From: Johannes Weiner <hannes@cmpxchg.org>
To: Michal Hocko <mhocko@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Tejun Heo <tj@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org
Subject: Re: [PATCH -v2 4/6] memcg: make sure that memcg is not offline when charging
Date: Wed, 5 Feb 2014 11:45:43 -0500 [thread overview]
Message-ID: <20140205164543.GZ6963@cmpxchg.org> (raw)
In-Reply-To: <20140205161940.GE2425@dhcp22.suse.cz>
On Wed, Feb 05, 2014 at 05:19:40PM +0100, Michal Hocko wrote:
> On Wed 05-02-14 10:28:21, Johannes Weiner wrote:
> > Here is the only exception to the above: swapout records maintain
> > permanent css references, so they prevent css_free() from running.
> > For that reason alone we should run one optimistic reparenting in
> > css_offline() to make sure one swap record does not pin gigabytes of
> > pages in an offlined cgroup, which is unreachable for reclaim. But
>
> How can reparenting help for swapped out pages? Or did you mean to at
> least get rid of swapcache pages?
I was thinking primarily of page cache. There could be a lot of it
left in the group and once css_tryget() is disabled we can't reclaim
it anymore. So we'd clean that out at offline time optimistically and
at css_free() we catch any charges raced that showed up afterwards.
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WARNING: multiple messages have this Message-ID (diff)
From: Johannes Weiner <hannes@cmpxchg.org>
To: Michal Hocko <mhocko@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Tejun Heo <tj@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org
Subject: Re: [PATCH -v2 4/6] memcg: make sure that memcg is not offline when charging
Date: Wed, 5 Feb 2014 11:45:43 -0500 [thread overview]
Message-ID: <20140205164543.GZ6963@cmpxchg.org> (raw)
In-Reply-To: <20140205161940.GE2425@dhcp22.suse.cz>
On Wed, Feb 05, 2014 at 05:19:40PM +0100, Michal Hocko wrote:
> On Wed 05-02-14 10:28:21, Johannes Weiner wrote:
> > Here is the only exception to the above: swapout records maintain
> > permanent css references, so they prevent css_free() from running.
> > For that reason alone we should run one optimistic reparenting in
> > css_offline() to make sure one swap record does not pin gigabytes of
> > pages in an offlined cgroup, which is unreachable for reclaim. But
>
> How can reparenting help for swapped out pages? Or did you mean to at
> least get rid of swapcache pages?
I was thinking primarily of page cache. There could be a lot of it
left in the group and once css_tryget() is disabled we can't reclaim
it anymore. So we'd clean that out at offline time optimistically and
at css_free() we catch any charges raced that showed up afterwards.
next prev parent reply other threads:[~2014-02-05 16:45 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-04 13:28 [PATCH -v2 0/6] memcg: some charge path cleanups + css offline vs. charge race fix Michal Hocko
2014-02-04 13:28 ` Michal Hocko
2014-02-04 13:28 ` [PATCH -v2 1/6] memcg: do not replicate try_get_mem_cgroup_from_mm in __mem_cgroup_try_charge Michal Hocko
2014-02-04 13:28 ` Michal Hocko
2014-02-04 15:55 ` Johannes Weiner
2014-02-04 15:55 ` Johannes Weiner
2014-02-04 16:05 ` Michal Hocko
2014-02-04 16:05 ` Michal Hocko
2014-02-05 13:49 ` Michal Hocko
2014-02-05 13:49 ` Michal Hocko
2014-02-04 13:28 ` [PATCH -v2 2/6] memcg: cleanup charge routines Michal Hocko
2014-02-04 13:28 ` Michal Hocko
2014-02-04 16:05 ` Johannes Weiner
2014-02-04 16:05 ` Johannes Weiner
2014-02-04 16:12 ` Michal Hocko
2014-02-04 16:12 ` Michal Hocko
2014-02-04 16:40 ` Johannes Weiner
2014-02-04 16:40 ` Johannes Weiner
2014-02-04 19:11 ` Michal Hocko
2014-02-04 19:11 ` Michal Hocko
2014-02-04 19:36 ` Johannes Weiner
2014-02-04 19:36 ` Johannes Weiner
2014-02-04 13:28 ` [PATCH -v2 3/6] memcg: mm == NULL is not allowed for mem_cgroup_try_charge_mm Michal Hocko
2014-02-04 13:28 ` Michal Hocko
2014-02-04 16:05 ` Johannes Weiner
2014-02-04 16:05 ` Johannes Weiner
2014-02-04 13:28 ` [PATCH -v2 4/6] memcg: make sure that memcg is not offline when charging Michal Hocko
2014-02-04 13:28 ` Michal Hocko
2014-02-04 16:29 ` Johannes Weiner
2014-02-04 16:29 ` Johannes Weiner
2014-02-05 13:38 ` Michal Hocko
2014-02-05 13:38 ` Michal Hocko
2014-02-05 15:28 ` Johannes Weiner
2014-02-05 15:28 ` Johannes Weiner
2014-02-05 15:42 ` Tejun Heo
2014-02-05 15:42 ` Tejun Heo
2014-02-05 16:19 ` Michal Hocko
2014-02-05 16:19 ` Michal Hocko
2014-02-05 16:29 ` Michal Hocko
2014-02-05 16:29 ` Michal Hocko
2014-02-05 16:30 ` Tejun Heo
2014-02-05 16:30 ` Tejun Heo
2014-02-05 16:45 ` Johannes Weiner [this message]
2014-02-05 16:45 ` Johannes Weiner
2014-02-05 17:23 ` Michal Hocko
2014-02-05 17:23 ` Michal Hocko
2014-02-04 13:28 ` [PATCH -v2 5/6] memcg, kmem: clean up memcg parameter handling Michal Hocko
2014-02-04 13:28 ` Michal Hocko
2014-02-04 16:32 ` Johannes Weiner
2014-02-04 16:32 ` Johannes Weiner
2014-02-04 16:42 ` Michal Hocko
2014-02-04 16:42 ` Michal Hocko
2014-02-04 13:29 ` [PATCH -v2 6/6] Revert "mm: memcg: fix race condition between memcg teardown and swapin" Michal Hocko
2014-02-04 13:29 ` Michal Hocko
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