From: Roman Gushchin <guro@fb.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Kernel Team <Kernel-team@fb.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH] mm: memcg/slab: wait for !root kmem_cache refcnt killing on root kmem_cache destruction
Date: Wed, 27 Nov 2019 17:27:29 +0000 [thread overview]
Message-ID: <20191127172724.GA67742@localhost.localdomain> (raw)
In-Reply-To: <20191127123225.GR20912@dhcp22.suse.cz>
On Wed, Nov 27, 2019 at 01:32:25PM +0100, Michal Hocko wrote:
> On Tue 26-11-19 18:41:41, Roman Gushchin wrote:
> > On Tue, Nov 26, 2019 at 10:29:18AM +0100, Michal Hocko wrote:
> > > On Mon 25-11-19 10:54:53, Roman Gushchin wrote:
> [...]
> > > > So in a rare case when not all children kmem_caches are destroyed
> > > > at the moment when the root kmem_cache is about to be gone, we need
> > > > to wait another rcu grace period before destroying the root
> > > > kmem_cache.
> > >
> > > Could you explain how rare this really is please?
> >
> > It seems that we don't destroy root kmem_caches with enabled memcg
> > accounting that often, but maybe I'm biased here.
>
> So this happens each time a root kmem_cache is destroyed? Which would
> imply that only dynamically created ones?
Yes, only dynamically created and only in those cases when destruction
of the root cache happens immediately after the deactivation of the
non-root cache. Tbh I can't imagine any other case except rmmod after
removing the cgroup.
Thanks!
next prev parent reply other threads:[~2019-11-27 17:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-25 18:54 [PATCH] mm: memcg/slab: wait for !root kmem_cache refcnt killing on root kmem_cache destruction Roman Gushchin
2019-11-25 19:20 ` Shakeel Butt
2019-11-26 9:29 ` Michal Hocko
2019-11-26 9:33 ` Christian Borntraeger
2019-11-26 18:41 ` Roman Gushchin
2019-11-27 12:32 ` Michal Hocko
2019-11-27 17:27 ` Roman Gushchin [this message]
2019-11-28 9:43 ` Michal Hocko
2019-11-29 2:28 ` Roman Gushchin
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