Messages in this thread | | | Date | Thu, 27 Jul 2017 16:47:55 +0200 | From | Michal Hocko <> | Subject | Re: [PATCH 1/2] mm, memcg: reset memory.low during memcg offlining |
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On Thu 27-07-17 14:04:27, Roman Gushchin wrote: > A removed memory cgroup with a defined memory.low and some belonging > pagecache has very low chances to be freed. > > If a cgroup has been removed, there is likely no memory pressure inside > the cgroup, and the pagecache is protected from the external pressure > by the defined low limit. The cgroup will be freed only after > the reclaim of all belonging pages. And it will not happen until > there are any reclaimable memory in the system. That means, > there is a good chance, that a cold pagecache will reside > in the memory for an undefined amount of time, wasting > system resources. > > This problem was fixed earlier by commit fa06235b8eb0 > ("cgroup: reset css on destruction"), but it's not a best way > to do it, as we can't really reset all limits/counters during > cgroup offlining. > > Signed-off-by: Roman Gushchin <guro@fb.com> > Cc: Vladimir Davydov <vdavydov.dev@gmail.com> > Cc: Tejun Heo <tj@kernel.org> > Cc: Johannes Weiner <hannes@cmpxchg.org> > Cc: Michal Hocko <mhocko@kernel.org> > Cc: kernel-team@fb.com > Cc: cgroups@vger.kernel.org > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org
my ack for this patch still holds. Acked-by: Michal Hocko <mhocko@suse.com>
> --- > mm/memcontrol.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index d61133e6af99..7b24210596ea 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -4300,6 +4300,8 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) > } > spin_unlock(&memcg->event_list_lock); > > + memcg->low = 0; > + > memcg_offline_kmem(memcg); > wb_memcg_offline(memcg); > > -- > 2.13.3
-- Michal Hocko SUSE Labs
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