2 * mm/rmap.c - physical to virtual reverse mappings
4 * Copyright 2001, Rik van Riel <riel@conectiva.com.br>
5 * Released under the General Public License (GPL).
7 * Simple, low overhead reverse mapping scheme.
8 * Please try to keep this thing as modular as possible.
10 * Provides methods for unmapping each kind of mapped page:
11 * the anon methods track anonymous pages, and
12 * the file methods track pages belonging to an inode.
14 * Original design by Rik van Riel <riel@conectiva.com.br> 2001
15 * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004
16 * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004
17 * Contributions by Hugh Dickins 2003, 2004
21 * Lock ordering in mm:
23 * inode->i_mutex (while writing or truncating, not reading or faulting)
24 * inode->i_alloc_sem (vmtruncate_range)
26 * page->flags PG_locked (lock_page)
27 * mapping->i_mmap_lock
29 * mm->page_table_lock or pte_lock
30 * zone->lru_lock (in mark_page_accessed, isolate_lru_page)
31 * swap_lock (in swap_duplicate, swap_info_get)
32 * mmlist_lock (in mmput, drain_mmlist and others)
33 * mapping->private_lock (in __set_page_dirty_buffers)
34 * inode_lock (in set_page_dirty's __mark_inode_dirty)
35 * sb_lock (within inode_lock in fs/fs-writeback.c)
36 * mapping->tree_lock (widely used, in set_page_dirty,
37 * in arch-dependent flush_dcache_mmap_lock,
38 * within inode_lock in __sync_single_inode)
40 * (code doesn't rely on that order so it could be switched around)
42 * anon_vma->lock (memory_failure, collect_procs_anon)
47 #include <linux/pagemap.h>
48 #include <linux/swap.h>
49 #include <linux/swapops.h>
50 #include <linux/slab.h>
51 #include <linux/init.h>
52 #include <linux/ksm.h>
53 #include <linux/rmap.h>
54 #include <linux/rcupdate.h>
55 #include <linux/module.h>
56 #include <linux/memcontrol.h>
57 #include <linux/mmu_notifier.h>
58 #include <linux/migrate.h>
59 #include <linux/hugetlb.h>
61 #include <asm/tlbflush.h>
65 static struct kmem_cache
*anon_vma_cachep
;
66 static struct kmem_cache
*anon_vma_chain_cachep
;
68 static inline struct anon_vma
*anon_vma_alloc(void)
70 return kmem_cache_alloc(anon_vma_cachep
, GFP_KERNEL
);
73 void anon_vma_free(struct anon_vma
*anon_vma
)
75 kmem_cache_free(anon_vma_cachep
, anon_vma
);
78 static inline struct anon_vma_chain
*anon_vma_chain_alloc(void)
80 return kmem_cache_alloc(anon_vma_chain_cachep
, GFP_KERNEL
);
83 void anon_vma_chain_free(struct anon_vma_chain
*anon_vma_chain
)
85 kmem_cache_free(anon_vma_chain_cachep
, anon_vma_chain
);
89 * anon_vma_prepare - attach an anon_vma to a memory region
90 * @vma: the memory region in question
92 * This makes sure the memory mapping described by 'vma' has
93 * an 'anon_vma' attached to it, so that we can associate the
94 * anonymous pages mapped into it with that anon_vma.
96 * The common case will be that we already have one, but if
97 * if not we either need to find an adjacent mapping that we
98 * can re-use the anon_vma from (very common when the only
99 * reason for splitting a vma has been mprotect()), or we
100 * allocate a new one.
102 * Anon-vma allocations are very subtle, because we may have
103 * optimistically looked up an anon_vma in page_lock_anon_vma()
104 * and that may actually touch the spinlock even in the newly
105 * allocated vma (it depends on RCU to make sure that the
106 * anon_vma isn't actually destroyed).
108 * As a result, we need to do proper anon_vma locking even
109 * for the new allocation. At the same time, we do not want
110 * to do any locking for the common case of already having
113 * This must be called with the mmap_sem held for reading.
115 int anon_vma_prepare(struct vm_area_struct
*vma
)
117 struct anon_vma
*anon_vma
= vma
->anon_vma
;
118 struct anon_vma_chain
*avc
;
121 if (unlikely(!anon_vma
)) {
122 struct mm_struct
*mm
= vma
->vm_mm
;
123 struct anon_vma
*allocated
;
125 avc
= anon_vma_chain_alloc();
129 anon_vma
= find_mergeable_anon_vma(vma
);
132 anon_vma
= anon_vma_alloc();
133 if (unlikely(!anon_vma
))
134 goto out_enomem_free_avc
;
135 allocated
= anon_vma
;
138 spin_lock(&anon_vma
->lock
);
139 /* page_table_lock to protect against threads */
140 spin_lock(&mm
->page_table_lock
);
141 if (likely(!vma
->anon_vma
)) {
142 vma
->anon_vma
= anon_vma
;
143 avc
->anon_vma
= anon_vma
;
145 list_add(&avc
->same_vma
, &vma
->anon_vma_chain
);
146 list_add(&avc
->same_anon_vma
, &anon_vma
->head
);
150 spin_unlock(&mm
->page_table_lock
);
151 spin_unlock(&anon_vma
->lock
);
153 if (unlikely(allocated
))
154 anon_vma_free(allocated
);
156 anon_vma_chain_free(avc
);
161 anon_vma_chain_free(avc
);
166 static void anon_vma_chain_link(struct vm_area_struct
*vma
,
167 struct anon_vma_chain
*avc
,
168 struct anon_vma
*anon_vma
)
171 avc
->anon_vma
= anon_vma
;
172 list_add(&avc
->same_vma
, &vma
->anon_vma_chain
);
174 spin_lock(&anon_vma
->lock
);
175 list_add_tail(&avc
->same_anon_vma
, &anon_vma
->head
);
176 spin_unlock(&anon_vma
->lock
);
180 * Attach the anon_vmas from src to dst.
181 * Returns 0 on success, -ENOMEM on failure.
183 int anon_vma_clone(struct vm_area_struct
*dst
, struct vm_area_struct
*src
)
185 struct anon_vma_chain
*avc
, *pavc
;
187 list_for_each_entry_reverse(pavc
, &src
->anon_vma_chain
, same_vma
) {
188 avc
= anon_vma_chain_alloc();
191 anon_vma_chain_link(dst
, avc
, pavc
->anon_vma
);
196 unlink_anon_vmas(dst
);
201 * Attach vma to its own anon_vma, as well as to the anon_vmas that
202 * the corresponding VMA in the parent process is attached to.
203 * Returns 0 on success, non-zero on failure.
205 int anon_vma_fork(struct vm_area_struct
*vma
, struct vm_area_struct
*pvma
)
207 struct anon_vma_chain
*avc
;
208 struct anon_vma
*anon_vma
;
210 /* Don't bother if the parent process has no anon_vma here. */
215 * First, attach the new VMA to the parent VMA's anon_vmas,
216 * so rmap can find non-COWed pages in child processes.
218 if (anon_vma_clone(vma
, pvma
))
221 /* Then add our own anon_vma. */
222 anon_vma
= anon_vma_alloc();
225 avc
= anon_vma_chain_alloc();
227 goto out_error_free_anon_vma
;
228 anon_vma_chain_link(vma
, avc
, anon_vma
);
229 /* Mark this anon_vma as the one where our new (COWed) pages go. */
230 vma
->anon_vma
= anon_vma
;
234 out_error_free_anon_vma
:
235 anon_vma_free(anon_vma
);
237 unlink_anon_vmas(vma
);
241 static void anon_vma_unlink(struct anon_vma_chain
*anon_vma_chain
)
243 struct anon_vma
*anon_vma
= anon_vma_chain
->anon_vma
;
246 /* If anon_vma_fork fails, we can get an empty anon_vma_chain. */
250 spin_lock(&anon_vma
->lock
);
251 list_del(&anon_vma_chain
->same_anon_vma
);
253 /* We must garbage collect the anon_vma if it's empty */
254 empty
= list_empty(&anon_vma
->head
) && !anonvma_external_refcount(anon_vma
);
255 spin_unlock(&anon_vma
->lock
);
258 anon_vma_free(anon_vma
);
261 void unlink_anon_vmas(struct vm_area_struct
*vma
)
263 struct anon_vma_chain
*avc
, *next
;
265 /* Unlink each anon_vma chained to the VMA. */
266 list_for_each_entry_safe(avc
, next
, &vma
->anon_vma_chain
, same_vma
) {
267 anon_vma_unlink(avc
);
268 list_del(&avc
->same_vma
);
269 anon_vma_chain_free(avc
);
273 static void anon_vma_ctor(void *data
)
275 struct anon_vma
*anon_vma
= data
;
277 spin_lock_init(&anon_vma
->lock
);
278 anonvma_external_refcount_init(anon_vma
);
279 INIT_LIST_HEAD(&anon_vma
->head
);
282 void __init
anon_vma_init(void)
284 anon_vma_cachep
= kmem_cache_create("anon_vma", sizeof(struct anon_vma
),
285 0, SLAB_DESTROY_BY_RCU
|SLAB_PANIC
, anon_vma_ctor
);
286 anon_vma_chain_cachep
= KMEM_CACHE(anon_vma_chain
, SLAB_PANIC
);
290 * Getting a lock on a stable anon_vma from a page off the LRU is
291 * tricky: page_lock_anon_vma rely on RCU to guard against the races.
293 struct anon_vma
*page_lock_anon_vma(struct page
*page
)
295 struct anon_vma
*anon_vma
;
296 unsigned long anon_mapping
;
299 anon_mapping
= (unsigned long) ACCESS_ONCE(page
->mapping
);
300 if ((anon_mapping
& PAGE_MAPPING_FLAGS
) != PAGE_MAPPING_ANON
)
302 if (!page_mapped(page
))
305 anon_vma
= (struct anon_vma
*) (anon_mapping
- PAGE_MAPPING_ANON
);
306 spin_lock(&anon_vma
->lock
);
313 void page_unlock_anon_vma(struct anon_vma
*anon_vma
)
315 spin_unlock(&anon_vma
->lock
);
320 * At what user virtual address is page expected in @vma?
321 * Returns virtual address or -EFAULT if page's index/offset is not
322 * within the range mapped the @vma.
324 static inline unsigned long
325 vma_address(struct page
*page
, struct vm_area_struct
*vma
)
327 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
328 unsigned long address
;
330 if (unlikely(is_vm_hugetlb_page(vma
)))
331 pgoff
= page
->index
<< huge_page_order(page_hstate(page
));
332 address
= vma
->vm_start
+ ((pgoff
- vma
->vm_pgoff
) << PAGE_SHIFT
);
333 if (unlikely(address
< vma
->vm_start
|| address
>= vma
->vm_end
)) {
334 /* page should be within @vma mapping range */
341 * At what user virtual address is page expected in vma?
342 * Caller should check the page is actually part of the vma.
344 unsigned long page_address_in_vma(struct page
*page
, struct vm_area_struct
*vma
)
348 else if (page
->mapping
&& !(vma
->vm_flags
& VM_NONLINEAR
)) {
350 vma
->vm_file
->f_mapping
!= page
->mapping
)
354 return vma_address(page
, vma
);
358 * Check that @page is mapped at @address into @mm.
360 * If @sync is false, page_check_address may perform a racy check to avoid
361 * the page table lock when the pte is not present (helpful when reclaiming
362 * highly shared pages).
364 * On success returns with pte mapped and locked.
366 pte_t
*page_check_address(struct page
*page
, struct mm_struct
*mm
,
367 unsigned long address
, spinlock_t
**ptlp
, int sync
)
375 if (unlikely(PageHuge(page
))) {
376 pte
= huge_pte_offset(mm
, address
);
377 ptl
= &mm
->page_table_lock
;
381 pgd
= pgd_offset(mm
, address
);
382 if (!pgd_present(*pgd
))
385 pud
= pud_offset(pgd
, address
);
386 if (!pud_present(*pud
))
389 pmd
= pmd_offset(pud
, address
);
390 if (!pmd_present(*pmd
))
393 pte
= pte_offset_map(pmd
, address
);
394 /* Make a quick check before getting the lock */
395 if (!sync
&& !pte_present(*pte
)) {
400 ptl
= pte_lockptr(mm
, pmd
);
403 if (pte_present(*pte
) && page_to_pfn(page
) == pte_pfn(*pte
)) {
407 pte_unmap_unlock(pte
, ptl
);
412 * page_mapped_in_vma - check whether a page is really mapped in a VMA
413 * @page: the page to test
414 * @vma: the VMA to test
416 * Returns 1 if the page is mapped into the page tables of the VMA, 0
417 * if the page is not mapped into the page tables of this VMA. Only
418 * valid for normal file or anonymous VMAs.
420 int page_mapped_in_vma(struct page
*page
, struct vm_area_struct
*vma
)
422 unsigned long address
;
426 address
= vma_address(page
, vma
);
427 if (address
== -EFAULT
) /* out of vma range */
429 pte
= page_check_address(page
, vma
->vm_mm
, address
, &ptl
, 1);
430 if (!pte
) /* the page is not in this mm */
432 pte_unmap_unlock(pte
, ptl
);
438 * Subfunctions of page_referenced: page_referenced_one called
439 * repeatedly from either page_referenced_anon or page_referenced_file.
441 int page_referenced_one(struct page
*page
, struct vm_area_struct
*vma
,
442 unsigned long address
, unsigned int *mapcount
,
443 unsigned long *vm_flags
)
445 struct mm_struct
*mm
= vma
->vm_mm
;
450 pte
= page_check_address(page
, mm
, address
, &ptl
, 0);
455 * Don't want to elevate referenced for mlocked page that gets this far,
456 * in order that it progresses to try_to_unmap and is moved to the
459 if (vma
->vm_flags
& VM_LOCKED
) {
460 *mapcount
= 1; /* break early from loop */
461 *vm_flags
|= VM_LOCKED
;
465 if (ptep_clear_flush_young_notify(vma
, address
, pte
)) {
467 * Don't treat a reference through a sequentially read
468 * mapping as such. If the page has been used in
469 * another mapping, we will catch it; if this other
470 * mapping is already gone, the unmap path will have
471 * set PG_referenced or activated the page.
473 if (likely(!VM_SequentialReadHint(vma
)))
477 /* Pretend the page is referenced if the task has the
478 swap token and is in the middle of a page fault. */
479 if (mm
!= current
->mm
&& has_swap_token(mm
) &&
480 rwsem_is_locked(&mm
->mmap_sem
))
485 pte_unmap_unlock(pte
, ptl
);
488 *vm_flags
|= vma
->vm_flags
;
493 static int page_referenced_anon(struct page
*page
,
494 struct mem_cgroup
*mem_cont
,
495 unsigned long *vm_flags
)
497 unsigned int mapcount
;
498 struct anon_vma
*anon_vma
;
499 struct anon_vma_chain
*avc
;
502 anon_vma
= page_lock_anon_vma(page
);
506 mapcount
= page_mapcount(page
);
507 list_for_each_entry(avc
, &anon_vma
->head
, same_anon_vma
) {
508 struct vm_area_struct
*vma
= avc
->vma
;
509 unsigned long address
= vma_address(page
, vma
);
510 if (address
== -EFAULT
)
513 * If we are reclaiming on behalf of a cgroup, skip
514 * counting on behalf of references from different
517 if (mem_cont
&& !mm_match_cgroup(vma
->vm_mm
, mem_cont
))
519 referenced
+= page_referenced_one(page
, vma
, address
,
520 &mapcount
, vm_flags
);
525 page_unlock_anon_vma(anon_vma
);
530 * page_referenced_file - referenced check for object-based rmap
531 * @page: the page we're checking references on.
532 * @mem_cont: target memory controller
533 * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
535 * For an object-based mapped page, find all the places it is mapped and
536 * check/clear the referenced flag. This is done by following the page->mapping
537 * pointer, then walking the chain of vmas it holds. It returns the number
538 * of references it found.
540 * This function is only called from page_referenced for object-based pages.
542 static int page_referenced_file(struct page
*page
,
543 struct mem_cgroup
*mem_cont
,
544 unsigned long *vm_flags
)
546 unsigned int mapcount
;
547 struct address_space
*mapping
= page
->mapping
;
548 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
549 struct vm_area_struct
*vma
;
550 struct prio_tree_iter iter
;
554 * The caller's checks on page->mapping and !PageAnon have made
555 * sure that this is a file page: the check for page->mapping
556 * excludes the case just before it gets set on an anon page.
558 BUG_ON(PageAnon(page
));
561 * The page lock not only makes sure that page->mapping cannot
562 * suddenly be NULLified by truncation, it makes sure that the
563 * structure at mapping cannot be freed and reused yet,
564 * so we can safely take mapping->i_mmap_lock.
566 BUG_ON(!PageLocked(page
));
568 spin_lock(&mapping
->i_mmap_lock
);
571 * i_mmap_lock does not stabilize mapcount at all, but mapcount
572 * is more likely to be accurate if we note it after spinning.
574 mapcount
= page_mapcount(page
);
576 vma_prio_tree_foreach(vma
, &iter
, &mapping
->i_mmap
, pgoff
, pgoff
) {
577 unsigned long address
= vma_address(page
, vma
);
578 if (address
== -EFAULT
)
581 * If we are reclaiming on behalf of a cgroup, skip
582 * counting on behalf of references from different
585 if (mem_cont
&& !mm_match_cgroup(vma
->vm_mm
, mem_cont
))
587 referenced
+= page_referenced_one(page
, vma
, address
,
588 &mapcount
, vm_flags
);
593 spin_unlock(&mapping
->i_mmap_lock
);
598 * page_referenced - test if the page was referenced
599 * @page: the page to test
600 * @is_locked: caller holds lock on the page
601 * @mem_cont: target memory controller
602 * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
604 * Quick test_and_clear_referenced for all mappings to a page,
605 * returns the number of ptes which referenced the page.
607 int page_referenced(struct page
*page
,
609 struct mem_cgroup
*mem_cont
,
610 unsigned long *vm_flags
)
616 if (page_mapped(page
) && page_rmapping(page
)) {
617 if (!is_locked
&& (!PageAnon(page
) || PageKsm(page
))) {
618 we_locked
= trylock_page(page
);
624 if (unlikely(PageKsm(page
)))
625 referenced
+= page_referenced_ksm(page
, mem_cont
,
627 else if (PageAnon(page
))
628 referenced
+= page_referenced_anon(page
, mem_cont
,
630 else if (page
->mapping
)
631 referenced
+= page_referenced_file(page
, mem_cont
,
637 if (page_test_and_clear_young(page
))
643 static int page_mkclean_one(struct page
*page
, struct vm_area_struct
*vma
,
644 unsigned long address
)
646 struct mm_struct
*mm
= vma
->vm_mm
;
651 pte
= page_check_address(page
, mm
, address
, &ptl
, 1);
655 if (pte_dirty(*pte
) || pte_write(*pte
)) {
658 flush_cache_page(vma
, address
, pte_pfn(*pte
));
659 entry
= ptep_clear_flush_notify(vma
, address
, pte
);
660 entry
= pte_wrprotect(entry
);
661 entry
= pte_mkclean(entry
);
662 set_pte_at(mm
, address
, pte
, entry
);
666 pte_unmap_unlock(pte
, ptl
);
671 static int page_mkclean_file(struct address_space
*mapping
, struct page
*page
)
673 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
674 struct vm_area_struct
*vma
;
675 struct prio_tree_iter iter
;
678 BUG_ON(PageAnon(page
));
680 spin_lock(&mapping
->i_mmap_lock
);
681 vma_prio_tree_foreach(vma
, &iter
, &mapping
->i_mmap
, pgoff
, pgoff
) {
682 if (vma
->vm_flags
& VM_SHARED
) {
683 unsigned long address
= vma_address(page
, vma
);
684 if (address
== -EFAULT
)
686 ret
+= page_mkclean_one(page
, vma
, address
);
689 spin_unlock(&mapping
->i_mmap_lock
);
693 int page_mkclean(struct page
*page
)
697 BUG_ON(!PageLocked(page
));
699 if (page_mapped(page
)) {
700 struct address_space
*mapping
= page_mapping(page
);
702 ret
= page_mkclean_file(mapping
, page
);
703 if (page_test_dirty(page
)) {
704 page_clear_dirty(page
);
712 EXPORT_SYMBOL_GPL(page_mkclean
);
715 * page_move_anon_rmap - move a page to our anon_vma
716 * @page: the page to move to our anon_vma
717 * @vma: the vma the page belongs to
718 * @address: the user virtual address mapped
720 * When a page belongs exclusively to one process after a COW event,
721 * that page can be moved into the anon_vma that belongs to just that
722 * process, so the rmap code will not search the parent or sibling
725 void page_move_anon_rmap(struct page
*page
,
726 struct vm_area_struct
*vma
, unsigned long address
)
728 struct anon_vma
*anon_vma
= vma
->anon_vma
;
730 VM_BUG_ON(!PageLocked(page
));
731 VM_BUG_ON(!anon_vma
);
732 VM_BUG_ON(page
->index
!= linear_page_index(vma
, address
));
734 anon_vma
= (void *) anon_vma
+ PAGE_MAPPING_ANON
;
735 page
->mapping
= (struct address_space
*) anon_vma
;
739 * __page_set_anon_rmap - setup new anonymous rmap
740 * @page: the page to add the mapping to
741 * @vma: the vm area in which the mapping is added
742 * @address: the user virtual address mapped
743 * @exclusive: the page is exclusively owned by the current process
745 static void __page_set_anon_rmap(struct page
*page
,
746 struct vm_area_struct
*vma
, unsigned long address
, int exclusive
)
748 struct anon_vma
*anon_vma
= vma
->anon_vma
;
753 * If the page isn't exclusively mapped into this vma,
754 * we must use the _oldest_ possible anon_vma for the
757 * So take the last AVC chain entry in the vma, which is
758 * the deepest ancestor, and use the anon_vma from that.
761 struct anon_vma_chain
*avc
;
762 avc
= list_entry(vma
->anon_vma_chain
.prev
, struct anon_vma_chain
, same_vma
);
763 anon_vma
= avc
->anon_vma
;
766 anon_vma
= (void *) anon_vma
+ PAGE_MAPPING_ANON
;
767 page
->mapping
= (struct address_space
*) anon_vma
;
768 page
->index
= linear_page_index(vma
, address
);
772 * __page_check_anon_rmap - sanity check anonymous rmap addition
773 * @page: the page to add the mapping to
774 * @vma: the vm area in which the mapping is added
775 * @address: the user virtual address mapped
777 static void __page_check_anon_rmap(struct page
*page
,
778 struct vm_area_struct
*vma
, unsigned long address
)
780 #ifdef CONFIG_DEBUG_VM
782 * The page's anon-rmap details (mapping and index) are guaranteed to
783 * be set up correctly at this point.
785 * We have exclusion against page_add_anon_rmap because the caller
786 * always holds the page locked, except if called from page_dup_rmap,
787 * in which case the page is already known to be setup.
789 * We have exclusion against page_add_new_anon_rmap because those pages
790 * are initially only visible via the pagetables, and the pte is locked
791 * over the call to page_add_new_anon_rmap.
793 BUG_ON(page
->index
!= linear_page_index(vma
, address
));
798 * page_add_anon_rmap - add pte mapping to an anonymous page
799 * @page: the page to add the mapping to
800 * @vma: the vm area in which the mapping is added
801 * @address: the user virtual address mapped
803 * The caller needs to hold the pte lock, and the page must be locked in
804 * the anon_vma case: to serialize mapping,index checking after setting,
805 * and to ensure that PageAnon is not being upgraded racily to PageKsm
806 * (but PageKsm is never downgraded to PageAnon).
808 void page_add_anon_rmap(struct page
*page
,
809 struct vm_area_struct
*vma
, unsigned long address
)
811 int first
= atomic_inc_and_test(&page
->_mapcount
);
813 __inc_zone_page_state(page
, NR_ANON_PAGES
);
814 if (unlikely(PageKsm(page
)))
817 VM_BUG_ON(!PageLocked(page
));
818 VM_BUG_ON(address
< vma
->vm_start
|| address
>= vma
->vm_end
);
820 __page_set_anon_rmap(page
, vma
, address
, 0);
822 __page_check_anon_rmap(page
, vma
, address
);
826 * page_add_new_anon_rmap - add pte mapping to a new anonymous page
827 * @page: the page to add the mapping to
828 * @vma: the vm area in which the mapping is added
829 * @address: the user virtual address mapped
831 * Same as page_add_anon_rmap but must only be called on *new* pages.
832 * This means the inc-and-test can be bypassed.
833 * Page does not have to be locked.
835 void page_add_new_anon_rmap(struct page
*page
,
836 struct vm_area_struct
*vma
, unsigned long address
)
838 VM_BUG_ON(address
< vma
->vm_start
|| address
>= vma
->vm_end
);
839 SetPageSwapBacked(page
);
840 atomic_set(&page
->_mapcount
, 0); /* increment count (starts at -1) */
841 __inc_zone_page_state(page
, NR_ANON_PAGES
);
842 __page_set_anon_rmap(page
, vma
, address
, 1);
843 if (page_evictable(page
, vma
))
844 lru_cache_add_lru(page
, LRU_ACTIVE_ANON
);
846 add_page_to_unevictable_list(page
);
850 * page_add_file_rmap - add pte mapping to a file page
851 * @page: the page to add the mapping to
853 * The caller needs to hold the pte lock.
855 void page_add_file_rmap(struct page
*page
)
857 if (atomic_inc_and_test(&page
->_mapcount
)) {
858 __inc_zone_page_state(page
, NR_FILE_MAPPED
);
859 mem_cgroup_update_file_mapped(page
, 1);
864 * page_remove_rmap - take down pte mapping from a page
865 * @page: page to remove mapping from
867 * The caller needs to hold the pte lock.
869 void page_remove_rmap(struct page
*page
)
871 /* page still mapped by someone else? */
872 if (!atomic_add_negative(-1, &page
->_mapcount
))
876 * Now that the last pte has gone, s390 must transfer dirty
877 * flag from storage key to struct page. We can usually skip
878 * this if the page is anon, so about to be freed; but perhaps
879 * not if it's in swapcache - there might be another pte slot
880 * containing the swap entry, but page not yet written to swap.
882 if ((!PageAnon(page
) || PageSwapCache(page
)) && page_test_dirty(page
)) {
883 page_clear_dirty(page
);
884 set_page_dirty(page
);
887 * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED
888 * and not charged by memcg for now.
890 if (unlikely(PageHuge(page
)))
892 if (PageAnon(page
)) {
893 mem_cgroup_uncharge_page(page
);
894 __dec_zone_page_state(page
, NR_ANON_PAGES
);
896 __dec_zone_page_state(page
, NR_FILE_MAPPED
);
897 mem_cgroup_update_file_mapped(page
, -1);
900 * It would be tidy to reset the PageAnon mapping here,
901 * but that might overwrite a racing page_add_anon_rmap
902 * which increments mapcount after us but sets mapping
903 * before us: so leave the reset to free_hot_cold_page,
904 * and remember that it's only reliable while mapped.
905 * Leaving it set also helps swapoff to reinstate ptes
906 * faster for those pages still in swapcache.
911 * Subfunctions of try_to_unmap: try_to_unmap_one called
912 * repeatedly from either try_to_unmap_anon or try_to_unmap_file.
914 int try_to_unmap_one(struct page
*page
, struct vm_area_struct
*vma
,
915 unsigned long address
, enum ttu_flags flags
)
917 struct mm_struct
*mm
= vma
->vm_mm
;
921 int ret
= SWAP_AGAIN
;
923 pte
= page_check_address(page
, mm
, address
, &ptl
, 0);
928 * If the page is mlock()d, we cannot swap it out.
929 * If it's recently referenced (perhaps page_referenced
930 * skipped over this mm) then we should reactivate it.
932 if (!(flags
& TTU_IGNORE_MLOCK
)) {
933 if (vma
->vm_flags
& VM_LOCKED
)
936 if (TTU_ACTION(flags
) == TTU_MUNLOCK
)
939 if (!(flags
& TTU_IGNORE_ACCESS
)) {
940 if (ptep_clear_flush_young_notify(vma
, address
, pte
)) {
946 /* Nuke the page table entry. */
947 flush_cache_page(vma
, address
, page_to_pfn(page
));
948 pteval
= ptep_clear_flush_notify(vma
, address
, pte
);
950 /* Move the dirty bit to the physical page now the pte is gone. */
951 if (pte_dirty(pteval
))
952 set_page_dirty(page
);
954 /* Update high watermark before we lower rss */
955 update_hiwater_rss(mm
);
957 if (PageHWPoison(page
) && !(flags
& TTU_IGNORE_HWPOISON
)) {
959 dec_mm_counter(mm
, MM_ANONPAGES
);
961 dec_mm_counter(mm
, MM_FILEPAGES
);
962 set_pte_at(mm
, address
, pte
,
963 swp_entry_to_pte(make_hwpoison_entry(page
)));
964 } else if (PageAnon(page
)) {
965 swp_entry_t entry
= { .val
= page_private(page
) };
967 if (PageSwapCache(page
)) {
969 * Store the swap location in the pte.
970 * See handle_pte_fault() ...
972 if (swap_duplicate(entry
) < 0) {
973 set_pte_at(mm
, address
, pte
, pteval
);
977 if (list_empty(&mm
->mmlist
)) {
978 spin_lock(&mmlist_lock
);
979 if (list_empty(&mm
->mmlist
))
980 list_add(&mm
->mmlist
, &init_mm
.mmlist
);
981 spin_unlock(&mmlist_lock
);
983 dec_mm_counter(mm
, MM_ANONPAGES
);
984 inc_mm_counter(mm
, MM_SWAPENTS
);
985 } else if (PAGE_MIGRATION
) {
987 * Store the pfn of the page in a special migration
988 * pte. do_swap_page() will wait until the migration
989 * pte is removed and then restart fault handling.
991 BUG_ON(TTU_ACTION(flags
) != TTU_MIGRATION
);
992 entry
= make_migration_entry(page
, pte_write(pteval
));
994 set_pte_at(mm
, address
, pte
, swp_entry_to_pte(entry
));
995 BUG_ON(pte_file(*pte
));
996 } else if (PAGE_MIGRATION
&& (TTU_ACTION(flags
) == TTU_MIGRATION
)) {
997 /* Establish migration entry for a file page */
999 entry
= make_migration_entry(page
, pte_write(pteval
));
1000 set_pte_at(mm
, address
, pte
, swp_entry_to_pte(entry
));
1002 dec_mm_counter(mm
, MM_FILEPAGES
);
1004 page_remove_rmap(page
);
1005 page_cache_release(page
);
1008 pte_unmap_unlock(pte
, ptl
);
1013 pte_unmap_unlock(pte
, ptl
);
1017 * We need mmap_sem locking, Otherwise VM_LOCKED check makes
1018 * unstable result and race. Plus, We can't wait here because
1019 * we now hold anon_vma->lock or mapping->i_mmap_lock.
1020 * if trylock failed, the page remain in evictable lru and later
1021 * vmscan could retry to move the page to unevictable lru if the
1022 * page is actually mlocked.
1024 if (down_read_trylock(&vma
->vm_mm
->mmap_sem
)) {
1025 if (vma
->vm_flags
& VM_LOCKED
) {
1026 mlock_vma_page(page
);
1029 up_read(&vma
->vm_mm
->mmap_sem
);
1035 * objrmap doesn't work for nonlinear VMAs because the assumption that
1036 * offset-into-file correlates with offset-into-virtual-addresses does not hold.
1037 * Consequently, given a particular page and its ->index, we cannot locate the
1038 * ptes which are mapping that page without an exhaustive linear search.
1040 * So what this code does is a mini "virtual scan" of each nonlinear VMA which
1041 * maps the file to which the target page belongs. The ->vm_private_data field
1042 * holds the current cursor into that scan. Successive searches will circulate
1043 * around the vma's virtual address space.
1045 * So as more replacement pressure is applied to the pages in a nonlinear VMA,
1046 * more scanning pressure is placed against them as well. Eventually pages
1047 * will become fully unmapped and are eligible for eviction.
1049 * For very sparsely populated VMAs this is a little inefficient - chances are
1050 * there there won't be many ptes located within the scan cluster. In this case
1051 * maybe we could scan further - to the end of the pte page, perhaps.
1053 * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can
1054 * acquire it without blocking. If vma locked, mlock the pages in the cluster,
1055 * rather than unmapping them. If we encounter the "check_page" that vmscan is
1056 * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN.
1058 #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE)
1059 #define CLUSTER_MASK (~(CLUSTER_SIZE - 1))
1061 static int try_to_unmap_cluster(unsigned long cursor
, unsigned int *mapcount
,
1062 struct vm_area_struct
*vma
, struct page
*check_page
)
1064 struct mm_struct
*mm
= vma
->vm_mm
;
1072 unsigned long address
;
1074 int ret
= SWAP_AGAIN
;
1077 address
= (vma
->vm_start
+ cursor
) & CLUSTER_MASK
;
1078 end
= address
+ CLUSTER_SIZE
;
1079 if (address
< vma
->vm_start
)
1080 address
= vma
->vm_start
;
1081 if (end
> vma
->vm_end
)
1084 pgd
= pgd_offset(mm
, address
);
1085 if (!pgd_present(*pgd
))
1088 pud
= pud_offset(pgd
, address
);
1089 if (!pud_present(*pud
))
1092 pmd
= pmd_offset(pud
, address
);
1093 if (!pmd_present(*pmd
))
1097 * If we can acquire the mmap_sem for read, and vma is VM_LOCKED,
1098 * keep the sem while scanning the cluster for mlocking pages.
1100 if (down_read_trylock(&vma
->vm_mm
->mmap_sem
)) {
1101 locked_vma
= (vma
->vm_flags
& VM_LOCKED
);
1103 up_read(&vma
->vm_mm
->mmap_sem
); /* don't need it */
1106 pte
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
1108 /* Update high watermark before we lower rss */
1109 update_hiwater_rss(mm
);
1111 for (; address
< end
; pte
++, address
+= PAGE_SIZE
) {
1112 if (!pte_present(*pte
))
1114 page
= vm_normal_page(vma
, address
, *pte
);
1115 BUG_ON(!page
|| PageAnon(page
));
1118 mlock_vma_page(page
); /* no-op if already mlocked */
1119 if (page
== check_page
)
1121 continue; /* don't unmap */
1124 if (ptep_clear_flush_young_notify(vma
, address
, pte
))
1127 /* Nuke the page table entry. */
1128 flush_cache_page(vma
, address
, pte_pfn(*pte
));
1129 pteval
= ptep_clear_flush_notify(vma
, address
, pte
);
1131 /* If nonlinear, store the file page offset in the pte. */
1132 if (page
->index
!= linear_page_index(vma
, address
))
1133 set_pte_at(mm
, address
, pte
, pgoff_to_pte(page
->index
));
1135 /* Move the dirty bit to the physical page now the pte is gone. */
1136 if (pte_dirty(pteval
))
1137 set_page_dirty(page
);
1139 page_remove_rmap(page
);
1140 page_cache_release(page
);
1141 dec_mm_counter(mm
, MM_FILEPAGES
);
1144 pte_unmap_unlock(pte
- 1, ptl
);
1146 up_read(&vma
->vm_mm
->mmap_sem
);
1150 static bool is_vma_temporary_stack(struct vm_area_struct
*vma
)
1152 int maybe_stack
= vma
->vm_flags
& (VM_GROWSDOWN
| VM_GROWSUP
);
1157 if ((vma
->vm_flags
& VM_STACK_INCOMPLETE_SETUP
) ==
1158 VM_STACK_INCOMPLETE_SETUP
)
1165 * try_to_unmap_anon - unmap or unlock anonymous page using the object-based
1167 * @page: the page to unmap/unlock
1168 * @flags: action and flags
1170 * Find all the mappings of a page using the mapping pointer and the vma chains
1171 * contained in the anon_vma struct it points to.
1173 * This function is only called from try_to_unmap/try_to_munlock for
1175 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1176 * where the page was found will be held for write. So, we won't recheck
1177 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1180 static int try_to_unmap_anon(struct page
*page
, enum ttu_flags flags
)
1182 struct anon_vma
*anon_vma
;
1183 struct anon_vma_chain
*avc
;
1184 int ret
= SWAP_AGAIN
;
1186 anon_vma
= page_lock_anon_vma(page
);
1190 list_for_each_entry(avc
, &anon_vma
->head
, same_anon_vma
) {
1191 struct vm_area_struct
*vma
= avc
->vma
;
1192 unsigned long address
;
1195 * During exec, a temporary VMA is setup and later moved.
1196 * The VMA is moved under the anon_vma lock but not the
1197 * page tables leading to a race where migration cannot
1198 * find the migration ptes. Rather than increasing the
1199 * locking requirements of exec(), migration skips
1200 * temporary VMAs until after exec() completes.
1202 if (PAGE_MIGRATION
&& (flags
& TTU_MIGRATION
) &&
1203 is_vma_temporary_stack(vma
))
1206 address
= vma_address(page
, vma
);
1207 if (address
== -EFAULT
)
1209 ret
= try_to_unmap_one(page
, vma
, address
, flags
);
1210 if (ret
!= SWAP_AGAIN
|| !page_mapped(page
))
1214 page_unlock_anon_vma(anon_vma
);
1219 * try_to_unmap_file - unmap/unlock file page using the object-based rmap method
1220 * @page: the page to unmap/unlock
1221 * @flags: action and flags
1223 * Find all the mappings of a page using the mapping pointer and the vma chains
1224 * contained in the address_space struct it points to.
1226 * This function is only called from try_to_unmap/try_to_munlock for
1227 * object-based pages.
1228 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1229 * where the page was found will be held for write. So, we won't recheck
1230 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1233 static int try_to_unmap_file(struct page
*page
, enum ttu_flags flags
)
1235 struct address_space
*mapping
= page
->mapping
;
1236 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
1237 struct vm_area_struct
*vma
;
1238 struct prio_tree_iter iter
;
1239 int ret
= SWAP_AGAIN
;
1240 unsigned long cursor
;
1241 unsigned long max_nl_cursor
= 0;
1242 unsigned long max_nl_size
= 0;
1243 unsigned int mapcount
;
1245 spin_lock(&mapping
->i_mmap_lock
);
1246 vma_prio_tree_foreach(vma
, &iter
, &mapping
->i_mmap
, pgoff
, pgoff
) {
1247 unsigned long address
= vma_address(page
, vma
);
1248 if (address
== -EFAULT
)
1250 ret
= try_to_unmap_one(page
, vma
, address
, flags
);
1251 if (ret
!= SWAP_AGAIN
|| !page_mapped(page
))
1255 if (list_empty(&mapping
->i_mmap_nonlinear
))
1259 * We don't bother to try to find the munlocked page in nonlinears.
1260 * It's costly. Instead, later, page reclaim logic may call
1261 * try_to_unmap(TTU_MUNLOCK) and recover PG_mlocked lazily.
1263 if (TTU_ACTION(flags
) == TTU_MUNLOCK
)
1266 list_for_each_entry(vma
, &mapping
->i_mmap_nonlinear
,
1267 shared
.vm_set
.list
) {
1268 cursor
= (unsigned long) vma
->vm_private_data
;
1269 if (cursor
> max_nl_cursor
)
1270 max_nl_cursor
= cursor
;
1271 cursor
= vma
->vm_end
- vma
->vm_start
;
1272 if (cursor
> max_nl_size
)
1273 max_nl_size
= cursor
;
1276 if (max_nl_size
== 0) { /* all nonlinears locked or reserved ? */
1282 * We don't try to search for this page in the nonlinear vmas,
1283 * and page_referenced wouldn't have found it anyway. Instead
1284 * just walk the nonlinear vmas trying to age and unmap some.
1285 * The mapcount of the page we came in with is irrelevant,
1286 * but even so use it as a guide to how hard we should try?
1288 mapcount
= page_mapcount(page
);
1291 cond_resched_lock(&mapping
->i_mmap_lock
);
1293 max_nl_size
= (max_nl_size
+ CLUSTER_SIZE
- 1) & CLUSTER_MASK
;
1294 if (max_nl_cursor
== 0)
1295 max_nl_cursor
= CLUSTER_SIZE
;
1298 list_for_each_entry(vma
, &mapping
->i_mmap_nonlinear
,
1299 shared
.vm_set
.list
) {
1300 cursor
= (unsigned long) vma
->vm_private_data
;
1301 while ( cursor
< max_nl_cursor
&&
1302 cursor
< vma
->vm_end
- vma
->vm_start
) {
1303 if (try_to_unmap_cluster(cursor
, &mapcount
,
1304 vma
, page
) == SWAP_MLOCK
)
1306 cursor
+= CLUSTER_SIZE
;
1307 vma
->vm_private_data
= (void *) cursor
;
1308 if ((int)mapcount
<= 0)
1311 vma
->vm_private_data
= (void *) max_nl_cursor
;
1313 cond_resched_lock(&mapping
->i_mmap_lock
);
1314 max_nl_cursor
+= CLUSTER_SIZE
;
1315 } while (max_nl_cursor
<= max_nl_size
);
1318 * Don't loop forever (perhaps all the remaining pages are
1319 * in locked vmas). Reset cursor on all unreserved nonlinear
1320 * vmas, now forgetting on which ones it had fallen behind.
1322 list_for_each_entry(vma
, &mapping
->i_mmap_nonlinear
, shared
.vm_set
.list
)
1323 vma
->vm_private_data
= NULL
;
1325 spin_unlock(&mapping
->i_mmap_lock
);
1330 * try_to_unmap - try to remove all page table mappings to a page
1331 * @page: the page to get unmapped
1332 * @flags: action and flags
1334 * Tries to remove all the page table entries which are mapping this
1335 * page, used in the pageout path. Caller must hold the page lock.
1336 * Return values are:
1338 * SWAP_SUCCESS - we succeeded in removing all mappings
1339 * SWAP_AGAIN - we missed a mapping, try again later
1340 * SWAP_FAIL - the page is unswappable
1341 * SWAP_MLOCK - page is mlocked.
1343 int try_to_unmap(struct page
*page
, enum ttu_flags flags
)
1347 BUG_ON(!PageLocked(page
));
1349 if (unlikely(PageKsm(page
)))
1350 ret
= try_to_unmap_ksm(page
, flags
);
1351 else if (PageAnon(page
))
1352 ret
= try_to_unmap_anon(page
, flags
);
1354 ret
= try_to_unmap_file(page
, flags
);
1355 if (ret
!= SWAP_MLOCK
&& !page_mapped(page
))
1361 * try_to_munlock - try to munlock a page
1362 * @page: the page to be munlocked
1364 * Called from munlock code. Checks all of the VMAs mapping the page
1365 * to make sure nobody else has this page mlocked. The page will be
1366 * returned with PG_mlocked cleared if no other vmas have it mlocked.
1368 * Return values are:
1370 * SWAP_AGAIN - no vma is holding page mlocked, or,
1371 * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem
1372 * SWAP_FAIL - page cannot be located at present
1373 * SWAP_MLOCK - page is now mlocked.
1375 int try_to_munlock(struct page
*page
)
1377 VM_BUG_ON(!PageLocked(page
) || PageLRU(page
));
1379 if (unlikely(PageKsm(page
)))
1380 return try_to_unmap_ksm(page
, TTU_MUNLOCK
);
1381 else if (PageAnon(page
))
1382 return try_to_unmap_anon(page
, TTU_MUNLOCK
);
1384 return try_to_unmap_file(page
, TTU_MUNLOCK
);
1387 #ifdef CONFIG_MIGRATION
1389 * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file():
1390 * Called by migrate.c to remove migration ptes, but might be used more later.
1392 static int rmap_walk_anon(struct page
*page
, int (*rmap_one
)(struct page
*,
1393 struct vm_area_struct
*, unsigned long, void *), void *arg
)
1395 struct anon_vma
*anon_vma
;
1396 struct anon_vma_chain
*avc
;
1397 int ret
= SWAP_AGAIN
;
1400 * Note: remove_migration_ptes() cannot use page_lock_anon_vma()
1401 * because that depends on page_mapped(); but not all its usages
1402 * are holding mmap_sem. Users without mmap_sem are required to
1403 * take a reference count to prevent the anon_vma disappearing
1405 anon_vma
= page_anon_vma(page
);
1408 spin_lock(&anon_vma
->lock
);
1409 list_for_each_entry(avc
, &anon_vma
->head
, same_anon_vma
) {
1410 struct vm_area_struct
*vma
= avc
->vma
;
1411 unsigned long address
= vma_address(page
, vma
);
1412 if (address
== -EFAULT
)
1414 ret
= rmap_one(page
, vma
, address
, arg
);
1415 if (ret
!= SWAP_AGAIN
)
1418 spin_unlock(&anon_vma
->lock
);
1422 static int rmap_walk_file(struct page
*page
, int (*rmap_one
)(struct page
*,
1423 struct vm_area_struct
*, unsigned long, void *), void *arg
)
1425 struct address_space
*mapping
= page
->mapping
;
1426 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
1427 struct vm_area_struct
*vma
;
1428 struct prio_tree_iter iter
;
1429 int ret
= SWAP_AGAIN
;
1433 spin_lock(&mapping
->i_mmap_lock
);
1434 vma_prio_tree_foreach(vma
, &iter
, &mapping
->i_mmap
, pgoff
, pgoff
) {
1435 unsigned long address
= vma_address(page
, vma
);
1436 if (address
== -EFAULT
)
1438 ret
= rmap_one(page
, vma
, address
, arg
);
1439 if (ret
!= SWAP_AGAIN
)
1443 * No nonlinear handling: being always shared, nonlinear vmas
1444 * never contain migration ptes. Decide what to do about this
1445 * limitation to linear when we need rmap_walk() on nonlinear.
1447 spin_unlock(&mapping
->i_mmap_lock
);
1451 int rmap_walk(struct page
*page
, int (*rmap_one
)(struct page
*,
1452 struct vm_area_struct
*, unsigned long, void *), void *arg
)
1454 VM_BUG_ON(!PageLocked(page
));
1456 if (unlikely(PageKsm(page
)))
1457 return rmap_walk_ksm(page
, rmap_one
, arg
);
1458 else if (PageAnon(page
))
1459 return rmap_walk_anon(page
, rmap_one
, arg
);
1461 return rmap_walk_file(page
, rmap_one
, arg
);
1463 #endif /* CONFIG_MIGRATION */
1465 #ifdef CONFIG_HUGETLB_PAGE
1467 * The following three functions are for anonymous (private mapped) hugepages.
1468 * Unlike common anonymous pages, anonymous hugepages have no accounting code
1469 * and no lru code, because we handle hugepages differently from common pages.
1471 static void __hugepage_set_anon_rmap(struct page
*page
,
1472 struct vm_area_struct
*vma
, unsigned long address
, int exclusive
)
1474 struct anon_vma
*anon_vma
= vma
->anon_vma
;
1477 struct anon_vma_chain
*avc
;
1478 avc
= list_entry(vma
->anon_vma_chain
.prev
,
1479 struct anon_vma_chain
, same_vma
);
1480 anon_vma
= avc
->anon_vma
;
1482 anon_vma
= (void *) anon_vma
+ PAGE_MAPPING_ANON
;
1483 page
->mapping
= (struct address_space
*) anon_vma
;
1484 page
->index
= linear_page_index(vma
, address
);
1487 void hugepage_add_anon_rmap(struct page
*page
,
1488 struct vm_area_struct
*vma
, unsigned long address
)
1490 struct anon_vma
*anon_vma
= vma
->anon_vma
;
1493 BUG_ON(address
< vma
->vm_start
|| address
>= vma
->vm_end
);
1494 first
= atomic_inc_and_test(&page
->_mapcount
);
1496 __hugepage_set_anon_rmap(page
, vma
, address
, 0);
1499 void hugepage_add_new_anon_rmap(struct page
*page
,
1500 struct vm_area_struct
*vma
, unsigned long address
)
1502 BUG_ON(address
< vma
->vm_start
|| address
>= vma
->vm_end
);
1503 atomic_set(&page
->_mapcount
, 0);
1504 __hugepage_set_anon_rmap(page
, vma
, address
, 1);
1506 #endif /* CONFIG_HUGETLB_PAGE */