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From: Michal Hocko <mhocko@kernel.org>
To: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Petr Mladek <pmladek@suse.com>,
	cgroups@vger.kernel.org, Cyril Hrubis <chrubis@suse.cz>,
	linux-kernel@vger.kernel.org
Subject: Re: [BUG] cgroup/workques/fork: deadlock when moving cgroups
Date: Sun, 17 Apr 2016 08:00:55 -0400	[thread overview]
Message-ID: <20160417120053.GB21757@dhcp22.suse.cz> (raw)
In-Reply-To: <20160415152526.GJ12583@htj.duckdns.org>

On Fri 15-04-16 11:25:26, Tejun Heo wrote:
> Hello,

Hi,

> On Fri, Apr 15, 2016 at 05:08:15PM +0200, Michal Hocko wrote:
[...]
> > Well it certainly is not that trivial because it relies on being
> > exclusive with global context. I will have to look closer of course but
> > I cannot guarantee I will get to it before I get back from LSF. We can
> > certainly discuss that at the conference. Johannes will be there as
> > well.
> 
> I see.  For cpuset, it didn't really matter but what we can do is
> creating a mechanism on cgroup core side which is called after a
> migration operation is done after dropping the usual locks and
> guarantees that no new migration will be started before the callbacks
> finish.  If we have that, relocating charge moving outside the attach
> path should be pretty trivial, right?

Yeah, I guess this should work as well. I would have to double check the
code, I cannot say it would be my favorite so I might have forgot some
subtle details.
-- 
Michal Hocko
SUSE Labs

WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
	Petr Mladek <pmladek-IBi9RG/b67k@public.gmane.org>,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Cyril Hrubis <chrubis-AlSwsSmVLrQ@public.gmane.org>,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [BUG] cgroup/workques/fork: deadlock when moving cgroups
Date: Sun, 17 Apr 2016 08:00:55 -0400	[thread overview]
Message-ID: <20160417120053.GB21757@dhcp22.suse.cz> (raw)
In-Reply-To: <20160415152526.GJ12583-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>

On Fri 15-04-16 11:25:26, Tejun Heo wrote:
> Hello,

Hi,

> On Fri, Apr 15, 2016 at 05:08:15PM +0200, Michal Hocko wrote:
[...]
> > Well it certainly is not that trivial because it relies on being
> > exclusive with global context. I will have to look closer of course but
> > I cannot guarantee I will get to it before I get back from LSF. We can
> > certainly discuss that at the conference. Johannes will be there as
> > well.
> 
> I see.  For cpuset, it didn't really matter but what we can do is
> creating a mechanism on cgroup core side which is called after a
> migration operation is done after dropping the usual locks and
> guarantees that no new migration will be started before the callbacks
> finish.  If we have that, relocating charge moving outside the attach
> path should be pretty trivial, right?

Yeah, I guess this should work as well. I would have to double check the
code, I cannot say it would be my favorite so I might have forgot some
subtle details.
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2016-04-17 12:01 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-13  9:42 [BUG] cgroup/workques/fork: deadlock when moving cgroups Petr Mladek
2016-04-13 18:33 ` Tejun Heo
2016-04-13 18:33   ` Tejun Heo
2016-04-13 18:57   ` Tejun Heo
2016-04-13 18:57     ` Tejun Heo
2016-04-13 19:23   ` Michal Hocko
2016-04-13 19:23     ` Michal Hocko
2016-04-13 19:28     ` Michal Hocko
2016-04-13 19:28       ` Michal Hocko
2016-04-13 19:37     ` Tejun Heo
2016-04-13 19:48       ` Michal Hocko
2016-04-14  7:06         ` Michal Hocko
2016-04-14  7:06           ` Michal Hocko
2016-04-14 15:32           ` Tejun Heo
2016-04-14 15:32             ` Tejun Heo
2016-04-14 17:50     ` Johannes Weiner
2016-04-15  7:06       ` Michal Hocko
2016-04-15 14:38         ` Tejun Heo
2016-04-15 14:38           ` Tejun Heo
2016-04-15 15:08           ` Michal Hocko
2016-04-15 15:08             ` Michal Hocko
2016-04-15 15:25             ` Tejun Heo
2016-04-15 15:25               ` Tejun Heo
2016-04-17 12:00               ` Michal Hocko [this message]
2016-04-17 12:00                 ` Michal Hocko
2016-04-18 14:40           ` Petr Mladek
2016-04-18 14:40             ` Petr Mladek
2016-04-19 14:01             ` Michal Hocko
2016-04-19 14:01               ` Michal Hocko
2016-04-19 15:39               ` Petr Mladek
2016-04-15 19:17       ` [PATCH for-4.6-fixes] memcg: remove lru_add_drain_all() invocation from mem_cgroup_move_charge() Tejun Heo
2016-04-17 12:07         ` Michal Hocko
2016-04-17 12:07           ` Michal Hocko
2016-04-20 21:29           ` Tejun Heo
2016-04-20 21:29             ` Tejun Heo
2016-04-21  3:27             ` Michal Hocko
2016-04-21  3:27               ` Michal Hocko
2016-04-21 15:00               ` Petr Mladek
2016-04-21 15:00                 ` Petr Mladek
2016-04-21 15:51                 ` Tejun Heo
2016-04-21 23:06           ` [PATCH 1/2] cgroup, cpuset: replace cpuset_post_attach_flush() with cgroup_subsys->post_attach callback Tejun Heo
2016-04-21 23:06             ` Tejun Heo
2016-04-21 23:09             ` [PATCH 2/2] memcg: relocate charge moving from ->attach to ->post_attach Tejun Heo
2016-04-21 23:09               ` Tejun Heo
2016-04-22 13:57               ` Petr Mladek
2016-04-22 13:57                 ` Petr Mladek
2016-04-25  8:25               ` Michal Hocko
2016-04-25  8:25                 ` Michal Hocko
2016-04-25 19:42                 ` Tejun Heo
2016-04-25 19:42                   ` Tejun Heo
2016-04-25 19:44               ` Tejun Heo
2016-04-25 19:44                 ` Tejun Heo
2016-04-21 23:11             ` [PATCH 1/2] cgroup, cpuset: replace cpuset_post_attach_flush() with cgroup_subsys->post_attach callback Tejun Heo
2016-04-21 23:11               ` Tejun Heo
2016-04-21 15:56         ` [PATCH for-4.6-fixes] memcg: remove lru_add_drain_all() invocation from mem_cgroup_move_charge() Tejun Heo
2016-04-21 15:56           ` Tejun Heo

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