4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
6 * Swap reorganised 29.12.95, Stephen Tweedie.
7 * kswapd added: 7.1.96 sct
8 * Removed kswapd_ctl limits, and swap out as many pages as needed
9 * to bring the system back to freepages.high: 2.4.97, Rik van Riel.
10 * Zone aware kswapd started 02/00, Kanoj Sarcar (kanoj@sgi.com).
11 * Multiqueue VM started 5.8.00, Rik van Riel.
15 #include <linux/module.h>
16 #include <linux/gfp.h>
17 #include <linux/kernel_stat.h>
18 #include <linux/swap.h>
19 #include <linux/pagemap.h>
20 #include <linux/init.h>
21 #include <linux/highmem.h>
22 #include <linux/vmpressure.h>
23 #include <linux/vmstat.h>
24 #include <linux/file.h>
25 #include <linux/writeback.h>
26 #include <linux/blkdev.h>
27 #include <linux/buffer_head.h> /* for try_to_release_page(),
28 buffer_heads_over_limit */
29 #include <linux/mm_inline.h>
30 #include <linux/backing-dev.h>
31 #include <linux/rmap.h>
32 #include <linux/topology.h>
33 #include <linux/cpu.h>
34 #include <linux/cpuset.h>
35 #include <linux/compaction.h>
36 #include <linux/notifier.h>
37 #include <linux/rwsem.h>
38 #include <linux/delay.h>
39 #include <linux/kthread.h>
40 #include <linux/freezer.h>
41 #include <linux/memcontrol.h>
42 #include <linux/delayacct.h>
43 #include <linux/sysctl.h>
44 #include <linux/oom.h>
45 #include <linux/prefetch.h>
46 #include <linux/debugfs.h>
48 #include <asm/tlbflush.h>
49 #include <asm/div64.h>
51 #include <linux/swapops.h>
52 #include <linux/balloon_compaction.h>
56 #define CREATE_TRACE_POINTS
57 #include <trace/events/vmscan.h>
60 /* Incremented by the number of inactive pages that were scanned */
61 unsigned long nr_scanned
;
63 /* Number of pages freed so far during a call to shrink_zones() */
64 unsigned long nr_reclaimed
;
66 /* How many pages shrink_list() should reclaim */
67 unsigned long nr_to_reclaim
;
69 unsigned long hibernation_mode
;
71 /* This context's GFP mask */
76 /* Can mapped pages be reclaimed? */
79 /* Can pages be swapped as part of reclaim? */
84 /* Scan (total_size >> priority) pages at once */
88 * The memory cgroup that hit its limit and as a result is the
89 * primary target of this reclaim invocation.
91 struct mem_cgroup
*target_mem_cgroup
;
94 * Nodemask of nodes allowed by the caller. If NULL, all nodes
100 #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
102 #ifdef ARCH_HAS_PREFETCH
103 #define prefetch_prev_lru_page(_page, _base, _field) \
105 if ((_page)->lru.prev != _base) { \
108 prev = lru_to_page(&(_page->lru)); \
109 prefetch(&prev->_field); \
113 #define prefetch_prev_lru_page(_page, _base, _field) do { } while (0)
116 #ifdef ARCH_HAS_PREFETCHW
117 #define prefetchw_prev_lru_page(_page, _base, _field) \
119 if ((_page)->lru.prev != _base) { \
122 prev = lru_to_page(&(_page->lru)); \
123 prefetchw(&prev->_field); \
127 #define prefetchw_prev_lru_page(_page, _base, _field) do { } while (0)
131 * From 0 .. 100. Higher means more swappy.
133 int vm_swappiness
= 60;
134 unsigned long vm_total_pages
; /* The total number of pages which the VM controls */
136 static LIST_HEAD(shrinker_list
);
137 static DECLARE_RWSEM(shrinker_rwsem
);
140 static bool global_reclaim(struct scan_control
*sc
)
142 return !sc
->target_mem_cgroup
;
145 static bool global_reclaim(struct scan_control
*sc
)
151 static unsigned long get_lru_size(struct lruvec
*lruvec
, enum lru_list lru
)
153 if (!mem_cgroup_disabled())
154 return mem_cgroup_get_lru_size(lruvec
, lru
);
156 return zone_page_state(lruvec_zone(lruvec
), NR_LRU_BASE
+ lru
);
159 struct dentry
*debug_file
;
161 static int debug_shrinker_show(struct seq_file
*s
, void *unused
)
163 struct shrinker
*shrinker
;
164 struct shrink_control sc
;
169 down_read(&shrinker_rwsem
);
170 list_for_each_entry(shrinker
, &shrinker_list
, list
) {
173 num_objs
= shrinker
->shrink(shrinker
, &sc
);
174 seq_printf(s
, "%pf %d\n", shrinker
->shrink
, num_objs
);
176 up_read(&shrinker_rwsem
);
180 static int debug_shrinker_open(struct inode
*inode
, struct file
*file
)
182 return single_open(file
, debug_shrinker_show
, inode
->i_private
);
185 static const struct file_operations debug_shrinker_fops
= {
186 .open
= debug_shrinker_open
,
189 .release
= single_release
,
193 * Add a shrinker callback to be called from the vm
195 void register_shrinker(struct shrinker
*shrinker
)
197 atomic_long_set(&shrinker
->nr_in_batch
, 0);
198 down_write(&shrinker_rwsem
);
199 list_add_tail(&shrinker
->list
, &shrinker_list
);
200 up_write(&shrinker_rwsem
);
202 EXPORT_SYMBOL(register_shrinker
);
204 static int __init
add_shrinker_debug(void)
206 debugfs_create_file("shrinker", 0644, NULL
, NULL
,
207 &debug_shrinker_fops
);
211 late_initcall(add_shrinker_debug
);
216 void unregister_shrinker(struct shrinker
*shrinker
)
218 down_write(&shrinker_rwsem
);
219 list_del(&shrinker
->list
);
220 up_write(&shrinker_rwsem
);
222 EXPORT_SYMBOL(unregister_shrinker
);
224 static inline int do_shrinker_shrink(struct shrinker
*shrinker
,
225 struct shrink_control
*sc
,
226 unsigned long nr_to_scan
)
228 sc
->nr_to_scan
= nr_to_scan
;
229 return (*shrinker
->shrink
)(shrinker
, sc
);
232 #define SHRINK_BATCH 128
234 * Call the shrink functions to age shrinkable caches
236 * Here we assume it costs one seek to replace a lru page and that it also
237 * takes a seek to recreate a cache object. With this in mind we age equal
238 * percentages of the lru and ageable caches. This should balance the seeks
239 * generated by these structures.
241 * If the vm encountered mapped pages on the LRU it increase the pressure on
242 * slab to avoid swapping.
244 * We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits.
246 * `lru_pages' represents the number of on-LRU pages in all the zones which
247 * are eligible for the caller's allocation attempt. It is used for balancing
248 * slab reclaim versus page reclaim.
250 * Returns the number of slab objects which we shrunk.
252 unsigned long shrink_slab(struct shrink_control
*shrink
,
253 unsigned long nr_pages_scanned
,
254 unsigned long lru_pages
)
256 struct shrinker
*shrinker
;
257 unsigned long ret
= 0;
259 if (nr_pages_scanned
== 0)
260 nr_pages_scanned
= SWAP_CLUSTER_MAX
;
262 if (!down_read_trylock(&shrinker_rwsem
)) {
263 /* Assume we'll be able to shrink next time */
268 list_for_each_entry(shrinker
, &shrinker_list
, list
) {
269 unsigned long long delta
;
275 long batch_size
= shrinker
->batch
? shrinker
->batch
278 max_pass
= do_shrinker_shrink(shrinker
, shrink
, 0);
283 * copy the current shrinker scan count into a local variable
284 * and zero it so that other concurrent shrinker invocations
285 * don't also do this scanning work.
287 nr
= atomic_long_xchg(&shrinker
->nr_in_batch
, 0);
290 delta
= (4 * nr_pages_scanned
) / shrinker
->seeks
;
292 do_div(delta
, lru_pages
+ 1);
294 if (total_scan
< 0) {
295 printk(KERN_ERR
"shrink_slab: %pF negative objects to "
297 shrinker
->shrink
, total_scan
);
298 total_scan
= max_pass
;
302 * We need to avoid excessive windup on filesystem shrinkers
303 * due to large numbers of GFP_NOFS allocations causing the
304 * shrinkers to return -1 all the time. This results in a large
305 * nr being built up so when a shrink that can do some work
306 * comes along it empties the entire cache due to nr >>>
307 * max_pass. This is bad for sustaining a working set in
310 * Hence only allow the shrinker to scan the entire cache when
311 * a large delta change is calculated directly.
313 if (delta
< max_pass
/ 4)
314 total_scan
= min(total_scan
, max_pass
/ 2);
317 * Avoid risking looping forever due to too large nr value:
318 * never try to free more than twice the estimate number of
321 if (total_scan
> max_pass
* 2)
322 total_scan
= max_pass
* 2;
324 trace_mm_shrink_slab_start(shrinker
, shrink
, nr
,
325 nr_pages_scanned
, lru_pages
,
326 max_pass
, delta
, total_scan
);
328 while (total_scan
>= batch_size
) {
331 nr_before
= do_shrinker_shrink(shrinker
, shrink
, 0);
332 shrink_ret
= do_shrinker_shrink(shrinker
, shrink
,
334 if (shrink_ret
== -1)
336 if (shrink_ret
< nr_before
)
337 ret
+= nr_before
- shrink_ret
;
338 count_vm_events(SLABS_SCANNED
, batch_size
);
339 total_scan
-= batch_size
;
345 * move the unused scan count back into the shrinker in a
346 * manner that handles concurrent updates. If we exhausted the
347 * scan, there is no need to do an update.
350 new_nr
= atomic_long_add_return(total_scan
,
351 &shrinker
->nr_in_batch
);
353 new_nr
= atomic_long_read(&shrinker
->nr_in_batch
);
355 trace_mm_shrink_slab_end(shrinker
, shrink_ret
, nr
, new_nr
);
357 up_read(&shrinker_rwsem
);
363 static inline int is_page_cache_freeable(struct page
*page
)
366 * A freeable page cache page is referenced only by the caller
367 * that isolated the page, the page cache radix tree and
368 * optional buffer heads at page->private.
370 return page_count(page
) - page_has_private(page
) == 2;
373 static int may_write_to_queue(struct backing_dev_info
*bdi
,
374 struct scan_control
*sc
)
376 if (current
->flags
& PF_SWAPWRITE
)
378 if (!bdi_write_congested(bdi
))
380 if (bdi
== current
->backing_dev_info
)
386 * We detected a synchronous write error writing a page out. Probably
387 * -ENOSPC. We need to propagate that into the address_space for a subsequent
388 * fsync(), msync() or close().
390 * The tricky part is that after writepage we cannot touch the mapping: nothing
391 * prevents it from being freed up. But we have a ref on the page and once
392 * that page is locked, the mapping is pinned.
394 * We're allowed to run sleeping lock_page() here because we know the caller has
397 static void handle_write_error(struct address_space
*mapping
,
398 struct page
*page
, int error
)
401 if (page_mapping(page
) == mapping
)
402 mapping_set_error(mapping
, error
);
406 /* possible outcome of pageout() */
408 /* failed to write page out, page is locked */
410 /* move page to the active list, page is locked */
412 /* page has been sent to the disk successfully, page is unlocked */
414 /* page is clean and locked */
419 * pageout is called by shrink_page_list() for each dirty page.
420 * Calls ->writepage().
422 static pageout_t
pageout(struct page
*page
, struct address_space
*mapping
,
423 struct scan_control
*sc
)
426 * If the page is dirty, only perform writeback if that write
427 * will be non-blocking. To prevent this allocation from being
428 * stalled by pagecache activity. But note that there may be
429 * stalls if we need to run get_block(). We could test
430 * PagePrivate for that.
432 * If this process is currently in __generic_file_aio_write() against
433 * this page's queue, we can perform writeback even if that
436 * If the page is swapcache, write it back even if that would
437 * block, for some throttling. This happens by accident, because
438 * swap_backing_dev_info is bust: it doesn't reflect the
439 * congestion state of the swapdevs. Easy to fix, if needed.
441 if (!is_page_cache_freeable(page
))
445 * Some data journaling orphaned pages can have
446 * page->mapping == NULL while being dirty with clean buffers.
448 if (page_has_private(page
)) {
449 if (try_to_free_buffers(page
)) {
450 ClearPageDirty(page
);
451 printk("%s: orphaned page\n", __func__
);
457 if (mapping
->a_ops
->writepage
== NULL
)
458 return PAGE_ACTIVATE
;
459 if (!may_write_to_queue(mapping
->backing_dev_info
, sc
))
462 if (clear_page_dirty_for_io(page
)) {
464 struct writeback_control wbc
= {
465 .sync_mode
= WB_SYNC_NONE
,
466 .nr_to_write
= SWAP_CLUSTER_MAX
,
468 .range_end
= LLONG_MAX
,
472 SetPageReclaim(page
);
473 res
= mapping
->a_ops
->writepage(page
, &wbc
);
475 handle_write_error(mapping
, page
, res
);
476 if (res
== AOP_WRITEPAGE_ACTIVATE
) {
477 ClearPageReclaim(page
);
478 return PAGE_ACTIVATE
;
481 if (!PageWriteback(page
)) {
482 /* synchronous write or broken a_ops? */
483 ClearPageReclaim(page
);
485 trace_mm_vmscan_writepage(page
, trace_reclaim_flags(page
));
486 inc_zone_page_state(page
, NR_VMSCAN_WRITE
);
494 * Same as remove_mapping, but if the page is removed from the mapping, it
495 * gets returned with a refcount of 0.
497 static int __remove_mapping(struct address_space
*mapping
, struct page
*page
)
499 BUG_ON(!PageLocked(page
));
500 BUG_ON(mapping
!= page_mapping(page
));
502 spin_lock_irq(&mapping
->tree_lock
);
504 * The non racy check for a busy page.
506 * Must be careful with the order of the tests. When someone has
507 * a ref to the page, it may be possible that they dirty it then
508 * drop the reference. So if PageDirty is tested before page_count
509 * here, then the following race may occur:
511 * get_user_pages(&page);
512 * [user mapping goes away]
514 * !PageDirty(page) [good]
515 * SetPageDirty(page);
517 * !page_count(page) [good, discard it]
519 * [oops, our write_to data is lost]
521 * Reversing the order of the tests ensures such a situation cannot
522 * escape unnoticed. The smp_rmb is needed to ensure the page->flags
523 * load is not satisfied before that of page->_count.
525 * Note that if SetPageDirty is always performed via set_page_dirty,
526 * and thus under tree_lock, then this ordering is not required.
528 if (!page_freeze_refs(page
, 2))
530 /* note: atomic_cmpxchg in page_freeze_refs provides the smp_rmb */
531 if (unlikely(PageDirty(page
))) {
532 page_unfreeze_refs(page
, 2);
536 if (PageSwapCache(page
)) {
537 swp_entry_t swap
= { .val
= page_private(page
) };
538 __delete_from_swap_cache(page
);
539 spin_unlock_irq(&mapping
->tree_lock
);
540 swapcache_free(swap
, page
);
542 void (*freepage
)(struct page
*);
544 freepage
= mapping
->a_ops
->freepage
;
546 __delete_from_page_cache(page
);
547 spin_unlock_irq(&mapping
->tree_lock
);
548 mem_cgroup_uncharge_cache_page(page
);
550 if (freepage
!= NULL
)
557 spin_unlock_irq(&mapping
->tree_lock
);
562 * Attempt to detach a locked page from its ->mapping. If it is dirty or if
563 * someone else has a ref on the page, abort and return 0. If it was
564 * successfully detached, return 1. Assumes the caller has a single ref on
567 int remove_mapping(struct address_space
*mapping
, struct page
*page
)
569 if (__remove_mapping(mapping
, page
)) {
571 * Unfreezing the refcount with 1 rather than 2 effectively
572 * drops the pagecache ref for us without requiring another
575 page_unfreeze_refs(page
, 1);
582 * putback_lru_page - put previously isolated page onto appropriate LRU list
583 * @page: page to be put back to appropriate lru list
585 * Add previously isolated @page to appropriate LRU list.
586 * Page may still be unevictable for other reasons.
588 * lru_lock must not be held, interrupts must be enabled.
590 void putback_lru_page(struct page
*page
)
593 int active
= !!TestClearPageActive(page
);
594 int was_unevictable
= PageUnevictable(page
);
596 VM_BUG_ON(PageLRU(page
));
599 ClearPageUnevictable(page
);
601 if (page_evictable(page
)) {
603 * For evictable pages, we can use the cache.
604 * In event of a race, worst case is we end up with an
605 * unevictable page on [in]active list.
606 * We know how to handle that.
608 lru
= active
+ page_lru_base_type(page
);
609 lru_cache_add_lru(page
, lru
);
612 * Put unevictable pages directly on zone's unevictable
615 lru
= LRU_UNEVICTABLE
;
616 add_page_to_unevictable_list(page
);
618 * When racing with an mlock or AS_UNEVICTABLE clearing
619 * (page is unlocked) make sure that if the other thread
620 * does not observe our setting of PG_lru and fails
621 * isolation/check_move_unevictable_pages,
622 * we see PG_mlocked/AS_UNEVICTABLE cleared below and move
623 * the page back to the evictable list.
625 * The other side is TestClearPageMlocked() or shmem_lock().
631 * page's status can change while we move it among lru. If an evictable
632 * page is on unevictable list, it never be freed. To avoid that,
633 * check after we added it to the list, again.
635 if (lru
== LRU_UNEVICTABLE
&& page_evictable(page
)) {
636 if (!isolate_lru_page(page
)) {
640 /* This means someone else dropped this page from LRU
641 * So, it will be freed or putback to LRU again. There is
642 * nothing to do here.
646 if (was_unevictable
&& lru
!= LRU_UNEVICTABLE
)
647 count_vm_event(UNEVICTABLE_PGRESCUED
);
648 else if (!was_unevictable
&& lru
== LRU_UNEVICTABLE
)
649 count_vm_event(UNEVICTABLE_PGCULLED
);
651 put_page(page
); /* drop ref from isolate */
654 enum page_references
{
656 PAGEREF_RECLAIM_CLEAN
,
661 static enum page_references
page_check_references(struct page
*page
,
662 struct scan_control
*sc
)
664 int referenced_ptes
, referenced_page
;
665 unsigned long vm_flags
;
667 referenced_ptes
= page_referenced(page
, 1, sc
->target_mem_cgroup
,
669 referenced_page
= TestClearPageReferenced(page
);
672 * Mlock lost the isolation race with us. Let try_to_unmap()
673 * move the page to the unevictable list.
675 if (vm_flags
& VM_LOCKED
)
676 return PAGEREF_RECLAIM
;
678 if (referenced_ptes
) {
679 if (PageSwapBacked(page
))
680 return PAGEREF_ACTIVATE
;
682 * All mapped pages start out with page table
683 * references from the instantiating fault, so we need
684 * to look twice if a mapped file page is used more
687 * Mark it and spare it for another trip around the
688 * inactive list. Another page table reference will
689 * lead to its activation.
691 * Note: the mark is set for activated pages as well
692 * so that recently deactivated but used pages are
695 SetPageReferenced(page
);
697 if (referenced_page
|| referenced_ptes
> 1)
698 return PAGEREF_ACTIVATE
;
701 * Activate file-backed executable pages after first usage.
703 if (vm_flags
& VM_EXEC
)
704 return PAGEREF_ACTIVATE
;
709 /* Reclaim if clean, defer dirty pages to writeback */
710 if (referenced_page
&& !PageSwapBacked(page
))
711 return PAGEREF_RECLAIM_CLEAN
;
713 return PAGEREF_RECLAIM
;
717 * shrink_page_list() returns the number of reclaimed pages
719 static unsigned long shrink_page_list(struct list_head
*page_list
,
721 struct scan_control
*sc
,
722 enum ttu_flags ttu_flags
,
723 unsigned long *ret_nr_dirty
,
724 unsigned long *ret_nr_writeback
,
727 LIST_HEAD(ret_pages
);
728 LIST_HEAD(free_pages
);
730 unsigned long nr_dirty
= 0;
731 unsigned long nr_congested
= 0;
732 unsigned long nr_reclaimed
= 0;
733 unsigned long nr_writeback
= 0;
737 mem_cgroup_uncharge_start();
738 while (!list_empty(page_list
)) {
739 struct address_space
*mapping
;
742 enum page_references references
= PAGEREF_RECLAIM_CLEAN
;
746 page
= lru_to_page(page_list
);
747 list_del(&page
->lru
);
749 if (!trylock_page(page
))
752 VM_BUG_ON(PageActive(page
));
753 VM_BUG_ON(page_zone(page
) != zone
);
757 if (unlikely(!page_evictable(page
)))
760 if (!sc
->may_unmap
&& page_mapped(page
))
763 /* Double the slab pressure for mapped and swapcache pages */
764 if (page_mapped(page
) || PageSwapCache(page
))
767 may_enter_fs
= (sc
->gfp_mask
& __GFP_FS
) ||
768 (PageSwapCache(page
) && (sc
->gfp_mask
& __GFP_IO
));
770 if (PageWriteback(page
)) {
772 * memcg doesn't have any dirty pages throttling so we
773 * could easily OOM just because too many pages are in
774 * writeback and there is nothing else to reclaim.
776 * Check __GFP_IO, certainly because a loop driver
777 * thread might enter reclaim, and deadlock if it waits
778 * on a page for which it is needed to do the write
779 * (loop masks off __GFP_IO|__GFP_FS for this reason);
780 * but more thought would probably show more reasons.
782 * Don't require __GFP_FS, since we're not going into
783 * the FS, just waiting on its writeback completion.
784 * Worryingly, ext4 gfs2 and xfs allocate pages with
785 * grab_cache_page_write_begin(,,AOP_FLAG_NOFS), so
786 * testing may_enter_fs here is liable to OOM on them.
788 if (global_reclaim(sc
) ||
789 !PageReclaim(page
) || !(sc
->gfp_mask
& __GFP_IO
)) {
791 * This is slightly racy - end_page_writeback()
792 * might have just cleared PageReclaim, then
793 * setting PageReclaim here end up interpreted
794 * as PageReadahead - but that does not matter
795 * enough to care. What we do want is for this
796 * page to have PageReclaim set next time memcg
797 * reclaim reaches the tests above, so it will
798 * then wait_on_page_writeback() to avoid OOM;
799 * and it's also appropriate in global reclaim.
801 SetPageReclaim(page
);
805 wait_on_page_writeback(page
);
809 references
= page_check_references(page
, sc
);
811 switch (references
) {
812 case PAGEREF_ACTIVATE
:
813 goto activate_locked
;
816 case PAGEREF_RECLAIM
:
817 case PAGEREF_RECLAIM_CLEAN
:
818 ; /* try to reclaim the page below */
822 * Anonymous process memory has backing store?
823 * Try to allocate it some swap space here.
825 if (PageAnon(page
) && !PageSwapCache(page
)) {
826 if (!(sc
->gfp_mask
& __GFP_IO
))
828 if (!add_to_swap(page
, page_list
))
829 goto activate_locked
;
833 mapping
= page_mapping(page
);
836 * The page is mapped into the page tables of one or more
837 * processes. Try to unmap it here.
839 if (page_mapped(page
) && mapping
) {
840 switch (try_to_unmap(page
, ttu_flags
)) {
842 goto activate_locked
;
848 ; /* try to free the page below */
852 if (PageDirty(page
)) {
856 * Only kswapd can writeback filesystem pages to
857 * avoid risk of stack overflow but do not writeback
858 * unless under significant pressure.
860 if (page_is_file_cache(page
) &&
861 (!current_is_kswapd() ||
862 sc
->priority
>= DEF_PRIORITY
- 2)) {
864 * Immediately reclaim when written back.
865 * Similar in principal to deactivate_page()
866 * except we already have the page isolated
867 * and know it's dirty
869 inc_zone_page_state(page
, NR_VMSCAN_IMMEDIATE
);
870 SetPageReclaim(page
);
875 if (references
== PAGEREF_RECLAIM_CLEAN
)
879 if (!sc
->may_writepage
)
882 /* Page is dirty, try to write it out here */
883 switch (pageout(page
, mapping
, sc
)) {
888 goto activate_locked
;
890 if (PageWriteback(page
))
896 * A synchronous write - probably a ramdisk. Go
897 * ahead and try to reclaim the page.
899 if (!trylock_page(page
))
901 if (PageDirty(page
) || PageWriteback(page
))
903 mapping
= page_mapping(page
);
905 ; /* try to free the page below */
910 * If the page has buffers, try to free the buffer mappings
911 * associated with this page. If we succeed we try to free
914 * We do this even if the page is PageDirty().
915 * try_to_release_page() does not perform I/O, but it is
916 * possible for a page to have PageDirty set, but it is actually
917 * clean (all its buffers are clean). This happens if the
918 * buffers were written out directly, with submit_bh(). ext3
919 * will do this, as well as the blockdev mapping.
920 * try_to_release_page() will discover that cleanness and will
921 * drop the buffers and mark the page clean - it can be freed.
923 * Rarely, pages can have buffers and no ->mapping. These are
924 * the pages which were not successfully invalidated in
925 * truncate_complete_page(). We try to drop those buffers here
926 * and if that worked, and the page is no longer mapped into
927 * process address space (page_count == 1) it can be freed.
928 * Otherwise, leave the page on the LRU so it is swappable.
930 if (page_has_private(page
)) {
931 if (!try_to_release_page(page
, sc
->gfp_mask
))
932 goto activate_locked
;
933 if (!mapping
&& page_count(page
) == 1) {
935 if (put_page_testzero(page
))
939 * rare race with speculative reference.
940 * the speculative reference will free
941 * this page shortly, so we may
942 * increment nr_reclaimed here (and
943 * leave it off the LRU).
951 if (!mapping
|| !__remove_mapping(mapping
, page
))
955 * At this point, we have no other references and there is
956 * no way to pick any more up (removed from LRU, removed
957 * from pagecache). Can use non-atomic bitops now (and
958 * we obviously don't have to worry about waking up a process
959 * waiting on the page lock, because there are no references.
961 __clear_page_locked(page
);
966 * Is there need to periodically free_page_list? It would
967 * appear not as the counts should be low
969 list_add(&page
->lru
, &free_pages
);
973 if (PageSwapCache(page
))
974 try_to_free_swap(page
);
976 putback_lru_page(page
);
980 /* Not a candidate for swapping, so reclaim swap space. */
981 if (PageSwapCache(page
) && vm_swap_full())
982 try_to_free_swap(page
);
983 VM_BUG_ON(PageActive(page
));
989 list_add(&page
->lru
, &ret_pages
);
990 VM_BUG_ON(PageLRU(page
) || PageUnevictable(page
));
994 * Tag a zone as congested if all the dirty pages encountered were
995 * backed by a congested BDI. In this case, reclaimers should just
996 * back off and wait for congestion to clear because further reclaim
997 * will encounter the same problem
999 if (nr_dirty
&& nr_dirty
== nr_congested
&& global_reclaim(sc
))
1000 zone_set_flag(zone
, ZONE_CONGESTED
);
1002 free_hot_cold_page_list(&free_pages
, 1);
1004 list_splice(&ret_pages
, page_list
);
1005 count_vm_events(PGACTIVATE
, pgactivate
);
1006 mem_cgroup_uncharge_end();
1007 *ret_nr_dirty
+= nr_dirty
;
1008 *ret_nr_writeback
+= nr_writeback
;
1009 return nr_reclaimed
;
1012 unsigned long reclaim_clean_pages_from_list(struct zone
*zone
,
1013 struct list_head
*page_list
)
1015 struct scan_control sc
= {
1016 .gfp_mask
= GFP_KERNEL
,
1017 .priority
= DEF_PRIORITY
,
1020 unsigned long ret
, dummy1
, dummy2
;
1021 struct page
*page
, *next
;
1022 LIST_HEAD(clean_pages
);
1024 list_for_each_entry_safe(page
, next
, page_list
, lru
) {
1025 if (page_is_file_cache(page
) && !PageDirty(page
) &&
1026 !isolated_balloon_page(page
)) {
1027 ClearPageActive(page
);
1028 list_move(&page
->lru
, &clean_pages
);
1032 ret
= shrink_page_list(&clean_pages
, zone
, &sc
,
1033 TTU_UNMAP
|TTU_IGNORE_ACCESS
,
1034 &dummy1
, &dummy2
, true);
1035 list_splice(&clean_pages
, page_list
);
1036 __mod_zone_page_state(zone
, NR_ISOLATED_FILE
, -ret
);
1041 * Attempt to remove the specified page from its LRU. Only take this page
1042 * if it is of the appropriate PageActive status. Pages which are being
1043 * freed elsewhere are also ignored.
1045 * page: page to consider
1046 * mode: one of the LRU isolation modes defined above
1048 * returns 0 on success, -ve errno on failure.
1050 int __isolate_lru_page(struct page
*page
, isolate_mode_t mode
)
1054 /* Only take pages on the LRU. */
1058 /* Compaction should not handle unevictable pages but CMA can do so */
1059 if (PageUnevictable(page
) && !(mode
& ISOLATE_UNEVICTABLE
))
1065 * To minimise LRU disruption, the caller can indicate that it only
1066 * wants to isolate pages it will be able to operate on without
1067 * blocking - clean pages for the most part.
1069 * ISOLATE_CLEAN means that only clean pages should be isolated. This
1070 * is used by reclaim when it is cannot write to backing storage
1072 * ISOLATE_ASYNC_MIGRATE is used to indicate that it only wants to pages
1073 * that it is possible to migrate without blocking
1075 if (mode
& (ISOLATE_CLEAN
|ISOLATE_ASYNC_MIGRATE
)) {
1076 /* All the caller can do on PageWriteback is block */
1077 if (PageWriteback(page
))
1080 if (PageDirty(page
)) {
1081 struct address_space
*mapping
;
1083 /* ISOLATE_CLEAN means only clean pages */
1084 if (mode
& ISOLATE_CLEAN
)
1088 * Only pages without mappings or that have a
1089 * ->migratepage callback are possible to migrate
1092 mapping
= page_mapping(page
);
1093 if (mapping
&& !mapping
->a_ops
->migratepage
)
1098 if ((mode
& ISOLATE_UNMAPPED
) && page_mapped(page
))
1101 if (likely(get_page_unless_zero(page
))) {
1103 * Be careful not to clear PageLRU until after we're
1104 * sure the page is not being freed elsewhere -- the
1105 * page release code relies on it.
1115 * zone->lru_lock is heavily contended. Some of the functions that
1116 * shrink the lists perform better by taking out a batch of pages
1117 * and working on them outside the LRU lock.
1119 * For pagecache intensive workloads, this function is the hottest
1120 * spot in the kernel (apart from copy_*_user functions).
1122 * Appropriate locks must be held before calling this function.
1124 * @nr_to_scan: The number of pages to look through on the list.
1125 * @lruvec: The LRU vector to pull pages from.
1126 * @dst: The temp list to put pages on to.
1127 * @nr_scanned: The number of pages that were scanned.
1128 * @sc: The scan_control struct for this reclaim session
1129 * @mode: One of the LRU isolation modes
1130 * @lru: LRU list id for isolating
1132 * returns how many pages were moved onto *@dst.
1134 static unsigned long isolate_lru_pages(unsigned long nr_to_scan
,
1135 struct lruvec
*lruvec
, struct list_head
*dst
,
1136 unsigned long *nr_scanned
, struct scan_control
*sc
,
1137 isolate_mode_t mode
, enum lru_list lru
)
1139 struct list_head
*src
= &lruvec
->lists
[lru
];
1140 unsigned long nr_taken
= 0;
1143 for (scan
= 0; scan
< nr_to_scan
&& !list_empty(src
); scan
++) {
1147 page
= lru_to_page(src
);
1148 prefetchw_prev_lru_page(page
, src
, flags
);
1150 VM_BUG_ON(!PageLRU(page
));
1152 switch (__isolate_lru_page(page
, mode
)) {
1154 nr_pages
= hpage_nr_pages(page
);
1155 mem_cgroup_update_lru_size(lruvec
, lru
, -nr_pages
);
1156 list_move(&page
->lru
, dst
);
1157 nr_taken
+= nr_pages
;
1161 /* else it is being freed elsewhere */
1162 list_move(&page
->lru
, src
);
1171 trace_mm_vmscan_lru_isolate(sc
->order
, nr_to_scan
, scan
,
1172 nr_taken
, mode
, is_file_lru(lru
));
1177 * isolate_lru_page - tries to isolate a page from its LRU list
1178 * @page: page to isolate from its LRU list
1180 * Isolates a @page from an LRU list, clears PageLRU and adjusts the
1181 * vmstat statistic corresponding to whatever LRU list the page was on.
1183 * Returns 0 if the page was removed from an LRU list.
1184 * Returns -EBUSY if the page was not on an LRU list.
1186 * The returned page will have PageLRU() cleared. If it was found on
1187 * the active list, it will have PageActive set. If it was found on
1188 * the unevictable list, it will have the PageUnevictable bit set. That flag
1189 * may need to be cleared by the caller before letting the page go.
1191 * The vmstat statistic corresponding to the list on which the page was
1192 * found will be decremented.
1195 * (1) Must be called with an elevated refcount on the page. This is a
1196 * fundamentnal difference from isolate_lru_pages (which is called
1197 * without a stable reference).
1198 * (2) the lru_lock must not be held.
1199 * (3) interrupts must be enabled.
1201 int isolate_lru_page(struct page
*page
)
1205 VM_BUG_ON(!page_count(page
));
1207 if (PageLRU(page
)) {
1208 struct zone
*zone
= page_zone(page
);
1209 struct lruvec
*lruvec
;
1211 spin_lock_irq(&zone
->lru_lock
);
1212 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
1213 if (PageLRU(page
)) {
1214 int lru
= page_lru(page
);
1217 del_page_from_lru_list(page
, lruvec
, lru
);
1220 spin_unlock_irq(&zone
->lru_lock
);
1226 * A direct reclaimer may isolate SWAP_CLUSTER_MAX pages from the LRU list and
1227 * then get resheduled. When there are massive number of tasks doing page
1228 * allocation, such sleeping direct reclaimers may keep piling up on each CPU,
1229 * the LRU list will go small and be scanned faster than necessary, leading to
1230 * unnecessary swapping, thrashing and OOM.
1232 static int too_many_isolated(struct zone
*zone
, int file
,
1233 struct scan_control
*sc
)
1235 unsigned long inactive
, isolated
;
1237 if (current_is_kswapd() || sc
->hibernation_mode
)
1240 if (!global_reclaim(sc
))
1244 inactive
= zone_page_state(zone
, NR_INACTIVE_FILE
);
1245 isolated
= zone_page_state(zone
, NR_ISOLATED_FILE
);
1247 inactive
= zone_page_state(zone
, NR_INACTIVE_ANON
);
1248 isolated
= zone_page_state(zone
, NR_ISOLATED_ANON
);
1252 * GFP_NOIO/GFP_NOFS callers are allowed to isolate more pages, so they
1253 * won't get blocked by normal direct-reclaimers, forming a circular
1256 if ((sc
->gfp_mask
& GFP_IOFS
) == GFP_IOFS
)
1259 return isolated
> inactive
;
1262 static noinline_for_stack
void
1263 putback_inactive_pages(struct lruvec
*lruvec
, struct list_head
*page_list
)
1265 struct zone_reclaim_stat
*reclaim_stat
= &lruvec
->reclaim_stat
;
1266 struct zone
*zone
= lruvec_zone(lruvec
);
1267 LIST_HEAD(pages_to_free
);
1270 * Put back any unfreeable pages.
1272 while (!list_empty(page_list
)) {
1273 struct page
*page
= lru_to_page(page_list
);
1276 VM_BUG_ON(PageLRU(page
));
1277 list_del(&page
->lru
);
1278 if (unlikely(!page_evictable(page
))) {
1279 spin_unlock_irq(&zone
->lru_lock
);
1280 putback_lru_page(page
);
1281 spin_lock_irq(&zone
->lru_lock
);
1285 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
1288 lru
= page_lru(page
);
1289 add_page_to_lru_list(page
, lruvec
, lru
);
1291 if (is_active_lru(lru
)) {
1292 int file
= is_file_lru(lru
);
1293 int numpages
= hpage_nr_pages(page
);
1294 reclaim_stat
->recent_rotated
[file
] += numpages
;
1296 if (put_page_testzero(page
)) {
1297 __ClearPageLRU(page
);
1298 __ClearPageActive(page
);
1299 del_page_from_lru_list(page
, lruvec
, lru
);
1301 if (unlikely(PageCompound(page
))) {
1302 spin_unlock_irq(&zone
->lru_lock
);
1303 (*get_compound_page_dtor(page
))(page
);
1304 spin_lock_irq(&zone
->lru_lock
);
1306 list_add(&page
->lru
, &pages_to_free
);
1311 * To save our caller's stack, now use input list for pages to free.
1313 list_splice(&pages_to_free
, page_list
);
1317 * shrink_inactive_list() is a helper for shrink_zone(). It returns the number
1318 * of reclaimed pages
1320 static noinline_for_stack
unsigned long
1321 shrink_inactive_list(unsigned long nr_to_scan
, struct lruvec
*lruvec
,
1322 struct scan_control
*sc
, enum lru_list lru
)
1324 LIST_HEAD(page_list
);
1325 unsigned long nr_scanned
;
1326 unsigned long nr_reclaimed
= 0;
1327 unsigned long nr_taken
;
1328 unsigned long nr_dirty
= 0;
1329 unsigned long nr_writeback
= 0;
1330 isolate_mode_t isolate_mode
= 0;
1331 int file
= is_file_lru(lru
);
1332 struct zone
*zone
= lruvec_zone(lruvec
);
1333 struct zone_reclaim_stat
*reclaim_stat
= &lruvec
->reclaim_stat
;
1335 while (unlikely(too_many_isolated(zone
, file
, sc
))) {
1336 congestion_wait(BLK_RW_ASYNC
, HZ
/10);
1338 /* We are about to die and free our memory. Return now. */
1339 if (fatal_signal_pending(current
))
1340 return SWAP_CLUSTER_MAX
;
1346 isolate_mode
|= ISOLATE_UNMAPPED
;
1347 if (!sc
->may_writepage
)
1348 isolate_mode
|= ISOLATE_CLEAN
;
1350 spin_lock_irq(&zone
->lru_lock
);
1352 nr_taken
= isolate_lru_pages(nr_to_scan
, lruvec
, &page_list
,
1353 &nr_scanned
, sc
, isolate_mode
, lru
);
1355 __mod_zone_page_state(zone
, NR_LRU_BASE
+ lru
, -nr_taken
);
1356 __mod_zone_page_state(zone
, NR_ISOLATED_ANON
+ file
, nr_taken
);
1358 if (global_reclaim(sc
)) {
1359 zone
->pages_scanned
+= nr_scanned
;
1360 if (current_is_kswapd())
1361 __count_zone_vm_events(PGSCAN_KSWAPD
, zone
, nr_scanned
);
1363 __count_zone_vm_events(PGSCAN_DIRECT
, zone
, nr_scanned
);
1365 spin_unlock_irq(&zone
->lru_lock
);
1370 nr_reclaimed
= shrink_page_list(&page_list
, zone
, sc
, TTU_UNMAP
,
1371 &nr_dirty
, &nr_writeback
, false);
1373 spin_lock_irq(&zone
->lru_lock
);
1375 reclaim_stat
->recent_scanned
[file
] += nr_taken
;
1377 if (global_reclaim(sc
)) {
1378 if (current_is_kswapd())
1379 __count_zone_vm_events(PGSTEAL_KSWAPD
, zone
,
1382 __count_zone_vm_events(PGSTEAL_DIRECT
, zone
,
1386 putback_inactive_pages(lruvec
, &page_list
);
1388 __mod_zone_page_state(zone
, NR_ISOLATED_ANON
+ file
, -nr_taken
);
1390 spin_unlock_irq(&zone
->lru_lock
);
1392 free_hot_cold_page_list(&page_list
, 1);
1395 * If reclaim is isolating dirty pages under writeback, it implies
1396 * that the long-lived page allocation rate is exceeding the page
1397 * laundering rate. Either the global limits are not being effective
1398 * at throttling processes due to the page distribution throughout
1399 * zones or there is heavy usage of a slow backing device. The
1400 * only option is to throttle from reclaim context which is not ideal
1401 * as there is no guarantee the dirtying process is throttled in the
1402 * same way balance_dirty_pages() manages.
1404 * This scales the number of dirty pages that must be under writeback
1405 * before throttling depending on priority. It is a simple backoff
1406 * function that has the most effect in the range DEF_PRIORITY to
1407 * DEF_PRIORITY-2 which is the priority reclaim is considered to be
1408 * in trouble and reclaim is considered to be in trouble.
1410 * DEF_PRIORITY 100% isolated pages must be PageWriteback to throttle
1411 * DEF_PRIORITY-1 50% must be PageWriteback
1412 * DEF_PRIORITY-2 25% must be PageWriteback, kswapd in trouble
1414 * DEF_PRIORITY-6 For SWAP_CLUSTER_MAX isolated pages, throttle if any
1415 * isolated page is PageWriteback
1417 if (nr_writeback
&& nr_writeback
>=
1418 (nr_taken
>> (DEF_PRIORITY
- sc
->priority
)))
1419 wait_iff_congested(zone
, BLK_RW_ASYNC
, HZ
/10);
1421 trace_mm_vmscan_lru_shrink_inactive(zone
->zone_pgdat
->node_id
,
1423 nr_scanned
, nr_reclaimed
,
1425 trace_shrink_flags(file
));
1426 return nr_reclaimed
;
1430 * This moves pages from the active list to the inactive list.
1432 * We move them the other way if the page is referenced by one or more
1433 * processes, from rmap.
1435 * If the pages are mostly unmapped, the processing is fast and it is
1436 * appropriate to hold zone->lru_lock across the whole operation. But if
1437 * the pages are mapped, the processing is slow (page_referenced()) so we
1438 * should drop zone->lru_lock around each page. It's impossible to balance
1439 * this, so instead we remove the pages from the LRU while processing them.
1440 * It is safe to rely on PG_active against the non-LRU pages in here because
1441 * nobody will play with that bit on a non-LRU page.
1443 * The downside is that we have to touch page->_count against each page.
1444 * But we had to alter page->flags anyway.
1447 static void move_active_pages_to_lru(struct lruvec
*lruvec
,
1448 struct list_head
*list
,
1449 struct list_head
*pages_to_free
,
1452 struct zone
*zone
= lruvec_zone(lruvec
);
1453 unsigned long pgmoved
= 0;
1457 while (!list_empty(list
)) {
1458 page
= lru_to_page(list
);
1459 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
1461 VM_BUG_ON(PageLRU(page
));
1464 nr_pages
= hpage_nr_pages(page
);
1465 mem_cgroup_update_lru_size(lruvec
, lru
, nr_pages
);
1466 list_move(&page
->lru
, &lruvec
->lists
[lru
]);
1467 pgmoved
+= nr_pages
;
1469 if (put_page_testzero(page
)) {
1470 __ClearPageLRU(page
);
1471 __ClearPageActive(page
);
1472 del_page_from_lru_list(page
, lruvec
, lru
);
1474 if (unlikely(PageCompound(page
))) {
1475 spin_unlock_irq(&zone
->lru_lock
);
1476 (*get_compound_page_dtor(page
))(page
);
1477 spin_lock_irq(&zone
->lru_lock
);
1479 list_add(&page
->lru
, pages_to_free
);
1482 __mod_zone_page_state(zone
, NR_LRU_BASE
+ lru
, pgmoved
);
1483 if (!is_active_lru(lru
))
1484 __count_vm_events(PGDEACTIVATE
, pgmoved
);
1487 static void shrink_active_list(unsigned long nr_to_scan
,
1488 struct lruvec
*lruvec
,
1489 struct scan_control
*sc
,
1492 unsigned long nr_taken
;
1493 unsigned long nr_scanned
;
1494 unsigned long vm_flags
;
1495 LIST_HEAD(l_hold
); /* The pages which were snipped off */
1496 LIST_HEAD(l_active
);
1497 LIST_HEAD(l_inactive
);
1499 struct zone_reclaim_stat
*reclaim_stat
= &lruvec
->reclaim_stat
;
1500 unsigned long nr_rotated
= 0;
1501 isolate_mode_t isolate_mode
= 0;
1502 int file
= is_file_lru(lru
);
1503 struct zone
*zone
= lruvec_zone(lruvec
);
1508 isolate_mode
|= ISOLATE_UNMAPPED
;
1509 if (!sc
->may_writepage
)
1510 isolate_mode
|= ISOLATE_CLEAN
;
1512 spin_lock_irq(&zone
->lru_lock
);
1514 nr_taken
= isolate_lru_pages(nr_to_scan
, lruvec
, &l_hold
,
1515 &nr_scanned
, sc
, isolate_mode
, lru
);
1516 if (global_reclaim(sc
))
1517 zone
->pages_scanned
+= nr_scanned
;
1519 reclaim_stat
->recent_scanned
[file
] += nr_taken
;
1521 __count_zone_vm_events(PGREFILL
, zone
, nr_scanned
);
1522 __mod_zone_page_state(zone
, NR_LRU_BASE
+ lru
, -nr_taken
);
1523 __mod_zone_page_state(zone
, NR_ISOLATED_ANON
+ file
, nr_taken
);
1524 spin_unlock_irq(&zone
->lru_lock
);
1526 while (!list_empty(&l_hold
)) {
1528 page
= lru_to_page(&l_hold
);
1529 list_del(&page
->lru
);
1531 if (unlikely(!page_evictable(page
))) {
1532 putback_lru_page(page
);
1536 if (unlikely(buffer_heads_over_limit
)) {
1537 if (page_has_private(page
) && trylock_page(page
)) {
1538 if (page_has_private(page
))
1539 try_to_release_page(page
, 0);
1544 if (page_referenced(page
, 0, sc
->target_mem_cgroup
,
1546 nr_rotated
+= hpage_nr_pages(page
);
1548 * Identify referenced, file-backed active pages and
1549 * give them one more trip around the active list. So
1550 * that executable code get better chances to stay in
1551 * memory under moderate memory pressure. Anon pages
1552 * are not likely to be evicted by use-once streaming
1553 * IO, plus JVM can create lots of anon VM_EXEC pages,
1554 * so we ignore them here.
1556 if ((vm_flags
& VM_EXEC
) && page_is_file_cache(page
)) {
1557 list_add(&page
->lru
, &l_active
);
1562 ClearPageActive(page
); /* we are de-activating */
1563 list_add(&page
->lru
, &l_inactive
);
1567 * Move pages back to the lru list.
1569 spin_lock_irq(&zone
->lru_lock
);
1571 * Count referenced pages from currently used mappings as rotated,
1572 * even though only some of them are actually re-activated. This
1573 * helps balance scan pressure between file and anonymous pages in
1576 reclaim_stat
->recent_rotated
[file
] += nr_rotated
;
1578 move_active_pages_to_lru(lruvec
, &l_active
, &l_hold
, lru
);
1579 move_active_pages_to_lru(lruvec
, &l_inactive
, &l_hold
, lru
- LRU_ACTIVE
);
1580 __mod_zone_page_state(zone
, NR_ISOLATED_ANON
+ file
, -nr_taken
);
1581 spin_unlock_irq(&zone
->lru_lock
);
1583 free_hot_cold_page_list(&l_hold
, 1);
1587 static int inactive_anon_is_low_global(struct zone
*zone
)
1589 unsigned long active
, inactive
;
1591 active
= zone_page_state(zone
, NR_ACTIVE_ANON
);
1592 inactive
= zone_page_state(zone
, NR_INACTIVE_ANON
);
1594 if (inactive
* zone
->inactive_ratio
< active
)
1601 * inactive_anon_is_low - check if anonymous pages need to be deactivated
1602 * @lruvec: LRU vector to check
1604 * Returns true if the zone does not have enough inactive anon pages,
1605 * meaning some active anon pages need to be deactivated.
1607 static int inactive_anon_is_low(struct lruvec
*lruvec
)
1610 * If we don't have swap space, anonymous page deactivation
1613 if (!total_swap_pages
)
1616 if (!mem_cgroup_disabled())
1617 return mem_cgroup_inactive_anon_is_low(lruvec
);
1619 return inactive_anon_is_low_global(lruvec_zone(lruvec
));
1622 static inline int inactive_anon_is_low(struct lruvec
*lruvec
)
1629 * inactive_file_is_low - check if file pages need to be deactivated
1630 * @lruvec: LRU vector to check
1632 * When the system is doing streaming IO, memory pressure here
1633 * ensures that active file pages get deactivated, until more
1634 * than half of the file pages are on the inactive list.
1636 * Once we get to that situation, protect the system's working
1637 * set from being evicted by disabling active file page aging.
1639 * This uses a different ratio than the anonymous pages, because
1640 * the page cache uses a use-once replacement algorithm.
1642 static int inactive_file_is_low(struct lruvec
*lruvec
)
1644 unsigned long inactive
;
1645 unsigned long active
;
1647 inactive
= get_lru_size(lruvec
, LRU_INACTIVE_FILE
);
1648 active
= get_lru_size(lruvec
, LRU_ACTIVE_FILE
);
1650 return active
> inactive
;
1653 static int inactive_list_is_low(struct lruvec
*lruvec
, enum lru_list lru
)
1655 if (is_file_lru(lru
))
1656 return inactive_file_is_low(lruvec
);
1658 return inactive_anon_is_low(lruvec
);
1661 static unsigned long shrink_list(enum lru_list lru
, unsigned long nr_to_scan
,
1662 struct lruvec
*lruvec
, struct scan_control
*sc
)
1664 if (is_active_lru(lru
)) {
1665 if (inactive_list_is_low(lruvec
, lru
))
1666 shrink_active_list(nr_to_scan
, lruvec
, sc
, lru
);
1670 return shrink_inactive_list(nr_to_scan
, lruvec
, sc
, lru
);
1673 static int vmscan_swappiness(struct scan_control
*sc
)
1675 if (global_reclaim(sc
))
1676 return vm_swappiness
;
1677 return mem_cgroup_swappiness(sc
->target_mem_cgroup
);
1689 static int vmscan_swap_file_ratio
= 1;
1690 module_param_named(swap_file_ratio
, vmscan_swap_file_ratio
, int, S_IRUGO
| S_IWUSR
);
1692 #if defined(CONFIG_ZRAM) && defined(CONFIG_MTK_LCA_RAM_OPTIMIZE)
1695 static int vmscan_swap_sum
= 200;
1696 module_param_named(swap_sum
, vmscan_swap_sum
, int, S_IRUGO
| S_IWUSR
);
1699 static int vmscan_scan_file_sum
= 0;
1700 static int vmscan_scan_anon_sum
= 0;
1701 static int vmscan_recent_scanned_anon
= 0;
1702 static int vmscan_recent_scanned_file
= 0;
1703 static int vmscan_recent_rotated_anon
= 0;
1704 static int vmscan_recent_rotated_file
= 0;
1705 module_param_named(scan_file_sum
, vmscan_scan_file_sum
, int, S_IRUGO
);
1706 module_param_named(scan_anon_sum
, vmscan_scan_anon_sum
, int, S_IRUGO
);
1707 module_param_named(recent_scanned_anon
, vmscan_recent_scanned_anon
, int, S_IRUGO
);
1708 module_param_named(recent_scanned_file
, vmscan_recent_scanned_file
, int, S_IRUGO
);
1709 module_param_named(recent_rotated_anon
, vmscan_recent_rotated_anon
, int, S_IRUGO
);
1710 module_param_named(recent_rotated_file
, vmscan_recent_rotated_file
, int, S_IRUGO
);
1711 #endif // CONFIG_ZRAM
1714 #if defined(CONFIG_ZRAM) && defined(CONFIG_MTK_LCA_RAM_OPTIMIZE)
1715 //#define LOGTAG "VMSCAN"
1716 static unsigned long t
=0;
1717 static unsigned long history
[2] = {0};
1718 extern int lowmem_minfree
[9];
1721 #endif // CONFIG_ZRAM
1724 * Determine how aggressively the anon and file LRU lists should be
1725 * scanned. The relative value of each set of LRU lists is determined
1726 * by looking at the fraction of the pages scanned we did rotate back
1727 * onto the active list instead of evict.
1729 * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan
1730 * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan
1732 static void get_scan_count(struct lruvec
*lruvec
, struct scan_control
*sc
,
1735 struct zone_reclaim_stat
*reclaim_stat
= &lruvec
->reclaim_stat
;
1737 u64 denominator
= 0; /* gcc */
1738 struct zone
*zone
= lruvec_zone(lruvec
);
1739 unsigned long anon_prio
, file_prio
;
1740 enum scan_balance scan_balance
;
1741 unsigned long anon
, file
, free
;
1742 bool force_scan
= false;
1743 unsigned long ap
, fp
;
1745 #if defined(CONFIG_ZRAM) && defined(CONFIG_MTK_LCA_RAM_OPTIMIZE)
1747 unsigned long SwapinCount
, SwapoutCount
, cached
;
1748 bool bThrashing
= false;
1752 * If the zone or memcg is small, nr[l] can be 0. This
1753 * results in no scanning on this priority and a potential
1754 * priority drop. Global direct reclaim can go to the next
1755 * zone and tends to have no problems. Global kswapd is for
1756 * zone balancing and it needs to scan a minimum amount. When
1757 * reclaiming for a memcg, a priority drop can cause high
1758 * latencies, so it's better to scan a minimum amount there as
1761 if (current_is_kswapd() && zone
->all_unreclaimable
)
1763 if (!global_reclaim(sc
))
1766 /* If we have no swap space, do not bother scanning anon pages. */
1767 if (!sc
->may_swap
|| (get_nr_swap_pages() <= 0)) {
1768 scan_balance
= SCAN_FILE
;
1773 * Global reclaim will swap to prevent OOM even with no
1774 * swappiness, but memcg users want to use this knob to
1775 * disable swapping for individual groups completely when
1776 * using the memory controller's swap limit feature would be
1779 if (!global_reclaim(sc
) && !vmscan_swappiness(sc
)) {
1780 scan_balance
= SCAN_FILE
;
1785 * Do not apply any pressure balancing cleverness when the
1786 * system is close to OOM, scan both anon and file equally
1787 * (unless the swappiness setting disagrees with swapping).
1789 if (!sc
->priority
&& vmscan_swappiness(sc
)) {
1790 scan_balance
= SCAN_EQUAL
;
1794 anon
= get_lru_size(lruvec
, LRU_ACTIVE_ANON
) +
1795 get_lru_size(lruvec
, LRU_INACTIVE_ANON
);
1796 file
= get_lru_size(lruvec
, LRU_ACTIVE_FILE
) +
1797 get_lru_size(lruvec
, LRU_INACTIVE_FILE
);
1800 * If it's foreseeable that reclaiming the file cache won't be
1801 * enough to get the zone back into a desirable shape, we have
1802 * to swap. Better start now and leave the - probably heavily
1803 * thrashing - remaining file pages alone.
1805 if (global_reclaim(sc
)) {
1806 free
= zone_page_state(zone
, NR_FREE_PAGES
);
1807 if (unlikely(file
+ free
<= high_wmark_pages(zone
))) {
1808 scan_balance
= SCAN_ANON
;
1814 * There is enough inactive page cache, do not reclaim
1815 * anything from the anonymous working set right now.
1817 if (!inactive_file_is_low(lruvec
)) {
1818 scan_balance
= SCAN_FILE
;
1822 scan_balance
= SCAN_FRACT
;
1825 * With swappiness at 100, anonymous and file have the same priority.
1826 * This scanning priority is essentially the inverse of IO cost.
1828 anon_prio
= vmscan_swappiness(sc
);
1829 file_prio
= 200 - anon_prio
;
1832 * With swappiness at 100, anonymous and file have the same priority.
1833 * This scanning priority is essentially the inverse of IO cost.
1835 #if defined(CONFIG_ZRAM) && defined(CONFIG_MTK_LCA_RAM_OPTIMIZE)
1836 if (vmscan_swap_file_ratio
) {
1841 if (time_after(jiffies
, t
+ 1 * HZ
)) {
1843 for_each_online_cpu(cpu
) {
1844 struct vm_event_state
*this = &per_cpu(vm_event_states
, cpu
);
1845 SwapinCount
+= this->event
[PSWPIN
];
1846 SwapoutCount
+= this->event
[PSWPOUT
];
1849 if( ((SwapinCount
-history
[0] + SwapoutCount
- history
[1]) / (jiffies
-t
) * HZ
) > 3000){
1851 //xlog_printk(ANDROID_LOG_ERROR, LOGTAG, "!!! thrashing !!!\n");
1854 //xlog_printk(ANDROID_LOG_WARN, LOGTAG, "!!! NO thrashing !!!\n");
1856 history
[0] = SwapinCount
;
1857 history
[1] = SwapoutCount
;
1865 anon_prio
= (vmscan_swappiness(sc
) * anon
) / (anon
+ file
+ 1);
1866 file_prio
= (vmscan_swap_sum
- vmscan_swappiness(sc
)) * file
/ (anon
+ file
+ 1);
1867 //xlog_printk(ANDROID_LOG_DEBUG, LOGTAG, "1 anon_prio: %d, file_prio: %d \n", anon_prio, file_prio);
1870 cached
= global_page_state(NR_FILE_PAGES
) - global_page_state(NR_SHMEM
) - total_swapcache_pages();
1871 if(cached
> lowmem_minfree
[2]) {
1872 anon_prio
= vmscan_swappiness(sc
);
1873 file_prio
= vmscan_swap_sum
- vmscan_swappiness(sc
);
1874 //xlog_printk(ANDROID_LOG_ERROR, LOGTAG, "2 anon_prio: %d, file_prio: %d \n", anon_prio, file_prio);
1876 anon_prio
= (vmscan_swappiness(sc
) * anon
) / (anon
+ file
+ 1);
1877 file_prio
= (vmscan_swap_sum
- vmscan_swappiness(sc
)) * file
/ (anon
+ file
+ 1);
1878 //xlog_printk(ANDROID_LOG_ERROR, LOGTAG, "3 anon_prio: %d, file_prio: %d \n", anon_prio, file_prio);
1883 anon_prio
= vmscan_swappiness(sc
);
1884 file_prio
= vmscan_swap_sum
- vmscan_swappiness(sc
);
1886 #elif defined(CONFIG_ZRAM) // CONFIG_ZRAM
1887 if (vmscan_swap_file_ratio
) {
1888 anon_prio
= anon_prio
* anon
/ (anon
+ file
+ 1);
1889 file_prio
= file_prio
* file
/ (anon
+ file
+ 1);
1891 #endif // CONFIG_ZRAM
1896 * OK, so we have swap space and a fair amount of page cache
1897 * pages. We use the recently rotated / recently scanned
1898 * ratios to determine how valuable each cache is.
1900 * Because workloads change over time (and to avoid overflow)
1901 * we keep these statistics as a floating average, which ends
1902 * up weighing recent references more than old ones.
1904 * anon in [0], file in [1]
1906 spin_lock_irq(&zone
->lru_lock
);
1907 if (unlikely(reclaim_stat
->recent_scanned
[0] > anon
/ 4)) {
1908 reclaim_stat
->recent_scanned
[0] /= 2;
1909 reclaim_stat
->recent_rotated
[0] /= 2;
1912 if (unlikely(reclaim_stat
->recent_scanned
[1] > file
/ 4)) {
1913 reclaim_stat
->recent_scanned
[1] /= 2;
1914 reclaim_stat
->recent_rotated
[1] /= 2;
1918 * The amount of pressure on anon vs file pages is inversely
1919 * proportional to the fraction of recently scanned pages on
1920 * each list that were recently referenced and in active use.
1922 ap
= anon_prio
* (reclaim_stat
->recent_scanned
[0] + 1);
1923 ap
/= reclaim_stat
->recent_rotated
[0] + 1;
1925 fp
= file_prio
* (reclaim_stat
->recent_scanned
[1] + 1);
1926 fp
/= reclaim_stat
->recent_rotated
[1] + 1;
1927 spin_unlock_irq(&zone
->lru_lock
);
1931 denominator
= ap
+ fp
+ 1;
1933 for_each_evictable_lru(lru
) {
1934 int file
= is_file_lru(lru
);
1938 size
= get_lru_size(lruvec
, lru
);
1939 scan
= size
>> sc
->priority
;
1941 if (!scan
&& force_scan
)
1942 scan
= min(size
, SWAP_CLUSTER_MAX
);
1944 switch (scan_balance
) {
1946 /* Scan lists relative to size */
1950 * Scan types proportional to swappiness and
1951 * their relative recent reclaim efficiency.
1953 scan
= div64_u64(scan
* fraction
[file
], denominator
);
1957 /* Scan one type exclusively */
1958 if ((scan_balance
== SCAN_FILE
) != file
)
1962 /* Look ma, no brain */
1970 * This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
1972 static void shrink_lruvec(struct lruvec
*lruvec
, struct scan_control
*sc
)
1974 unsigned long nr
[NR_LRU_LISTS
];
1975 unsigned long nr_to_scan
;
1977 unsigned long nr_reclaimed
= 0;
1978 unsigned long nr_to_reclaim
= sc
->nr_to_reclaim
;
1979 struct blk_plug plug
;
1981 get_scan_count(lruvec
, sc
, nr
);
1983 blk_start_plug(&plug
);
1984 while (nr
[LRU_INACTIVE_ANON
] || nr
[LRU_ACTIVE_FILE
] ||
1985 nr
[LRU_INACTIVE_FILE
]) {
1986 for_each_evictable_lru(lru
) {
1988 nr_to_scan
= min(nr
[lru
], SWAP_CLUSTER_MAX
);
1989 nr
[lru
] -= nr_to_scan
;
1991 nr_reclaimed
+= shrink_list(lru
, nr_to_scan
,
1996 * On large memory systems, scan >> priority can become
1997 * really large. This is fine for the starting priority;
1998 * we want to put equal scanning pressure on each zone.
1999 * However, if the VM has a harder time of freeing pages,
2000 * with multiple processes reclaiming pages, the total
2001 * freeing target can get unreasonably large.
2003 if (nr_reclaimed
>= nr_to_reclaim
&&
2004 sc
->priority
< DEF_PRIORITY
)
2007 blk_finish_plug(&plug
);
2008 sc
->nr_reclaimed
+= nr_reclaimed
;
2011 * Even if we did not try to evict anon pages at all, we want to
2012 * rebalance the anon lru active/inactive ratio.
2014 if (inactive_anon_is_low(lruvec
))
2015 shrink_active_list(SWAP_CLUSTER_MAX
, lruvec
,
2016 sc
, LRU_ACTIVE_ANON
);
2018 throttle_vm_writeout(sc
->gfp_mask
);
2021 /* Use reclaim/compaction for costly allocs or under memory pressure */
2022 static bool in_reclaim_compaction(struct scan_control
*sc
)
2024 if (IS_ENABLED(CONFIG_COMPACTION
) && sc
->order
&&
2025 (sc
->order
> PAGE_ALLOC_COSTLY_ORDER
||
2026 sc
->priority
< DEF_PRIORITY
- 2))
2033 * Reclaim/compaction is used for high-order allocation requests. It reclaims
2034 * order-0 pages before compacting the zone. should_continue_reclaim() returns
2035 * true if more pages should be reclaimed such that when the page allocator
2036 * calls try_to_compact_zone() that it will have enough free pages to succeed.
2037 * It will give up earlier than that if there is difficulty reclaiming pages.
2039 static inline bool should_continue_reclaim(struct zone
*zone
,
2040 unsigned long nr_reclaimed
,
2041 unsigned long nr_scanned
,
2042 struct scan_control
*sc
)
2044 unsigned long pages_for_compaction
;
2045 unsigned long inactive_lru_pages
;
2047 /* If not in reclaim/compaction mode, stop */
2048 if (!in_reclaim_compaction(sc
))
2051 /* Consider stopping depending on scan and reclaim activity */
2052 if (sc
->gfp_mask
& __GFP_REPEAT
) {
2054 * For __GFP_REPEAT allocations, stop reclaiming if the
2055 * full LRU list has been scanned and we are still failing
2056 * to reclaim pages. This full LRU scan is potentially
2057 * expensive but a __GFP_REPEAT caller really wants to succeed
2059 if (!nr_reclaimed
&& !nr_scanned
)
2063 * For non-__GFP_REPEAT allocations which can presumably
2064 * fail without consequence, stop if we failed to reclaim
2065 * any pages from the last SWAP_CLUSTER_MAX number of
2066 * pages that were scanned. This will return to the
2067 * caller faster at the risk reclaim/compaction and
2068 * the resulting allocation attempt fails
2075 * If we have not reclaimed enough pages for compaction and the
2076 * inactive lists are large enough, continue reclaiming
2078 pages_for_compaction
= (2UL << sc
->order
);
2079 inactive_lru_pages
= zone_page_state(zone
, NR_INACTIVE_FILE
);
2080 if (get_nr_swap_pages() > 0)
2081 inactive_lru_pages
+= zone_page_state(zone
, NR_INACTIVE_ANON
);
2082 if (sc
->nr_reclaimed
< pages_for_compaction
&&
2083 inactive_lru_pages
> pages_for_compaction
)
2086 /* If compaction would go ahead or the allocation would succeed, stop */
2087 switch (compaction_suitable(zone
, sc
->order
)) {
2088 case COMPACT_PARTIAL
:
2089 case COMPACT_CONTINUE
:
2096 static void shrink_zone(struct zone
*zone
, struct scan_control
*sc
)
2098 unsigned long nr_reclaimed
, nr_scanned
;
2101 struct mem_cgroup
*root
= sc
->target_mem_cgroup
;
2102 struct mem_cgroup_reclaim_cookie reclaim
= {
2104 .priority
= sc
->priority
,
2106 struct mem_cgroup
*memcg
;
2108 nr_reclaimed
= sc
->nr_reclaimed
;
2109 nr_scanned
= sc
->nr_scanned
;
2111 memcg
= mem_cgroup_iter(root
, NULL
, &reclaim
);
2113 struct lruvec
*lruvec
;
2115 lruvec
= mem_cgroup_zone_lruvec(zone
, memcg
);
2117 shrink_lruvec(lruvec
, sc
);
2120 * Direct reclaim and kswapd have to scan all memory
2121 * cgroups to fulfill the overall scan target for the
2124 * Limit reclaim, on the other hand, only cares about
2125 * nr_to_reclaim pages to be reclaimed and it will
2126 * retry with decreasing priority if one round over the
2127 * whole hierarchy is not sufficient.
2129 if (!global_reclaim(sc
) &&
2130 sc
->nr_reclaimed
>= sc
->nr_to_reclaim
) {
2131 mem_cgroup_iter_break(root
, memcg
);
2134 memcg
= mem_cgroup_iter(root
, memcg
, &reclaim
);
2137 vmpressure(sc
->gfp_mask
, sc
->target_mem_cgroup
,
2138 sc
->nr_scanned
- nr_scanned
,
2139 sc
->nr_reclaimed
- nr_reclaimed
);
2141 } while (should_continue_reclaim(zone
, sc
->nr_reclaimed
- nr_reclaimed
,
2142 sc
->nr_scanned
- nr_scanned
, sc
));
2145 /* Returns true if compaction should go ahead for a high-order request */
2146 static inline bool compaction_ready(struct zone
*zone
, struct scan_control
*sc
)
2148 unsigned long balance_gap
, watermark
;
2151 /* Do not consider compaction for orders reclaim is meant to satisfy */
2152 if (sc
->order
<= PAGE_ALLOC_COSTLY_ORDER
)
2156 * Compaction takes time to run and there are potentially other
2157 * callers using the pages just freed. Continue reclaiming until
2158 * there is a buffer of free pages available to give compaction
2159 * a reasonable chance of completing and allocating the page
2161 balance_gap
= min(low_wmark_pages(zone
),
2162 (zone
->managed_pages
+ KSWAPD_ZONE_BALANCE_GAP_RATIO
-1) /
2163 KSWAPD_ZONE_BALANCE_GAP_RATIO
);
2164 watermark
= high_wmark_pages(zone
) + balance_gap
+ (2UL << sc
->order
);
2165 watermark_ok
= zone_watermark_ok_safe(zone
, 0, watermark
, 0, 0);
2168 * If compaction is deferred, reclaim up to a point where
2169 * compaction will have a chance of success when re-enabled
2171 if (compaction_deferred(zone
, sc
->order
))
2172 return watermark_ok
;
2174 /* If compaction is not ready to start, keep reclaiming */
2175 if (!compaction_suitable(zone
, sc
->order
))
2178 return watermark_ok
;
2182 * This is the direct reclaim path, for page-allocating processes. We only
2183 * try to reclaim pages from zones which will satisfy the caller's allocation
2186 * We reclaim from a zone even if that zone is over high_wmark_pages(zone).
2188 * a) The caller may be trying to free *extra* pages to satisfy a higher-order
2190 * b) The target zone may be at high_wmark_pages(zone) but the lower zones
2191 * must go *over* high_wmark_pages(zone) to satisfy the `incremental min'
2192 * zone defense algorithm.
2194 * If a zone is deemed to be full of pinned pages then just give it a light
2195 * scan then give up on it.
2197 * This function returns true if a zone is being reclaimed for a costly
2198 * high-order allocation and compaction is ready to begin. This indicates to
2199 * the caller that it should consider retrying the allocation instead of
2202 static bool shrink_zones(struct zonelist
*zonelist
, struct scan_control
*sc
)
2206 unsigned long nr_soft_reclaimed
;
2207 unsigned long nr_soft_scanned
;
2208 bool aborted_reclaim
= false;
2211 * If the number of buffer_heads in the machine exceeds the maximum
2212 * allowed level, force direct reclaim to scan the highmem zone as
2213 * highmem pages could be pinning lowmem pages storing buffer_heads
2215 if (buffer_heads_over_limit
)
2216 sc
->gfp_mask
|= __GFP_HIGHMEM
;
2218 for_each_zone_zonelist_nodemask(zone
, z
, zonelist
,
2219 gfp_zone(sc
->gfp_mask
), sc
->nodemask
) {
2220 if (!populated_zone(zone
))
2223 * Take care memory controller reclaiming has small influence
2226 if (global_reclaim(sc
)) {
2227 if (!cpuset_zone_allowed_hardwall(zone
, GFP_KERNEL
))
2229 if (zone
->all_unreclaimable
&&
2230 sc
->priority
!= DEF_PRIORITY
)
2231 continue; /* Let kswapd poll it */
2232 if (IS_ENABLED(CONFIG_COMPACTION
) && !sc
->hibernation_mode
) {
2234 * If we already have plenty of memory free for
2235 * compaction in this zone, don't free any more.
2236 * Even though compaction is invoked for any
2237 * non-zero order, only frequent costly order
2238 * reclamation is disruptive enough to become a
2239 * noticeable problem, like transparent huge
2242 if (compaction_ready(zone
, sc
)) {
2243 aborted_reclaim
= true;
2248 * This steals pages from memory cgroups over softlimit
2249 * and returns the number of reclaimed pages and
2250 * scanned pages. This works for global memory pressure
2251 * and balancing, not for a memcg's limit.
2253 nr_soft_scanned
= 0;
2254 nr_soft_reclaimed
= mem_cgroup_soft_limit_reclaim(zone
,
2255 sc
->order
, sc
->gfp_mask
,
2257 sc
->nr_reclaimed
+= nr_soft_reclaimed
;
2258 sc
->nr_scanned
+= nr_soft_scanned
;
2259 /* need some check for avoid more shrink_zone() */
2262 shrink_zone(zone
, sc
);
2265 return aborted_reclaim
;
2268 static unsigned long zone_reclaimable_pages(struct zone
*zone
)
2272 nr
= zone_page_state(zone
, NR_ACTIVE_FILE
) +
2273 zone_page_state(zone
, NR_INACTIVE_FILE
);
2275 if (get_nr_swap_pages() > 0)
2276 nr
+= zone_page_state(zone
, NR_ACTIVE_ANON
) +
2277 zone_page_state(zone
, NR_INACTIVE_ANON
);
2282 static bool zone_reclaimable(struct zone
*zone
)
2284 return zone
->pages_scanned
< zone_reclaimable_pages(zone
) * 6;
2287 /* All zones in zonelist are unreclaimable? */
2288 static bool all_unreclaimable(struct zonelist
*zonelist
,
2289 struct scan_control
*sc
)
2294 for_each_zone_zonelist_nodemask(zone
, z
, zonelist
,
2295 gfp_zone(sc
->gfp_mask
), sc
->nodemask
) {
2296 if (!populated_zone(zone
))
2298 if (!cpuset_zone_allowed_hardwall(zone
, GFP_KERNEL
))
2300 if (!zone
->all_unreclaimable
)
2308 * This is the main entry point to direct page reclaim.
2310 * If a full scan of the inactive list fails to free enough memory then we
2311 * are "out of memory" and something needs to be killed.
2313 * If the caller is !__GFP_FS then the probability of a failure is reasonably
2314 * high - the zone may be full of dirty or under-writeback pages, which this
2315 * caller can't do much about. We kick the writeback threads and take explicit
2316 * naps in the hope that some of these pages can be written. But if the
2317 * allocating task holds filesystem locks which prevent writeout this might not
2318 * work, and the allocation attempt will fail.
2320 * returns: 0, if no pages reclaimed
2321 * else, the number of pages reclaimed
2323 static unsigned long do_try_to_free_pages(struct zonelist
*zonelist
,
2324 struct scan_control
*sc
,
2325 struct shrink_control
*shrink
)
2327 unsigned long total_scanned
= 0;
2328 struct reclaim_state
*reclaim_state
= current
->reclaim_state
;
2331 unsigned long writeback_threshold
;
2332 bool aborted_reclaim
;
2334 #ifdef CONFIG_FREEZER
2335 if (unlikely(pm_freezing
&& !sc
->hibernation_mode
))
2339 delayacct_freepages_start();
2341 if (global_reclaim(sc
))
2342 count_vm_event(ALLOCSTALL
);
2345 vmpressure_prio(sc
->gfp_mask
, sc
->target_mem_cgroup
,
2348 aborted_reclaim
= shrink_zones(zonelist
, sc
);
2351 * Don't shrink slabs when reclaiming memory from
2352 * over limit cgroups
2354 if (global_reclaim(sc
)) {
2355 unsigned long lru_pages
= 0;
2356 for_each_zone_zonelist(zone
, z
, zonelist
,
2357 gfp_zone(sc
->gfp_mask
)) {
2358 if (!cpuset_zone_allowed_hardwall(zone
, GFP_KERNEL
))
2361 lru_pages
+= zone_reclaimable_pages(zone
);
2364 shrink_slab(shrink
, sc
->nr_scanned
, lru_pages
);
2365 if (reclaim_state
) {
2366 sc
->nr_reclaimed
+= reclaim_state
->reclaimed_slab
;
2367 reclaim_state
->reclaimed_slab
= 0;
2370 total_scanned
+= sc
->nr_scanned
;
2371 if (sc
->nr_reclaimed
>= sc
->nr_to_reclaim
)
2375 * If we're getting trouble reclaiming, start doing
2376 * writepage even in laptop mode.
2378 if (sc
->priority
< DEF_PRIORITY
- 2)
2379 sc
->may_writepage
= 1;
2382 * Try to write back as many pages as we just scanned. This
2383 * tends to cause slow streaming writers to write data to the
2384 * disk smoothly, at the dirtying rate, which is nice. But
2385 * that's undesirable in laptop mode, where we *want* lumpy
2386 * writeout. So in laptop mode, write out the whole world.
2388 writeback_threshold
= sc
->nr_to_reclaim
+ sc
->nr_to_reclaim
/ 2;
2389 if (total_scanned
> writeback_threshold
) {
2390 wakeup_flusher_threads(laptop_mode
? 0 : total_scanned
,
2391 WB_REASON_TRY_TO_FREE_PAGES
);
2392 sc
->may_writepage
= 1;
2395 /* Take a nap, wait for some writeback to complete */
2396 if (!sc
->hibernation_mode
&& sc
->nr_scanned
&&
2397 sc
->priority
< DEF_PRIORITY
- 2) {
2398 struct zone
*preferred_zone
;
2400 first_zones_zonelist(zonelist
, gfp_zone(sc
->gfp_mask
),
2401 &cpuset_current_mems_allowed
,
2403 wait_iff_congested(preferred_zone
, BLK_RW_ASYNC
, HZ
/10);
2405 } while (--sc
->priority
>= 0);
2408 delayacct_freepages_end();
2410 if (sc
->nr_reclaimed
)
2411 return sc
->nr_reclaimed
;
2414 * As hibernation is going on, kswapd is freezed so that it can't mark
2415 * the zone into all_unreclaimable. Thus bypassing all_unreclaimable
2418 if (oom_killer_disabled
)
2421 /* Aborted reclaim to try compaction? don't OOM, then */
2422 if (aborted_reclaim
)
2425 /* top priority shrink_zones still had more to do? don't OOM, then */
2426 if (global_reclaim(sc
) && !all_unreclaimable(zonelist
, sc
))
2432 static bool pfmemalloc_watermark_ok(pg_data_t
*pgdat
)
2435 unsigned long pfmemalloc_reserve
= 0;
2436 unsigned long free_pages
= 0;
2440 for (i
= 0; i
<= ZONE_NORMAL
; i
++) {
2441 zone
= &pgdat
->node_zones
[i
];
2442 if (!populated_zone(zone
))
2445 pfmemalloc_reserve
+= min_wmark_pages(zone
);
2446 free_pages
+= zone_page_state(zone
, NR_FREE_PAGES
);
2449 /* If there are no reserves (unexpected config) then do not throttle */
2450 if (!pfmemalloc_reserve
)
2453 wmark_ok
= free_pages
> pfmemalloc_reserve
/ 2;
2455 /* kswapd must be awake if processes are being throttled */
2456 if (!wmark_ok
&& waitqueue_active(&pgdat
->kswapd_wait
)) {
2457 pgdat
->classzone_idx
= min(pgdat
->classzone_idx
,
2458 (enum zone_type
)ZONE_NORMAL
);
2459 wake_up_interruptible(&pgdat
->kswapd_wait
);
2466 * Throttle direct reclaimers if backing storage is backed by the network
2467 * and the PFMEMALLOC reserve for the preferred node is getting dangerously
2468 * depleted. kswapd will continue to make progress and wake the processes
2469 * when the low watermark is reached.
2471 * Returns true if a fatal signal was delivered during throttling. If this
2472 * happens, the page allocator should not consider triggering the OOM killer.
2474 static bool throttle_direct_reclaim(gfp_t gfp_mask
, struct zonelist
*zonelist
,
2475 nodemask_t
*nodemask
)
2479 pg_data_t
*pgdat
= NULL
;
2482 * Kernel threads should not be throttled as they may be indirectly
2483 * responsible for cleaning pages necessary for reclaim to make forward
2484 * progress. kjournald for example may enter direct reclaim while
2485 * committing a transaction where throttling it could forcing other
2486 * processes to block on log_wait_commit().
2488 if (current
->flags
& PF_KTHREAD
)
2492 * If a fatal signal is pending, this process should not throttle.
2493 * It should return quickly so it can exit and free its memory
2495 if (fatal_signal_pending(current
))
2499 * Check if the pfmemalloc reserves are ok by finding the first node
2500 * with a usable ZONE_NORMAL or lower zone. The expectation is that
2501 * GFP_KERNEL will be required for allocating network buffers when
2502 * swapping over the network so ZONE_HIGHMEM is unusable.
2504 * Throttling is based on the first usable node and throttled processes
2505 * wait on a queue until kswapd makes progress and wakes them. There
2506 * is an affinity then between processes waking up and where reclaim
2507 * progress has been made assuming the process wakes on the same node.
2508 * More importantly, processes running on remote nodes will not compete
2509 * for remote pfmemalloc reserves and processes on different nodes
2510 * should make reasonable progress.
2512 for_each_zone_zonelist_nodemask(zone
, z
, zonelist
,
2513 gfp_mask
, nodemask
) {
2514 if (zone_idx(zone
) > ZONE_NORMAL
)
2517 /* Throttle based on the first usable node */
2518 pgdat
= zone
->zone_pgdat
;
2519 if (pfmemalloc_watermark_ok(pgdat
))
2524 /* If no zone was usable by the allocation flags then do not throttle */
2528 /* Account for the throttling */
2529 count_vm_event(PGSCAN_DIRECT_THROTTLE
);
2532 * If the caller cannot enter the filesystem, it's possible that it
2533 * is due to the caller holding an FS lock or performing a journal
2534 * transaction in the case of a filesystem like ext[3|4]. In this case,
2535 * it is not safe to block on pfmemalloc_wait as kswapd could be
2536 * blocked waiting on the same lock. Instead, throttle for up to a
2537 * second before continuing.
2539 if (!(gfp_mask
& __GFP_FS
)) {
2540 wait_event_interruptible_timeout(pgdat
->pfmemalloc_wait
,
2541 pfmemalloc_watermark_ok(pgdat
), HZ
);
2546 /* Throttle until kswapd wakes the process */
2547 wait_event_killable(zone
->zone_pgdat
->pfmemalloc_wait
,
2548 pfmemalloc_watermark_ok(pgdat
));
2551 if (fatal_signal_pending(current
))
2558 unsigned long try_to_free_pages(struct zonelist
*zonelist
, int order
,
2559 gfp_t gfp_mask
, nodemask_t
*nodemask
)
2561 unsigned long nr_reclaimed
;
2562 struct scan_control sc
= {
2563 .gfp_mask
= (gfp_mask
= memalloc_noio_flags(gfp_mask
)),
2564 .may_writepage
= !laptop_mode
,
2565 .nr_to_reclaim
= SWAP_CLUSTER_MAX
,
2569 .priority
= DEF_PRIORITY
,
2570 .target_mem_cgroup
= NULL
,
2571 .nodemask
= nodemask
,
2573 struct shrink_control shrink
= {
2574 .gfp_mask
= sc
.gfp_mask
,
2578 * Do not enter reclaim if fatal signal was delivered while throttled.
2579 * 1 is returned so that the page allocator does not OOM kill at this
2582 if (throttle_direct_reclaim(gfp_mask
, zonelist
, nodemask
))
2585 trace_mm_vmscan_direct_reclaim_begin(order
,
2589 nr_reclaimed
= do_try_to_free_pages(zonelist
, &sc
, &shrink
);
2591 trace_mm_vmscan_direct_reclaim_end(nr_reclaimed
);
2593 return nr_reclaimed
;
2598 unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup
*memcg
,
2599 gfp_t gfp_mask
, bool noswap
,
2601 unsigned long *nr_scanned
)
2603 struct scan_control sc
= {
2605 .nr_to_reclaim
= SWAP_CLUSTER_MAX
,
2606 .may_writepage
= !laptop_mode
,
2608 .may_swap
= !noswap
,
2611 .target_mem_cgroup
= memcg
,
2613 struct lruvec
*lruvec
= mem_cgroup_zone_lruvec(zone
, memcg
);
2615 sc
.gfp_mask
= (gfp_mask
& GFP_RECLAIM_MASK
) |
2616 (GFP_HIGHUSER_MOVABLE
& ~GFP_RECLAIM_MASK
);
2618 trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc
.order
,
2623 * NOTE: Although we can get the priority field, using it
2624 * here is not a good idea, since it limits the pages we can scan.
2625 * if we don't reclaim here, the shrink_zone from balance_pgdat
2626 * will pick up pages from other mem cgroup's as well. We hack
2627 * the priority and make it zero.
2629 shrink_lruvec(lruvec
, &sc
);
2631 trace_mm_vmscan_memcg_softlimit_reclaim_end(sc
.nr_reclaimed
);
2633 *nr_scanned
= sc
.nr_scanned
;
2634 return sc
.nr_reclaimed
;
2637 unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup
*memcg
,
2641 struct zonelist
*zonelist
;
2642 unsigned long nr_reclaimed
;
2644 struct scan_control sc
= {
2645 .may_writepage
= !laptop_mode
,
2647 .may_swap
= !noswap
,
2648 .nr_to_reclaim
= SWAP_CLUSTER_MAX
,
2650 .priority
= DEF_PRIORITY
,
2651 .target_mem_cgroup
= memcg
,
2652 .nodemask
= NULL
, /* we don't care the placement */
2653 .gfp_mask
= (gfp_mask
& GFP_RECLAIM_MASK
) |
2654 (GFP_HIGHUSER_MOVABLE
& ~GFP_RECLAIM_MASK
),
2656 struct shrink_control shrink
= {
2657 .gfp_mask
= sc
.gfp_mask
,
2661 * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't
2662 * take care of from where we get pages. So the node where we start the
2663 * scan does not need to be the current node.
2665 nid
= mem_cgroup_select_victim_node(memcg
);
2667 zonelist
= NODE_DATA(nid
)->node_zonelists
;
2669 trace_mm_vmscan_memcg_reclaim_begin(0,
2673 nr_reclaimed
= do_try_to_free_pages(zonelist
, &sc
, &shrink
);
2675 trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed
);
2677 return nr_reclaimed
;
2681 static void age_active_anon(struct zone
*zone
, struct scan_control
*sc
)
2683 struct mem_cgroup
*memcg
;
2685 if (!total_swap_pages
)
2688 memcg
= mem_cgroup_iter(NULL
, NULL
, NULL
);
2690 struct lruvec
*lruvec
= mem_cgroup_zone_lruvec(zone
, memcg
);
2692 if (inactive_anon_is_low(lruvec
))
2693 shrink_active_list(SWAP_CLUSTER_MAX
, lruvec
,
2694 sc
, LRU_ACTIVE_ANON
);
2696 memcg
= mem_cgroup_iter(NULL
, memcg
, NULL
);
2700 static bool zone_balanced(struct zone
*zone
, int order
,
2701 unsigned long balance_gap
, int classzone_idx
)
2703 if (!zone_watermark_ok_safe(zone
, order
, high_wmark_pages(zone
) +
2704 balance_gap
, classzone_idx
, 0))
2707 if (IS_ENABLED(CONFIG_COMPACTION
) && order
&&
2708 !compaction_suitable(zone
, order
))
2715 * pgdat_balanced() is used when checking if a node is balanced.
2717 * For order-0, all zones must be balanced!
2719 * For high-order allocations only zones that meet watermarks and are in a
2720 * zone allowed by the callers classzone_idx are added to balanced_pages. The
2721 * total of balanced pages must be at least 25% of the zones allowed by
2722 * classzone_idx for the node to be considered balanced. Forcing all zones to
2723 * be balanced for high orders can cause excessive reclaim when there are
2725 * The choice of 25% is due to
2726 * o a 16M DMA zone that is balanced will not balance a zone on any
2727 * reasonable sized machine
2728 * o On all other machines, the top zone must be at least a reasonable
2729 * percentage of the middle zones. For example, on 32-bit x86, highmem
2730 * would need to be at least 256M for it to be balance a whole node.
2731 * Similarly, on x86-64 the Normal zone would need to be at least 1G
2732 * to balance a node on its own. These seemed like reasonable ratios.
2734 static bool pgdat_balanced(pg_data_t
*pgdat
, int order
, int classzone_idx
)
2736 unsigned long managed_pages
= 0;
2737 unsigned long balanced_pages
= 0;
2740 /* Check the watermark levels */
2741 for (i
= 0; i
<= classzone_idx
; i
++) {
2742 struct zone
*zone
= pgdat
->node_zones
+ i
;
2744 if (!populated_zone(zone
))
2747 managed_pages
+= zone
->managed_pages
;
2750 * A special case here:
2752 * balance_pgdat() skips over all_unreclaimable after
2753 * DEF_PRIORITY. Effectively, it considers them balanced so
2754 * they must be considered balanced here as well!
2756 if (zone
->all_unreclaimable
) {
2757 balanced_pages
+= zone
->managed_pages
;
2761 if (zone_balanced(zone
, order
, 0, i
))
2762 balanced_pages
+= zone
->managed_pages
;
2768 return balanced_pages
>= (managed_pages
>> 2);
2774 * Prepare kswapd for sleeping. This verifies that there are no processes
2775 * waiting in throttle_direct_reclaim() and that watermarks have been met.
2777 * Returns true if kswapd is ready to sleep
2779 static bool prepare_kswapd_sleep(pg_data_t
*pgdat
, int order
, long remaining
,
2782 /* If a direct reclaimer woke kswapd within HZ/10, it's premature */
2787 * The throttled processes are normally woken up in balance_pgdat() as
2788 * soon as pfmemalloc_watermark_ok() is true. But there is a potential
2789 * race between when kswapd checks the watermarks and a process gets
2790 * throttled. There is also a potential race if processes get
2791 * throttled, kswapd wakes, a large process exits thereby balancing the
2792 * zones, which causes kswapd to exit balance_pgdat() before reaching
2793 * the wake up checks. If kswapd is going to sleep, no process should
2794 * be sleeping on pfmemalloc_wait, so wake them now if necessary. If
2795 * the wake up is premature, processes will wake kswapd and get
2796 * throttled again. The difference from wake ups in balance_pgdat() is
2797 * that here we are under prepare_to_wait().
2799 if (waitqueue_active(&pgdat
->pfmemalloc_wait
))
2800 wake_up_all(&pgdat
->pfmemalloc_wait
);
2802 return pgdat_balanced(pgdat
, order
, classzone_idx
);
2806 * For kswapd, balance_pgdat() will work across all this node's zones until
2807 * they are all at high_wmark_pages(zone).
2809 * Returns the final order kswapd was reclaiming at
2811 * There is special handling here for zones which are full of pinned pages.
2812 * This can happen if the pages are all mlocked, or if they are all used by
2813 * device drivers (say, ZONE_DMA). Or if they are all in use by hugetlb.
2814 * What we do is to detect the case where all pages in the zone have been
2815 * scanned twice and there has been zero successful reclaim. Mark the zone as
2816 * dead and from now on, only perform a short scan. Basically we're polling
2817 * the zone for when the problem goes away.
2819 * kswapd scans the zones in the highmem->normal->dma direction. It skips
2820 * zones which have free_pages > high_wmark_pages(zone), but once a zone is
2821 * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the
2822 * lower zones regardless of the number of free pages in the lower zones. This
2823 * interoperates with the page allocator fallback scheme to ensure that aging
2824 * of pages is balanced across the zones.
2826 static unsigned long balance_pgdat(pg_data_t
*pgdat
, int order
,
2829 bool pgdat_is_balanced
= false;
2831 int end_zone
= 0; /* Inclusive. 0 = ZONE_DMA */
2832 struct reclaim_state
*reclaim_state
= current
->reclaim_state
;
2833 unsigned long nr_soft_reclaimed
;
2834 unsigned long nr_soft_scanned
;
2835 struct scan_control sc
= {
2836 .gfp_mask
= GFP_KERNEL
,
2840 * kswapd doesn't want to be bailed out while reclaim. because
2841 * we want to put equal scanning pressure on each zone.
2843 .nr_to_reclaim
= ULONG_MAX
,
2845 .target_mem_cgroup
= NULL
,
2847 struct shrink_control shrink
= {
2848 .gfp_mask
= sc
.gfp_mask
,
2851 sc
.priority
= DEF_PRIORITY
;
2852 sc
.nr_reclaimed
= 0;
2853 sc
.may_writepage
= !laptop_mode
;
2854 count_vm_event(PAGEOUTRUN
);
2857 unsigned long lru_pages
= 0;
2860 * Scan in the highmem->dma direction for the highest
2861 * zone which needs scanning
2863 for (i
= pgdat
->nr_zones
- 1; i
>= 0; i
--) {
2864 struct zone
*zone
= pgdat
->node_zones
+ i
;
2866 if (!populated_zone(zone
))
2869 if (zone
->all_unreclaimable
&&
2870 sc
.priority
!= DEF_PRIORITY
)
2874 * Do some background aging of the anon list, to give
2875 * pages a chance to be referenced before reclaiming.
2877 age_active_anon(zone
, &sc
);
2880 * If the number of buffer_heads in the machine
2881 * exceeds the maximum allowed level and this node
2882 * has a highmem zone, force kswapd to reclaim from
2883 * it to relieve lowmem pressure.
2885 if (buffer_heads_over_limit
&& is_highmem_idx(i
)) {
2890 if (!zone_balanced(zone
, order
, 0, 0)) {
2894 /* If balanced, clear the congested flag */
2895 zone_clear_flag(zone
, ZONE_CONGESTED
);
2900 pgdat_is_balanced
= true;
2904 for (i
= 0; i
<= end_zone
; i
++) {
2905 struct zone
*zone
= pgdat
->node_zones
+ i
;
2907 lru_pages
+= zone_reclaimable_pages(zone
);
2911 * Now scan the zone in the dma->highmem direction, stopping
2912 * at the last zone which needs scanning.
2914 * We do this because the page allocator works in the opposite
2915 * direction. This prevents the page allocator from allocating
2916 * pages behind kswapd's direction of progress, which would
2917 * cause too much scanning of the lower zones.
2919 for (i
= 0; i
<= end_zone
; i
++) {
2920 struct zone
*zone
= pgdat
->node_zones
+ i
;
2921 int nr_slab
, testorder
;
2922 unsigned long balance_gap
;
2924 if (!populated_zone(zone
))
2927 if (zone
->all_unreclaimable
&&
2928 sc
.priority
!= DEF_PRIORITY
)
2933 nr_soft_scanned
= 0;
2935 * Call soft limit reclaim before calling shrink_zone.
2937 nr_soft_reclaimed
= mem_cgroup_soft_limit_reclaim(zone
,
2940 sc
.nr_reclaimed
+= nr_soft_reclaimed
;
2943 * We put equal pressure on every zone, unless
2944 * one zone has way too many pages free
2945 * already. The "too many pages" is defined
2946 * as the high wmark plus a "gap" where the
2947 * gap is either the low watermark or 1%
2948 * of the zone, whichever is smaller.
2950 balance_gap
= min(low_wmark_pages(zone
),
2951 (zone
->managed_pages
+
2952 KSWAPD_ZONE_BALANCE_GAP_RATIO
-1) /
2953 KSWAPD_ZONE_BALANCE_GAP_RATIO
);
2955 * Kswapd reclaims only single pages with compaction
2956 * enabled. Trying too hard to reclaim until contiguous
2957 * free pages have become available can hurt performance
2958 * by evicting too much useful data from memory.
2959 * Do not reclaim more than needed for compaction.
2962 if (IS_ENABLED(CONFIG_COMPACTION
) && order
&&
2963 compaction_suitable(zone
, order
) !=
2967 if ((buffer_heads_over_limit
&& is_highmem_idx(i
)) ||
2968 !zone_balanced(zone
, testorder
,
2969 balance_gap
, end_zone
)) {
2970 shrink_zone(zone
, &sc
);
2972 reclaim_state
->reclaimed_slab
= 0;
2973 nr_slab
= shrink_slab(&shrink
, sc
.nr_scanned
, lru_pages
);
2974 sc
.nr_reclaimed
+= reclaim_state
->reclaimed_slab
;
2976 if (nr_slab
== 0 && !zone_reclaimable(zone
))
2977 zone
->all_unreclaimable
= 1;
2981 * If we're getting trouble reclaiming, start doing
2982 * writepage even in laptop mode.
2984 if (sc
.priority
< DEF_PRIORITY
- 2)
2985 sc
.may_writepage
= 1;
2987 if (zone
->all_unreclaimable
) {
2988 if (end_zone
&& end_zone
== i
)
2993 if (zone_balanced(zone
, testorder
, 0, end_zone
))
2995 * If a zone reaches its high watermark,
2996 * consider it to be no longer congested. It's
2997 * possible there are dirty pages backed by
2998 * congested BDIs but as pressure is relieved,
2999 * speculatively avoid congestion waits
3001 zone_clear_flag(zone
, ZONE_CONGESTED
);
3005 * If the low watermark is met there is no need for processes
3006 * to be throttled on pfmemalloc_wait as they should not be
3007 * able to safely make forward progress. Wake them
3009 if (waitqueue_active(&pgdat
->pfmemalloc_wait
) &&
3010 pfmemalloc_watermark_ok(pgdat
))
3011 wake_up(&pgdat
->pfmemalloc_wait
);
3013 if (pgdat_balanced(pgdat
, order
, *classzone_idx
)) {
3014 pgdat_is_balanced
= true;
3015 break; /* kswapd: all done */
3019 * We do this so kswapd doesn't build up large priorities for
3020 * example when it is freeing in parallel with allocators. It
3021 * matches the direct reclaim path behaviour in terms of impact
3022 * on zone->*_priority.
3024 if (sc
.nr_reclaimed
>= SWAP_CLUSTER_MAX
)
3026 } while (--sc
.priority
>= 0);
3029 if (!pgdat_is_balanced
) {
3035 * Fragmentation may mean that the system cannot be
3036 * rebalanced for high-order allocations in all zones.
3037 * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX,
3038 * it means the zones have been fully scanned and are still
3039 * not balanced. For high-order allocations, there is
3040 * little point trying all over again as kswapd may
3043 * Instead, recheck all watermarks at order-0 as they
3044 * are the most important. If watermarks are ok, kswapd will go
3045 * back to sleep. High-order users can still perform direct
3046 * reclaim if they wish.
3048 if (sc
.nr_reclaimed
< SWAP_CLUSTER_MAX
)
3049 order
= sc
.order
= 0;
3055 * If kswapd was reclaiming at a higher order, it has the option of
3056 * sleeping without all zones being balanced. Before it does, it must
3057 * ensure that the watermarks for order-0 on *all* zones are met and
3058 * that the congestion flags are cleared. The congestion flag must
3059 * be cleared as kswapd is the only mechanism that clears the flag
3060 * and it is potentially going to sleep here.
3063 int zones_need_compaction
= 1;
3065 for (i
= 0; i
<= end_zone
; i
++) {
3066 struct zone
*zone
= pgdat
->node_zones
+ i
;
3068 if (!populated_zone(zone
))
3071 /* Check if the memory needs to be defragmented. */
3072 if (zone_watermark_ok(zone
, order
,
3073 low_wmark_pages(zone
), *classzone_idx
, 0))
3074 zones_need_compaction
= 0;
3077 if (zones_need_compaction
)
3078 compact_pgdat(pgdat
, order
);
3082 * Return the order we were reclaiming at so prepare_kswapd_sleep()
3083 * makes a decision on the order we were last reclaiming at. However,
3084 * if another caller entered the allocator slow path while kswapd
3085 * was awake, order will remain at the higher level
3087 *classzone_idx
= end_zone
;
3091 static void kswapd_try_to_sleep(pg_data_t
*pgdat
, int order
, int classzone_idx
)
3096 if (freezing(current
) || kthread_should_stop())
3099 prepare_to_wait(&pgdat
->kswapd_wait
, &wait
, TASK_INTERRUPTIBLE
);
3101 /* Try to sleep for a short interval */
3102 if (prepare_kswapd_sleep(pgdat
, order
, remaining
, classzone_idx
)) {
3103 remaining
= schedule_timeout(HZ
/10);
3104 finish_wait(&pgdat
->kswapd_wait
, &wait
);
3105 prepare_to_wait(&pgdat
->kswapd_wait
, &wait
, TASK_INTERRUPTIBLE
);
3109 * After a short sleep, check if it was a premature sleep. If not, then
3110 * go fully to sleep until explicitly woken up.
3112 if (prepare_kswapd_sleep(pgdat
, order
, remaining
, classzone_idx
)) {
3113 trace_mm_vmscan_kswapd_sleep(pgdat
->node_id
);
3116 * vmstat counters are not perfectly accurate and the estimated
3117 * value for counters such as NR_FREE_PAGES can deviate from the
3118 * true value by nr_online_cpus * threshold. To avoid the zone
3119 * watermarks being breached while under pressure, we reduce the
3120 * per-cpu vmstat threshold while kswapd is awake and restore
3121 * them before going back to sleep.
3123 set_pgdat_percpu_threshold(pgdat
, calculate_normal_threshold
);
3126 * Compaction records what page blocks it recently failed to
3127 * isolate pages from and skips them in the future scanning.
3128 * When kswapd is going to sleep, it is reasonable to assume
3129 * that pages and compaction may succeed so reset the cache.
3131 reset_isolation_suitable(pgdat
);
3133 if (!kthread_should_stop())
3136 set_pgdat_percpu_threshold(pgdat
, calculate_pressure_threshold
);
3139 count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY
);
3141 count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY
);
3143 finish_wait(&pgdat
->kswapd_wait
, &wait
);
3147 * The background pageout daemon, started as a kernel thread
3148 * from the init process.
3150 * This basically trickles out pages so that we have _some_
3151 * free memory available even if there is no other activity
3152 * that frees anything up. This is needed for things like routing
3153 * etc, where we otherwise might have all activity going on in
3154 * asynchronous contexts that cannot page things out.
3156 * If there are applications that are active memory-allocators
3157 * (most normal use), this basically shouldn't matter.
3159 static int kswapd(void *p
)
3161 unsigned long order
, new_order
;
3162 unsigned balanced_order
;
3163 int classzone_idx
, new_classzone_idx
;
3164 int balanced_classzone_idx
;
3165 pg_data_t
*pgdat
= (pg_data_t
*)p
;
3166 struct task_struct
*tsk
= current
;
3168 struct reclaim_state reclaim_state
= {
3169 .reclaimed_slab
= 0,
3171 const struct cpumask
*cpumask
= cpumask_of_node(pgdat
->node_id
);
3173 lockdep_set_current_reclaim_state(GFP_KERNEL
);
3175 if (!cpumask_empty(cpumask
))
3176 set_cpus_allowed_ptr(tsk
, cpumask
);
3177 current
->reclaim_state
= &reclaim_state
;
3180 * Tell the memory management that we're a "memory allocator",
3181 * and that if we need more memory we should get access to it
3182 * regardless (see "__alloc_pages()"). "kswapd" should
3183 * never get caught in the normal page freeing logic.
3185 * (Kswapd normally doesn't need memory anyway, but sometimes
3186 * you need a small amount of memory in order to be able to
3187 * page out something else, and this flag essentially protects
3188 * us from recursively trying to free more memory as we're
3189 * trying to free the first piece of memory in the first place).
3191 tsk
->flags
|= PF_MEMALLOC
| PF_SWAPWRITE
| PF_KSWAPD
;
3194 order
= new_order
= 0;
3196 classzone_idx
= new_classzone_idx
= pgdat
->nr_zones
- 1;
3197 balanced_classzone_idx
= classzone_idx
;
3202 * If the last balance_pgdat was unsuccessful it's unlikely a
3203 * new request of a similar or harder type will succeed soon
3204 * so consider going to sleep on the basis we reclaimed at
3206 if (balanced_classzone_idx
>= new_classzone_idx
&&
3207 balanced_order
== new_order
) {
3208 new_order
= pgdat
->kswapd_max_order
;
3209 new_classzone_idx
= pgdat
->classzone_idx
;
3210 pgdat
->kswapd_max_order
= 0;
3211 pgdat
->classzone_idx
= pgdat
->nr_zones
- 1;
3214 if (order
< new_order
|| classzone_idx
> new_classzone_idx
) {
3216 * Don't sleep if someone wants a larger 'order'
3217 * allocation or has tigher zone constraints
3220 classzone_idx
= new_classzone_idx
;
3222 kswapd_try_to_sleep(pgdat
, balanced_order
,
3223 balanced_classzone_idx
);
3224 order
= pgdat
->kswapd_max_order
;
3225 classzone_idx
= pgdat
->classzone_idx
;
3227 new_classzone_idx
= classzone_idx
;
3228 pgdat
->kswapd_max_order
= 0;
3229 pgdat
->classzone_idx
= pgdat
->nr_zones
- 1;
3232 ret
= try_to_freeze();
3233 if (kthread_should_stop())
3237 * We can speed up thawing tasks if we don't call balance_pgdat
3238 * after returning from the refrigerator
3241 trace_mm_vmscan_kswapd_wake(pgdat
->node_id
, order
);
3242 balanced_classzone_idx
= classzone_idx
;
3243 balanced_order
= balance_pgdat(pgdat
, order
,
3244 &balanced_classzone_idx
);
3248 tsk
->flags
&= ~(PF_MEMALLOC
| PF_SWAPWRITE
| PF_KSWAPD
);
3249 current
->reclaim_state
= NULL
;
3250 lockdep_clear_current_reclaim_state();
3256 * A zone is low on free memory, so wake its kswapd task to service it.
3258 void wakeup_kswapd(struct zone
*zone
, int order
, enum zone_type classzone_idx
)
3262 if (!populated_zone(zone
))
3265 #ifdef CONFIG_FREEZER
3270 if (!cpuset_zone_allowed_hardwall(zone
, GFP_KERNEL
))
3272 pgdat
= zone
->zone_pgdat
;
3273 if (pgdat
->kswapd_max_order
< order
) {
3274 pgdat
->kswapd_max_order
= order
;
3275 pgdat
->classzone_idx
= min(pgdat
->classzone_idx
, classzone_idx
);
3277 if (!waitqueue_active(&pgdat
->kswapd_wait
))
3279 if (zone_watermark_ok_safe(zone
, order
, low_wmark_pages(zone
), 0, 0))
3282 trace_mm_vmscan_wakeup_kswapd(pgdat
->node_id
, zone_idx(zone
), order
);
3283 wake_up_interruptible(&pgdat
->kswapd_wait
);
3286 #ifdef CONFIG_HIBERNATION
3288 * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of
3291 * Rather than trying to age LRUs the aim is to preserve the overall
3292 * LRU order by reclaiming preferentially
3293 * inactive > active > active referenced > active mapped
3295 unsigned long shrink_memory_mask(unsigned long nr_to_reclaim
, gfp_t mask
)
3297 struct reclaim_state reclaim_state
;
3298 struct scan_control sc
= {
3303 .nr_to_reclaim
= nr_to_reclaim
,
3304 .hibernation_mode
= 1,
3306 .priority
= DEF_PRIORITY
,
3308 struct shrink_control shrink
= {
3309 .gfp_mask
= sc
.gfp_mask
,
3311 struct zonelist
*zonelist
= node_zonelist(numa_node_id(), sc
.gfp_mask
);
3312 struct task_struct
*p
= current
;
3313 unsigned long nr_reclaimed
;
3315 p
->flags
|= PF_MEMALLOC
;
3316 lockdep_set_current_reclaim_state(sc
.gfp_mask
);
3317 reclaim_state
.reclaimed_slab
= 0;
3318 p
->reclaim_state
= &reclaim_state
;
3320 nr_reclaimed
= do_try_to_free_pages(zonelist
, &sc
, &shrink
);
3322 p
->reclaim_state
= NULL
;
3323 lockdep_clear_current_reclaim_state();
3324 p
->flags
&= ~PF_MEMALLOC
;
3326 return nr_reclaimed
;
3328 EXPORT_SYMBOL_GPL(shrink_memory_mask
);
3330 #ifdef CONFIG_MTKPASR
3331 extern void shrink_mtkpasr_all(void);
3333 #define shrink_mtkpasr_all() do {} while (0)
3335 unsigned long shrink_all_memory(unsigned long nr_to_reclaim
)
3337 shrink_mtkpasr_all();
3338 return shrink_memory_mask(nr_to_reclaim
, GFP_HIGHUSER_MOVABLE
);
3340 EXPORT_SYMBOL_GPL(shrink_all_memory
);
3341 #endif /* CONFIG_HIBERNATION */
3343 /* It's optimal to keep kswapds on the same CPUs as their memory, but
3344 not required for correctness. So if the last cpu in a node goes
3345 away, we get changed to run anywhere: as the first one comes back,
3346 restore their cpu bindings. */
3347 static int cpu_callback(struct notifier_block
*nfb
, unsigned long action
,
3352 if (action
== CPU_ONLINE
|| action
== CPU_ONLINE_FROZEN
) {
3353 for_each_node_state(nid
, N_MEMORY
) {
3354 pg_data_t
*pgdat
= NODE_DATA(nid
);
3355 const struct cpumask
*mask
;
3357 mask
= cpumask_of_node(pgdat
->node_id
);
3359 if (cpumask_any_and(cpu_online_mask
, mask
) < nr_cpu_ids
)
3360 /* One of our CPUs online: restore mask */
3361 set_cpus_allowed_ptr(pgdat
->kswapd
, mask
);
3368 * This kswapd start function will be called by init and node-hot-add.
3369 * On node-hot-add, kswapd will moved to proper cpus if cpus are hot-added.
3371 int kswapd_run(int nid
)
3373 pg_data_t
*pgdat
= NODE_DATA(nid
);
3379 pgdat
->kswapd
= kthread_run(kswapd
, pgdat
, "kswapd%d", nid
);
3380 if (IS_ERR(pgdat
->kswapd
)) {
3381 /* failure at boot is fatal */
3382 BUG_ON(system_state
== SYSTEM_BOOTING
);
3383 pr_err("Failed to start kswapd on node %d\n", nid
);
3384 ret
= PTR_ERR(pgdat
->kswapd
);
3385 pgdat
->kswapd
= NULL
;
3391 * Called by memory hotplug when all memory in a node is offlined. Caller must
3392 * hold lock_memory_hotplug().
3394 void kswapd_stop(int nid
)
3396 struct task_struct
*kswapd
= NODE_DATA(nid
)->kswapd
;
3399 kthread_stop(kswapd
);
3400 NODE_DATA(nid
)->kswapd
= NULL
;
3404 static int __init
kswapd_init(void)
3409 for_each_node_state(nid
, N_MEMORY
)
3411 hotcpu_notifier(cpu_callback
, 0);
3415 module_init(kswapd_init
)
3421 * If non-zero call zone_reclaim when the number of free pages falls below
3424 int zone_reclaim_mode __read_mostly
;
3426 #define RECLAIM_OFF 0
3427 #define RECLAIM_ZONE (1<<0) /* Run shrink_inactive_list on the zone */
3428 #define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */
3429 #define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */
3432 * Priority for ZONE_RECLAIM. This determines the fraction of pages
3433 * of a node considered for each zone_reclaim. 4 scans 1/16th of
3436 #define ZONE_RECLAIM_PRIORITY 4
3439 * Percentage of pages in a zone that must be unmapped for zone_reclaim to
3442 int sysctl_min_unmapped_ratio
= 1;
3445 * If the number of slab pages in a zone grows beyond this percentage then
3446 * slab reclaim needs to occur.
3448 int sysctl_min_slab_ratio
= 5;
3450 static inline unsigned long zone_unmapped_file_pages(struct zone
*zone
)
3452 unsigned long file_mapped
= zone_page_state(zone
, NR_FILE_MAPPED
);
3453 unsigned long file_lru
= zone_page_state(zone
, NR_INACTIVE_FILE
) +
3454 zone_page_state(zone
, NR_ACTIVE_FILE
);
3457 * It's possible for there to be more file mapped pages than
3458 * accounted for by the pages on the file LRU lists because
3459 * tmpfs pages accounted for as ANON can also be FILE_MAPPED
3461 return (file_lru
> file_mapped
) ? (file_lru
- file_mapped
) : 0;
3464 /* Work out how many page cache pages we can reclaim in this reclaim_mode */
3465 static long zone_pagecache_reclaimable(struct zone
*zone
)
3467 long nr_pagecache_reclaimable
;
3471 * If RECLAIM_SWAP is set, then all file pages are considered
3472 * potentially reclaimable. Otherwise, we have to worry about
3473 * pages like swapcache and zone_unmapped_file_pages() provides
3476 if (zone_reclaim_mode
& RECLAIM_SWAP
)
3477 nr_pagecache_reclaimable
= zone_page_state(zone
, NR_FILE_PAGES
);
3479 nr_pagecache_reclaimable
= zone_unmapped_file_pages(zone
);
3481 /* If we can't clean pages, remove dirty pages from consideration */
3482 if (!(zone_reclaim_mode
& RECLAIM_WRITE
))
3483 delta
+= zone_page_state(zone
, NR_FILE_DIRTY
);
3485 /* Watch for any possible underflows due to delta */
3486 if (unlikely(delta
> nr_pagecache_reclaimable
))
3487 delta
= nr_pagecache_reclaimable
;
3489 return nr_pagecache_reclaimable
- delta
;
3493 * Try to free up some pages from this zone through reclaim.
3495 static int __zone_reclaim(struct zone
*zone
, gfp_t gfp_mask
, unsigned int order
)
3497 /* Minimum pages needed in order to stay on node */
3498 const unsigned long nr_pages
= 1 << order
;
3499 struct task_struct
*p
= current
;
3500 struct reclaim_state reclaim_state
;
3501 struct scan_control sc
= {
3502 .may_writepage
= !!(zone_reclaim_mode
& RECLAIM_WRITE
),
3503 .may_unmap
= !!(zone_reclaim_mode
& RECLAIM_SWAP
),
3505 .nr_to_reclaim
= max(nr_pages
, SWAP_CLUSTER_MAX
),
3506 .gfp_mask
= (gfp_mask
= memalloc_noio_flags(gfp_mask
)),
3508 .priority
= ZONE_RECLAIM_PRIORITY
,
3510 struct shrink_control shrink
= {
3511 .gfp_mask
= sc
.gfp_mask
,
3513 unsigned long nr_slab_pages0
, nr_slab_pages1
;
3517 * We need to be able to allocate from the reserves for RECLAIM_SWAP
3518 * and we also need to be able to write out pages for RECLAIM_WRITE
3521 p
->flags
|= PF_MEMALLOC
| PF_SWAPWRITE
;
3522 lockdep_set_current_reclaim_state(gfp_mask
);
3523 reclaim_state
.reclaimed_slab
= 0;
3524 p
->reclaim_state
= &reclaim_state
;
3526 if (zone_pagecache_reclaimable(zone
) > zone
->min_unmapped_pages
) {
3528 * Free memory by calling shrink zone with increasing
3529 * priorities until we have enough memory freed.
3532 shrink_zone(zone
, &sc
);
3533 } while (sc
.nr_reclaimed
< nr_pages
&& --sc
.priority
>= 0);
3536 nr_slab_pages0
= zone_page_state(zone
, NR_SLAB_RECLAIMABLE
);
3537 if (nr_slab_pages0
> zone
->min_slab_pages
) {
3539 * shrink_slab() does not currently allow us to determine how
3540 * many pages were freed in this zone. So we take the current
3541 * number of slab pages and shake the slab until it is reduced
3542 * by the same nr_pages that we used for reclaiming unmapped
3545 * Note that shrink_slab will free memory on all zones and may
3549 unsigned long lru_pages
= zone_reclaimable_pages(zone
);
3551 /* No reclaimable slab or very low memory pressure */
3552 if (!shrink_slab(&shrink
, sc
.nr_scanned
, lru_pages
))
3555 /* Freed enough memory */
3556 nr_slab_pages1
= zone_page_state(zone
,
3557 NR_SLAB_RECLAIMABLE
);
3558 if (nr_slab_pages1
+ nr_pages
<= nr_slab_pages0
)
3563 * Update nr_reclaimed by the number of slab pages we
3564 * reclaimed from this zone.
3566 nr_slab_pages1
= zone_page_state(zone
, NR_SLAB_RECLAIMABLE
);
3567 if (nr_slab_pages1
< nr_slab_pages0
)
3568 sc
.nr_reclaimed
+= nr_slab_pages0
- nr_slab_pages1
;
3571 p
->reclaim_state
= NULL
;
3572 current
->flags
&= ~(PF_MEMALLOC
| PF_SWAPWRITE
);
3573 lockdep_clear_current_reclaim_state();
3574 return sc
.nr_reclaimed
>= nr_pages
;
3577 int zone_reclaim(struct zone
*zone
, gfp_t gfp_mask
, unsigned int order
)
3583 * Zone reclaim reclaims unmapped file backed pages and
3584 * slab pages if we are over the defined limits.
3586 * A small portion of unmapped file backed pages is needed for
3587 * file I/O otherwise pages read by file I/O will be immediately
3588 * thrown out if the zone is overallocated. So we do not reclaim
3589 * if less than a specified percentage of the zone is used by
3590 * unmapped file backed pages.
3592 if (zone_pagecache_reclaimable(zone
) <= zone
->min_unmapped_pages
&&
3593 zone_page_state(zone
, NR_SLAB_RECLAIMABLE
) <= zone
->min_slab_pages
)
3594 return ZONE_RECLAIM_FULL
;
3596 if (zone
->all_unreclaimable
)
3597 return ZONE_RECLAIM_FULL
;
3600 * Do not scan if the allocation should not be delayed.
3602 if (!(gfp_mask
& __GFP_WAIT
) || (current
->flags
& PF_MEMALLOC
))
3603 return ZONE_RECLAIM_NOSCAN
;
3606 * Only run zone reclaim on the local zone or on zones that do not
3607 * have associated processors. This will favor the local processor
3608 * over remote processors and spread off node memory allocations
3609 * as wide as possible.
3611 node_id
= zone_to_nid(zone
);
3612 if (node_state(node_id
, N_CPU
) && node_id
!= numa_node_id())
3613 return ZONE_RECLAIM_NOSCAN
;
3615 if (zone_test_and_set_flag(zone
, ZONE_RECLAIM_LOCKED
))
3616 return ZONE_RECLAIM_NOSCAN
;
3618 ret
= __zone_reclaim(zone
, gfp_mask
, order
);
3619 zone_clear_flag(zone
, ZONE_RECLAIM_LOCKED
);
3622 count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED
);
3629 * page_evictable - test whether a page is evictable
3630 * @page: the page to test
3632 * Test whether page is evictable--i.e., should be placed on active/inactive
3633 * lists vs unevictable list.
3635 * Reasons page might not be evictable:
3636 * (1) page's mapping marked unevictable
3637 * (2) page is part of an mlocked VMA
3640 int page_evictable(struct page
*page
)
3642 return !mapping_unevictable(page_mapping(page
)) && !PageMlocked(page
);
3647 * check_move_unevictable_pages - check pages for evictability and move to appropriate zone lru list
3648 * @pages: array of pages to check
3649 * @nr_pages: number of pages to check
3651 * Checks pages for evictability and moves them to the appropriate lru list.
3653 * This function is only used for SysV IPC SHM_UNLOCK.
3655 void check_move_unevictable_pages(struct page
**pages
, int nr_pages
)
3657 struct lruvec
*lruvec
;
3658 struct zone
*zone
= NULL
;
3663 for (i
= 0; i
< nr_pages
; i
++) {
3664 struct page
*page
= pages
[i
];
3665 struct zone
*pagezone
;
3668 pagezone
= page_zone(page
);
3669 if (pagezone
!= zone
) {
3671 spin_unlock_irq(&zone
->lru_lock
);
3673 spin_lock_irq(&zone
->lru_lock
);
3675 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
3677 if (!PageLRU(page
) || !PageUnevictable(page
))
3680 if (page_evictable(page
)) {
3681 enum lru_list lru
= page_lru_base_type(page
);
3683 VM_BUG_ON(PageActive(page
));
3684 ClearPageUnevictable(page
);
3685 del_page_from_lru_list(page
, lruvec
, LRU_UNEVICTABLE
);
3686 add_page_to_lru_list(page
, lruvec
, lru
);
3692 __count_vm_events(UNEVICTABLE_PGRESCUED
, pgrescued
);
3693 __count_vm_events(UNEVICTABLE_PGSCANNED
, pgscanned
);
3694 spin_unlock_irq(&zone
->lru_lock
);
3697 #endif /* CONFIG_SHMEM */
3699 static void warn_scan_unevictable_pages(void)
3701 printk_once(KERN_WARNING
3702 "%s: The scan_unevictable_pages sysctl/node-interface has been "
3703 "disabled for lack of a legitimate use case. If you have "
3704 "one, please send an email to linux-mm@kvack.org.\n",
3709 * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of
3710 * all nodes' unevictable lists for evictable pages
3712 unsigned long scan_unevictable_pages
;
3714 int scan_unevictable_handler(struct ctl_table
*table
, int write
,
3715 void __user
*buffer
,
3716 size_t *length
, loff_t
*ppos
)
3718 warn_scan_unevictable_pages();
3719 proc_doulongvec_minmax(table
, write
, buffer
, length
, ppos
);
3720 scan_unevictable_pages
= 0;
3726 * per node 'scan_unevictable_pages' attribute. On demand re-scan of
3727 * a specified node's per zone unevictable lists for evictable pages.
3730 static ssize_t
read_scan_unevictable_node(struct device
*dev
,
3731 struct device_attribute
*attr
,
3734 warn_scan_unevictable_pages();
3735 return sprintf(buf
, "0\n"); /* always zero; should fit... */
3738 static ssize_t
write_scan_unevictable_node(struct device
*dev
,
3739 struct device_attribute
*attr
,
3740 const char *buf
, size_t count
)
3742 warn_scan_unevictable_pages();
3747 static DEVICE_ATTR(scan_unevictable_pages
, S_IRUGO
| S_IWUSR
,
3748 read_scan_unevictable_node
,
3749 write_scan_unevictable_node
);
3751 int scan_unevictable_register_node(struct node
*node
)
3753 return device_create_file(&node
->dev
, &dev_attr_scan_unevictable_pages
);
3756 void scan_unevictable_unregister_node(struct node
*node
)
3758 device_remove_file(&node
->dev
, &dev_attr_scan_unevictable_pages
);
3762 #ifdef CONFIG_MTKPASR
3763 void try_to_shrink_slab(void)
3765 struct shrinker
*shrinker
;
3766 struct shrink_control shrink
= {
3767 .gfp_mask
= GFP_KERNEL
|__GFP_HIGHMEM
,
3770 if (!down_read_trylock(&shrinker_rwsem
)) {
3774 list_for_each_entry(shrinker
, &shrinker_list
, list
) {
3779 num_objs
= do_shrinker_shrink(shrinker
, &shrink
, 0);
3785 shrink_ret
= do_shrinker_shrink(shrinker
, &shrink
, num_objs
);
3786 if (shrink_ret
== -1)
3789 num_objs
= do_shrinker_shrink(shrinker
, &shrink
, 0);
3795 up_read(&shrinker_rwsem
);
3798 extern void free_hot_cold_page(struct page
*page
, int cold
);
3799 /* Isolate pages for PASR */
3800 #ifdef CONFIG_MTKPASR_ALLEXTCOMP
3801 int mtkpasr_isolate_page(struct page
*page
, int check_swap
)
3803 int mtkpasr_isolate_page(struct page
*page
)
3806 struct zone
*zone
= page_zone(page
);
3807 struct lruvec
*lruvec
;
3808 unsigned long flags
;
3809 isolate_mode_t mode
= ISOLATE_ASYNC_MIGRATE
;
3811 /* Lock this zone - USE trylock version! */
3812 if (!spin_trylock_irqsave(&zone
->lru_lock
, flags
)) {
3813 printk(KERN_ALERT
"\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n");
3814 printk(KERN_ALERT
"[%s][%d] Failed to lock this zone!\n",__FUNCTION__
,__LINE__
);
3815 printk(KERN_ALERT
"\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n");
3819 #ifdef CONFIG_MTKPASR_ALLEXTCOMP
3820 /* Check whether we should handle SwapBacked, SwapCache pages */
3822 if (PageSwapBacked(page
) || PageSwapCache(page
)) {
3823 spin_unlock_irqrestore(&zone
->lru_lock
, flags
);
3829 /* Try to isolate this page */
3830 if (__isolate_lru_page(page
, mode
) != 0) {
3831 spin_unlock_irqrestore(&zone
->lru_lock
, flags
);
3835 /* Successfully isolated */
3836 lruvec
= mem_cgroup_page_lruvec(page
, zone
);
3837 del_page_from_lru_list(page
, lruvec
, page_lru(page
));
3839 /* Unlock this zone */
3840 spin_unlock_irqrestore(&zone
->lru_lock
, flags
);
3845 /* Drop page (in File/Anon LRUs) (Imitate the behavior of shrink_page_list) */
3846 /* If returns error, caller needs to putback page by itself. */
3847 int mtkpasr_drop_page(struct page
*page
)
3850 unsigned long vm_flags
= 0x0;
3851 bool active
= false;
3852 struct address_space
*mapping
;
3853 enum ttu_flags unmap_flags
= TTU_UNMAP
;
3855 /* Suitable scan control */
3856 struct scan_control sc
= {
3857 .gfp_mask
= GFP_KERNEL
,
3858 .order
= PAGE_ALLOC_COSTLY_ORDER
+ 1,
3859 //.reclaim_mode = RECLAIM_MODE_SINGLE|RECLAIM_MODE_SYNC, // We only handle "SwapBacked" pages in this reclaim_mode!
3862 /* Try to isolate this page */
3863 #ifdef CONFIG_MTKPASR_ALLEXTCOMP
3864 ret
= mtkpasr_isolate_page(page
, 0x1);
3866 ret
= mtkpasr_isolate_page(page
);
3872 /* Check whether it is evictable! */
3873 if (unlikely(!page_evictable(page
))) {
3874 putback_lru_page(page
);
3878 /* If it is Active, reference and deactivate it */
3879 if (PageActive(page
)) {
3880 active
= TestClearPageActive(page
);
3883 /* If we fail to lock this page, ignore it */
3884 if (!trylock_page(page
)) {
3888 /* If page is in writeback, we don't handle it here! */
3889 if (PageWriteback(page
)) {
3894 * Anonymous process memory has backing store?
3895 * Try to allocate it some swap space here.
3897 if (PageAnon(page
) && !PageSwapCache(page
)) {
3898 /* Check whether we have enough free memory */
3899 if (vm_swap_full()) {
3903 /* Ok! It is safe to add this page to swap. */
3904 if (!add_to_swap(page
, NULL
)){
3909 /* We don't handle dirty file cache here (Related devices may be suspended) */
3910 if (page_is_file_cache(page
)) {
3911 /* How do we handle pages in VM_EXEC vmas? */
3912 if ((vm_flags
& VM_EXEC
)) {
3915 /* We don't handle dirty file pages! */
3916 if (PageDirty(page
)) {
3917 #ifdef CONFIG_MTKPASR_DEBUG
3918 printk(KERN_ALERT
"\n\n\n\n\n\n [%s][%d]\n\n\n\n\n\n",__FUNCTION__
,__LINE__
);
3925 * The page is mapped into the page tables of one or more
3926 * processes. Try to unmap it here.
3928 mapping
= page_mapping(page
);
3929 if (page_mapped(page
) && mapping
) {
3931 /* Indicate unmap action for SwapBacked pages */
3932 if (PageSwapBacked(page
)) {
3933 unmap_flags
|= TTU_IGNORE_ACCESS
;
3937 switch (try_to_unmap(page
, unmap_flags
)) {
3939 /* try to free the page below */
3951 /* Check whether it is dirtied.
3952 * We have filtered out dirty file pages above. (IMPORTANT!)
3953 * "VM_BUG_ON(!PageSwapBacked(page))"
3955 if (PageDirty(page
)) {
3956 /* Page is dirty, try to write it out here */
3957 /* It's ok for zram swap! */
3958 /* Should we need to apply GFP_IOFS? */
3959 switch (pageout(page
, mapping
, &sc
)) {
3961 if (PageWriteback(page
)) {
3964 if (PageDirty(page
)) {
3969 * A synchronous write - probably a ramdisk. Go
3970 * ahead and try to reclaim the page.
3972 if (!trylock_page(page
)) {
3975 if (PageDirty(page
) || PageWriteback(page
)) {
3978 mapping
= page_mapping(page
);
3980 /* try to free the page below */
3983 #ifdef CONFIG_MTKPASR_DEBUG
3984 /*printk(KERN_ALERT "\n\n\n\n\n\n [%s][%d]\n\n\n\n\n\n",__FUNCTION__,__LINE__);*/
3990 /* Release buffer */
3991 if (page_has_private(page
)) {
3992 if (!try_to_release_page(page
, sc
.gfp_mask
)) {
3995 if (!mapping
&& page_count(page
) == 1) {
3997 if (put_page_testzero(page
)) {
4001 printk(KERN_ALERT
"\n\n\n\n\n\n [%s][%d] RACE!!\n\n\n\n\n\n",__FUNCTION__
,__LINE__
);
4006 if (!mapping
|| !__remove_mapping(mapping
, page
)) {
4010 __clear_page_locked(page
);
4013 free_hot_cold_page(page
, 0);
4020 if (PageSwapCache(page
))
4021 try_to_free_swap(page
);
4027 /* Activate it again if needed! */
4029 SetPageActive(page
);
4031 /* We don't putback them to corresponding LRUs, because we want to do more tasks outside this function!
4032 putback_lru_page(page); */
4034 /* Failedly dropped pages. Do migration! */