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Commit 5f93ad67 authored by Roman Gushchin's avatar Roman Gushchin Committed by Linus Torvalds
Browse files

mm: treat memory.low value inclusive 

If memcg's usage is equal to the memory.low value, avoid reclaiming from
this cgroup while there is a surplus of reclaimable memory.

This sounds more logical and also matches memory.high and memory.max
behavior: both are inclusive.

Empty cgroups are not considered protected, so MEMCG_LOW events are not
emitted for empty cgroups, if there is no more reclaimable memory in the
system.

Link: http://lkml.kernel.org/r/20180406122132.GA7185@castle


Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 23067153

mm/memcontrol.c

+3 −3
Original line number Diff line number Diff line
@@ -5344,14 +5344,14 @@ struct cgroup_subsys memory_cgrp_subsys = { 
};



/**

 * mem_cgroup_low - check if memory consumption is below the normal range

 * mem_cgroup_low - check if memory consumption is in the normal range

 * @root: the top ancestor of the sub-tree being checked

 * @memcg: the memory cgroup to check

 *

 * WARNING: This function is not stateless! It can only be used as part

 *          of a top-down tree iteration, not for isolated queries.

 *

 * Returns %true if memory consumption of @memcg is below the normal range.

 * Returns %true if memory consumption of @memcg is in the normal range.

 *

 * @root is exclusive; it is never low when looked at directly

 *
@@ -5445,7 +5445,7 @@ bool mem_cgroup_low(struct mem_cgroup *root, struct mem_cgroup *memcg) 
	elow = min(elow, parent_elow * low_usage / siblings_low_usage);

exit:

	memcg->memory.elow = elow;

	return usage < elow;

	return usage && usage <= elow;

}



/**