When a cgroup directory is removed, the memory cgroup subsys state does not disappear immediately. Instead, it's left hanging around until the last reference to it is gone, which implies reclaiming all pages from its lruvec. In the unified hierarchy, there's the memory.low knob, which can be used to set a best-effort protection for a memory cgroup - the reclaimer first scans those cgroups whose consumption is above memory.low, and only if it fails to reclaim enough pages, it gets to the rest. Currently this protection is not reset when the cgroup directory is removed. As a result, if a dead memory cgroup has a lot of page cache charged to it and a high value of memory.low, it will result in higher pressure exerted on live cgroups, and userspace will have no ways to detect such consumers and reconfigure memory.low properly. To fix this, let's reset memory.low on css offline. Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> --- mm/memcontrol.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index ae8b81c55685..ab7bfe870c7d 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4214,6 +4214,8 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) memcg_offline_kmem(memcg); wb_memcg_offline(memcg); + + memcg->low = 0; } static void mem_cgroup_css_released(struct cgroup_subsys_state *css) -- 2.1.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>