![Mel Gorman](/assets/img/avatar_default.png)
The number of LRU pages, dirty pages and writeback pages must be
accounted for on both zones and nodes because of the reclaim retry
logic, compaction retry logic and highmem calculations all depending on
per-zone stats.
Many lowmem allocations are immune from OOM kill due to a check in
__alloc_pages_may_oom for (ac->high_zoneidx < ZONE_NORMAL) since commit
03668b3ceb
("oom: avoid oom killer for lowmem allocations"). The
exception is costly high-order allocations or allocations that cannot
fail. If the __alloc_pages_may_oom avoids OOM-kill for low-order lowmem
allocations then it would fall through to __alloc_pages_direct_compact.
This patch will blindly retry reclaim for zone-constrained allocations
in should_reclaim_retry up to MAX_RECLAIM_RETRIES. This is not ideal
but without per-zone stats there are not many alternatives. The impact
it that zone-constrained allocations may delay before considering the
OOM killer.
As there is no guarantee enough memory can ever be freed to satisfy
compaction, this patch avoids retrying compaction for zone-contrained
allocations.
In combination, that means that the per-node stats can be used when
deciding whether to continue reclaim using a rough approximation. While
it is possible this will make the wrong decision on occasion, it will
not infinite loop as the number of reclaim attempts is capped by
MAX_RECLAIM_RETRIES.
The final step is calculating the number of dirtyable highmem pages. As
those calculations only care about the global count of file pages in
highmem. This patch uses a global counter used instead of per-zone
stats as it is sufficient.
In combination, this allows the per-zone LRU and dirty state counters to
be removed.
[mgorman@techsingularity.net: fix acct_highmem_file_pages()]
Link: http://lkml.kernel.org/r/1468853426-12858-4-git-send-email-mgorman@techsingularity.netLink: http://lkml.kernel.org/r/1467970510-21195-35-git-send-email-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Suggested by: Michal Hocko <mhocko@kernel.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
139 lines
3.5 KiB
C
139 lines
3.5 KiB
C
#ifndef LINUX_MM_INLINE_H
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#define LINUX_MM_INLINE_H
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#include <linux/huge_mm.h>
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#include <linux/swap.h>
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#ifdef CONFIG_HIGHMEM
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extern atomic_t highmem_file_pages;
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static inline void acct_highmem_file_pages(int zid, enum lru_list lru,
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int nr_pages)
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{
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if (is_highmem_idx(zid) && is_file_lru(lru))
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atomic_add(nr_pages, &highmem_file_pages);
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}
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#else
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static inline void acct_highmem_file_pages(int zid, enum lru_list lru,
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int nr_pages)
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{
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}
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#endif
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/**
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* page_is_file_cache - should the page be on a file LRU or anon LRU?
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* @page: the page to test
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*
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* Returns 1 if @page is page cache page backed by a regular filesystem,
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* or 0 if @page is anonymous, tmpfs or otherwise ram or swap backed.
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* Used by functions that manipulate the LRU lists, to sort a page
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* onto the right LRU list.
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*
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* We would like to get this info without a page flag, but the state
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* needs to survive until the page is last deleted from the LRU, which
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* could be as far down as __page_cache_release.
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*/
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static inline int page_is_file_cache(struct page *page)
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{
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return !PageSwapBacked(page);
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}
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static __always_inline void __update_lru_size(struct lruvec *lruvec,
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enum lru_list lru, enum zone_type zid,
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int nr_pages)
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{
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struct pglist_data *pgdat = lruvec_pgdat(lruvec);
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__mod_node_page_state(pgdat, NR_LRU_BASE + lru, nr_pages);
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acct_highmem_file_pages(zid, lru, nr_pages);
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}
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static __always_inline void update_lru_size(struct lruvec *lruvec,
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enum lru_list lru, enum zone_type zid,
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int nr_pages)
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{
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#ifdef CONFIG_MEMCG
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mem_cgroup_update_lru_size(lruvec, lru, zid, nr_pages);
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#else
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__update_lru_size(lruvec, lru, zid, nr_pages);
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#endif
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}
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static __always_inline void add_page_to_lru_list(struct page *page,
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struct lruvec *lruvec, enum lru_list lru)
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{
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update_lru_size(lruvec, lru, page_zonenum(page), hpage_nr_pages(page));
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list_add(&page->lru, &lruvec->lists[lru]);
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}
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static __always_inline void del_page_from_lru_list(struct page *page,
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struct lruvec *lruvec, enum lru_list lru)
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{
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list_del(&page->lru);
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update_lru_size(lruvec, lru, page_zonenum(page), -hpage_nr_pages(page));
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}
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/**
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* page_lru_base_type - which LRU list type should a page be on?
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* @page: the page to test
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*
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* Used for LRU list index arithmetic.
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*
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* Returns the base LRU type - file or anon - @page should be on.
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*/
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static inline enum lru_list page_lru_base_type(struct page *page)
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{
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if (page_is_file_cache(page))
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return LRU_INACTIVE_FILE;
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return LRU_INACTIVE_ANON;
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}
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/**
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* page_off_lru - which LRU list was page on? clearing its lru flags.
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* @page: the page to test
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*
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* Returns the LRU list a page was on, as an index into the array of LRU
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* lists; and clears its Unevictable or Active flags, ready for freeing.
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*/
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static __always_inline enum lru_list page_off_lru(struct page *page)
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{
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enum lru_list lru;
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if (PageUnevictable(page)) {
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__ClearPageUnevictable(page);
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lru = LRU_UNEVICTABLE;
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} else {
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lru = page_lru_base_type(page);
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if (PageActive(page)) {
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__ClearPageActive(page);
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lru += LRU_ACTIVE;
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}
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}
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return lru;
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}
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/**
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* page_lru - which LRU list should a page be on?
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* @page: the page to test
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*
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* Returns the LRU list a page should be on, as an index
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* into the array of LRU lists.
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*/
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static __always_inline enum lru_list page_lru(struct page *page)
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{
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enum lru_list lru;
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if (PageUnevictable(page))
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lru = LRU_UNEVICTABLE;
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else {
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lru = page_lru_base_type(page);
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if (PageActive(page))
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lru += LRU_ACTIVE;
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}
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return lru;
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}
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#define lru_to_page(head) (list_entry((head)->prev, struct page, lru))
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#endif
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