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memcg: fix behavior of mem_cgroup_resize_limit()

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commit 108b6a7846 upstream.

Commit 22a668d7c3 ("memcg: fix behavior under memory.limit equals to
memsw.limit") introduced "memsw_is_minimum" flag, which becomes true
when mem_limit == memsw_limit.  The flag is checked at the beginning of
reclaim, and "noswap" is set if the flag is true, because using swap is
meaningless in this case.

This works well in most cases, but when we try to shrink mem_limit,
which is the same as memsw_limit now, we might fail to shrink mem_limit
because swap doesn't used.

This patch fixes this behavior by:
 - check MEM_CGROUP_RECLAIM_SHRINK at the begining of reclaim
 - If it is set, don't set "noswap" flag even if memsw_is_minimum is true.

Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <bsingharora@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Daisuke Nishimura 2011-07-26 16:08:25 -07:00 • committed by Greg Kroah-Hartman
commit a6f0411fbd
1 changed files with 1 additions and 1 deletions
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2
mm/memcontrol.c
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@ -1730,7 +1730,7 @@ static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
excess = res_counter_soft_limit_excess(&root_mem->res) >> PAGE_SHIFT;
/* If memsw_is_minimum==1, swap-out is of-no-use. */
if (!check_soft && root_mem->memsw_is_minimum)
if (!check_soft && !shrink && root_mem->memsw_is_minimum)
noswap = true;
while (1) {