416                 get_mm_counter(mm, MM_SHMEMPAGES);
1417 }
1418 
1419 static inline unsigned long get_mm_hiwater_rss(struct mm_struct *mm)
1420 {
1421         return max(mm->hiwater_rss, get_mm_rss(mm));
1422 }
1423 
1424 static inline unsigned long get_mm_hiwater_vm(struct mm_struct *mm)
1425 {
1426         return max(mm->hiwater_vm, mm->total_vm);
1427 }
1428 
1429 static inline void update_hiwater_rss(struct mm_struct *mm)
1430 {
1431         unsigned long _rss = get_mm_rss(mm);
1432 
1433         if ((mm)->hiwater_rss < _rss)
1434                 (mm)->hiwater_rss = _rss;
1435 }
1436 
1437 static inline void update_hiwater_vm(struct mm_struct *mm)
1438 {
1439         if (mm->hiwater_vm < mm->total_vm)
1440                 mm->hiwater_vm = mm->total_vm;
1441 }
1442 
1443 static inline void reset_mm_hiwater_rss(struct mm_struct *mm)
1444 {
1445         mm->hiwater_rss = get_mm_rss(mm);
1446 }
1447 
1448 static inline void setmax_mm_hiwater_rss(unsigned long *maxrss,
1449                                          struct mm_struct *mm)
1450 {
1451         unsigned long hiwater_rss = get_mm_hiwater_rss(mm);
1452 
1453         if (*maxrss < hiwater_rss)
1454                 *maxrss = hiwater_rss;
1455 }
1456 
1457 #if defined(SPLIT_RSS_COUNTING)
1458 void sync_mm_rss(struct mm_struct *mm);
1459 #else
1460 static inline void sync_mm_rss(struct mm_struct *mm)
1461 {
1462 }
1463 #endif
1464 
1465 #ifndef __HAVE_ARCH_PTE_DEVMAP
1466 static inline int pte_devmap(pte_t pte)
1467 {
1468         return 0;
1469 }
1470 #endif
1471 
1472 int vma_wants_writenotify(struct vm_area_struct *vma);
1473 
1474 extern pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1475                                spinlock_t **ptl);
1476 static inline pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
1477                                     spinlock_t **ptl)
1478 {
1479         pte_t *ptep;
1480         __cond_lock(*ptl, ptep = __get_locked_pte(mm, addr, ptl));
1481         return ptep;
1482 }
1483 
1484 #ifdef __PAGETABLE_PUD_FOLDED
1485 static inline int __pud_alloc(struct mm_struct *mm, pgd_t *pgd,
1486                                                 unsigned long address)
1487 {
1488         return 0;
1489 }
1490 #else
1491 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address);
1492 #endif
1493 
1494 #if defined(__PAGETABLE_PMD_FOLDED) || !defined(CONFIG_MMU)
1495 static inline int __pmd_alloc(struct mm_struct *mm, pud_t *pud,
1496                                                 unsigned long address)
1497 {
1498         return 0;
1499 }
1500 
1501 static inline void mm_nr_pmds_init(struct mm_struct *mm) {}
1502 
1503 static inline unsigned long mm_nr_pmds(struct mm_struct *mm)
1504 {
1505         return 0;
1506 }
1507 
1508 static inline void mm_inc_nr_pmds(struct mm_struct *mm) {}
1509 static inline void mm_dec_nr_pmds(struct mm_struct *mm) {}
1510 
1511 #else
1512 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address);
1513 
1514 static inline void mm_nr_pmds_init(struct mm_struct *mm)
1515 {
1516         atomic_long_set(&mm->nr_pmds, 0);
1517 }
1518 
1519 static inline unsigned long mm_nr_pmds(struct mm_struct *mm)
1520 {
1521         return atomic_long_read(&mm->nr_pmds);
1522 }
1523 
1524 static inline void mm_inc_nr_pmds(struct mm_struct *mm)
1525 {
1526         atomic_long_inc(&mm->nr_pmds);
1527 }
1528 
1529 static inline void mm_dec_nr_pmds(struct mm_struct *mm)
1530 {
1531         atomic_long_dec(&mm->nr_pmds);
1532 }
1533 #endif
1534 
1535 int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
1536                 pmd_t *pmd, unsigned long address);
1537 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address);
1538 
1539 /*
1540  * The following ifdef needed to get the 4level-fixup.h header to work.
1541  * Remove it when 4level-fixup.h has been removed.
1542  */
1543 #if defined(CONFIG_MMU) && !defined(__ARCH_HAS_4LEVEL_HACK)
1544 static inline pud_t *pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
1545 {
1546         return (unlikely(pgd_none(*pgd)) && __pud_alloc(mm, pgd, address))?
1547                 NULL: pud_offset(pgd, address);
1548 }
1549 
1550 static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
1551 {
1552         return (unlikely(pud_none(*pud)) && __pmd_alloc(mm, pud, address))?
1553                 NULL: pmd_offset(pud, address);
1554 }
1555 #endif /* CONFIG_MMU && !__ARCH_HAS_4LEVEL_HACK */
1556 
1557 #if USE_SPLIT_PTE_PTLOCKS
1558 #if ALLOC_SPLIT_PTLOCKS
1559 void __init ptlock_cache_init(void);
1560 extern bool ptlock_alloc(struct page *page);
1561 extern void ptlock_free(struct page *page);
1562 
1563 static inline spinlock_t *ptlock_ptr(struct page *page)
1564 {
1565         return page->ptl;
1566 }
1567 #else /* ALLOC_SPLIT_PTLOCKS */
1568 static inline void ptlock_cache_init(void)
1569 {
1570 }
1571 
1572 static inline bool ptlock_alloc(struct page *page)
1573 {
1574         return true;
1575 }
1576 
1577 static inline void ptlock_free(struct page *page)
1578 {
1579 }
1580 
1581 static inline spinlock_t *ptlock_ptr(struct page *page)
1582 {
1583         return &page->ptl;
1584 }
1585 #endif /* ALLOC_SPLIT_PTLOCKS */
1586 
1587 static inline spinlock_t *pte_lockptr(struct mm_struct *mm, pmd_t *pmd)
1588 {
1589         return ptlock_ptr(pmd_page(*pmd));
1590 }
1591 
1592 static inline bool ptlock_init(struct page *page)
1593 {
1594         /*
1595          * prep_new_page() initialize page->private (and therefore page->ptl)
1596          * with 0. Make sure nobody took it in use in between.
1597          *
1598          * It can happen if arch try to use slab for page table allocation:
1599          * slab code uses page->slab_cache, which share storage with page->ptl.
1600          */
1601         VM_BUG_ON_PAGE(*(unsigned long *)&page->ptl, page);
1602         if (!ptlock_alloc(page))
1603                 return false;
1604         spin_lock_init(ptlock_ptr(page));
1605         return true;
1606 }
1607 
1608 /* Reset page->mapping so free_pages_check won't complain. */
1609 static inline void pte_lock_deinit(struct page *page)
1610 {
1611         page->mapping = NULL;
1612         ptlock_free(page);
1613 }
1614 
1615 #else   /* !USE_SPLIT_PTE_PTLOCKS */
1616 /*
1617  * We use mm->page_table_lock to guard all pagetable pages of the mm.
1618  */
1619 static inline spinlock_t *pte_lockptr(struct mm_struct *mm, pmd_t *pmd)
1620 {
1621         return &mm->page_table_lock;
1622 }
1623 static inline void ptlock_cache_init(void) {}
1624 static inline bool ptlock_init(struct page *page) { return true; }
1625 static inline void pte_lock_deinit(struct page *page) {}
1626 #endif /* USE_SPLIT_PTE_PTLOCKS */
1627 
1628 static inline void pgtable_init(void)
1629 {
1630         ptlock_cache_init();
1631         pgtable_cache_init();
1632 }
1633 
1634 static inline bool pgtable_page_ctor(struct page *page)
1635 {
1636         if (!ptlock_init(page))
1637                 return false;
1638         inc_zone_page_state(page, NR_PAGETABLE);
1639         return true;
1640 }
1641 
1642 static inline void pgtable_page_dtor(struct page *page)
1643 {
1644         pte_lock_deinit(page);
1645         dec_zone_page_state(page, NR_PAGETABLE);
1646 }
1647 
1648 #define pte_offset_map_lock(mm, pmd, address, ptlp)     \
1649 ({                                                      \
1650         spinlock_t *__ptl = pte_lockptr(mm, pmd);       \
1651         pte_t *__pte = pte_offset_map(pmd, address);    \
1652         *(ptlp) = __ptl;                                \
1653         spin_lock(__ptl);                               \
1654         __pte;                                          \
1655 })
1656 
1657 #define pte_unmap_unlock(pte, ptl)      do {            \
1658         spin_unlock(ptl);                               \
1659         pte_unmap(pte);                                 \
1660 } while (0)
1661 
1662 #define pte_alloc_map(mm, vma, pmd, address)                            \
1663         ((unlikely(pmd_none(*(pmd))) && __pte_alloc(mm, vma,    \
1664                                                         pmd, address))? \
1665          NULL: pte_offset_map(pmd, address))
1666 
1667 #define pte_alloc_map_lock(mm, pmd, address, ptlp)      \
1668         ((unlikely(pmd_none(*(pmd))) && __pte_alloc(mm, NULL,   \
1669                                                         pmd, address))? \
1670                 NULL: pte_offset_map_lock(mm, pmd, address, ptlp))
1671 
1672 #define pte_alloc_kernel(pmd, address)                  \
1673         ((unlikely(pmd_none(*(pmd))) && __pte_alloc_kernel(pmd, address))? \
1674                 NULL: pte_offset_kernel(pmd, address))
1675 
1676 #if USE_SPLIT_PMD_PTLOCKS
1677 
1678 static struct page *pmd_to_page(pmd_t *pmd)
1679 {
1680         unsigned long mask = ~(PTRS_PER_PMD * sizeof(pmd_t) - 1);
1681         return virt_to_page((void *)((unsigned long) pmd & mask));
1682 }
1683 
1684 static inline spinlock_t *pmd_lockptr(struct mm_struct *mm, pmd_t *pmd)
1685 {
1686         return ptlock_ptr(pmd_to_page(pmd));
1687 }
1688 
1689 static inline bool pgtable_pmd_page_ctor(struct page *page)
1690 {
1691 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
1692         page->pmd_huge_pte = NULL;
1693 #endif
1694         return ptlock_init(page);
1695 }
1696 
1697 static inline void pgtable_pmd_page_dtor(struct page *page)
1698 {
1699 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
1700         VM_BUG_ON_PAGE(page->pmd_huge_pte, page);
1701 #endif
1702         ptlock_free(page);
1703 }
1704 
1705 #define pmd_huge_pte(mm, pmd) (pmd_to_page(pmd)->pmd_huge_pte)
1706 
1707 #else
1708 
1709 static inline spinlock_t *pmd_lockptr(struct mm_struct *mm, pmd_t *pmd)
1710 {
1711         return &mm->page_table_lock;
1712 }
1713 
1714 static inline bool pgtable_pmd_page_ctor(struct page *page) { return true; }
1715 static inline void pgtable_pmd_page_dtor(struct page *page) {}
1716 
1717 #define pmd_huge_pte(mm, pmd) ((mm)->pmd_huge_pte)
1718 
1719 #endif
1720 
1721 static inline spinlock_t *pmd_lock(struct mm_struct *mm, pmd_t *pmd)
1722 {
1723         spinlock_t *ptl = pmd_lockptr(mm, pmd);
1724         spin_lock(ptl);
1725         return ptl;
1726 }
1727 
1728 extern void free_area_init(unsigned long * zones_size);
1729 extern void free_area_init_node(int nid, unsigned long * zones_size,
1730                 unsigned long zone_start_pfn, unsigned long *zholes_size);
1731 extern void free_initmem(void);
1732 
1733 /*
1734  * Free reserved pages within range [PAGE_ALIGN(start), end & PAGE_MASK)
1735  * into the buddy system. The freed pages will be poisoned with pattern
1736  * "poison" if it's within range [0, UCHAR_MAX].
1737  * Return pages freed into the buddy system.
1738  */
1739 extern unsigned long free_reserved_area(void *start, void *end,
1740                                         int poison, char *s);
1741 
1742 #ifdef  CONFIG_HIGHMEM
1743 /*
1744  * Free a highmem page into the buddy system, adjusting totalhigh_pages
1745  * and totalram_pages.
1746  */
1747 extern void free_highmem_page(struct page *page);
1748 #endif
1749 
1750 extern void adjust_managed_page_count(struct page *page, long count);
1751 extern void mem_init_print_info(const char *str);
1752 
1753 extern void reserve_bootmem_region(unsigned long start, unsigned long end);
1754 
1755 /* Free the reserved page into the buddy system, so it gets managed. */
1756 static inline void __free_reserved_page(struct page *page)
1757 {
1758         ClearPageReserved(page);
1759         init_page_count(page);
1760         __free_page(page);
1761 }
1762 
1763 static inline void free_reserved_page(struct page *page)
1764 {
1765         __free_reserved_page(page);
1766         adjust_managed_page_count(page, 1);
1767 }
1768 
1769 static inline void mark_page_reserved(struct page *page)
1770 {
1771         SetPageReserved(page);
1772         adjust_managed_page_count(page, -1);
1773 }
1774 
1775 /*
1776  * Default method to free all the __init memory into the buddy system.
1777  * The freed pages will be poisoned with pattern "poison" if it's within
1778  * range [0, UCHAR_MAX].
1779  * Return pages freed into the buddy system.
1780  */
1781 static inline unsigned long free_initmem_default(int poison)
1782 {
1783         extern char __init_begin[], __init_end[];
1784 
1785         return free_reserved_area(&__init_begin, &__init_end,
1786                                   poison, "unused kernel");
1787 }
1788 
1789 static inline unsigned long get_num_physpages(void)
1790 {
1791         int nid;
1792         unsigned long phys_pages = 0;
1793 
1794         for_each_online_node(nid)
1795                 phys_pages += node_present_pages(nid);
1796 
1797         return phys_pages;
1798 }
1799 
1800 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
1801 /*
1802  * With CONFIG_HAVE_MEMBLOCK_NODE_MAP set, an architecture may initialise its
1803  * zones, allocate the backing mem_map and account for memory holes in a more
1804  * architecture independent manner. This is a substitute for creating the
1805  * zone_sizes[] and zholes_size[] arrays and passing them to
1806  * free_area_init_node()
1807  *
1808  * An architecture is expected to register range of page frames backed by
1809  * physical memory with memblock_add[_node]() before calling
1810  * free_area_init_nodes() passing in the PFN each zone ends at. At a basic
1811  * usage, an architecture is expected to do something like
1812  *
1813  * unsigned long max_zone_pfns[MAX_NR_ZONES] = {max_dma, max_normal_pfn,
1814  *                                                       max_highmem_pfn};
1815  * for_each_valid_physical_page_range()
1816  *      memblock_add_node(base, size, nid)
1817  * free_area_init_nodes(max_zone_pfns);
1818  *
1819  * free_bootmem_with_active_regions() calls free_bootmem_node() for each
1820  * registered physical page range.  Similarly
1821  * sparse_memory_present_with_active_regions() calls memory_present() for
1822  * each range when SPARSEMEM is enabled.
1823  *
1824  * See mm/page_alloc.c for more information on each function exposed by
1825  * CONFIG_HAVE_MEMBLOCK_NODE_MAP.
1826  */
1827 extern void free_area_init_nodes(unsigned long *max_zone_pfn);
1828 unsigned long node_map_pfn_alignment(void);
1829 unsigned long __absent_pages_in_range(int nid, unsigned long start_pfn,
1830                                                 unsigned long end_pfn);
1831 extern unsigned long absent_pages_in_range(unsigned long start_pfn,
1832                                                 unsigned long end_pfn);
1833 extern void get_pfn_range_for_nid(unsigned int nid,
1834                         unsigned long *start_pfn, unsigned long *end_pfn);
1835 extern unsigned long find_min_pfn_with_active_regions(void);
1836 extern void free_bootmem_with_active_regions(int nid,
1837                                                 unsigned long max_low_pfn);
1838 extern void sparse_memory_present_with_active_regions(int nid);
1839 
1840 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
1841 
1842 #if !defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP) && \
1843     !defined(CONFIG_HAVE_ARCH_EARLY_PFN_TO_NID)
1844 static inline int __early_pfn_to_nid(unsigned long pfn,
1845                                         struct mminit_pfnnid_cache *state)
1846 {
1847         return 0;
1848 }
1849 #else
1850 /* please see mm/page_alloc.c */
1851 extern int __meminit early_pfn_to_nid(unsigned long pfn);
1852 /* there is a per-arch backend function. */
1853 extern int __meminit __early_pfn_to_nid(unsigned long pfn,
1854                                         struct mminit_pfnnid_cache *state);
1855 #endif
1856 
1857 extern void set_dma_reserve(unsigned long new_dma_reserve);
1858 extern void memmap_init_zone(unsigned long, int, unsigned long,
1859                                 unsigned long, enum memmap_context);
1860 extern void setup_per_zone_wmarks(void);
1861 extern int __meminit init_per_zone_wmark_min(void);
1862 extern void mem_init(void);
1863 extern void __init mmap_init(void);
1864 extern void show_mem(unsigned int flags);
1865 extern void si_meminfo(struct sysinfo * val);
1866 extern void si_meminfo_node(struct sysinfo *val, int nid);
1867 
1868 extern __printf(3, 4)
1869 void warn_alloc_failed(gfp_t gfp_mask, unsigned int order,
1870                 const char *fmt, ...);
1871 
1872 extern void setup_per_cpu_pageset(void);
1873 
1874 extern void zone_pcp_update(struct zone *zone);
1875 extern void zone_pcp_reset(struct zone *zone);
1876 
1877 /* page_alloc.c */
1878 extern int min_free_kbytes;
1879 
1880 /* nommu.c */
1881 extern atomic_long_t mmap_pages_allocated;
1882 extern int nommu_shrink_inode_mappings(struct inode *, size_t, size_t);
1883 
1884 /* interval_tree.c */
1885 void vma_interval_tree_insert(struct vm_area_struct *node,
1886                               struct rb_root *root);
1887 void vma_interval_tree_insert_after(struct vm_area_struct *node,
1888                                     struct vm_area_struct *prev,
1889                                     struct rb_root *root);
1890 void vma_interval_tree_remove(struct vm_area_struct *node,
1891                               struct rb_root *root);
1892 struct vm_area_struct *vma_interval_tree_iter_first(struct rb_root *root,
1893                                 unsigned long start, unsigned long last);
1894 struct vm_area_struct *vma_interval_tree_iter_next(struct vm_area_struct *node,
1895                                 unsigned long start, unsigned long last);
1896 
1897 #define vma_interval_tree_foreach(vma, root, start, last)               \
1898         for (vma = vma_interval_tree_iter_first(root, start, last);     \
1899              vma; vma = vma_interval_tree_iter_next(vma, start, last))
1900 
1901 void anon_vma_interval_tree_insert(struct anon_vma_chain *node,
1902                                    struct rb_root *root);
1903 void anon_vma_interval_tree_remove(struct anon_vma_chain *node,
1904                                    struct rb_root *root);
1905 struct anon_vma_chain *anon_vma_interval_tree_iter_first(
1906         struct rb_root *root, unsigned long start, unsigned long last);
1907 struct anon_vma_chain *anon_vma_interval_tree_iter_next(
1908         struct anon_vma_chain *node, unsigned long start, unsigned long last);
1909 #ifdef CONFIG_DEBUG_VM_RB
1910 void anon_vma_interval_tree_verify(struct anon_vma_chain *node);
1911 #endif
1912 
1913 #define anon_vma_interval_tree_foreach(avc, root, start, last)           \
1914         for (avc = anon_vma_interval_tree_iter_first(root, start, last); \
1915              avc; avc = anon_vma_interval_tree_iter_next(avc, start, last))
1916 
1917 /* mmap.c */
1918 extern int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin);
1919 extern int vma_adjust(struct vm_area_struct *vma, unsigned long start,
1920         unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert);
1921 extern struct vm_area_struct *vma_merge(struct mm_struct *,
1922         struct vm_area_struct *prev, unsigned long addr, unsigned long end,
1923         unsigned long vm_flags, struct anon_vma *, struct file *, pgoff_t,
1924         struct mempolicy *, struct vm_userfaultfd_ctx);
1925 extern struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *);
1926 extern int split_vma(struct mm_struct *,
1927         struct vm_area_struct *, unsigned long addr, int new_below);
1928 extern int insert_vm_struct(struct mm_struct *, struct vm_area_struct *);
1929 extern void __vma_link_rb(struct mm_struct *, struct vm_area_struct *,
1930         struct rb_node **, struct rb_node *);
1931 extern void unlink_file_vma(struct vm_area_struct *);
1932 extern struct vm_area_struct *copy_vma(struct vm_area_struct **,
1933         unsigned long addr, unsigned long len, pgoff_t pgoff,
1934         bool *need_rmap_locks);
1935 extern void exit_mmap(struct mm_struct *);
1936 
1937 static inline int check_data_rlimit(unsigned long rlim,
1938                                     unsigned long new,
1939                                     unsigned long start,
1940                                     unsigned long end_data,
1941                                     unsigned long start_data)
1942 {
1943         if (rlim < RLIM_INFINITY) {
1944                 if (((new - start) + (end_data - start_data)) > rlim)
1945                         return -ENOSPC;
1946         }
1947 
1948         return 0;
1949 }
1950 
1951 extern int mm_take_all_locks(struct mm_struct *mm);
1952 extern void mm_drop_all_locks(struct mm_struct *mm);
1953 
1954 extern void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file);
1955 extern struct file *get_mm_exe_file(struct mm_struct *mm);
1956 
1957 extern bool may_expand_vm(struct mm_struct *, vm_flags_t, unsigned long npages);
1958 extern void vm_stat_account(struct mm_struct *, vm_flags_t, long npages);
1959 
1960 extern struct vm_area_struct *_install_special_mapping(struct mm_struct *mm,
1961                                    unsigned long addr, unsigned long len,
1962                                    unsigned long flags,
1963                                    const struct vm_special_mapping *spec);
1964 /* This is an obsolete alternative to _install_special_mapping. */
1965 extern int install_special_mapping(struct mm_struct *mm,
1966                                    unsigned long addr, unsigned long len,
1967                                    unsigned long flags, struct page **pages);
1968 
1969 extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
1970 
1971 extern unsigned long mmap_region(struct file *file, unsigned long addr,
1972         unsigned long len, vm_flags_t vm_flags, unsigned long pgoff);
1973 extern unsigned long do_mmap(struct file *file, unsigned long addr,
1974         unsigned long len, unsigned long prot, unsigned long flags,
1975         vm_flags_t vm_flags, unsigned long pgoff, unsigned long *populate);
1976 extern int do_munmap(struct mm_struct *, unsigned long, size_t);
1977 
1978 static inline unsigned long
1979 do_mmap_pgoff(struct file *file, unsigned long addr,
1980         unsigned long len, unsigned long prot, unsigned long flags,
1981         unsigned long pgoff, unsigned long *populate)
1982 {
1983         return do_mmap(file, addr, len, prot, flags, 0, pgoff, populate);
1984 }
1985 
1986 #ifdef CONFIG_MMU
1987 extern int __mm_populate(unsigned long addr, unsigned long len,
1988                          int ignore_errors);
1989 static inline void mm_populate(unsigned long addr, unsigned long len)
1990 {
1991         /* Ignore errors */
1992         (void) __mm_populate(addr, len, 1);
1993 }
1994 #else
1995 static inline void mm_populate(unsigned long addr, unsigned long len) {}
1996 #endif
1997 
1998 /* These take the mm semaphore themselves */
1999 extern unsigned long vm_brk(unsigned long, unsigned long);
2000 extern int vm_munmap(unsigned long, size_t);
2001 extern unsigned long vm_mmap(struct file *, unsigned long,
2002         unsigned long, unsigned long,
2003         unsigned long, unsigned long);
2004 
2005 struct vm_unmapped_area_info {
2006 #define VM_UNMAPPED_AREA_TOPDOWN 1
2007         unsigned long flags;
2008         unsigned long length;
2009         unsigned long low_limit;
2010         unsigned long high_limit;
2011         unsigned long align_mask;
2012         unsigned long align_offset;
2013 };
2014 
2015 extern unsigned long unmapped_area(struct vm_unmapped_area_info *info);
2016 extern unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info);
2017 
2018 /*
2019  * Search for an unmapped address range.
2020  *
2021  * We are looking for a range that:
2022  * - does not intersect with any VMA;
2023  * - is contained within the [low_limit, high_limit) interval;
2024  * - is at least the desired size.
2025  * - satisfies (begin_addr & align_mask) == (align_offset & align_mask)
2026  */
2027 static inline unsigned long
2028 vm_unmapped_area(struct vm_unmapped_area_info *info)
2029 {
2030         if (info->flags & VM_UNMAPPED_AREA_TOPDOWN)
2031                 return unmapped_area_topdown(info);
2032         else
2033                 return unmapped_area(info);
2034 }
2035 
2036 /* truncate.c */
2037 extern void truncate_inode_pages(struct address_space *, loff_t);
2038 extern void truncate_inode_pages_range(struct address_space *,
2039                                        loff_t lstart, loff_t lend);
2040 extern void truncate_inode_pages_final(struct address_space *);
2041 
2042 /* generic vm_area_ops exported for stackable file systems */
2043 extern int filemap_fault(struct vm_area_struct *, struct vm_fault *);
2044 extern void filemap_map_pages(struct vm_area_struct *vma, struct vm_fault *vmf);
2045 extern int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf);
2046 
2047 /* mm/page-writeback.c */
2048 int write_one_page(struct page *page, int wait);
2049 void task_dirty_inc(struct task_struct *tsk);
2050 
2051 /* readahead.c */
2052 #define VM_MAX_READAHEAD        128     /* kbytes */
2053 #define VM_MIN_READAHEAD        16      /* kbytes (includes current page) */
2054 
2055 int force_page_cache_readahead(struct address_space *mapping, struct file *filp,
2056                         pgoff_t offset, unsigned long nr_to_read);
2057 
2058 void page_cache_sync_readahead(struct address_space *mapping,
2059                                struct file_ra_state *ra,
2060                                struct file *filp,
2061                                pgoff_t offset,
2062                                unsigned long size);
2063 
2064 void page_cache_async_readahead(struct address_space *mapping,
2065                                 struct file_ra_state *ra,
2066                                 struct file *filp,
2067                                 struct page *pg,
2068                                 pgoff_t offset,
2069                                 unsigned long size);
2070 
2071 /* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */
2072 extern int expand_stack(struct vm_area_struct *vma, unsigned long address);
2073 
2074 /* CONFIG_STACK_GROWSUP still needs to to grow downwards at some places */
2075 extern int expand_downwards(struct vm_area_struct *vma,
2076                 unsigned long address);
2077 #if VM_GROWSUP
2078 extern int expand_upwards(struct vm_area_struct *vma, unsigned long address);
2079 #else
2080   #define expand_upwards(vma, address) (0)
2081 #endif
2082 
2083 /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
2084 extern struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr);
2085 extern struct vm_area_struct * find_vma_prev(struct mm_struct * mm, unsigned long addr,
2086                                              struct vm_area_struct **pprev);
2087 
2088 /* Look up the first VMA which intersects the interval start_addr..end_addr-1,
2089    NULL if none.  Assume start_addr < end_addr. */
2090 static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * mm, unsigned long start_addr, unsigned long end_addr)
2091 {
2092         struct vm_area_struct * vma = find_vma(mm,start_addr);
2093 
2094         if (vma && end_addr <= vma->vm_start)
2095                 vma = NULL;
2096         return vma;
2097 }
2098 
2099 static inline unsigned long vma_pages(struct vm_area_struct *vma)
2100 {
2101         return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
2102 }
2103 
2104 /* Look up the first VMA which exactly match the interval vm_start ... vm_end */
2105 static inline struct vm_area_struct *find_exact_vma(struct mm_struct *mm,
2106                                 unsigned long vm_start, unsigned long vm_end)
2107 {
2108         struct vm_area_struct *vma = find_vma(mm, vm_start);
2109 
2110         if (vma && (vma->vm_start != vm_start || vma->vm_end != vm_end))
2111                 vma = NULL;
2112 
2113         return vma;
2114 }
2115 
2116 #ifdef CONFIG_MMU
2117 pgprot_t vm_get_page_prot(unsigned long vm_flags);
2118 void vma_set_page_prot(struct vm_area_struct *vma);
2119 #else
2120 static inline pgprot_t vm_get_page_prot(unsigned long vm_flags)
2121 {
2122         return __pgprot(0);
2123 }
2124 static inline void vma_set_page_prot(struct vm_area_struct *vma)
2125 {
2126         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2127 }
2128 #endif
2129 
2130 #ifdef CONFIG_NUMA_BALANCING
2131 unsigned long change_prot_numa(struct vm_area_struct *vma,
2132                         unsigned long start, unsigned long end);
2133 #endif
2134 
2135 struct vm_area_struct *find_extend_vma(struct mm_struct *, unsigned long addr);
2136 int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
2137                         unsigned long pfn, unsigned long size, pgprot_t);
2138 int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *);
2139 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2140                         unsigned long pfn);
2141 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2142                         pfn_t pfn);
2143 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
2144 
2145 
2146 struct page *follow_page_mask(struct vm_area_struct *vma,
2147                               unsigned long address, unsigned int foll_flags,
2148                               unsigned int *page_mask);
2149 
2150 static inline struct page *follow_page(struct vm_area_struct *vma,
2151                 unsigned long address, unsigned int foll_flags)
2152 {
2153         unsigned int unused_page_mask;
2154         return follow_page_mask(vma, address, foll_flags, &unused_page_mask);
2155 }
2156 
2157 #define FOLL_WRITE      0x01    /* check pte is writable */
2158 #define FOLL_TOUCH      0x02    /* mark page accessed */
2159 #define FOLL_GET        0x04    /* do get_page on page */
2160 #define FOLL_DUMP       0x08    /* give error on hole if it would be zero */
2161 #define FOLL_FORCE      0x10    /* get_user_pages read/write w/o permission */
2162 #define FOLL_NOWAIT     0x20    /* if a disk transfer is needed, start the IO
2163                                  * and return without waiting upon it */
2164 #define FOLL_POPULATE   0x40    /* fault in page */
2165 #define FOLL_SPLIT      0x80    /* don't return transhuge pages, split them */
2166 #define FOLL_HWPOISON   0x100   /* check page is hwpoisoned */
2167 #define FOLL_NUMA       0x200   /* force NUMA hinting page fault */
2168 #define FOLL_MIGRATION  0x400   /* wait for page to replace migration entry */
2169 #define FOLL_TRIED      0x800   /* a retry, previous pass started an IO */
2170 #define FOLL_MLOCK      0x1000  /* lock present pages */
2171 
2172 typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr,
2173                         void *data);
2174 extern int apply_to_page_range(struct mm_struct *mm, unsigned long address,
2175                                unsigned long size, pte_fn_t fn, void *data);
2176 
2177 
2178 #ifdef CONFIG_DEBUG_PAGEALLOC
2179 extern bool _debug_pagealloc_enabled;
2180 extern void __kernel_map_pages(struct page *page, int numpages, int enable);
2181 
2182 static inline bool debug_pagealloc_enabled(void)
2183 {
2184         return _debug_pagealloc_enabled;
2185 }
2186 
2187 static inline void
2188 kernel_map_pages(struct page *page, int numpages, int enable)
2189 {
2190         if (!debug_pagealloc_enabled())
2191                 return;
2192 
2193         __kernel_map_pages(page, numpages, enable);
2194 }
2195 #ifdef CONFIG_HIBERNATION
2196 extern bool kernel_page_present(struct page *page);
2197 #endif /* CONFIG_HIBERNATION */
2198 #else
2199 static inline void
2200 kernel_map_pages(struct page *page, int numpages, int enable) {}
2201 #ifdef CONFIG_HIBERNATION
2202 static inline bool kernel_page_present(struct page *page) { return true; }
2203 #endif /* CONFIG_HIBERNATION */
2204 #endif
2205 
2206 #ifdef __HAVE_ARCH_GATE_AREA
2207 extern struct vm_area_struct *get_gate_vma(struct mm_struct *mm);
2208 extern int in_gate_area_no_mm(unsigned long addr);
2209 extern int in_gate_area(struct mm_struct *mm, unsigned long addr);
2210 #else
2211 static inline struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
2212 {
2213         return NULL;
2214 }
2215 static inline int in_gate_area_no_mm(unsigned long addr) { return 0; }
2216 static inline int in_gate_area(struct mm_struct *mm, unsigned long addr)
2217 {
2218         return 0;
2219 }
2220 #endif  /* __HAVE_ARCH_GATE_AREA */
2221 
2222 #ifdef CONFIG_SYSCTL
2223 extern int sysctl_drop_caches;
2224 int drop_caches_sysctl_handler(struct ctl_table *, int,
2225                                         void __user *, size_t *, loff_t *);
2226 #endif
2227 
2228 void drop_slab(void);
2229 void drop_slab_node(int nid);
2230 
2231 #ifndef CONFIG_MMU
2232 #define randomize_va_space 0
2233 #else
2234 extern int randomize_va_space;
2235 #endif
2236 
2237 const char * arch_vma_name(struct vm_area_struct *vma);
2238 void print_vma_addr(char *prefix, unsigned long rip);
2239 
2240 void sparse_mem_maps_populate_node(struct page **map_map,
2241                                    unsigned long pnum_begin,
2242                                    unsigned long pnum_end,
2243                                    unsigned long map_count,
2244                                    int nodeid);
2245 
2246 struct page *sparse_mem_map_populate(unsigned long pnum, int nid);
2247 pgd_t *vmemmap_pgd_populate(unsigned long addr, int node);
2248 pud_t *vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node);
2249 pmd_t *vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node);
2250 pte_t *vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node);
2251 void *vmemmap_alloc_block(unsigned long size, int node);
2252 struct vmem_altmap;
2253 void *__vmemmap_alloc_block_buf(unsigned long size, int node,
2254                 struct vmem_altmap *altmap);
2255 static inline void *vmemmap_alloc_block_buf(unsigned long size, int node)
2256 {
2257         return __vmemmap_alloc_block_buf(size, node, NULL);
2258 }
2259 
2260 void vmemmap_verify(pte_t *, int, unsigned long, unsigned long);
2261 int vmemmap_populate_basepages(unsigned long start, unsigned long end,
2262                                int node);
2263 int vmemmap_populate(unsigned long start, unsigned long end, int node);
2264 void vmemmap_populate_print_last(void);
2265 #ifdef CONFIG_MEMORY_HOTPLUG
2266 void vmemmap_free(unsigned long start, unsigned long end);
2267 #endif
2268 void register_page_bootmem_memmap(unsigned long section_nr, struct page *map,
2269                                   unsigned long size);
2270 
2271 enum mf_flags {
2272         MF_COUNT_INCREASED = 1 << 0,
2273         MF_ACTION_REQUIRED = 1 << 1,
2274         MF_MUST_KILL = 1 << 2,
2275         MF_SOFT_OFFLINE = 1 << 3,
2276 };
2277 extern int memory_failure(unsigned long pfn, int trapno, int flags);
2278 extern void memory_failure_queue(unsigned long pfn, int trapno, int flags);
2279 extern int unpoison_memory(unsigned long pfn);
2280 extern int get_hwpoison_page(struct page *page);
2281 #define put_hwpoison_page(page) put_page(page)
2282 extern int sysctl_memory_failure_early_kill;
2283 extern int sysctl_memory_failure_recovery;
2284 extern void shake_page(struct page *p, int access);
2285 extern atomic_long_t num_poisoned_pages;
2286 extern int soft_offline_page(struct page *page, int flags);
2287 
2288 
2289 /*
2290  * Error handlers for various types of pages.
2291  */
2292 enum mf_result {
2293         MF_IGNORED,     /* Error: cannot be handled */
2294         MF_FAILED,      /* Error: handling failed */
2295         MF_DELAYED,     /* Will be handled later */
2296         MF_RECOVERED,   /* Successfully recovered */
2297 };
2298 
2299 enum mf_action_page_type {
2300         MF_MSG_KERNEL,
2301         MF_MSG_KERNEL_HIGH_ORDER,
2302         MF_MSG_SLAB,
2303         MF_MSG_DIFFERENT_COMPOUND,
2304         MF_MSG_POISONED_HUGE,
2305         MF_MSG_HUGE,
2306         MF_MSG_FREE_HUGE,
2307         MF_MSG_UNMAP_FAILED,
2308         MF_MSG_DIRTY_SWAPCACHE,
2309         MF_MSG_CLEAN_SWAPCACHE,
2310         MF_MSG_DIRTY_MLOCKED_LRU,
2311         MF_MSG_CLEAN_MLOCKED_LRU,
2312         MF_MSG_DIRTY_UNEVICTABLE_LRU,
2313         MF_MSG_CLEAN_UNEVICTABLE_LRU,
2314         MF_MSG_DIRTY_LRU,
2315         MF_MSG_CLEAN_LRU,
2316         MF_MSG_TRUNCATED_LRU,
2317         MF_MSG_BUDDY,
2318         MF_MSG_BUDDY_2ND,
2319         MF_MSG_UNKNOWN,
2320 };
2321 
2322 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
2323 extern void clear_huge_page(struct page *page,
2324                             unsigned long addr,
2325                             unsigned int pages_per_huge_page);
2326 extern void copy_user_huge_page(struct page *dst, struct page *src,
2327                                 unsigned long addr, struct vm_area_struct *vma,
2328                                 unsigned int pages_per_huge_page);
2329 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
2330 
2331 extern struct page_ext_operations debug_guardpage_ops;
2332 extern struct page_ext_operations page_poisoning_ops;
2333 
2334 #ifdef CONFIG_DEBUG_PAGEALLOC
2335 extern unsigned int _debug_guardpage_minorder;
2336 extern bool _debug_guardpage_enabled;
2337 
2338 static inline unsigned int debug_guardpage_minorder(void)
2339 {
2340         return _debug_guardpage_minorder;
2341 }
2342 
2343 static inline bool debug_guardpage_enabled(void)
2344 {
2345         return _debug_guardpage_enabled;
2346 }
2347 
2348 static inline bool page_is_guard(struct page *page)
2349 {
2350         struct page_ext *page_ext;
2351 
2352         if (!debug_guardpage_enabled())
2353                 return false;
2354 
2355         page_ext = lookup_page_ext(page);
2356         return test_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);
2357 }
2358 #else
2359 static inline unsigned int debug_guardpage_minorder(void) { return 0; }
2360 static inline bool debug_guardpage_enabled(void) { return false; }
2361 static inline bool page_is_guard(struct page *page) { return false; }
2362 #endif /* CONFIG_DEBUG_PAGEALLOC */
2363 
2364 #if MAX_NUMNODES > 1
2365 void __init setup_nr_node_ids(void);
2366 #else
2367 static inline void setup_nr_node_ids(void) {}
2368 #endif
2369 
2370 #endif /* __KERNEL__ */
2371 #endif /* _LINUX_MM_H */
2372 

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