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) * (see huegtlbfs below)
26 * hugetlbfs_i_mmap_rwsem_key (in huge_pmd_share)
27 * mapping->i_mmap_rwsem
28 * hugetlb_fault_mutex (hugetlbfs specific page fault mutex)
30 * mm->page_table_lock or pte_lock
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 * lock_page_memcg move_lock (in __set_page_dirty_buffers)
35 * i_pages lock (widely used)
36 * lruvec->lru_lock (in lock_page_lruvec_irq)
37 * inode->i_lock (in set_page_dirty's __mark_inode_dirty)
38 * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
39 * sb_lock (within inode_lock in fs/fs-writeback.c)
40 * i_pages lock (widely used, in set_page_dirty,
41 * in arch-dependent flush_dcache_mmap_lock,
42 * within bdi.wb->list_lock in __sync_single_inode)
44 * anon_vma->rwsem,mapping->i_mutex (memory_failure, collect_procs_anon)
48 * * hugetlbfs PageHuge() pages take locks in this order:
49 * mapping->i_mmap_rwsem
50 * hugetlb_fault_mutex (hugetlbfs specific page fault mutex)
51 * page->flags PG_locked (lock_page)
55 #include <linux/sched/mm.h>
56 #include <linux/sched/task.h>
57 #include <linux/pagemap.h>
58 #include <linux/swap.h>
59 #include <linux/swapops.h>
60 #include <linux/slab.h>
61 #include <linux/init.h>
62 #include <linux/ksm.h>
63 #include <linux/rmap.h>
64 #include <linux/rcupdate.h>
65 #include <linux/export.h>
66 #include <linux/memcontrol.h>
67 #include <linux/mmu_notifier.h>
68 #include <linux/migrate.h>
69 #include <linux/hugetlb.h>
70 #include <linux/huge_mm.h>
71 #include <linux/backing-dev.h>
72 #include <linux/page_idle.h>
73 #include <linux/memremap.h>
74 #include <linux/userfaultfd_k.h>
76 #include <asm/tlbflush.h>
78 #include <trace/events/tlb.h>
82 static struct kmem_cache
*anon_vma_cachep
;
83 static struct kmem_cache
*anon_vma_chain_cachep
;
85 static inline struct anon_vma
*anon_vma_alloc(void)
87 struct anon_vma
*anon_vma
;
89 anon_vma
= kmem_cache_alloc(anon_vma_cachep
, GFP_KERNEL
);
91 atomic_set(&anon_vma
->refcount
, 1);
92 anon_vma
->degree
= 1; /* Reference for first vma */
93 anon_vma
->parent
= anon_vma
;
95 * Initialise the anon_vma root to point to itself. If called
96 * from fork, the root will be reset to the parents anon_vma.
98 anon_vma
->root
= anon_vma
;
104 static inline void anon_vma_free(struct anon_vma
*anon_vma
)
106 VM_BUG_ON(atomic_read(&anon_vma
->refcount
));
109 * Synchronize against page_lock_anon_vma_read() such that
110 * we can safely hold the lock without the anon_vma getting
113 * Relies on the full mb implied by the atomic_dec_and_test() from
114 * put_anon_vma() against the acquire barrier implied by
115 * down_read_trylock() from page_lock_anon_vma_read(). This orders:
117 * page_lock_anon_vma_read() VS put_anon_vma()
118 * down_read_trylock() atomic_dec_and_test()
120 * atomic_read() rwsem_is_locked()
122 * LOCK should suffice since the actual taking of the lock must
123 * happen _before_ what follows.
126 if (rwsem_is_locked(&anon_vma
->root
->rwsem
)) {
127 anon_vma_lock_write(anon_vma
);
128 anon_vma_unlock_write(anon_vma
);
131 kmem_cache_free(anon_vma_cachep
, anon_vma
);
134 static inline struct anon_vma_chain
*anon_vma_chain_alloc(gfp_t gfp
)
136 return kmem_cache_alloc(anon_vma_chain_cachep
, gfp
);
139 static void anon_vma_chain_free(struct anon_vma_chain
*anon_vma_chain
)
141 kmem_cache_free(anon_vma_chain_cachep
, anon_vma_chain
);
144 static void anon_vma_chain_link(struct vm_area_struct
*vma
,
145 struct anon_vma_chain
*avc
,
146 struct anon_vma
*anon_vma
)
149 avc
->anon_vma
= anon_vma
;
150 list_add(&avc
->same_vma
, &vma
->anon_vma_chain
);
151 anon_vma_interval_tree_insert(avc
, &anon_vma
->rb_root
);
155 * __anon_vma_prepare - attach an anon_vma to a memory region
156 * @vma: the memory region in question
158 * This makes sure the memory mapping described by 'vma' has
159 * an 'anon_vma' attached to it, so that we can associate the
160 * anonymous pages mapped into it with that anon_vma.
162 * The common case will be that we already have one, which
163 * is handled inline by anon_vma_prepare(). But if
164 * not we either need to find an adjacent mapping that we
165 * can re-use the anon_vma from (very common when the only
166 * reason for splitting a vma has been mprotect()), or we
167 * allocate a new one.
169 * Anon-vma allocations are very subtle, because we may have
170 * optimistically looked up an anon_vma in page_lock_anon_vma_read()
171 * and that may actually touch the rwsem even in the newly
172 * allocated vma (it depends on RCU to make sure that the
173 * anon_vma isn't actually destroyed).
175 * As a result, we need to do proper anon_vma locking even
176 * for the new allocation. At the same time, we do not want
177 * to do any locking for the common case of already having
180 * This must be called with the mmap_lock held for reading.
182 int __anon_vma_prepare(struct vm_area_struct
*vma
)
184 struct mm_struct
*mm
= vma
->vm_mm
;
185 struct anon_vma
*anon_vma
, *allocated
;
186 struct anon_vma_chain
*avc
;
190 avc
= anon_vma_chain_alloc(GFP_KERNEL
);
194 anon_vma
= find_mergeable_anon_vma(vma
);
197 anon_vma
= anon_vma_alloc();
198 if (unlikely(!anon_vma
))
199 goto out_enomem_free_avc
;
200 allocated
= anon_vma
;
203 anon_vma_lock_write(anon_vma
);
204 /* page_table_lock to protect against threads */
205 spin_lock(&mm
->page_table_lock
);
206 if (likely(!vma
->anon_vma
)) {
207 vma
->anon_vma
= anon_vma
;
208 anon_vma_chain_link(vma
, avc
, anon_vma
);
209 /* vma reference or self-parent link for new root */
214 spin_unlock(&mm
->page_table_lock
);
215 anon_vma_unlock_write(anon_vma
);
217 if (unlikely(allocated
))
218 put_anon_vma(allocated
);
220 anon_vma_chain_free(avc
);
225 anon_vma_chain_free(avc
);
231 * This is a useful helper function for locking the anon_vma root as
232 * we traverse the vma->anon_vma_chain, looping over anon_vma's that
235 * Such anon_vma's should have the same root, so you'd expect to see
236 * just a single mutex_lock for the whole traversal.
238 static inline struct anon_vma
*lock_anon_vma_root(struct anon_vma
*root
, struct anon_vma
*anon_vma
)
240 struct anon_vma
*new_root
= anon_vma
->root
;
241 if (new_root
!= root
) {
242 if (WARN_ON_ONCE(root
))
243 up_write(&root
->rwsem
);
245 down_write(&root
->rwsem
);
250 static inline void unlock_anon_vma_root(struct anon_vma
*root
)
253 up_write(&root
->rwsem
);
257 * Attach the anon_vmas from src to dst.
258 * Returns 0 on success, -ENOMEM on failure.
260 * anon_vma_clone() is called by __vma_adjust(), __split_vma(), copy_vma() and
261 * anon_vma_fork(). The first three want an exact copy of src, while the last
262 * one, anon_vma_fork(), may try to reuse an existing anon_vma to prevent
263 * endless growth of anon_vma. Since dst->anon_vma is set to NULL before call,
264 * we can identify this case by checking (!dst->anon_vma && src->anon_vma).
266 * If (!dst->anon_vma && src->anon_vma) is true, this function tries to find
267 * and reuse existing anon_vma which has no vmas and only one child anon_vma.
268 * This prevents degradation of anon_vma hierarchy to endless linear chain in
269 * case of constantly forking task. On the other hand, an anon_vma with more
270 * than one child isn't reused even if there was no alive vma, thus rmap
271 * walker has a good chance of avoiding scanning the whole hierarchy when it
272 * searches where page is mapped.
274 int anon_vma_clone(struct vm_area_struct
*dst
, struct vm_area_struct
*src
)
276 struct anon_vma_chain
*avc
, *pavc
;
277 struct anon_vma
*root
= NULL
;
279 list_for_each_entry_reverse(pavc
, &src
->anon_vma_chain
, same_vma
) {
280 struct anon_vma
*anon_vma
;
282 avc
= anon_vma_chain_alloc(GFP_NOWAIT
| __GFP_NOWARN
);
283 if (unlikely(!avc
)) {
284 unlock_anon_vma_root(root
);
286 avc
= anon_vma_chain_alloc(GFP_KERNEL
);
290 anon_vma
= pavc
->anon_vma
;
291 root
= lock_anon_vma_root(root
, anon_vma
);
292 anon_vma_chain_link(dst
, avc
, anon_vma
);
295 * Reuse existing anon_vma if its degree lower than two,
296 * that means it has no vma and only one anon_vma child.
298 * Do not chose parent anon_vma, otherwise first child
299 * will always reuse it. Root anon_vma is never reused:
300 * it has self-parent reference and at least one child.
302 if (!dst
->anon_vma
&& src
->anon_vma
&&
303 anon_vma
!= src
->anon_vma
&& anon_vma
->degree
< 2)
304 dst
->anon_vma
= anon_vma
;
307 dst
->anon_vma
->degree
++;
308 unlock_anon_vma_root(root
);
313 * dst->anon_vma is dropped here otherwise its degree can be incorrectly
314 * decremented in unlink_anon_vmas().
315 * We can safely do this because callers of anon_vma_clone() don't care
316 * about dst->anon_vma if anon_vma_clone() failed.
318 dst
->anon_vma
= NULL
;
319 unlink_anon_vmas(dst
);
324 * Attach vma to its own anon_vma, as well as to the anon_vmas that
325 * the corresponding VMA in the parent process is attached to.
326 * Returns 0 on success, non-zero on failure.
328 int anon_vma_fork(struct vm_area_struct
*vma
, struct vm_area_struct
*pvma
)
330 struct anon_vma_chain
*avc
;
331 struct anon_vma
*anon_vma
;
334 /* Don't bother if the parent process has no anon_vma here. */
338 /* Drop inherited anon_vma, we'll reuse existing or allocate new. */
339 vma
->anon_vma
= NULL
;
342 * First, attach the new VMA to the parent VMA's anon_vmas,
343 * so rmap can find non-COWed pages in child processes.
345 error
= anon_vma_clone(vma
, pvma
);
349 /* An existing anon_vma has been reused, all done then. */
353 /* Then add our own anon_vma. */
354 anon_vma
= anon_vma_alloc();
357 avc
= anon_vma_chain_alloc(GFP_KERNEL
);
359 goto out_error_free_anon_vma
;
362 * The root anon_vma's rwsem is the lock actually used when we
363 * lock any of the anon_vmas in this anon_vma tree.
365 anon_vma
->root
= pvma
->anon_vma
->root
;
366 anon_vma
->parent
= pvma
->anon_vma
;
368 * With refcounts, an anon_vma can stay around longer than the
369 * process it belongs to. The root anon_vma needs to be pinned until
370 * this anon_vma is freed, because the lock lives in the root.
372 get_anon_vma(anon_vma
->root
);
373 /* Mark this anon_vma as the one where our new (COWed) pages go. */
374 vma
->anon_vma
= anon_vma
;
375 anon_vma_lock_write(anon_vma
);
376 anon_vma_chain_link(vma
, avc
, anon_vma
);
377 anon_vma
->parent
->degree
++;
378 anon_vma_unlock_write(anon_vma
);
382 out_error_free_anon_vma
:
383 put_anon_vma(anon_vma
);
385 unlink_anon_vmas(vma
);
389 void unlink_anon_vmas(struct vm_area_struct
*vma
)
391 struct anon_vma_chain
*avc
, *next
;
392 struct anon_vma
*root
= NULL
;
395 * Unlink each anon_vma chained to the VMA. This list is ordered
396 * from newest to oldest, ensuring the root anon_vma gets freed last.
398 list_for_each_entry_safe(avc
, next
, &vma
->anon_vma_chain
, same_vma
) {
399 struct anon_vma
*anon_vma
= avc
->anon_vma
;
401 root
= lock_anon_vma_root(root
, anon_vma
);
402 anon_vma_interval_tree_remove(avc
, &anon_vma
->rb_root
);
405 * Leave empty anon_vmas on the list - we'll need
406 * to free them outside the lock.
408 if (RB_EMPTY_ROOT(&anon_vma
->rb_root
.rb_root
)) {
409 anon_vma
->parent
->degree
--;
413 list_del(&avc
->same_vma
);
414 anon_vma_chain_free(avc
);
417 vma
->anon_vma
->degree
--;
420 * vma would still be needed after unlink, and anon_vma will be prepared
423 vma
->anon_vma
= NULL
;
425 unlock_anon_vma_root(root
);
428 * Iterate the list once more, it now only contains empty and unlinked
429 * anon_vmas, destroy them. Could not do before due to __put_anon_vma()
430 * needing to write-acquire the anon_vma->root->rwsem.
432 list_for_each_entry_safe(avc
, next
, &vma
->anon_vma_chain
, same_vma
) {
433 struct anon_vma
*anon_vma
= avc
->anon_vma
;
435 VM_WARN_ON(anon_vma
->degree
);
436 put_anon_vma(anon_vma
);
438 list_del(&avc
->same_vma
);
439 anon_vma_chain_free(avc
);
443 static void anon_vma_ctor(void *data
)
445 struct anon_vma
*anon_vma
= data
;
447 init_rwsem(&anon_vma
->rwsem
);
448 atomic_set(&anon_vma
->refcount
, 0);
449 anon_vma
->rb_root
= RB_ROOT_CACHED
;
452 void __init
anon_vma_init(void)
454 anon_vma_cachep
= kmem_cache_create("anon_vma", sizeof(struct anon_vma
),
455 0, SLAB_TYPESAFE_BY_RCU
|SLAB_PANIC
|SLAB_ACCOUNT
,
457 anon_vma_chain_cachep
= KMEM_CACHE(anon_vma_chain
,
458 SLAB_PANIC
|SLAB_ACCOUNT
);
462 * Getting a lock on a stable anon_vma from a page off the LRU is tricky!
464 * Since there is no serialization what so ever against page_remove_rmap()
465 * the best this function can do is return a refcount increased anon_vma
466 * that might have been relevant to this page.
468 * The page might have been remapped to a different anon_vma or the anon_vma
469 * returned may already be freed (and even reused).
471 * In case it was remapped to a different anon_vma, the new anon_vma will be a
472 * child of the old anon_vma, and the anon_vma lifetime rules will therefore
473 * ensure that any anon_vma obtained from the page will still be valid for as
474 * long as we observe page_mapped() [ hence all those page_mapped() tests ].
476 * All users of this function must be very careful when walking the anon_vma
477 * chain and verify that the page in question is indeed mapped in it
478 * [ something equivalent to page_mapped_in_vma() ].
480 * Since anon_vma's slab is SLAB_TYPESAFE_BY_RCU and we know from
481 * page_remove_rmap() that the anon_vma pointer from page->mapping is valid
482 * if there is a mapcount, we can dereference the anon_vma after observing
485 struct anon_vma
*page_get_anon_vma(struct page
*page
)
487 struct anon_vma
*anon_vma
= NULL
;
488 unsigned long anon_mapping
;
491 anon_mapping
= (unsigned long)READ_ONCE(page
->mapping
);
492 if ((anon_mapping
& PAGE_MAPPING_FLAGS
) != PAGE_MAPPING_ANON
)
494 if (!page_mapped(page
))
497 anon_vma
= (struct anon_vma
*) (anon_mapping
- PAGE_MAPPING_ANON
);
498 if (!atomic_inc_not_zero(&anon_vma
->refcount
)) {
504 * If this page is still mapped, then its anon_vma cannot have been
505 * freed. But if it has been unmapped, we have no security against the
506 * anon_vma structure being freed and reused (for another anon_vma:
507 * SLAB_TYPESAFE_BY_RCU guarantees that - so the atomic_inc_not_zero()
508 * above cannot corrupt).
510 if (!page_mapped(page
)) {
512 put_anon_vma(anon_vma
);
522 * Similar to page_get_anon_vma() except it locks the anon_vma.
524 * Its a little more complex as it tries to keep the fast path to a single
525 * atomic op -- the trylock. If we fail the trylock, we fall back to getting a
526 * reference like with page_get_anon_vma() and then block on the mutex.
528 struct anon_vma
*page_lock_anon_vma_read(struct page
*page
)
530 struct anon_vma
*anon_vma
= NULL
;
531 struct anon_vma
*root_anon_vma
;
532 unsigned long anon_mapping
;
535 anon_mapping
= (unsigned long)READ_ONCE(page
->mapping
);
536 if ((anon_mapping
& PAGE_MAPPING_FLAGS
) != PAGE_MAPPING_ANON
)
538 if (!page_mapped(page
))
541 anon_vma
= (struct anon_vma
*) (anon_mapping
- PAGE_MAPPING_ANON
);
542 root_anon_vma
= READ_ONCE(anon_vma
->root
);
543 if (down_read_trylock(&root_anon_vma
->rwsem
)) {
545 * If the page is still mapped, then this anon_vma is still
546 * its anon_vma, and holding the mutex ensures that it will
547 * not go away, see anon_vma_free().
549 if (!page_mapped(page
)) {
550 up_read(&root_anon_vma
->rwsem
);
556 /* trylock failed, we got to sleep */
557 if (!atomic_inc_not_zero(&anon_vma
->refcount
)) {
562 if (!page_mapped(page
)) {
564 put_anon_vma(anon_vma
);
568 /* we pinned the anon_vma, its safe to sleep */
570 anon_vma_lock_read(anon_vma
);
572 if (atomic_dec_and_test(&anon_vma
->refcount
)) {
574 * Oops, we held the last refcount, release the lock
575 * and bail -- can't simply use put_anon_vma() because
576 * we'll deadlock on the anon_vma_lock_write() recursion.
578 anon_vma_unlock_read(anon_vma
);
579 __put_anon_vma(anon_vma
);
590 void page_unlock_anon_vma_read(struct anon_vma
*anon_vma
)
592 anon_vma_unlock_read(anon_vma
);
595 #ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
597 * Flush TLB entries for recently unmapped pages from remote CPUs. It is
598 * important if a PTE was dirty when it was unmapped that it's flushed
599 * before any IO is initiated on the page to prevent lost writes. Similarly,
600 * it must be flushed before freeing to prevent data leakage.
602 void try_to_unmap_flush(void)
604 struct tlbflush_unmap_batch
*tlb_ubc
= ¤t
->tlb_ubc
;
606 if (!tlb_ubc
->flush_required
)
609 arch_tlbbatch_flush(&tlb_ubc
->arch
);
610 tlb_ubc
->flush_required
= false;
611 tlb_ubc
->writable
= false;
614 /* Flush iff there are potentially writable TLB entries that can race with IO */
615 void try_to_unmap_flush_dirty(void)
617 struct tlbflush_unmap_batch
*tlb_ubc
= ¤t
->tlb_ubc
;
619 if (tlb_ubc
->writable
)
620 try_to_unmap_flush();
623 static void set_tlb_ubc_flush_pending(struct mm_struct
*mm
, bool writable
)
625 struct tlbflush_unmap_batch
*tlb_ubc
= ¤t
->tlb_ubc
;
627 arch_tlbbatch_add_mm(&tlb_ubc
->arch
, mm
);
628 tlb_ubc
->flush_required
= true;
631 * Ensure compiler does not re-order the setting of tlb_flush_batched
632 * before the PTE is cleared.
635 mm
->tlb_flush_batched
= true;
638 * If the PTE was dirty then it's best to assume it's writable. The
639 * caller must use try_to_unmap_flush_dirty() or try_to_unmap_flush()
640 * before the page is queued for IO.
643 tlb_ubc
->writable
= true;
647 * Returns true if the TLB flush should be deferred to the end of a batch of
648 * unmap operations to reduce IPIs.
650 static bool should_defer_flush(struct mm_struct
*mm
, enum ttu_flags flags
)
652 bool should_defer
= false;
654 if (!(flags
& TTU_BATCH_FLUSH
))
657 /* If remote CPUs need to be flushed then defer batch the flush */
658 if (cpumask_any_but(mm_cpumask(mm
), get_cpu()) < nr_cpu_ids
)
666 * Reclaim unmaps pages under the PTL but do not flush the TLB prior to
667 * releasing the PTL if TLB flushes are batched. It's possible for a parallel
668 * operation such as mprotect or munmap to race between reclaim unmapping
669 * the page and flushing the page. If this race occurs, it potentially allows
670 * access to data via a stale TLB entry. Tracking all mm's that have TLB
671 * batching in flight would be expensive during reclaim so instead track
672 * whether TLB batching occurred in the past and if so then do a flush here
673 * if required. This will cost one additional flush per reclaim cycle paid
674 * by the first operation at risk such as mprotect and mumap.
676 * This must be called under the PTL so that an access to tlb_flush_batched
677 * that is potentially a "reclaim vs mprotect/munmap/etc" race will synchronise
680 void flush_tlb_batched_pending(struct mm_struct
*mm
)
682 if (data_race(mm
->tlb_flush_batched
)) {
686 * Do not allow the compiler to re-order the clearing of
687 * tlb_flush_batched before the tlb is flushed.
690 mm
->tlb_flush_batched
= false;
694 static void set_tlb_ubc_flush_pending(struct mm_struct
*mm
, bool writable
)
698 static bool should_defer_flush(struct mm_struct
*mm
, enum ttu_flags flags
)
702 #endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */
705 * At what user virtual address is page expected in vma?
706 * Caller should check the page is actually part of the vma.
708 unsigned long page_address_in_vma(struct page
*page
, struct vm_area_struct
*vma
)
710 if (PageAnon(page
)) {
711 struct anon_vma
*page__anon_vma
= page_anon_vma(page
);
713 * Note: swapoff's unuse_vma() is more efficient with this
714 * check, and needs it to match anon_vma when KSM is active.
716 if (!vma
->anon_vma
|| !page__anon_vma
||
717 vma
->anon_vma
->root
!= page__anon_vma
->root
)
719 } else if (!vma
->vm_file
) {
721 } else if (vma
->vm_file
->f_mapping
!= compound_head(page
)->mapping
) {
725 return vma_address(page
, vma
);
728 pmd_t
*mm_find_pmd(struct mm_struct
*mm
, unsigned long address
)
736 pgd
= pgd_offset(mm
, address
);
737 if (!pgd_present(*pgd
))
740 p4d
= p4d_offset(pgd
, address
);
741 if (!p4d_present(*p4d
))
744 pud
= pud_offset(p4d
, address
);
745 if (!pud_present(*pud
))
748 pmd
= pmd_offset(pud
, address
);
750 * Some THP functions use the sequence pmdp_huge_clear_flush(), set_pmd_at()
751 * without holding anon_vma lock for write. So when looking for a
752 * genuine pmde (in which to find pte), test present and !THP together.
756 if (!pmd_present(pmde
) || pmd_trans_huge(pmde
))
762 struct page_referenced_arg
{
765 unsigned long vm_flags
;
766 struct mem_cgroup
*memcg
;
769 * arg: page_referenced_arg will be passed
771 static bool page_referenced_one(struct page
*page
, struct vm_area_struct
*vma
,
772 unsigned long address
, void *arg
)
774 struct page_referenced_arg
*pra
= arg
;
775 struct page_vma_mapped_walk pvmw
= {
782 while (page_vma_mapped_walk(&pvmw
)) {
783 address
= pvmw
.address
;
785 if (vma
->vm_flags
& VM_LOCKED
) {
786 page_vma_mapped_walk_done(&pvmw
);
787 pra
->vm_flags
|= VM_LOCKED
;
788 return false; /* To break the loop */
792 if (ptep_clear_flush_young_notify(vma
, address
,
795 * Don't treat a reference through
796 * a sequentially read mapping as such.
797 * If the page has been used in another mapping,
798 * we will catch it; if this other mapping is
799 * already gone, the unmap path will have set
800 * PG_referenced or activated the page.
802 if (likely(!(vma
->vm_flags
& VM_SEQ_READ
)))
805 } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE
)) {
806 if (pmdp_clear_flush_young_notify(vma
, address
,
810 /* unexpected pmd-mapped page? */
818 clear_page_idle(page
);
819 if (test_and_clear_page_young(page
))
824 pra
->vm_flags
|= vma
->vm_flags
;
828 return false; /* To break the loop */
833 static bool invalid_page_referenced_vma(struct vm_area_struct
*vma
, void *arg
)
835 struct page_referenced_arg
*pra
= arg
;
836 struct mem_cgroup
*memcg
= pra
->memcg
;
838 if (!mm_match_cgroup(vma
->vm_mm
, memcg
))
845 * page_referenced - test if the page was referenced
846 * @page: the page to test
847 * @is_locked: caller holds lock on the page
848 * @memcg: target memory cgroup
849 * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
851 * Quick test_and_clear_referenced for all mappings to a page,
852 * returns the number of ptes which referenced the page.
854 int page_referenced(struct page
*page
,
856 struct mem_cgroup
*memcg
,
857 unsigned long *vm_flags
)
860 struct page_referenced_arg pra
= {
861 .mapcount
= total_mapcount(page
),
864 struct rmap_walk_control rwc
= {
865 .rmap_one
= page_referenced_one
,
867 .anon_lock
= page_lock_anon_vma_read
,
874 if (!page_rmapping(page
))
877 if (!is_locked
&& (!PageAnon(page
) || PageKsm(page
))) {
878 we_locked
= trylock_page(page
);
884 * If we are reclaiming on behalf of a cgroup, skip
885 * counting on behalf of references from different
889 rwc
.invalid_vma
= invalid_page_referenced_vma
;
892 rmap_walk(page
, &rwc
);
893 *vm_flags
= pra
.vm_flags
;
898 return pra
.referenced
;
901 static bool page_mkclean_one(struct page
*page
, struct vm_area_struct
*vma
,
902 unsigned long address
, void *arg
)
904 struct page_vma_mapped_walk pvmw
= {
910 struct mmu_notifier_range range
;
914 * We have to assume the worse case ie pmd for invalidation. Note that
915 * the page can not be free from this function.
917 mmu_notifier_range_init(&range
, MMU_NOTIFY_PROTECTION_PAGE
,
918 0, vma
, vma
->vm_mm
, address
,
919 vma_address_end(page
, vma
));
920 mmu_notifier_invalidate_range_start(&range
);
922 while (page_vma_mapped_walk(&pvmw
)) {
925 address
= pvmw
.address
;
928 pte_t
*pte
= pvmw
.pte
;
930 if (!pte_dirty(*pte
) && !pte_write(*pte
))
933 flush_cache_page(vma
, address
, pte_pfn(*pte
));
934 entry
= ptep_clear_flush(vma
, address
, pte
);
935 entry
= pte_wrprotect(entry
);
936 entry
= pte_mkclean(entry
);
937 set_pte_at(vma
->vm_mm
, address
, pte
, entry
);
940 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
941 pmd_t
*pmd
= pvmw
.pmd
;
944 if (!pmd_dirty(*pmd
) && !pmd_write(*pmd
))
947 flush_cache_page(vma
, address
, page_to_pfn(page
));
948 entry
= pmdp_invalidate(vma
, address
, pmd
);
949 entry
= pmd_wrprotect(entry
);
950 entry
= pmd_mkclean(entry
);
951 set_pmd_at(vma
->vm_mm
, address
, pmd
, entry
);
954 /* unexpected pmd-mapped page? */
960 * No need to call mmu_notifier_invalidate_range() as we are
961 * downgrading page table protection not changing it to point
964 * See Documentation/vm/mmu_notifier.rst
970 mmu_notifier_invalidate_range_end(&range
);
975 static bool invalid_mkclean_vma(struct vm_area_struct
*vma
, void *arg
)
977 if (vma
->vm_flags
& VM_SHARED
)
983 int page_mkclean(struct page
*page
)
986 struct address_space
*mapping
;
987 struct rmap_walk_control rwc
= {
988 .arg
= (void *)&cleaned
,
989 .rmap_one
= page_mkclean_one
,
990 .invalid_vma
= invalid_mkclean_vma
,
993 BUG_ON(!PageLocked(page
));
995 if (!page_mapped(page
))
998 mapping
= page_mapping(page
);
1002 rmap_walk(page
, &rwc
);
1006 EXPORT_SYMBOL_GPL(page_mkclean
);
1009 * page_move_anon_rmap - move a page to our anon_vma
1010 * @page: the page to move to our anon_vma
1011 * @vma: the vma the page belongs to
1013 * When a page belongs exclusively to one process after a COW event,
1014 * that page can be moved into the anon_vma that belongs to just that
1015 * process, so the rmap code will not search the parent or sibling
1018 void page_move_anon_rmap(struct page
*page
, struct vm_area_struct
*vma
)
1020 struct anon_vma
*anon_vma
= vma
->anon_vma
;
1022 page
= compound_head(page
);
1024 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1025 VM_BUG_ON_VMA(!anon_vma
, vma
);
1027 anon_vma
= (void *) anon_vma
+ PAGE_MAPPING_ANON
;
1029 * Ensure that anon_vma and the PAGE_MAPPING_ANON bit are written
1030 * simultaneously, so a concurrent reader (eg page_referenced()'s
1031 * PageAnon()) will not see one without the other.
1033 WRITE_ONCE(page
->mapping
, (struct address_space
*) anon_vma
);
1037 * __page_set_anon_rmap - set up new anonymous rmap
1038 * @page: Page or Hugepage to add to rmap
1039 * @vma: VM area to add page to.
1040 * @address: User virtual address of the mapping
1041 * @exclusive: the page is exclusively owned by the current process
1043 static void __page_set_anon_rmap(struct page
*page
,
1044 struct vm_area_struct
*vma
, unsigned long address
, int exclusive
)
1046 struct anon_vma
*anon_vma
= vma
->anon_vma
;
1054 * If the page isn't exclusively mapped into this vma,
1055 * we must use the _oldest_ possible anon_vma for the
1059 anon_vma
= anon_vma
->root
;
1062 * page_idle does a lockless/optimistic rmap scan on page->mapping.
1063 * Make sure the compiler doesn't split the stores of anon_vma and
1064 * the PAGE_MAPPING_ANON type identifier, otherwise the rmap code
1065 * could mistake the mapping for a struct address_space and crash.
1067 anon_vma
= (void *) anon_vma
+ PAGE_MAPPING_ANON
;
1068 WRITE_ONCE(page
->mapping
, (struct address_space
*) anon_vma
);
1069 page
->index
= linear_page_index(vma
, address
);
1073 * __page_check_anon_rmap - sanity check anonymous rmap addition
1074 * @page: the page to add the mapping to
1075 * @vma: the vm area in which the mapping is added
1076 * @address: the user virtual address mapped
1078 static void __page_check_anon_rmap(struct page
*page
,
1079 struct vm_area_struct
*vma
, unsigned long address
)
1082 * The page's anon-rmap details (mapping and index) are guaranteed to
1083 * be set up correctly at this point.
1085 * We have exclusion against page_add_anon_rmap because the caller
1086 * always holds the page locked.
1088 * We have exclusion against page_add_new_anon_rmap because those pages
1089 * are initially only visible via the pagetables, and the pte is locked
1090 * over the call to page_add_new_anon_rmap.
1092 VM_BUG_ON_PAGE(page_anon_vma(page
)->root
!= vma
->anon_vma
->root
, page
);
1093 VM_BUG_ON_PAGE(page_to_pgoff(page
) != linear_page_index(vma
, address
),
1098 * page_add_anon_rmap - add pte mapping to an anonymous page
1099 * @page: the page to add the mapping to
1100 * @vma: the vm area in which the mapping is added
1101 * @address: the user virtual address mapped
1102 * @compound: charge the page as compound or small page
1104 * The caller needs to hold the pte lock, and the page must be locked in
1105 * the anon_vma case: to serialize mapping,index checking after setting,
1106 * and to ensure that PageAnon is not being upgraded racily to PageKsm
1107 * (but PageKsm is never downgraded to PageAnon).
1109 void page_add_anon_rmap(struct page
*page
,
1110 struct vm_area_struct
*vma
, unsigned long address
, bool compound
)
1112 do_page_add_anon_rmap(page
, vma
, address
, compound
? RMAP_COMPOUND
: 0);
1116 * Special version of the above for do_swap_page, which often runs
1117 * into pages that are exclusively owned by the current process.
1118 * Everybody else should continue to use page_add_anon_rmap above.
1120 void do_page_add_anon_rmap(struct page
*page
,
1121 struct vm_area_struct
*vma
, unsigned long address
, int flags
)
1123 bool compound
= flags
& RMAP_COMPOUND
;
1126 if (unlikely(PageKsm(page
)))
1127 lock_page_memcg(page
);
1129 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1133 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1134 VM_BUG_ON_PAGE(!PageTransHuge(page
), page
);
1135 mapcount
= compound_mapcount_ptr(page
);
1136 first
= atomic_inc_and_test(mapcount
);
1138 first
= atomic_inc_and_test(&page
->_mapcount
);
1142 int nr
= compound
? thp_nr_pages(page
) : 1;
1144 * We use the irq-unsafe __{inc|mod}_zone_page_stat because
1145 * these counters are not modified in interrupt context, and
1146 * pte lock(a spinlock) is held, which implies preemption
1150 __mod_lruvec_page_state(page
, NR_ANON_THPS
, nr
);
1151 __mod_lruvec_page_state(page
, NR_ANON_MAPPED
, nr
);
1154 if (unlikely(PageKsm(page
))) {
1155 unlock_page_memcg(page
);
1159 /* address might be in next vma when migration races vma_adjust */
1161 __page_set_anon_rmap(page
, vma
, address
,
1162 flags
& RMAP_EXCLUSIVE
);
1164 __page_check_anon_rmap(page
, vma
, address
);
1168 * page_add_new_anon_rmap - add pte mapping to a new anonymous page
1169 * @page: the page to add the mapping to
1170 * @vma: the vm area in which the mapping is added
1171 * @address: the user virtual address mapped
1172 * @compound: charge the page as compound or small page
1174 * Same as page_add_anon_rmap but must only be called on *new* pages.
1175 * This means the inc-and-test can be bypassed.
1176 * Page does not have to be locked.
1178 void page_add_new_anon_rmap(struct page
*page
,
1179 struct vm_area_struct
*vma
, unsigned long address
, bool compound
)
1181 int nr
= compound
? thp_nr_pages(page
) : 1;
1183 VM_BUG_ON_VMA(address
< vma
->vm_start
|| address
>= vma
->vm_end
, vma
);
1184 __SetPageSwapBacked(page
);
1186 VM_BUG_ON_PAGE(!PageTransHuge(page
), page
);
1187 /* increment count (starts at -1) */
1188 atomic_set(compound_mapcount_ptr(page
), 0);
1189 if (hpage_pincount_available(page
))
1190 atomic_set(compound_pincount_ptr(page
), 0);
1192 __mod_lruvec_page_state(page
, NR_ANON_THPS
, nr
);
1194 /* Anon THP always mapped first with PMD */
1195 VM_BUG_ON_PAGE(PageTransCompound(page
), page
);
1196 /* increment count (starts at -1) */
1197 atomic_set(&page
->_mapcount
, 0);
1199 __mod_lruvec_page_state(page
, NR_ANON_MAPPED
, nr
);
1200 __page_set_anon_rmap(page
, vma
, address
, 1);
1204 * page_add_file_rmap - add pte mapping to a file page
1205 * @page: the page to add the mapping to
1206 * @compound: charge the page as compound or small page
1208 * The caller needs to hold the pte lock.
1210 void page_add_file_rmap(struct page
*page
, bool compound
)
1214 VM_BUG_ON_PAGE(compound
&& !PageTransHuge(page
), page
);
1215 lock_page_memcg(page
);
1216 if (compound
&& PageTransHuge(page
)) {
1217 int nr_pages
= thp_nr_pages(page
);
1219 for (i
= 0, nr
= 0; i
< nr_pages
; i
++) {
1220 if (atomic_inc_and_test(&page
[i
]._mapcount
))
1223 if (!atomic_inc_and_test(compound_mapcount_ptr(page
)))
1225 if (PageSwapBacked(page
))
1226 __mod_lruvec_page_state(page
, NR_SHMEM_PMDMAPPED
,
1229 __mod_lruvec_page_state(page
, NR_FILE_PMDMAPPED
,
1232 if (PageTransCompound(page
) && page_mapping(page
)) {
1233 VM_WARN_ON_ONCE(!PageLocked(page
));
1235 SetPageDoubleMap(compound_head(page
));
1236 if (PageMlocked(page
))
1237 clear_page_mlock(compound_head(page
));
1239 if (!atomic_inc_and_test(&page
->_mapcount
))
1242 __mod_lruvec_page_state(page
, NR_FILE_MAPPED
, nr
);
1244 unlock_page_memcg(page
);
1247 static void page_remove_file_rmap(struct page
*page
, bool compound
)
1251 VM_BUG_ON_PAGE(compound
&& !PageHead(page
), page
);
1253 /* Hugepages are not counted in NR_FILE_MAPPED for now. */
1254 if (unlikely(PageHuge(page
))) {
1255 /* hugetlb pages are always mapped with pmds */
1256 atomic_dec(compound_mapcount_ptr(page
));
1260 /* page still mapped by someone else? */
1261 if (compound
&& PageTransHuge(page
)) {
1262 int nr_pages
= thp_nr_pages(page
);
1264 for (i
= 0, nr
= 0; i
< nr_pages
; i
++) {
1265 if (atomic_add_negative(-1, &page
[i
]._mapcount
))
1268 if (!atomic_add_negative(-1, compound_mapcount_ptr(page
)))
1270 if (PageSwapBacked(page
))
1271 __mod_lruvec_page_state(page
, NR_SHMEM_PMDMAPPED
,
1274 __mod_lruvec_page_state(page
, NR_FILE_PMDMAPPED
,
1277 if (!atomic_add_negative(-1, &page
->_mapcount
))
1282 * We use the irq-unsafe __{inc|mod}_lruvec_page_state because
1283 * these counters are not modified in interrupt context, and
1284 * pte lock(a spinlock) is held, which implies preemption disabled.
1286 __mod_lruvec_page_state(page
, NR_FILE_MAPPED
, -nr
);
1288 if (unlikely(PageMlocked(page
)))
1289 clear_page_mlock(page
);
1292 static void page_remove_anon_compound_rmap(struct page
*page
)
1296 if (!atomic_add_negative(-1, compound_mapcount_ptr(page
)))
1299 /* Hugepages are not counted in NR_ANON_PAGES for now. */
1300 if (unlikely(PageHuge(page
)))
1303 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE
))
1306 __mod_lruvec_page_state(page
, NR_ANON_THPS
, -thp_nr_pages(page
));
1308 if (TestClearPageDoubleMap(page
)) {
1310 * Subpages can be mapped with PTEs too. Check how many of
1311 * them are still mapped.
1313 for (i
= 0, nr
= 0; i
< thp_nr_pages(page
); i
++) {
1314 if (atomic_add_negative(-1, &page
[i
]._mapcount
))
1319 * Queue the page for deferred split if at least one small
1320 * page of the compound page is unmapped, but at least one
1321 * small page is still mapped.
1323 if (nr
&& nr
< thp_nr_pages(page
))
1324 deferred_split_huge_page(page
);
1326 nr
= thp_nr_pages(page
);
1329 if (unlikely(PageMlocked(page
)))
1330 clear_page_mlock(page
);
1333 __mod_lruvec_page_state(page
, NR_ANON_MAPPED
, -nr
);
1337 * page_remove_rmap - take down pte mapping from a page
1338 * @page: page to remove mapping from
1339 * @compound: uncharge the page as compound or small page
1341 * The caller needs to hold the pte lock.
1343 void page_remove_rmap(struct page
*page
, bool compound
)
1345 lock_page_memcg(page
);
1347 if (!PageAnon(page
)) {
1348 page_remove_file_rmap(page
, compound
);
1353 page_remove_anon_compound_rmap(page
);
1357 /* page still mapped by someone else? */
1358 if (!atomic_add_negative(-1, &page
->_mapcount
))
1362 * We use the irq-unsafe __{inc|mod}_zone_page_stat because
1363 * these counters are not modified in interrupt context, and
1364 * pte lock(a spinlock) is held, which implies preemption disabled.
1366 __dec_lruvec_page_state(page
, NR_ANON_MAPPED
);
1368 if (unlikely(PageMlocked(page
)))
1369 clear_page_mlock(page
);
1371 if (PageTransCompound(page
))
1372 deferred_split_huge_page(compound_head(page
));
1375 * It would be tidy to reset the PageAnon mapping here,
1376 * but that might overwrite a racing page_add_anon_rmap
1377 * which increments mapcount after us but sets mapping
1378 * before us: so leave the reset to free_unref_page,
1379 * and remember that it's only reliable while mapped.
1380 * Leaving it set also helps swapoff to reinstate ptes
1381 * faster for those pages still in swapcache.
1384 unlock_page_memcg(page
);
1388 * @arg: enum ttu_flags will be passed to this argument
1390 static bool try_to_unmap_one(struct page
*page
, struct vm_area_struct
*vma
,
1391 unsigned long address
, void *arg
)
1393 struct mm_struct
*mm
= vma
->vm_mm
;
1394 struct page_vma_mapped_walk pvmw
= {
1400 struct page
*subpage
;
1402 struct mmu_notifier_range range
;
1403 enum ttu_flags flags
= (enum ttu_flags
)(long)arg
;
1406 * When racing against e.g. zap_pte_range() on another cpu,
1407 * in between its ptep_get_and_clear_full() and page_remove_rmap(),
1408 * try_to_unmap() may return before page_mapped() has become false,
1409 * if page table locking is skipped: use TTU_SYNC to wait for that.
1411 if (flags
& TTU_SYNC
)
1412 pvmw
.flags
= PVMW_SYNC
;
1414 if (flags
& TTU_SPLIT_HUGE_PMD
)
1415 split_huge_pmd_address(vma
, address
, false, page
);
1418 * For THP, we have to assume the worse case ie pmd for invalidation.
1419 * For hugetlb, it could be much worse if we need to do pud
1420 * invalidation in the case of pmd sharing.
1422 * Note that the page can not be free in this function as call of
1423 * try_to_unmap() must hold a reference on the page.
1425 range
.end
= PageKsm(page
) ?
1426 address
+ PAGE_SIZE
: vma_address_end(page
, vma
);
1427 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, vma
, vma
->vm_mm
,
1428 address
, range
.end
);
1429 if (PageHuge(page
)) {
1431 * If sharing is possible, start and end will be adjusted
1434 adjust_range_if_pmd_sharing_possible(vma
, &range
.start
,
1437 mmu_notifier_invalidate_range_start(&range
);
1439 while (page_vma_mapped_walk(&pvmw
)) {
1441 * If the page is mlock()d, we cannot swap it out.
1443 if (!(flags
& TTU_IGNORE_MLOCK
) &&
1444 (vma
->vm_flags
& VM_LOCKED
)) {
1446 * PTE-mapped THP are never marked as mlocked: so do
1447 * not set it on a DoubleMap THP, nor on an Anon THP
1448 * (which may still be PTE-mapped after DoubleMap was
1449 * cleared). But stop unmapping even in those cases.
1451 if (!PageTransCompound(page
) || (PageHead(page
) &&
1452 !PageDoubleMap(page
) && !PageAnon(page
)))
1453 mlock_vma_page(page
);
1454 page_vma_mapped_walk_done(&pvmw
);
1459 /* Unexpected PMD-mapped THP? */
1460 VM_BUG_ON_PAGE(!pvmw
.pte
, page
);
1462 subpage
= page
- page_to_pfn(page
) + pte_pfn(*pvmw
.pte
);
1463 address
= pvmw
.address
;
1465 if (PageHuge(page
) && !PageAnon(page
)) {
1467 * To call huge_pmd_unshare, i_mmap_rwsem must be
1468 * held in write mode. Caller needs to explicitly
1469 * do this outside rmap routines.
1471 VM_BUG_ON(!(flags
& TTU_RMAP_LOCKED
));
1472 if (huge_pmd_unshare(mm
, vma
, &address
, pvmw
.pte
)) {
1474 * huge_pmd_unshare unmapped an entire PMD
1475 * page. There is no way of knowing exactly
1476 * which PMDs may be cached for this mm, so
1477 * we must flush them all. start/end were
1478 * already adjusted above to cover this range.
1480 flush_cache_range(vma
, range
.start
, range
.end
);
1481 flush_tlb_range(vma
, range
.start
, range
.end
);
1482 mmu_notifier_invalidate_range(mm
, range
.start
,
1486 * The ref count of the PMD page was dropped
1487 * which is part of the way map counting
1488 * is done for shared PMDs. Return 'true'
1489 * here. When there is no other sharing,
1490 * huge_pmd_unshare returns false and we will
1491 * unmap the actual page and drop map count
1494 page_vma_mapped_walk_done(&pvmw
);
1499 /* Nuke the page table entry. */
1500 flush_cache_page(vma
, address
, pte_pfn(*pvmw
.pte
));
1501 if (should_defer_flush(mm
, flags
)) {
1503 * We clear the PTE but do not flush so potentially
1504 * a remote CPU could still be writing to the page.
1505 * If the entry was previously clean then the
1506 * architecture must guarantee that a clear->dirty
1507 * transition on a cached TLB entry is written through
1508 * and traps if the PTE is unmapped.
1510 pteval
= ptep_get_and_clear(mm
, address
, pvmw
.pte
);
1512 set_tlb_ubc_flush_pending(mm
, pte_dirty(pteval
));
1514 pteval
= ptep_clear_flush(vma
, address
, pvmw
.pte
);
1517 /* Move the dirty bit to the page. Now the pte is gone. */
1518 if (pte_dirty(pteval
))
1519 set_page_dirty(page
);
1521 /* Update high watermark before we lower rss */
1522 update_hiwater_rss(mm
);
1524 if (PageHWPoison(page
) && !(flags
& TTU_IGNORE_HWPOISON
)) {
1525 pteval
= swp_entry_to_pte(make_hwpoison_entry(subpage
));
1526 if (PageHuge(page
)) {
1527 hugetlb_count_sub(compound_nr(page
), mm
);
1528 set_huge_swap_pte_at(mm
, address
,
1530 vma_mmu_pagesize(vma
));
1532 dec_mm_counter(mm
, mm_counter(page
));
1533 set_pte_at(mm
, address
, pvmw
.pte
, pteval
);
1536 } else if (pte_unused(pteval
) && !userfaultfd_armed(vma
)) {
1538 * The guest indicated that the page content is of no
1539 * interest anymore. Simply discard the pte, vmscan
1540 * will take care of the rest.
1541 * A future reference will then fault in a new zero
1542 * page. When userfaultfd is active, we must not drop
1543 * this page though, as its main user (postcopy
1544 * migration) will not expect userfaults on already
1547 dec_mm_counter(mm
, mm_counter(page
));
1548 /* We have to invalidate as we cleared the pte */
1549 mmu_notifier_invalidate_range(mm
, address
,
1550 address
+ PAGE_SIZE
);
1551 } else if (PageAnon(page
)) {
1552 swp_entry_t entry
= { .val
= page_private(subpage
) };
1555 * Store the swap location in the pte.
1556 * See handle_pte_fault() ...
1558 if (unlikely(PageSwapBacked(page
) != PageSwapCache(page
))) {
1561 /* We have to invalidate as we cleared the pte */
1562 mmu_notifier_invalidate_range(mm
, address
,
1563 address
+ PAGE_SIZE
);
1564 page_vma_mapped_walk_done(&pvmw
);
1568 /* MADV_FREE page check */
1569 if (!PageSwapBacked(page
)) {
1570 if (!PageDirty(page
)) {
1571 /* Invalidate as we cleared the pte */
1572 mmu_notifier_invalidate_range(mm
,
1573 address
, address
+ PAGE_SIZE
);
1574 dec_mm_counter(mm
, MM_ANONPAGES
);
1579 * If the page was redirtied, it cannot be
1580 * discarded. Remap the page to page table.
1582 set_pte_at(mm
, address
, pvmw
.pte
, pteval
);
1583 SetPageSwapBacked(page
);
1585 page_vma_mapped_walk_done(&pvmw
);
1589 if (swap_duplicate(entry
) < 0) {
1590 set_pte_at(mm
, address
, pvmw
.pte
, pteval
);
1592 page_vma_mapped_walk_done(&pvmw
);
1595 if (arch_unmap_one(mm
, vma
, address
, pteval
) < 0) {
1596 set_pte_at(mm
, address
, pvmw
.pte
, pteval
);
1598 page_vma_mapped_walk_done(&pvmw
);
1601 if (list_empty(&mm
->mmlist
)) {
1602 spin_lock(&mmlist_lock
);
1603 if (list_empty(&mm
->mmlist
))
1604 list_add(&mm
->mmlist
, &init_mm
.mmlist
);
1605 spin_unlock(&mmlist_lock
);
1607 dec_mm_counter(mm
, MM_ANONPAGES
);
1608 inc_mm_counter(mm
, MM_SWAPENTS
);
1609 swp_pte
= swp_entry_to_pte(entry
);
1610 if (pte_soft_dirty(pteval
))
1611 swp_pte
= pte_swp_mksoft_dirty(swp_pte
);
1612 if (pte_uffd_wp(pteval
))
1613 swp_pte
= pte_swp_mkuffd_wp(swp_pte
);
1614 set_pte_at(mm
, address
, pvmw
.pte
, swp_pte
);
1615 /* Invalidate as we cleared the pte */
1616 mmu_notifier_invalidate_range(mm
, address
,
1617 address
+ PAGE_SIZE
);
1620 * This is a locked file-backed page, thus it cannot
1621 * be removed from the page cache and replaced by a new
1622 * page before mmu_notifier_invalidate_range_end, so no
1623 * concurrent thread might update its page table to
1624 * point at new page while a device still is using this
1627 * See Documentation/vm/mmu_notifier.rst
1629 dec_mm_counter(mm
, mm_counter_file(page
));
1633 * No need to call mmu_notifier_invalidate_range() it has be
1634 * done above for all cases requiring it to happen under page
1635 * table lock before mmu_notifier_invalidate_range_end()
1637 * See Documentation/vm/mmu_notifier.rst
1639 page_remove_rmap(subpage
, PageHuge(page
));
1643 mmu_notifier_invalidate_range_end(&range
);
1648 static bool invalid_migration_vma(struct vm_area_struct
*vma
, void *arg
)
1650 return vma_is_temporary_stack(vma
);
1653 static int page_not_mapped(struct page
*page
)
1655 return !page_mapped(page
);
1659 * try_to_unmap - try to remove all page table mappings to a page
1660 * @page: the page to get unmapped
1661 * @flags: action and flags
1663 * Tries to remove all the page table entries which are mapping this
1664 * page, used in the pageout path. Caller must hold the page lock.
1666 * It is the caller's responsibility to check if the page is still
1667 * mapped when needed (use TTU_SYNC to prevent accounting races).
1669 void try_to_unmap(struct page
*page
, enum ttu_flags flags
)
1671 struct rmap_walk_control rwc
= {
1672 .rmap_one
= try_to_unmap_one
,
1673 .arg
= (void *)flags
,
1674 .done
= page_not_mapped
,
1675 .anon_lock
= page_lock_anon_vma_read
,
1678 if (flags
& TTU_RMAP_LOCKED
)
1679 rmap_walk_locked(page
, &rwc
);
1681 rmap_walk(page
, &rwc
);
1685 * @arg: enum ttu_flags will be passed to this argument.
1687 * If TTU_SPLIT_HUGE_PMD is specified any PMD mappings will be split into PTEs
1688 * containing migration entries.
1690 static bool try_to_migrate_one(struct page
*page
, struct vm_area_struct
*vma
,
1691 unsigned long address
, void *arg
)
1693 struct mm_struct
*mm
= vma
->vm_mm
;
1694 struct page_vma_mapped_walk pvmw
= {
1700 struct page
*subpage
;
1702 struct mmu_notifier_range range
;
1703 enum ttu_flags flags
= (enum ttu_flags
)(long)arg
;
1706 * When racing against e.g. zap_pte_range() on another cpu,
1707 * in between its ptep_get_and_clear_full() and page_remove_rmap(),
1708 * try_to_migrate() may return before page_mapped() has become false,
1709 * if page table locking is skipped: use TTU_SYNC to wait for that.
1711 if (flags
& TTU_SYNC
)
1712 pvmw
.flags
= PVMW_SYNC
;
1715 * unmap_page() in mm/huge_memory.c is the only user of migration with
1716 * TTU_SPLIT_HUGE_PMD and it wants to freeze.
1718 if (flags
& TTU_SPLIT_HUGE_PMD
)
1719 split_huge_pmd_address(vma
, address
, true, page
);
1722 * For THP, we have to assume the worse case ie pmd for invalidation.
1723 * For hugetlb, it could be much worse if we need to do pud
1724 * invalidation in the case of pmd sharing.
1726 * Note that the page can not be free in this function as call of
1727 * try_to_unmap() must hold a reference on the page.
1729 range
.end
= PageKsm(page
) ?
1730 address
+ PAGE_SIZE
: vma_address_end(page
, vma
);
1731 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, vma
, vma
->vm_mm
,
1732 address
, range
.end
);
1733 if (PageHuge(page
)) {
1735 * If sharing is possible, start and end will be adjusted
1738 adjust_range_if_pmd_sharing_possible(vma
, &range
.start
,
1741 mmu_notifier_invalidate_range_start(&range
);
1743 while (page_vma_mapped_walk(&pvmw
)) {
1744 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1745 /* PMD-mapped THP migration entry */
1747 VM_BUG_ON_PAGE(PageHuge(page
) ||
1748 !PageTransCompound(page
), page
);
1750 set_pmd_migration_entry(&pvmw
, page
);
1755 /* Unexpected PMD-mapped THP? */
1756 VM_BUG_ON_PAGE(!pvmw
.pte
, page
);
1758 subpage
= page
- page_to_pfn(page
) + pte_pfn(*pvmw
.pte
);
1759 address
= pvmw
.address
;
1761 if (PageHuge(page
) && !PageAnon(page
)) {
1763 * To call huge_pmd_unshare, i_mmap_rwsem must be
1764 * held in write mode. Caller needs to explicitly
1765 * do this outside rmap routines.
1767 VM_BUG_ON(!(flags
& TTU_RMAP_LOCKED
));
1768 if (huge_pmd_unshare(mm
, vma
, &address
, pvmw
.pte
)) {
1770 * huge_pmd_unshare unmapped an entire PMD
1771 * page. There is no way of knowing exactly
1772 * which PMDs may be cached for this mm, so
1773 * we must flush them all. start/end were
1774 * already adjusted above to cover this range.
1776 flush_cache_range(vma
, range
.start
, range
.end
);
1777 flush_tlb_range(vma
, range
.start
, range
.end
);
1778 mmu_notifier_invalidate_range(mm
, range
.start
,
1782 * The ref count of the PMD page was dropped
1783 * which is part of the way map counting
1784 * is done for shared PMDs. Return 'true'
1785 * here. When there is no other sharing,
1786 * huge_pmd_unshare returns false and we will
1787 * unmap the actual page and drop map count
1790 page_vma_mapped_walk_done(&pvmw
);
1795 /* Nuke the page table entry. */
1796 flush_cache_page(vma
, address
, pte_pfn(*pvmw
.pte
));
1797 pteval
= ptep_clear_flush(vma
, address
, pvmw
.pte
);
1799 /* Move the dirty bit to the page. Now the pte is gone. */
1800 if (pte_dirty(pteval
))
1801 set_page_dirty(page
);
1803 /* Update high watermark before we lower rss */
1804 update_hiwater_rss(mm
);
1806 if (is_zone_device_page(page
)) {
1811 * Store the pfn of the page in a special migration
1812 * pte. do_swap_page() will wait until the migration
1813 * pte is removed and then restart fault handling.
1815 entry
= make_readable_migration_entry(
1817 swp_pte
= swp_entry_to_pte(entry
);
1820 * pteval maps a zone device page and is therefore
1823 if (pte_swp_soft_dirty(pteval
))
1824 swp_pte
= pte_swp_mksoft_dirty(swp_pte
);
1825 if (pte_swp_uffd_wp(pteval
))
1826 swp_pte
= pte_swp_mkuffd_wp(swp_pte
);
1827 set_pte_at(mm
, pvmw
.address
, pvmw
.pte
, swp_pte
);
1829 * No need to invalidate here it will synchronize on
1830 * against the special swap migration pte.
1832 * The assignment to subpage above was computed from a
1833 * swap PTE which results in an invalid pointer.
1834 * Since only PAGE_SIZE pages can currently be
1835 * migrated, just set it to page. This will need to be
1836 * changed when hugepage migrations to device private
1837 * memory are supported.
1840 } else if (PageHWPoison(page
)) {
1841 pteval
= swp_entry_to_pte(make_hwpoison_entry(subpage
));
1842 if (PageHuge(page
)) {
1843 hugetlb_count_sub(compound_nr(page
), mm
);
1844 set_huge_swap_pte_at(mm
, address
,
1846 vma_mmu_pagesize(vma
));
1848 dec_mm_counter(mm
, mm_counter(page
));
1849 set_pte_at(mm
, address
, pvmw
.pte
, pteval
);
1852 } else if (pte_unused(pteval
) && !userfaultfd_armed(vma
)) {
1854 * The guest indicated that the page content is of no
1855 * interest anymore. Simply discard the pte, vmscan
1856 * will take care of the rest.
1857 * A future reference will then fault in a new zero
1858 * page. When userfaultfd is active, we must not drop
1859 * this page though, as its main user (postcopy
1860 * migration) will not expect userfaults on already
1863 dec_mm_counter(mm
, mm_counter(page
));
1864 /* We have to invalidate as we cleared the pte */
1865 mmu_notifier_invalidate_range(mm
, address
,
1866 address
+ PAGE_SIZE
);
1871 if (arch_unmap_one(mm
, vma
, address
, pteval
) < 0) {
1872 set_pte_at(mm
, address
, pvmw
.pte
, pteval
);
1874 page_vma_mapped_walk_done(&pvmw
);
1879 * Store the pfn of the page in a special migration
1880 * pte. do_swap_page() will wait until the migration
1881 * pte is removed and then restart fault handling.
1883 if (pte_write(pteval
))
1884 entry
= make_writable_migration_entry(
1885 page_to_pfn(subpage
));
1887 entry
= make_readable_migration_entry(
1888 page_to_pfn(subpage
));
1890 swp_pte
= swp_entry_to_pte(entry
);
1891 if (pte_soft_dirty(pteval
))
1892 swp_pte
= pte_swp_mksoft_dirty(swp_pte
);
1893 if (pte_uffd_wp(pteval
))
1894 swp_pte
= pte_swp_mkuffd_wp(swp_pte
);
1895 set_pte_at(mm
, address
, pvmw
.pte
, swp_pte
);
1897 * No need to invalidate here it will synchronize on
1898 * against the special swap migration pte.
1903 * No need to call mmu_notifier_invalidate_range() it has be
1904 * done above for all cases requiring it to happen under page
1905 * table lock before mmu_notifier_invalidate_range_end()
1907 * See Documentation/vm/mmu_notifier.rst
1909 page_remove_rmap(subpage
, PageHuge(page
));
1913 mmu_notifier_invalidate_range_end(&range
);
1919 * try_to_migrate - try to replace all page table mappings with swap entries
1920 * @page: the page to replace page table entries for
1921 * @flags: action and flags
1923 * Tries to remove all the page table entries which are mapping this page and
1924 * replace them with special swap entries. Caller must hold the page lock.
1926 void try_to_migrate(struct page
*page
, enum ttu_flags flags
)
1928 struct rmap_walk_control rwc
= {
1929 .rmap_one
= try_to_migrate_one
,
1930 .arg
= (void *)flags
,
1931 .done
= page_not_mapped
,
1932 .anon_lock
= page_lock_anon_vma_read
,
1936 * Migration always ignores mlock and only supports TTU_RMAP_LOCKED and
1937 * TTU_SPLIT_HUGE_PMD and TTU_SYNC flags.
1939 if (WARN_ON_ONCE(flags
& ~(TTU_RMAP_LOCKED
| TTU_SPLIT_HUGE_PMD
|
1943 if (is_zone_device_page(page
) && !is_device_private_page(page
))
1947 * During exec, a temporary VMA is setup and later moved.
1948 * The VMA is moved under the anon_vma lock but not the
1949 * page tables leading to a race where migration cannot
1950 * find the migration ptes. Rather than increasing the
1951 * locking requirements of exec(), migration skips
1952 * temporary VMAs until after exec() completes.
1954 if (!PageKsm(page
) && PageAnon(page
))
1955 rwc
.invalid_vma
= invalid_migration_vma
;
1957 if (flags
& TTU_RMAP_LOCKED
)
1958 rmap_walk_locked(page
, &rwc
);
1960 rmap_walk(page
, &rwc
);
1964 * Walks the vma's mapping a page and mlocks the page if any locked vma's are
1965 * found. Once one is found the page is locked and the scan can be terminated.
1967 static bool page_mlock_one(struct page
*page
, struct vm_area_struct
*vma
,
1968 unsigned long address
, void *unused
)
1970 struct page_vma_mapped_walk pvmw
= {
1976 /* An un-locked vma doesn't have any pages to lock, continue the scan */
1977 if (!(vma
->vm_flags
& VM_LOCKED
))
1980 while (page_vma_mapped_walk(&pvmw
)) {
1982 * Need to recheck under the ptl to serialise with
1983 * __munlock_pagevec_fill() after VM_LOCKED is cleared in
1984 * munlock_vma_pages_range().
1986 if (vma
->vm_flags
& VM_LOCKED
) {
1988 * PTE-mapped THP are never marked as mlocked; but
1989 * this function is never called on a DoubleMap THP,
1990 * nor on an Anon THP (which may still be PTE-mapped
1991 * after DoubleMap was cleared).
1993 mlock_vma_page(page
);
1995 * No need to scan further once the page is marked
1998 page_vma_mapped_walk_done(&pvmw
);
2007 * page_mlock - try to mlock a page
2008 * @page: the page to be mlocked
2010 * Called from munlock code. Checks all of the VMAs mapping the page and mlocks
2011 * the page if any are found. The page will be returned with PG_mlocked cleared
2012 * if it is not mapped by any locked vmas.
2014 void page_mlock(struct page
*page
)
2016 struct rmap_walk_control rwc
= {
2017 .rmap_one
= page_mlock_one
,
2018 .done
= page_not_mapped
,
2019 .anon_lock
= page_lock_anon_vma_read
,
2023 VM_BUG_ON_PAGE(!PageLocked(page
) || PageLRU(page
), page
);
2024 VM_BUG_ON_PAGE(PageCompound(page
) && PageDoubleMap(page
), page
);
2026 /* Anon THP are only marked as mlocked when singly mapped */
2027 if (PageTransCompound(page
) && PageAnon(page
))
2030 rmap_walk(page
, &rwc
);
2033 #ifdef CONFIG_DEVICE_PRIVATE
2034 struct make_exclusive_args
{
2035 struct mm_struct
*mm
;
2036 unsigned long address
;
2041 static bool page_make_device_exclusive_one(struct page
*page
,
2042 struct vm_area_struct
*vma
, unsigned long address
, void *priv
)
2044 struct mm_struct
*mm
= vma
->vm_mm
;
2045 struct page_vma_mapped_walk pvmw
= {
2050 struct make_exclusive_args
*args
= priv
;
2052 struct page
*subpage
;
2054 struct mmu_notifier_range range
;
2058 mmu_notifier_range_init_owner(&range
, MMU_NOTIFY_EXCLUSIVE
, 0, vma
,
2059 vma
->vm_mm
, address
, min(vma
->vm_end
,
2060 address
+ page_size(page
)), args
->owner
);
2061 mmu_notifier_invalidate_range_start(&range
);
2063 while (page_vma_mapped_walk(&pvmw
)) {
2064 /* Unexpected PMD-mapped THP? */
2065 VM_BUG_ON_PAGE(!pvmw
.pte
, page
);
2067 if (!pte_present(*pvmw
.pte
)) {
2069 page_vma_mapped_walk_done(&pvmw
);
2073 subpage
= page
- page_to_pfn(page
) + pte_pfn(*pvmw
.pte
);
2074 address
= pvmw
.address
;
2076 /* Nuke the page table entry. */
2077 flush_cache_page(vma
, address
, pte_pfn(*pvmw
.pte
));
2078 pteval
= ptep_clear_flush(vma
, address
, pvmw
.pte
);
2080 /* Move the dirty bit to the page. Now the pte is gone. */
2081 if (pte_dirty(pteval
))
2082 set_page_dirty(page
);
2085 * Check that our target page is still mapped at the expected
2088 if (args
->mm
== mm
&& args
->address
== address
&&
2093 * Store the pfn of the page in a special migration
2094 * pte. do_swap_page() will wait until the migration
2095 * pte is removed and then restart fault handling.
2097 if (pte_write(pteval
))
2098 entry
= make_writable_device_exclusive_entry(
2099 page_to_pfn(subpage
));
2101 entry
= make_readable_device_exclusive_entry(
2102 page_to_pfn(subpage
));
2103 swp_pte
= swp_entry_to_pte(entry
);
2104 if (pte_soft_dirty(pteval
))
2105 swp_pte
= pte_swp_mksoft_dirty(swp_pte
);
2106 if (pte_uffd_wp(pteval
))
2107 swp_pte
= pte_swp_mkuffd_wp(swp_pte
);
2109 set_pte_at(mm
, address
, pvmw
.pte
, swp_pte
);
2112 * There is a reference on the page for the swap entry which has
2113 * been removed, so shouldn't take another.
2115 page_remove_rmap(subpage
, false);
2118 mmu_notifier_invalidate_range_end(&range
);
2124 * page_make_device_exclusive - mark the page exclusively owned by a device
2125 * @page: the page to replace page table entries for
2126 * @mm: the mm_struct where the page is expected to be mapped
2127 * @address: address where the page is expected to be mapped
2128 * @owner: passed to MMU_NOTIFY_EXCLUSIVE range notifier callbacks
2130 * Tries to remove all the page table entries which are mapping this page and
2131 * replace them with special device exclusive swap entries to grant a device
2132 * exclusive access to the page. Caller must hold the page lock.
2134 * Returns false if the page is still mapped, or if it could not be unmapped
2135 * from the expected address. Otherwise returns true (success).
2137 static bool page_make_device_exclusive(struct page
*page
, struct mm_struct
*mm
,
2138 unsigned long address
, void *owner
)
2140 struct make_exclusive_args args
= {
2146 struct rmap_walk_control rwc
= {
2147 .rmap_one
= page_make_device_exclusive_one
,
2148 .done
= page_not_mapped
,
2149 .anon_lock
= page_lock_anon_vma_read
,
2154 * Restrict to anonymous pages for now to avoid potential writeback
2155 * issues. Also tail pages shouldn't be passed to rmap_walk so skip
2158 if (!PageAnon(page
) || PageTail(page
))
2161 rmap_walk(page
, &rwc
);
2163 return args
.valid
&& !page_mapcount(page
);
2167 * make_device_exclusive_range() - Mark a range for exclusive use by a device
2168 * @mm: mm_struct of assoicated target process
2169 * @start: start of the region to mark for exclusive device access
2170 * @end: end address of region
2171 * @pages: returns the pages which were successfully marked for exclusive access
2172 * @owner: passed to MMU_NOTIFY_EXCLUSIVE range notifier to allow filtering
2174 * Returns: number of pages found in the range by GUP. A page is marked for
2175 * exclusive access only if the page pointer is non-NULL.
2177 * This function finds ptes mapping page(s) to the given address range, locks
2178 * them and replaces mappings with special swap entries preventing userspace CPU
2179 * access. On fault these entries are replaced with the original mapping after
2180 * calling MMU notifiers.
2182 * A driver using this to program access from a device must use a mmu notifier
2183 * critical section to hold a device specific lock during programming. Once
2184 * programming is complete it should drop the page lock and reference after
2185 * which point CPU access to the page will revoke the exclusive access.
2187 int make_device_exclusive_range(struct mm_struct
*mm
, unsigned long start
,
2188 unsigned long end
, struct page
**pages
,
2191 long npages
= (end
- start
) >> PAGE_SHIFT
;
2194 npages
= get_user_pages_remote(mm
, start
, npages
,
2195 FOLL_GET
| FOLL_WRITE
| FOLL_SPLIT_PMD
,
2200 for (i
= 0; i
< npages
; i
++, start
+= PAGE_SIZE
) {
2201 if (!trylock_page(pages
[i
])) {
2207 if (!page_make_device_exclusive(pages
[i
], mm
, start
, owner
)) {
2208 unlock_page(pages
[i
]);
2216 EXPORT_SYMBOL_GPL(make_device_exclusive_range
);
2219 void __put_anon_vma(struct anon_vma
*anon_vma
)
2221 struct anon_vma
*root
= anon_vma
->root
;
2223 anon_vma_free(anon_vma
);
2224 if (root
!= anon_vma
&& atomic_dec_and_test(&root
->refcount
))
2225 anon_vma_free(root
);
2228 static struct anon_vma
*rmap_walk_anon_lock(struct page
*page
,
2229 struct rmap_walk_control
*rwc
)
2231 struct anon_vma
*anon_vma
;
2234 return rwc
->anon_lock(page
);
2237 * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
2238 * because that depends on page_mapped(); but not all its usages
2239 * are holding mmap_lock. Users without mmap_lock are required to
2240 * take a reference count to prevent the anon_vma disappearing
2242 anon_vma
= page_anon_vma(page
);
2246 anon_vma_lock_read(anon_vma
);
2251 * rmap_walk_anon - do something to anonymous page using the object-based
2253 * @page: the page to be handled
2254 * @rwc: control variable according to each walk type
2256 * Find all the mappings of a page using the mapping pointer and the vma chains
2257 * contained in the anon_vma struct it points to.
2259 * When called from page_mlock(), the mmap_lock of the mm containing the vma
2260 * where the page was found will be held for write. So, we won't recheck
2261 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
2264 static void rmap_walk_anon(struct page
*page
, struct rmap_walk_control
*rwc
,
2267 struct anon_vma
*anon_vma
;
2268 pgoff_t pgoff_start
, pgoff_end
;
2269 struct anon_vma_chain
*avc
;
2272 anon_vma
= page_anon_vma(page
);
2273 /* anon_vma disappear under us? */
2274 VM_BUG_ON_PAGE(!anon_vma
, page
);
2276 anon_vma
= rmap_walk_anon_lock(page
, rwc
);
2281 pgoff_start
= page_to_pgoff(page
);
2282 pgoff_end
= pgoff_start
+ thp_nr_pages(page
) - 1;
2283 anon_vma_interval_tree_foreach(avc
, &anon_vma
->rb_root
,
2284 pgoff_start
, pgoff_end
) {
2285 struct vm_area_struct
*vma
= avc
->vma
;
2286 unsigned long address
= vma_address(page
, vma
);
2288 VM_BUG_ON_VMA(address
== -EFAULT
, vma
);
2291 if (rwc
->invalid_vma
&& rwc
->invalid_vma(vma
, rwc
->arg
))
2294 if (!rwc
->rmap_one(page
, vma
, address
, rwc
->arg
))
2296 if (rwc
->done
&& rwc
->done(page
))
2301 anon_vma_unlock_read(anon_vma
);
2305 * rmap_walk_file - do something to file page using the object-based rmap method
2306 * @page: the page to be handled
2307 * @rwc: control variable according to each walk type
2309 * Find all the mappings of a page using the mapping pointer and the vma chains
2310 * contained in the address_space struct it points to.
2312 * When called from page_mlock(), the mmap_lock of the mm containing the vma
2313 * where the page was found will be held for write. So, we won't recheck
2314 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
2317 static void rmap_walk_file(struct page
*page
, struct rmap_walk_control
*rwc
,
2320 struct address_space
*mapping
= page_mapping(page
);
2321 pgoff_t pgoff_start
, pgoff_end
;
2322 struct vm_area_struct
*vma
;
2325 * The page lock not only makes sure that page->mapping cannot
2326 * suddenly be NULLified by truncation, it makes sure that the
2327 * structure at mapping cannot be freed and reused yet,
2328 * so we can safely take mapping->i_mmap_rwsem.
2330 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
2335 pgoff_start
= page_to_pgoff(page
);
2336 pgoff_end
= pgoff_start
+ thp_nr_pages(page
) - 1;
2338 i_mmap_lock_read(mapping
);
2339 vma_interval_tree_foreach(vma
, &mapping
->i_mmap
,
2340 pgoff_start
, pgoff_end
) {
2341 unsigned long address
= vma_address(page
, vma
);
2343 VM_BUG_ON_VMA(address
== -EFAULT
, vma
);
2346 if (rwc
->invalid_vma
&& rwc
->invalid_vma(vma
, rwc
->arg
))
2349 if (!rwc
->rmap_one(page
, vma
, address
, rwc
->arg
))
2351 if (rwc
->done
&& rwc
->done(page
))
2357 i_mmap_unlock_read(mapping
);
2360 void rmap_walk(struct page
*page
, struct rmap_walk_control
*rwc
)
2362 if (unlikely(PageKsm(page
)))
2363 rmap_walk_ksm(page
, rwc
);
2364 else if (PageAnon(page
))
2365 rmap_walk_anon(page
, rwc
, false);
2367 rmap_walk_file(page
, rwc
, false);
2370 /* Like rmap_walk, but caller holds relevant rmap lock */
2371 void rmap_walk_locked(struct page
*page
, struct rmap_walk_control
*rwc
)
2373 /* no ksm support for now */
2374 VM_BUG_ON_PAGE(PageKsm(page
), page
);
2376 rmap_walk_anon(page
, rwc
, true);
2378 rmap_walk_file(page
, rwc
, true);
2381 #ifdef CONFIG_HUGETLB_PAGE
2383 * The following two functions are for anonymous (private mapped) hugepages.
2384 * Unlike common anonymous pages, anonymous hugepages have no accounting code
2385 * and no lru code, because we handle hugepages differently from common pages.
2387 void hugepage_add_anon_rmap(struct page
*page
,
2388 struct vm_area_struct
*vma
, unsigned long address
)
2390 struct anon_vma
*anon_vma
= vma
->anon_vma
;
2393 BUG_ON(!PageLocked(page
));
2395 /* address might be in next vma when migration races vma_adjust */
2396 first
= atomic_inc_and_test(compound_mapcount_ptr(page
));
2398 __page_set_anon_rmap(page
, vma
, address
, 0);
2401 void hugepage_add_new_anon_rmap(struct page
*page
,
2402 struct vm_area_struct
*vma
, unsigned long address
)
2404 BUG_ON(address
< vma
->vm_start
|| address
>= vma
->vm_end
);
2405 atomic_set(compound_mapcount_ptr(page
), 0);
2406 if (hpage_pincount_available(page
))
2407 atomic_set(compound_pincount_ptr(page
), 0);
2409 __page_set_anon_rmap(page
, vma
, address
, 1);
2411 #endif /* CONFIG_HUGETLB_PAGE */