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)
25 * page->flags PG_locked (lock_page)
26 * hugetlbfs_i_mmap_rwsem_key (in huge_pmd_share)
27 * mapping->i_mmap_rwsem
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 * mem_cgroup_{begin,end}_page_stat (memcg->move_lock)
35 * mapping->tree_lock (widely used)
36 * inode->i_lock (in set_page_dirty's __mark_inode_dirty)
37 * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
38 * sb_lock (within inode_lock in fs/fs-writeback.c)
39 * mapping->tree_lock (widely used, in set_page_dirty,
40 * in arch-dependent flush_dcache_mmap_lock,
41 * within bdi.wb->list_lock in __sync_single_inode)
43 * anon_vma->rwsem,mapping->i_mutex (memory_failure, collect_procs_anon)
49 #include <linux/sched/mm.h>
50 #include <linux/pagemap.h>
51 #include <linux/swap.h>
52 #include <linux/swapops.h>
53 #include <linux/slab.h>
54 #include <linux/init.h>
55 #include <linux/ksm.h>
56 #include <linux/rmap.h>
57 #include <linux/rcupdate.h>
58 #include <linux/export.h>
59 #include <linux/memcontrol.h>
60 #include <linux/mmu_notifier.h>
61 #include <linux/migrate.h>
62 #include <linux/hugetlb.h>
63 #include <linux/backing-dev.h>
64 #include <linux/page_idle.h>
66 #include <asm/tlbflush.h>
68 #include <trace/events/tlb.h>
72 static struct kmem_cache
*anon_vma_cachep
;
73 static struct kmem_cache
*anon_vma_chain_cachep
;
75 static inline struct anon_vma
*anon_vma_alloc(void)
77 struct anon_vma
*anon_vma
;
79 anon_vma
= kmem_cache_alloc(anon_vma_cachep
, GFP_KERNEL
);
81 atomic_set(&anon_vma
->refcount
, 1);
82 anon_vma
->degree
= 1; /* Reference for first vma */
83 anon_vma
->parent
= anon_vma
;
85 * Initialise the anon_vma root to point to itself. If called
86 * from fork, the root will be reset to the parents anon_vma.
88 anon_vma
->root
= anon_vma
;
94 static inline void anon_vma_free(struct anon_vma
*anon_vma
)
96 VM_BUG_ON(atomic_read(&anon_vma
->refcount
));
99 * Synchronize against page_lock_anon_vma_read() such that
100 * we can safely hold the lock without the anon_vma getting
103 * Relies on the full mb implied by the atomic_dec_and_test() from
104 * put_anon_vma() against the acquire barrier implied by
105 * down_read_trylock() from page_lock_anon_vma_read(). This orders:
107 * page_lock_anon_vma_read() VS put_anon_vma()
108 * down_read_trylock() atomic_dec_and_test()
110 * atomic_read() rwsem_is_locked()
112 * LOCK should suffice since the actual taking of the lock must
113 * happen _before_ what follows.
116 if (rwsem_is_locked(&anon_vma
->root
->rwsem
)) {
117 anon_vma_lock_write(anon_vma
);
118 anon_vma_unlock_write(anon_vma
);
121 kmem_cache_free(anon_vma_cachep
, anon_vma
);
124 static inline struct anon_vma_chain
*anon_vma_chain_alloc(gfp_t gfp
)
126 return kmem_cache_alloc(anon_vma_chain_cachep
, gfp
);
129 static void anon_vma_chain_free(struct anon_vma_chain
*anon_vma_chain
)
131 kmem_cache_free(anon_vma_chain_cachep
, anon_vma_chain
);
134 static void anon_vma_chain_link(struct vm_area_struct
*vma
,
135 struct anon_vma_chain
*avc
,
136 struct anon_vma
*anon_vma
)
139 avc
->anon_vma
= anon_vma
;
140 list_add(&avc
->same_vma
, &vma
->anon_vma_chain
);
141 anon_vma_interval_tree_insert(avc
, &anon_vma
->rb_root
);
145 * __anon_vma_prepare - attach an anon_vma to a memory region
146 * @vma: the memory region in question
148 * This makes sure the memory mapping described by 'vma' has
149 * an 'anon_vma' attached to it, so that we can associate the
150 * anonymous pages mapped into it with that anon_vma.
152 * The common case will be that we already have one, which
153 * is handled inline by anon_vma_prepare(). But if
154 * not we either need to find an adjacent mapping that we
155 * can re-use the anon_vma from (very common when the only
156 * reason for splitting a vma has been mprotect()), or we
157 * allocate a new one.
159 * Anon-vma allocations are very subtle, because we may have
160 * optimistically looked up an anon_vma in page_lock_anon_vma_read()
161 * and that may actually touch the spinlock even in the newly
162 * allocated vma (it depends on RCU to make sure that the
163 * anon_vma isn't actually destroyed).
165 * As a result, we need to do proper anon_vma locking even
166 * for the new allocation. At the same time, we do not want
167 * to do any locking for the common case of already having
170 * This must be called with the mmap_sem held for reading.
172 int __anon_vma_prepare(struct vm_area_struct
*vma
)
174 struct mm_struct
*mm
= vma
->vm_mm
;
175 struct anon_vma
*anon_vma
, *allocated
;
176 struct anon_vma_chain
*avc
;
180 avc
= anon_vma_chain_alloc(GFP_KERNEL
);
184 anon_vma
= find_mergeable_anon_vma(vma
);
187 anon_vma
= anon_vma_alloc();
188 if (unlikely(!anon_vma
))
189 goto out_enomem_free_avc
;
190 allocated
= anon_vma
;
193 anon_vma_lock_write(anon_vma
);
194 /* page_table_lock to protect against threads */
195 spin_lock(&mm
->page_table_lock
);
196 if (likely(!vma
->anon_vma
)) {
197 vma
->anon_vma
= anon_vma
;
198 anon_vma_chain_link(vma
, avc
, anon_vma
);
199 /* vma reference or self-parent link for new root */
204 spin_unlock(&mm
->page_table_lock
);
205 anon_vma_unlock_write(anon_vma
);
207 if (unlikely(allocated
))
208 put_anon_vma(allocated
);
210 anon_vma_chain_free(avc
);
215 anon_vma_chain_free(avc
);
221 * This is a useful helper function for locking the anon_vma root as
222 * we traverse the vma->anon_vma_chain, looping over anon_vma's that
225 * Such anon_vma's should have the same root, so you'd expect to see
226 * just a single mutex_lock for the whole traversal.
228 static inline struct anon_vma
*lock_anon_vma_root(struct anon_vma
*root
, struct anon_vma
*anon_vma
)
230 struct anon_vma
*new_root
= anon_vma
->root
;
231 if (new_root
!= root
) {
232 if (WARN_ON_ONCE(root
))
233 up_write(&root
->rwsem
);
235 down_write(&root
->rwsem
);
240 static inline void unlock_anon_vma_root(struct anon_vma
*root
)
243 up_write(&root
->rwsem
);
247 * Attach the anon_vmas from src to dst.
248 * Returns 0 on success, -ENOMEM on failure.
250 * If dst->anon_vma is NULL this function tries to find and reuse existing
251 * anon_vma which has no vmas and only one child anon_vma. This prevents
252 * degradation of anon_vma hierarchy to endless linear chain in case of
253 * constantly forking task. On the other hand, an anon_vma with more than one
254 * child isn't reused even if there was no alive vma, thus rmap walker has a
255 * good chance of avoiding scanning the whole hierarchy when it searches where
258 int anon_vma_clone(struct vm_area_struct
*dst
, struct vm_area_struct
*src
)
260 struct anon_vma_chain
*avc
, *pavc
;
261 struct anon_vma
*root
= NULL
;
263 list_for_each_entry_reverse(pavc
, &src
->anon_vma_chain
, same_vma
) {
264 struct anon_vma
*anon_vma
;
266 avc
= anon_vma_chain_alloc(GFP_NOWAIT
| __GFP_NOWARN
);
267 if (unlikely(!avc
)) {
268 unlock_anon_vma_root(root
);
270 avc
= anon_vma_chain_alloc(GFP_KERNEL
);
274 anon_vma
= pavc
->anon_vma
;
275 root
= lock_anon_vma_root(root
, anon_vma
);
276 anon_vma_chain_link(dst
, avc
, anon_vma
);
279 * Reuse existing anon_vma if its degree lower than two,
280 * that means it has no vma and only one anon_vma child.
282 * Do not chose parent anon_vma, otherwise first child
283 * will always reuse it. Root anon_vma is never reused:
284 * it has self-parent reference and at least one child.
286 if (!dst
->anon_vma
&& anon_vma
!= src
->anon_vma
&&
287 anon_vma
->degree
< 2)
288 dst
->anon_vma
= anon_vma
;
291 dst
->anon_vma
->degree
++;
292 unlock_anon_vma_root(root
);
297 * dst->anon_vma is dropped here otherwise its degree can be incorrectly
298 * decremented in unlink_anon_vmas().
299 * We can safely do this because callers of anon_vma_clone() don't care
300 * about dst->anon_vma if anon_vma_clone() failed.
302 dst
->anon_vma
= NULL
;
303 unlink_anon_vmas(dst
);
308 * Attach vma to its own anon_vma, as well as to the anon_vmas that
309 * the corresponding VMA in the parent process is attached to.
310 * Returns 0 on success, non-zero on failure.
312 int anon_vma_fork(struct vm_area_struct
*vma
, struct vm_area_struct
*pvma
)
314 struct anon_vma_chain
*avc
;
315 struct anon_vma
*anon_vma
;
318 /* Don't bother if the parent process has no anon_vma here. */
322 /* Drop inherited anon_vma, we'll reuse existing or allocate new. */
323 vma
->anon_vma
= NULL
;
326 * First, attach the new VMA to the parent VMA's anon_vmas,
327 * so rmap can find non-COWed pages in child processes.
329 error
= anon_vma_clone(vma
, pvma
);
333 /* An existing anon_vma has been reused, all done then. */
337 /* Then add our own anon_vma. */
338 anon_vma
= anon_vma_alloc();
341 avc
= anon_vma_chain_alloc(GFP_KERNEL
);
343 goto out_error_free_anon_vma
;
346 * The root anon_vma's spinlock is the lock actually used when we
347 * lock any of the anon_vmas in this anon_vma tree.
349 anon_vma
->root
= pvma
->anon_vma
->root
;
350 anon_vma
->parent
= pvma
->anon_vma
;
352 * With refcounts, an anon_vma can stay around longer than the
353 * process it belongs to. The root anon_vma needs to be pinned until
354 * this anon_vma is freed, because the lock lives in the root.
356 get_anon_vma(anon_vma
->root
);
357 /* Mark this anon_vma as the one where our new (COWed) pages go. */
358 vma
->anon_vma
= anon_vma
;
359 anon_vma_lock_write(anon_vma
);
360 anon_vma_chain_link(vma
, avc
, anon_vma
);
361 anon_vma
->parent
->degree
++;
362 anon_vma_unlock_write(anon_vma
);
366 out_error_free_anon_vma
:
367 put_anon_vma(anon_vma
);
369 unlink_anon_vmas(vma
);
373 void unlink_anon_vmas(struct vm_area_struct
*vma
)
375 struct anon_vma_chain
*avc
, *next
;
376 struct anon_vma
*root
= NULL
;
379 * Unlink each anon_vma chained to the VMA. This list is ordered
380 * from newest to oldest, ensuring the root anon_vma gets freed last.
382 list_for_each_entry_safe(avc
, next
, &vma
->anon_vma_chain
, same_vma
) {
383 struct anon_vma
*anon_vma
= avc
->anon_vma
;
385 root
= lock_anon_vma_root(root
, anon_vma
);
386 anon_vma_interval_tree_remove(avc
, &anon_vma
->rb_root
);
389 * Leave empty anon_vmas on the list - we'll need
390 * to free them outside the lock.
392 if (RB_EMPTY_ROOT(&anon_vma
->rb_root
)) {
393 anon_vma
->parent
->degree
--;
397 list_del(&avc
->same_vma
);
398 anon_vma_chain_free(avc
);
401 vma
->anon_vma
->degree
--;
402 unlock_anon_vma_root(root
);
405 * Iterate the list once more, it now only contains empty and unlinked
406 * anon_vmas, destroy them. Could not do before due to __put_anon_vma()
407 * needing to write-acquire the anon_vma->root->rwsem.
409 list_for_each_entry_safe(avc
, next
, &vma
->anon_vma_chain
, same_vma
) {
410 struct anon_vma
*anon_vma
= avc
->anon_vma
;
412 VM_WARN_ON(anon_vma
->degree
);
413 put_anon_vma(anon_vma
);
415 list_del(&avc
->same_vma
);
416 anon_vma_chain_free(avc
);
420 static void anon_vma_ctor(void *data
)
422 struct anon_vma
*anon_vma
= data
;
424 init_rwsem(&anon_vma
->rwsem
);
425 atomic_set(&anon_vma
->refcount
, 0);
426 anon_vma
->rb_root
= RB_ROOT
;
429 void __init
anon_vma_init(void)
431 anon_vma_cachep
= kmem_cache_create("anon_vma", sizeof(struct anon_vma
),
432 0, SLAB_DESTROY_BY_RCU
|SLAB_PANIC
|SLAB_ACCOUNT
,
434 anon_vma_chain_cachep
= KMEM_CACHE(anon_vma_chain
,
435 SLAB_PANIC
|SLAB_ACCOUNT
);
439 * Getting a lock on a stable anon_vma from a page off the LRU is tricky!
441 * Since there is no serialization what so ever against page_remove_rmap()
442 * the best this function can do is return a locked anon_vma that might
443 * have been relevant to this page.
445 * The page might have been remapped to a different anon_vma or the anon_vma
446 * returned may already be freed (and even reused).
448 * In case it was remapped to a different anon_vma, the new anon_vma will be a
449 * child of the old anon_vma, and the anon_vma lifetime rules will therefore
450 * ensure that any anon_vma obtained from the page will still be valid for as
451 * long as we observe page_mapped() [ hence all those page_mapped() tests ].
453 * All users of this function must be very careful when walking the anon_vma
454 * chain and verify that the page in question is indeed mapped in it
455 * [ something equivalent to page_mapped_in_vma() ].
457 * Since anon_vma's slab is DESTROY_BY_RCU and we know from page_remove_rmap()
458 * that the anon_vma pointer from page->mapping is valid if there is a
459 * mapcount, we can dereference the anon_vma after observing those.
461 struct anon_vma
*page_get_anon_vma(struct page
*page
)
463 struct anon_vma
*anon_vma
= NULL
;
464 unsigned long anon_mapping
;
467 anon_mapping
= (unsigned long)READ_ONCE(page
->mapping
);
468 if ((anon_mapping
& PAGE_MAPPING_FLAGS
) != PAGE_MAPPING_ANON
)
470 if (!page_mapped(page
))
473 anon_vma
= (struct anon_vma
*) (anon_mapping
- PAGE_MAPPING_ANON
);
474 if (!atomic_inc_not_zero(&anon_vma
->refcount
)) {
480 * If this page is still mapped, then its anon_vma cannot have been
481 * freed. But if it has been unmapped, we have no security against the
482 * anon_vma structure being freed and reused (for another anon_vma:
483 * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero()
484 * above cannot corrupt).
486 if (!page_mapped(page
)) {
488 put_anon_vma(anon_vma
);
498 * Similar to page_get_anon_vma() except it locks the anon_vma.
500 * Its a little more complex as it tries to keep the fast path to a single
501 * atomic op -- the trylock. If we fail the trylock, we fall back to getting a
502 * reference like with page_get_anon_vma() and then block on the mutex.
504 struct anon_vma
*page_lock_anon_vma_read(struct page
*page
)
506 struct anon_vma
*anon_vma
= NULL
;
507 struct anon_vma
*root_anon_vma
;
508 unsigned long anon_mapping
;
511 anon_mapping
= (unsigned long)READ_ONCE(page
->mapping
);
512 if ((anon_mapping
& PAGE_MAPPING_FLAGS
) != PAGE_MAPPING_ANON
)
514 if (!page_mapped(page
))
517 anon_vma
= (struct anon_vma
*) (anon_mapping
- PAGE_MAPPING_ANON
);
518 root_anon_vma
= READ_ONCE(anon_vma
->root
);
519 if (down_read_trylock(&root_anon_vma
->rwsem
)) {
521 * If the page is still mapped, then this anon_vma is still
522 * its anon_vma, and holding the mutex ensures that it will
523 * not go away, see anon_vma_free().
525 if (!page_mapped(page
)) {
526 up_read(&root_anon_vma
->rwsem
);
532 /* trylock failed, we got to sleep */
533 if (!atomic_inc_not_zero(&anon_vma
->refcount
)) {
538 if (!page_mapped(page
)) {
540 put_anon_vma(anon_vma
);
544 /* we pinned the anon_vma, its safe to sleep */
546 anon_vma_lock_read(anon_vma
);
548 if (atomic_dec_and_test(&anon_vma
->refcount
)) {
550 * Oops, we held the last refcount, release the lock
551 * and bail -- can't simply use put_anon_vma() because
552 * we'll deadlock on the anon_vma_lock_write() recursion.
554 anon_vma_unlock_read(anon_vma
);
555 __put_anon_vma(anon_vma
);
566 void page_unlock_anon_vma_read(struct anon_vma
*anon_vma
)
568 anon_vma_unlock_read(anon_vma
);
571 #ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
573 * Flush TLB entries for recently unmapped pages from remote CPUs. It is
574 * important if a PTE was dirty when it was unmapped that it's flushed
575 * before any IO is initiated on the page to prevent lost writes. Similarly,
576 * it must be flushed before freeing to prevent data leakage.
578 void try_to_unmap_flush(void)
580 struct tlbflush_unmap_batch
*tlb_ubc
= ¤t
->tlb_ubc
;
583 if (!tlb_ubc
->flush_required
)
588 if (cpumask_test_cpu(cpu
, &tlb_ubc
->cpumask
)) {
589 count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL
);
591 trace_tlb_flush(TLB_LOCAL_SHOOTDOWN
, TLB_FLUSH_ALL
);
594 if (cpumask_any_but(&tlb_ubc
->cpumask
, cpu
) < nr_cpu_ids
)
595 flush_tlb_others(&tlb_ubc
->cpumask
, NULL
, 0, TLB_FLUSH_ALL
);
596 cpumask_clear(&tlb_ubc
->cpumask
);
597 tlb_ubc
->flush_required
= false;
598 tlb_ubc
->writable
= false;
602 /* Flush iff there are potentially writable TLB entries that can race with IO */
603 void try_to_unmap_flush_dirty(void)
605 struct tlbflush_unmap_batch
*tlb_ubc
= ¤t
->tlb_ubc
;
607 if (tlb_ubc
->writable
)
608 try_to_unmap_flush();
611 static void set_tlb_ubc_flush_pending(struct mm_struct
*mm
, bool writable
)
613 struct tlbflush_unmap_batch
*tlb_ubc
= ¤t
->tlb_ubc
;
615 cpumask_or(&tlb_ubc
->cpumask
, &tlb_ubc
->cpumask
, mm_cpumask(mm
));
616 tlb_ubc
->flush_required
= true;
619 * If the PTE was dirty then it's best to assume it's writable. The
620 * caller must use try_to_unmap_flush_dirty() or try_to_unmap_flush()
621 * before the page is queued for IO.
624 tlb_ubc
->writable
= true;
628 * Returns true if the TLB flush should be deferred to the end of a batch of
629 * unmap operations to reduce IPIs.
631 static bool should_defer_flush(struct mm_struct
*mm
, enum ttu_flags flags
)
633 bool should_defer
= false;
635 if (!(flags
& TTU_BATCH_FLUSH
))
638 /* If remote CPUs need to be flushed then defer batch the flush */
639 if (cpumask_any_but(mm_cpumask(mm
), get_cpu()) < nr_cpu_ids
)
646 static void set_tlb_ubc_flush_pending(struct mm_struct
*mm
, bool writable
)
650 static bool should_defer_flush(struct mm_struct
*mm
, enum ttu_flags flags
)
654 #endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */
657 * At what user virtual address is page expected in vma?
658 * Caller should check the page is actually part of the vma.
660 unsigned long page_address_in_vma(struct page
*page
, struct vm_area_struct
*vma
)
662 unsigned long address
;
663 if (PageAnon(page
)) {
664 struct anon_vma
*page__anon_vma
= page_anon_vma(page
);
666 * Note: swapoff's unuse_vma() is more efficient with this
667 * check, and needs it to match anon_vma when KSM is active.
669 if (!vma
->anon_vma
|| !page__anon_vma
||
670 vma
->anon_vma
->root
!= page__anon_vma
->root
)
672 } else if (page
->mapping
) {
673 if (!vma
->vm_file
|| vma
->vm_file
->f_mapping
!= page
->mapping
)
677 address
= __vma_address(page
, vma
);
678 if (unlikely(address
< vma
->vm_start
|| address
>= vma
->vm_end
))
683 pmd_t
*mm_find_pmd(struct mm_struct
*mm
, unsigned long address
)
690 pgd
= pgd_offset(mm
, address
);
691 if (!pgd_present(*pgd
))
694 pud
= pud_offset(pgd
, address
);
695 if (!pud_present(*pud
))
698 pmd
= pmd_offset(pud
, address
);
700 * Some THP functions use the sequence pmdp_huge_clear_flush(), set_pmd_at()
701 * without holding anon_vma lock for write. So when looking for a
702 * genuine pmde (in which to find pte), test present and !THP together.
706 if (!pmd_present(pmde
) || pmd_trans_huge(pmde
))
712 struct page_referenced_arg
{
715 unsigned long vm_flags
;
716 struct mem_cgroup
*memcg
;
719 * arg: page_referenced_arg will be passed
721 static int page_referenced_one(struct page
*page
, struct vm_area_struct
*vma
,
722 unsigned long address
, void *arg
)
724 struct page_referenced_arg
*pra
= arg
;
725 struct page_vma_mapped_walk pvmw
= {
732 while (page_vma_mapped_walk(&pvmw
)) {
733 address
= pvmw
.address
;
735 if (vma
->vm_flags
& VM_LOCKED
) {
736 page_vma_mapped_walk_done(&pvmw
);
737 pra
->vm_flags
|= VM_LOCKED
;
738 return SWAP_FAIL
; /* To break the loop */
742 if (ptep_clear_flush_young_notify(vma
, address
,
745 * Don't treat a reference through
746 * a sequentially read mapping as such.
747 * If the page has been used in another mapping,
748 * we will catch it; if this other mapping is
749 * already gone, the unmap path will have set
750 * PG_referenced or activated the page.
752 if (likely(!(vma
->vm_flags
& VM_SEQ_READ
)))
755 } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE
)) {
756 if (pmdp_clear_flush_young_notify(vma
, address
,
760 /* unexpected pmd-mapped page? */
768 clear_page_idle(page
);
769 if (test_and_clear_page_young(page
))
774 pra
->vm_flags
|= vma
->vm_flags
;
778 return SWAP_SUCCESS
; /* To break the loop */
783 static bool invalid_page_referenced_vma(struct vm_area_struct
*vma
, void *arg
)
785 struct page_referenced_arg
*pra
= arg
;
786 struct mem_cgroup
*memcg
= pra
->memcg
;
788 if (!mm_match_cgroup(vma
->vm_mm
, memcg
))
795 * page_referenced - test if the page was referenced
796 * @page: the page to test
797 * @is_locked: caller holds lock on the page
798 * @memcg: target memory cgroup
799 * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
801 * Quick test_and_clear_referenced for all mappings to a page,
802 * returns the number of ptes which referenced the page.
804 int page_referenced(struct page
*page
,
806 struct mem_cgroup
*memcg
,
807 unsigned long *vm_flags
)
811 struct page_referenced_arg pra
= {
812 .mapcount
= total_mapcount(page
),
815 struct rmap_walk_control rwc
= {
816 .rmap_one
= page_referenced_one
,
818 .anon_lock
= page_lock_anon_vma_read
,
822 if (!page_mapped(page
))
825 if (!page_rmapping(page
))
828 if (!is_locked
&& (!PageAnon(page
) || PageKsm(page
))) {
829 we_locked
= trylock_page(page
);
835 * If we are reclaiming on behalf of a cgroup, skip
836 * counting on behalf of references from different
840 rwc
.invalid_vma
= invalid_page_referenced_vma
;
843 ret
= rmap_walk(page
, &rwc
);
844 *vm_flags
= pra
.vm_flags
;
849 return pra
.referenced
;
852 static int page_mkclean_one(struct page
*page
, struct vm_area_struct
*vma
,
853 unsigned long address
, void *arg
)
855 struct page_vma_mapped_walk pvmw
= {
863 while (page_vma_mapped_walk(&pvmw
)) {
865 address
= pvmw
.address
;
868 pte_t
*pte
= pvmw
.pte
;
870 if (!pte_dirty(*pte
) && !pte_write(*pte
))
873 flush_cache_page(vma
, address
, pte_pfn(*pte
));
874 entry
= ptep_clear_flush(vma
, address
, pte
);
875 entry
= pte_wrprotect(entry
);
876 entry
= pte_mkclean(entry
);
877 set_pte_at(vma
->vm_mm
, address
, pte
, entry
);
880 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
881 pmd_t
*pmd
= pvmw
.pmd
;
884 if (!pmd_dirty(*pmd
) && !pmd_write(*pmd
))
887 flush_cache_page(vma
, address
, page_to_pfn(page
));
888 entry
= pmdp_huge_clear_flush(vma
, address
, pmd
);
889 entry
= pmd_wrprotect(entry
);
890 entry
= pmd_mkclean(entry
);
891 set_pmd_at(vma
->vm_mm
, address
, pmd
, entry
);
894 /* unexpected pmd-mapped page? */
900 mmu_notifier_invalidate_page(vma
->vm_mm
, address
);
908 static bool invalid_mkclean_vma(struct vm_area_struct
*vma
, void *arg
)
910 if (vma
->vm_flags
& VM_SHARED
)
916 int page_mkclean(struct page
*page
)
919 struct address_space
*mapping
;
920 struct rmap_walk_control rwc
= {
921 .arg
= (void *)&cleaned
,
922 .rmap_one
= page_mkclean_one
,
923 .invalid_vma
= invalid_mkclean_vma
,
926 BUG_ON(!PageLocked(page
));
928 if (!page_mapped(page
))
931 mapping
= page_mapping(page
);
935 rmap_walk(page
, &rwc
);
939 EXPORT_SYMBOL_GPL(page_mkclean
);
942 * page_move_anon_rmap - move a page to our anon_vma
943 * @page: the page to move to our anon_vma
944 * @vma: the vma the page belongs to
946 * When a page belongs exclusively to one process after a COW event,
947 * that page can be moved into the anon_vma that belongs to just that
948 * process, so the rmap code will not search the parent or sibling
951 void page_move_anon_rmap(struct page
*page
, struct vm_area_struct
*vma
)
953 struct anon_vma
*anon_vma
= vma
->anon_vma
;
955 page
= compound_head(page
);
957 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
958 VM_BUG_ON_VMA(!anon_vma
, vma
);
960 anon_vma
= (void *) anon_vma
+ PAGE_MAPPING_ANON
;
962 * Ensure that anon_vma and the PAGE_MAPPING_ANON bit are written
963 * simultaneously, so a concurrent reader (eg page_referenced()'s
964 * PageAnon()) will not see one without the other.
966 WRITE_ONCE(page
->mapping
, (struct address_space
*) anon_vma
);
970 * __page_set_anon_rmap - set up new anonymous rmap
971 * @page: Page to add to rmap
972 * @vma: VM area to add page to.
973 * @address: User virtual address of the mapping
974 * @exclusive: the page is exclusively owned by the current process
976 static void __page_set_anon_rmap(struct page
*page
,
977 struct vm_area_struct
*vma
, unsigned long address
, int exclusive
)
979 struct anon_vma
*anon_vma
= vma
->anon_vma
;
987 * If the page isn't exclusively mapped into this vma,
988 * we must use the _oldest_ possible anon_vma for the
992 anon_vma
= anon_vma
->root
;
994 anon_vma
= (void *) anon_vma
+ PAGE_MAPPING_ANON
;
995 page
->mapping
= (struct address_space
*) anon_vma
;
996 page
->index
= linear_page_index(vma
, address
);
1000 * __page_check_anon_rmap - sanity check anonymous rmap addition
1001 * @page: the page to add the mapping to
1002 * @vma: the vm area in which the mapping is added
1003 * @address: the user virtual address mapped
1005 static void __page_check_anon_rmap(struct page
*page
,
1006 struct vm_area_struct
*vma
, unsigned long address
)
1008 #ifdef CONFIG_DEBUG_VM
1010 * The page's anon-rmap details (mapping and index) are guaranteed to
1011 * be set up correctly at this point.
1013 * We have exclusion against page_add_anon_rmap because the caller
1014 * always holds the page locked, except if called from page_dup_rmap,
1015 * in which case the page is already known to be setup.
1017 * We have exclusion against page_add_new_anon_rmap because those pages
1018 * are initially only visible via the pagetables, and the pte is locked
1019 * over the call to page_add_new_anon_rmap.
1021 BUG_ON(page_anon_vma(page
)->root
!= vma
->anon_vma
->root
);
1022 BUG_ON(page_to_pgoff(page
) != linear_page_index(vma
, address
));
1027 * page_add_anon_rmap - add pte mapping to an anonymous page
1028 * @page: the page to add the mapping to
1029 * @vma: the vm area in which the mapping is added
1030 * @address: the user virtual address mapped
1031 * @compound: charge the page as compound or small page
1033 * The caller needs to hold the pte lock, and the page must be locked in
1034 * the anon_vma case: to serialize mapping,index checking after setting,
1035 * and to ensure that PageAnon is not being upgraded racily to PageKsm
1036 * (but PageKsm is never downgraded to PageAnon).
1038 void page_add_anon_rmap(struct page
*page
,
1039 struct vm_area_struct
*vma
, unsigned long address
, bool compound
)
1041 do_page_add_anon_rmap(page
, vma
, address
, compound
? RMAP_COMPOUND
: 0);
1045 * Special version of the above for do_swap_page, which often runs
1046 * into pages that are exclusively owned by the current process.
1047 * Everybody else should continue to use page_add_anon_rmap above.
1049 void do_page_add_anon_rmap(struct page
*page
,
1050 struct vm_area_struct
*vma
, unsigned long address
, int flags
)
1052 bool compound
= flags
& RMAP_COMPOUND
;
1057 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1058 VM_BUG_ON_PAGE(!PageTransHuge(page
), page
);
1059 mapcount
= compound_mapcount_ptr(page
);
1060 first
= atomic_inc_and_test(mapcount
);
1062 first
= atomic_inc_and_test(&page
->_mapcount
);
1066 int nr
= compound
? hpage_nr_pages(page
) : 1;
1068 * We use the irq-unsafe __{inc|mod}_zone_page_stat because
1069 * these counters are not modified in interrupt context, and
1070 * pte lock(a spinlock) is held, which implies preemption
1074 __inc_node_page_state(page
, NR_ANON_THPS
);
1075 __mod_node_page_state(page_pgdat(page
), NR_ANON_MAPPED
, nr
);
1077 if (unlikely(PageKsm(page
)))
1080 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1082 /* address might be in next vma when migration races vma_adjust */
1084 __page_set_anon_rmap(page
, vma
, address
,
1085 flags
& RMAP_EXCLUSIVE
);
1087 __page_check_anon_rmap(page
, vma
, address
);
1091 * page_add_new_anon_rmap - add pte mapping to a new anonymous page
1092 * @page: the page to add the mapping to
1093 * @vma: the vm area in which the mapping is added
1094 * @address: the user virtual address mapped
1095 * @compound: charge the page as compound or small page
1097 * Same as page_add_anon_rmap but must only be called on *new* pages.
1098 * This means the inc-and-test can be bypassed.
1099 * Page does not have to be locked.
1101 void page_add_new_anon_rmap(struct page
*page
,
1102 struct vm_area_struct
*vma
, unsigned long address
, bool compound
)
1104 int nr
= compound
? hpage_nr_pages(page
) : 1;
1106 VM_BUG_ON_VMA(address
< vma
->vm_start
|| address
>= vma
->vm_end
, vma
);
1107 __SetPageSwapBacked(page
);
1109 VM_BUG_ON_PAGE(!PageTransHuge(page
), page
);
1110 /* increment count (starts at -1) */
1111 atomic_set(compound_mapcount_ptr(page
), 0);
1112 __inc_node_page_state(page
, NR_ANON_THPS
);
1114 /* Anon THP always mapped first with PMD */
1115 VM_BUG_ON_PAGE(PageTransCompound(page
), page
);
1116 /* increment count (starts at -1) */
1117 atomic_set(&page
->_mapcount
, 0);
1119 __mod_node_page_state(page_pgdat(page
), NR_ANON_MAPPED
, nr
);
1120 __page_set_anon_rmap(page
, vma
, address
, 1);
1124 * page_add_file_rmap - add pte mapping to a file page
1125 * @page: the page to add the mapping to
1127 * The caller needs to hold the pte lock.
1129 void page_add_file_rmap(struct page
*page
, bool compound
)
1133 VM_BUG_ON_PAGE(compound
&& !PageTransHuge(page
), page
);
1134 lock_page_memcg(page
);
1135 if (compound
&& PageTransHuge(page
)) {
1136 for (i
= 0, nr
= 0; i
< HPAGE_PMD_NR
; i
++) {
1137 if (atomic_inc_and_test(&page
[i
]._mapcount
))
1140 if (!atomic_inc_and_test(compound_mapcount_ptr(page
)))
1142 VM_BUG_ON_PAGE(!PageSwapBacked(page
), page
);
1143 __inc_node_page_state(page
, NR_SHMEM_PMDMAPPED
);
1145 if (PageTransCompound(page
) && page_mapping(page
)) {
1146 VM_WARN_ON_ONCE(!PageLocked(page
));
1148 SetPageDoubleMap(compound_head(page
));
1149 if (PageMlocked(page
))
1150 clear_page_mlock(compound_head(page
));
1152 if (!atomic_inc_and_test(&page
->_mapcount
))
1155 __mod_node_page_state(page_pgdat(page
), NR_FILE_MAPPED
, nr
);
1156 mem_cgroup_inc_page_stat(page
, MEM_CGROUP_STAT_FILE_MAPPED
);
1158 unlock_page_memcg(page
);
1161 static void page_remove_file_rmap(struct page
*page
, bool compound
)
1165 VM_BUG_ON_PAGE(compound
&& !PageHead(page
), page
);
1166 lock_page_memcg(page
);
1168 /* Hugepages are not counted in NR_FILE_MAPPED for now. */
1169 if (unlikely(PageHuge(page
))) {
1170 /* hugetlb pages are always mapped with pmds */
1171 atomic_dec(compound_mapcount_ptr(page
));
1175 /* page still mapped by someone else? */
1176 if (compound
&& PageTransHuge(page
)) {
1177 for (i
= 0, nr
= 0; i
< HPAGE_PMD_NR
; i
++) {
1178 if (atomic_add_negative(-1, &page
[i
]._mapcount
))
1181 if (!atomic_add_negative(-1, compound_mapcount_ptr(page
)))
1183 VM_BUG_ON_PAGE(!PageSwapBacked(page
), page
);
1184 __dec_node_page_state(page
, NR_SHMEM_PMDMAPPED
);
1186 if (!atomic_add_negative(-1, &page
->_mapcount
))
1191 * We use the irq-unsafe __{inc|mod}_zone_page_state because
1192 * these counters are not modified in interrupt context, and
1193 * pte lock(a spinlock) is held, which implies preemption disabled.
1195 __mod_node_page_state(page_pgdat(page
), NR_FILE_MAPPED
, -nr
);
1196 mem_cgroup_dec_page_stat(page
, MEM_CGROUP_STAT_FILE_MAPPED
);
1198 if (unlikely(PageMlocked(page
)))
1199 clear_page_mlock(page
);
1201 unlock_page_memcg(page
);
1204 static void page_remove_anon_compound_rmap(struct page
*page
)
1208 if (!atomic_add_negative(-1, compound_mapcount_ptr(page
)))
1211 /* Hugepages are not counted in NR_ANON_PAGES for now. */
1212 if (unlikely(PageHuge(page
)))
1215 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE
))
1218 __dec_node_page_state(page
, NR_ANON_THPS
);
1220 if (TestClearPageDoubleMap(page
)) {
1222 * Subpages can be mapped with PTEs too. Check how many of
1223 * themi are still mapped.
1225 for (i
= 0, nr
= 0; i
< HPAGE_PMD_NR
; i
++) {
1226 if (atomic_add_negative(-1, &page
[i
]._mapcount
))
1233 if (unlikely(PageMlocked(page
)))
1234 clear_page_mlock(page
);
1237 __mod_node_page_state(page_pgdat(page
), NR_ANON_MAPPED
, -nr
);
1238 deferred_split_huge_page(page
);
1243 * page_remove_rmap - take down pte mapping from a page
1244 * @page: page to remove mapping from
1245 * @compound: uncharge the page as compound or small page
1247 * The caller needs to hold the pte lock.
1249 void page_remove_rmap(struct page
*page
, bool compound
)
1251 if (!PageAnon(page
))
1252 return page_remove_file_rmap(page
, compound
);
1255 return page_remove_anon_compound_rmap(page
);
1257 /* page still mapped by someone else? */
1258 if (!atomic_add_negative(-1, &page
->_mapcount
))
1262 * We use the irq-unsafe __{inc|mod}_zone_page_stat because
1263 * these counters are not modified in interrupt context, and
1264 * pte lock(a spinlock) is held, which implies preemption disabled.
1266 __dec_node_page_state(page
, NR_ANON_MAPPED
);
1268 if (unlikely(PageMlocked(page
)))
1269 clear_page_mlock(page
);
1271 if (PageTransCompound(page
))
1272 deferred_split_huge_page(compound_head(page
));
1275 * It would be tidy to reset the PageAnon mapping here,
1276 * but that might overwrite a racing page_add_anon_rmap
1277 * which increments mapcount after us but sets mapping
1278 * before us: so leave the reset to free_hot_cold_page,
1279 * and remember that it's only reliable while mapped.
1280 * Leaving it set also helps swapoff to reinstate ptes
1281 * faster for those pages still in swapcache.
1285 struct rmap_private
{
1286 enum ttu_flags flags
;
1291 * @arg: enum ttu_flags will be passed to this argument
1293 static int try_to_unmap_one(struct page
*page
, struct vm_area_struct
*vma
,
1294 unsigned long address
, void *arg
)
1296 struct mm_struct
*mm
= vma
->vm_mm
;
1297 struct page_vma_mapped_walk pvmw
= {
1303 struct page
*subpage
;
1304 int ret
= SWAP_AGAIN
;
1305 struct rmap_private
*rp
= arg
;
1306 enum ttu_flags flags
= rp
->flags
;
1308 /* munlock has nothing to gain from examining un-locked vmas */
1309 if ((flags
& TTU_MUNLOCK
) && !(vma
->vm_flags
& VM_LOCKED
))
1312 if (flags
& TTU_SPLIT_HUGE_PMD
) {
1313 split_huge_pmd_address(vma
, address
,
1314 flags
& TTU_MIGRATION
, page
);
1317 while (page_vma_mapped_walk(&pvmw
)) {
1318 subpage
= page
- page_to_pfn(page
) + pte_pfn(*pvmw
.pte
);
1319 address
= pvmw
.address
;
1321 /* Unexpected PMD-mapped THP? */
1322 VM_BUG_ON_PAGE(!pvmw
.pte
, page
);
1325 * If the page is mlock()d, we cannot swap it out.
1326 * If it's recently referenced (perhaps page_referenced
1327 * skipped over this mm) then we should reactivate it.
1329 if (!(flags
& TTU_IGNORE_MLOCK
)) {
1330 if (vma
->vm_flags
& VM_LOCKED
) {
1331 /* PTE-mapped THP are never mlocked */
1332 if (!PageTransCompound(page
)) {
1334 * Holding pte lock, we do *not* need
1337 mlock_vma_page(page
);
1340 page_vma_mapped_walk_done(&pvmw
);
1343 if (flags
& TTU_MUNLOCK
)
1347 if (!(flags
& TTU_IGNORE_ACCESS
)) {
1348 if (ptep_clear_flush_young_notify(vma
, address
,
1351 page_vma_mapped_walk_done(&pvmw
);
1356 /* Nuke the page table entry. */
1357 flush_cache_page(vma
, address
, pte_pfn(*pvmw
.pte
));
1358 if (should_defer_flush(mm
, flags
)) {
1360 * We clear the PTE but do not flush so potentially
1361 * a remote CPU could still be writing to the page.
1362 * If the entry was previously clean then the
1363 * architecture must guarantee that a clear->dirty
1364 * transition on a cached TLB entry is written through
1365 * and traps if the PTE is unmapped.
1367 pteval
= ptep_get_and_clear(mm
, address
, pvmw
.pte
);
1369 set_tlb_ubc_flush_pending(mm
, pte_dirty(pteval
));
1371 pteval
= ptep_clear_flush(vma
, address
, pvmw
.pte
);
1374 /* Move the dirty bit to the page. Now the pte is gone. */
1375 if (pte_dirty(pteval
))
1376 set_page_dirty(page
);
1378 /* Update high watermark before we lower rss */
1379 update_hiwater_rss(mm
);
1381 if (PageHWPoison(page
) && !(flags
& TTU_IGNORE_HWPOISON
)) {
1382 if (PageHuge(page
)) {
1383 int nr
= 1 << compound_order(page
);
1384 hugetlb_count_sub(nr
, mm
);
1386 dec_mm_counter(mm
, mm_counter(page
));
1389 pteval
= swp_entry_to_pte(make_hwpoison_entry(subpage
));
1390 set_pte_at(mm
, address
, pvmw
.pte
, pteval
);
1391 } else if (pte_unused(pteval
)) {
1393 * The guest indicated that the page content is of no
1394 * interest anymore. Simply discard the pte, vmscan
1395 * will take care of the rest.
1397 dec_mm_counter(mm
, mm_counter(page
));
1398 } else if (IS_ENABLED(CONFIG_MIGRATION
) &&
1399 (flags
& TTU_MIGRATION
)) {
1403 * Store the pfn of the page in a special migration
1404 * pte. do_swap_page() will wait until the migration
1405 * pte is removed and then restart fault handling.
1407 entry
= make_migration_entry(subpage
,
1409 swp_pte
= swp_entry_to_pte(entry
);
1410 if (pte_soft_dirty(pteval
))
1411 swp_pte
= pte_swp_mksoft_dirty(swp_pte
);
1412 set_pte_at(mm
, address
, pvmw
.pte
, swp_pte
);
1413 } else if (PageAnon(page
)) {
1414 swp_entry_t entry
= { .val
= page_private(subpage
) };
1417 * Store the swap location in the pte.
1418 * See handle_pte_fault() ...
1420 VM_BUG_ON_PAGE(!PageSwapCache(page
), page
);
1422 if (!PageDirty(page
) && (flags
& TTU_LZFREE
)) {
1423 /* It's a freeable page by MADV_FREE */
1424 dec_mm_counter(mm
, MM_ANONPAGES
);
1429 if (swap_duplicate(entry
) < 0) {
1430 set_pte_at(mm
, address
, pvmw
.pte
, pteval
);
1432 page_vma_mapped_walk_done(&pvmw
);
1435 if (list_empty(&mm
->mmlist
)) {
1436 spin_lock(&mmlist_lock
);
1437 if (list_empty(&mm
->mmlist
))
1438 list_add(&mm
->mmlist
, &init_mm
.mmlist
);
1439 spin_unlock(&mmlist_lock
);
1441 dec_mm_counter(mm
, MM_ANONPAGES
);
1442 inc_mm_counter(mm
, MM_SWAPENTS
);
1443 swp_pte
= swp_entry_to_pte(entry
);
1444 if (pte_soft_dirty(pteval
))
1445 swp_pte
= pte_swp_mksoft_dirty(swp_pte
);
1446 set_pte_at(mm
, address
, pvmw
.pte
, swp_pte
);
1448 dec_mm_counter(mm
, mm_counter_file(page
));
1450 page_remove_rmap(subpage
, PageHuge(page
));
1452 mmu_notifier_invalidate_page(mm
, address
);
1457 bool is_vma_temporary_stack(struct vm_area_struct
*vma
)
1459 int maybe_stack
= vma
->vm_flags
& (VM_GROWSDOWN
| VM_GROWSUP
);
1464 if ((vma
->vm_flags
& VM_STACK_INCOMPLETE_SETUP
) ==
1465 VM_STACK_INCOMPLETE_SETUP
)
1471 static bool invalid_migration_vma(struct vm_area_struct
*vma
, void *arg
)
1473 return is_vma_temporary_stack(vma
);
1476 static int page_mapcount_is_zero(struct page
*page
)
1478 return !total_mapcount(page
);
1482 * try_to_unmap - try to remove all page table mappings to a page
1483 * @page: the page to get unmapped
1484 * @flags: action and flags
1486 * Tries to remove all the page table entries which are mapping this
1487 * page, used in the pageout path. Caller must hold the page lock.
1488 * Return values are:
1490 * SWAP_SUCCESS - we succeeded in removing all mappings
1491 * SWAP_AGAIN - we missed a mapping, try again later
1492 * SWAP_FAIL - the page is unswappable
1493 * SWAP_MLOCK - page is mlocked.
1495 int try_to_unmap(struct page
*page
, enum ttu_flags flags
)
1498 struct rmap_private rp
= {
1503 struct rmap_walk_control rwc
= {
1504 .rmap_one
= try_to_unmap_one
,
1506 .done
= page_mapcount_is_zero
,
1507 .anon_lock
= page_lock_anon_vma_read
,
1511 * During exec, a temporary VMA is setup and later moved.
1512 * The VMA is moved under the anon_vma lock but not the
1513 * page tables leading to a race where migration cannot
1514 * find the migration ptes. Rather than increasing the
1515 * locking requirements of exec(), migration skips
1516 * temporary VMAs until after exec() completes.
1518 if ((flags
& TTU_MIGRATION
) && !PageKsm(page
) && PageAnon(page
))
1519 rwc
.invalid_vma
= invalid_migration_vma
;
1521 if (flags
& TTU_RMAP_LOCKED
)
1522 ret
= rmap_walk_locked(page
, &rwc
);
1524 ret
= rmap_walk(page
, &rwc
);
1526 if (ret
!= SWAP_MLOCK
&& !page_mapcount(page
)) {
1528 if (rp
.lazyfreed
&& !PageDirty(page
))
1534 static int page_not_mapped(struct page
*page
)
1536 return !page_mapped(page
);
1540 * try_to_munlock - try to munlock a page
1541 * @page: the page to be munlocked
1543 * Called from munlock code. Checks all of the VMAs mapping the page
1544 * to make sure nobody else has this page mlocked. The page will be
1545 * returned with PG_mlocked cleared if no other vmas have it mlocked.
1547 * Return values are:
1549 * SWAP_AGAIN - no vma is holding page mlocked, or,
1550 * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem
1551 * SWAP_FAIL - page cannot be located at present
1552 * SWAP_MLOCK - page is now mlocked.
1554 int try_to_munlock(struct page
*page
)
1557 struct rmap_private rp
= {
1558 .flags
= TTU_MUNLOCK
,
1562 struct rmap_walk_control rwc
= {
1563 .rmap_one
= try_to_unmap_one
,
1565 .done
= page_not_mapped
,
1566 .anon_lock
= page_lock_anon_vma_read
,
1570 VM_BUG_ON_PAGE(!PageLocked(page
) || PageLRU(page
), page
);
1572 ret
= rmap_walk(page
, &rwc
);
1576 void __put_anon_vma(struct anon_vma
*anon_vma
)
1578 struct anon_vma
*root
= anon_vma
->root
;
1580 anon_vma_free(anon_vma
);
1581 if (root
!= anon_vma
&& atomic_dec_and_test(&root
->refcount
))
1582 anon_vma_free(root
);
1585 static struct anon_vma
*rmap_walk_anon_lock(struct page
*page
,
1586 struct rmap_walk_control
*rwc
)
1588 struct anon_vma
*anon_vma
;
1591 return rwc
->anon_lock(page
);
1594 * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
1595 * because that depends on page_mapped(); but not all its usages
1596 * are holding mmap_sem. Users without mmap_sem are required to
1597 * take a reference count to prevent the anon_vma disappearing
1599 anon_vma
= page_anon_vma(page
);
1603 anon_vma_lock_read(anon_vma
);
1608 * rmap_walk_anon - do something to anonymous page using the object-based
1610 * @page: the page to be handled
1611 * @rwc: control variable according to each walk type
1613 * Find all the mappings of a page using the mapping pointer and the vma chains
1614 * contained in the anon_vma struct it points to.
1616 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1617 * where the page was found will be held for write. So, we won't recheck
1618 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1621 static int rmap_walk_anon(struct page
*page
, struct rmap_walk_control
*rwc
,
1624 struct anon_vma
*anon_vma
;
1625 pgoff_t pgoff_start
, pgoff_end
;
1626 struct anon_vma_chain
*avc
;
1627 int ret
= SWAP_AGAIN
;
1630 anon_vma
= page_anon_vma(page
);
1631 /* anon_vma disappear under us? */
1632 VM_BUG_ON_PAGE(!anon_vma
, page
);
1634 anon_vma
= rmap_walk_anon_lock(page
, rwc
);
1639 pgoff_start
= page_to_pgoff(page
);
1640 pgoff_end
= pgoff_start
+ hpage_nr_pages(page
) - 1;
1641 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
,
1642 pgoff_start
, pgoff_end
) {
1643 struct vm_area_struct
*vma
= avc
->vma
;
1644 unsigned long address
= vma_address(page
, vma
);
1648 if (rwc
->invalid_vma
&& rwc
->invalid_vma(vma
, rwc
->arg
))
1651 ret
= rwc
->rmap_one(page
, vma
, address
, rwc
->arg
);
1652 if (ret
!= SWAP_AGAIN
)
1654 if (rwc
->done
&& rwc
->done(page
))
1659 anon_vma_unlock_read(anon_vma
);
1664 * rmap_walk_file - do something to file page using the object-based rmap method
1665 * @page: the page to be handled
1666 * @rwc: control variable according to each walk type
1668 * Find all the mappings of a page using the mapping pointer and the vma chains
1669 * contained in the address_space struct it points to.
1671 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1672 * where the page was found will be held for write. So, we won't recheck
1673 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1676 static int rmap_walk_file(struct page
*page
, struct rmap_walk_control
*rwc
,
1679 struct address_space
*mapping
= page_mapping(page
);
1680 pgoff_t pgoff_start
, pgoff_end
;
1681 struct vm_area_struct
*vma
;
1682 int ret
= SWAP_AGAIN
;
1685 * The page lock not only makes sure that page->mapping cannot
1686 * suddenly be NULLified by truncation, it makes sure that the
1687 * structure at mapping cannot be freed and reused yet,
1688 * so we can safely take mapping->i_mmap_rwsem.
1690 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1695 pgoff_start
= page_to_pgoff(page
);
1696 pgoff_end
= pgoff_start
+ hpage_nr_pages(page
) - 1;
1698 i_mmap_lock_read(mapping
);
1699 vma_interval_tree_foreach(vma
, &mapping
->i_mmap
,
1700 pgoff_start
, pgoff_end
) {
1701 unsigned long address
= vma_address(page
, vma
);
1705 if (rwc
->invalid_vma
&& rwc
->invalid_vma(vma
, rwc
->arg
))
1708 ret
= rwc
->rmap_one(page
, vma
, address
, rwc
->arg
);
1709 if (ret
!= SWAP_AGAIN
)
1711 if (rwc
->done
&& rwc
->done(page
))
1717 i_mmap_unlock_read(mapping
);
1721 int rmap_walk(struct page
*page
, struct rmap_walk_control
*rwc
)
1723 if (unlikely(PageKsm(page
)))
1724 return rmap_walk_ksm(page
, rwc
);
1725 else if (PageAnon(page
))
1726 return rmap_walk_anon(page
, rwc
, false);
1728 return rmap_walk_file(page
, rwc
, false);
1731 /* Like rmap_walk, but caller holds relevant rmap lock */
1732 int rmap_walk_locked(struct page
*page
, struct rmap_walk_control
*rwc
)
1734 /* no ksm support for now */
1735 VM_BUG_ON_PAGE(PageKsm(page
), page
);
1737 return rmap_walk_anon(page
, rwc
, true);
1739 return rmap_walk_file(page
, rwc
, true);
1742 #ifdef CONFIG_HUGETLB_PAGE
1744 * The following three functions are for anonymous (private mapped) hugepages.
1745 * Unlike common anonymous pages, anonymous hugepages have no accounting code
1746 * and no lru code, because we handle hugepages differently from common pages.
1748 static void __hugepage_set_anon_rmap(struct page
*page
,
1749 struct vm_area_struct
*vma
, unsigned long address
, int exclusive
)
1751 struct anon_vma
*anon_vma
= vma
->anon_vma
;
1758 anon_vma
= anon_vma
->root
;
1760 anon_vma
= (void *) anon_vma
+ PAGE_MAPPING_ANON
;
1761 page
->mapping
= (struct address_space
*) anon_vma
;
1762 page
->index
= linear_page_index(vma
, address
);
1765 void hugepage_add_anon_rmap(struct page
*page
,
1766 struct vm_area_struct
*vma
, unsigned long address
)
1768 struct anon_vma
*anon_vma
= vma
->anon_vma
;
1771 BUG_ON(!PageLocked(page
));
1773 /* address might be in next vma when migration races vma_adjust */
1774 first
= atomic_inc_and_test(compound_mapcount_ptr(page
));
1776 __hugepage_set_anon_rmap(page
, vma
, address
, 0);
1779 void hugepage_add_new_anon_rmap(struct page
*page
,
1780 struct vm_area_struct
*vma
, unsigned long address
)
1782 BUG_ON(address
< vma
->vm_start
|| address
>= vma
->vm_end
);
1783 atomic_set(compound_mapcount_ptr(page
), 0);
1784 __hugepage_set_anon_rmap(page
, vma
, address
, 1);
1786 #endif /* CONFIG_HUGETLB_PAGE */