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BACKPORT: mm: remove superfluous __ClearPageActive()

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To activate a page, mark_page_accessed() always holds a reference on it.
It either gets a new reference when adding a page to
lru_pvecs.activate_page or reuses an existing one it previously got when
it added a page to lru_pvecs.lru_add.  So it doesn't call SetPageActive()
on a page that doesn't have any reference left.  Therefore, the race is
impossible these days (I didn't brother to dig into its history).

For other paths, namely reclaim and migration, a reference count is always
held while calling SetPageActive() on a page.

SetPageSlabPfmemalloc() also uses SetPageActive(), but it's irrelevant to
LRU pages.

Signed-off-by: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Link: http://lkml.kernel.org/r/20200818184704.3625199-2-yuzhao@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 6f4dd8de4835563de9bae797ce1d7a13465a7a7d)
Bug: 228114874
Change-Id: Ie432a8580024926fe9d0fa18eeb5a31b23593b21
Signed-off-by: azrim <mirzaspc@gmail.com>
This commit is contained in:
Yu Zhao 2020-07-18 01:46:37 -06:00 committed by azrim
parent 367332e909
commit 83d218260d
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GPG Key ID: 497F8FB059B45D1C
2 changed files with 0 additions and 4 deletions
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2
kernel/memremap.c
View File

@ -539,8 +539,6 @@ void put_zone_device_private_or_public_page(struct page *page)
* holds a reference on the page.
*/
if (count == 1) {
/* Clear Active bit in case of parallel mark_page_accessed */
__ClearPageActive(page);
__ClearPageWaiters(page);
page->mapping = NULL;

2
mm/swap.c
View File

@ -807,8 +807,6 @@ void release_pages(struct page **pages, int nr, bool cold)
del_page_from_lru_list(page, lruvec, page_off_lru(page));
}
/* Clear Active bit in case of parallel mark_page_accessed */
__ClearPageActive(page);
__ClearPageWaiters(page);
list_add(&page->lru, &pages_to_free);