[PATCH v10 16/16] memcg: flush memcg items upon memcg destruction
From: Glauber Costa <hidden>
Date: 2013-07-07 15:57:37
Also in:
linux-fsdevel, linux-mm
Subsystem:
control group - memory resource controller (memcg), memory management, the rest · Maintainers:
Johannes Weiner, Michal Hocko, Roman Gushchin, Shakeel Butt, Andrew Morton, Linus Torvalds
When a memcg is destroyed, it won't be imediately released until all objects are gone. This means that if a memcg is restarted with the very same workload - a very common case, the objects already cached won't be billed to the new memcg. This is mostly undesirable since a container can exploit this by restarting itself every time it reaches its limit, and then coming up again with a fresh new limit. Since now we have targeted reclaim, I sustain that we should assume that a memcg that is destroyed should be flushed away. It makes perfect sense if we assume that a memcg that goes away most likely indicates an isolated workload that is terminated. Signed-off-by: Glauber Costa <redacted> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <redacted> Cc: Hugh Dickins <hughd@google.com> Cc: Kamezawa Hiroyuki <redacted> --- mm/memcontrol.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e2dc89c..90173bc 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c@@ -6310,10 +6310,27 @@ static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss) static void kmem_cgroup_css_offline(struct mem_cgroup *memcg) { + int ret; if (!memcg_kmem_is_active(memcg)) return; /* + * When a memcg is destroyed, it won't be imediately released until all + * objects are gone. This means that if a memcg is restarted with the + * very same workload - a very common case, the objects already cached + * won't be billed to the new memcg. This is mostly undesirable since a + * container can exploit this by restarting itself every time it + * reaches its limit, and then coming up again with a fresh new limit. + * + * Therefore a memcg that is destroyed should be flushed away. It makes + * perfect sense if we assume that a memcg that goes away indicates an + * isolated workload that is terminated. + */ + do { + ret = try_to_free_mem_cgroup_kmem(memcg, GFP_KERNEL); + } while (ret); + + /* * kmem charges can outlive the cgroup. In the case of slab * pages, for instance, a page contain objects from various * processes. As we prevent from taking a reference for every
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1.8.2.1