Commit 66a3bf90 authored Oct 30, 2021 by Muchun Song Committed by Zheng Zengkai Oct 30, 2021

mm: memcontrol: change ug->dummy_page only if memcg changed

mainline inclusion
from mainline-v5.13-rc1
commit 7ab345a8
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4C0GB
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7ab345a8973017c89a1be87b6c8722d1fee1fd95

----------------------------------------------------------------------

Just like assignment to ug->memcg, we only need to update ug->dummy_page
if memcg changed.  So move it to there.  This is a very small
optimization.

Link: https://lkml.kernel.org/r/20210319163821.20704-5-songmuchun@bytedance.com


Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Chen Huang <chenhuang5@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Chen Wandun <chenwandun@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>

parent 1abb5714

mm/memcontrol.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -7049,6 +7049,7 @@ static void uncharge_page(struct page page, struct uncharge_gather ug)
		uncharge_gather_clear(ug);
		}
		ug->memcg = page_memcg(page);
		ug->dummy_page = page;

		/* pairs with css_put in uncharge_batch */
		css_get(&ug->memcg->css);
		@@ -7062,7 +7063,6 @@ static void uncharge_page(struct page page, struct uncharge_gather ug)
		else
		ug->pgpgout++;

		ug->dummy_page = page;
		page->memcg_data = 0;
		css_put(&ug->memcg->css);
		}