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From: Andrew Morton <akpm@linux-foundation.org>
To: Glauber Costa <glommer@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>,
	linux-mm@kvack.org, cgroups@vger.kernel.org,
	linux-kernel@vger.kernel.org, Tejun Heo <tj@kernel.org>,
	Li Zefan <lizefan@huawei.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Balbir Singh <bsingharora@gmail.com>
Subject: Re: [PATCH v3 3/6] memcg: Simplify mem_cgroup_force_empty_list error handling
Date: Mon, 29 Oct 2012 15:00:22 -0700	[thread overview]
Message-ID: <20121029150022.a595b866.akpm@linux-foundation.org> (raw)
In-Reply-To: <508E8B95.406@parallels.com>

On Mon, 29 Oct 2012 17:58:45 +0400
Glauber Costa <glommer@parallels.com> wrote:

> > + * move charges to its parent or the root cgroup if the group has no
> > + * parent (aka use_hierarchy==0).
> > + * Although this might fail (get_page_unless_zero, isolate_lru_page or
> > + * mem_cgroup_move_account fails) the failure is always temporary and
> > + * it signals a race with a page removal/uncharge or migration. In the
> > + * first case the page is on the way out and it will vanish from the LRU
> > + * on the next attempt and the call should be retried later.
> > + * Isolation from the LRU fails only if page has been isolated from
> > + * the LRU since we looked at it and that usually means either global
> > + * reclaim or migration going on. The page will either get back to the
> > + * LRU or vanish.
> 
> I just wonder for how long can it go in the worst case?

If the kernel is uniprocessor and the caller is SCHED_FIFO: ad infinitum!

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  parent reply	other threads:[~2012-10-29 22:00 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-26 11:37 memcg/cgroup: do not fail fail on pre_destroy callbacks Michal Hocko
2012-10-26 11:37 ` [PATCH v3 1/6] memcg: split mem_cgroup_force_empty into reclaiming and reparenting parts Michal Hocko
2012-10-29 13:45   ` Glauber Costa
2012-10-31 16:29   ` Johannes Weiner
2012-10-26 11:37 ` [PATCH v3 2/6] memcg: root_cgroup cannot reach mem_cgroup_move_parent Michal Hocko
2012-10-29 13:48   ` Glauber Costa
2012-10-29 13:52     ` Michal Hocko
2012-10-31 16:31   ` Johannes Weiner
2012-10-26 11:37 ` [PATCH v3 3/6] memcg: Simplify mem_cgroup_force_empty_list error handling Michal Hocko
2012-10-29 13:58   ` Glauber Costa
2012-10-29 14:15     ` Michal Hocko
2012-10-29 15:09       ` Glauber Costa
2012-10-29 22:00     ` Andrew Morton [this message]
2012-10-30 10:35       ` Michal Hocko
2012-10-31 21:30         ` Andrew Morton
2012-11-13 21:10         ` Johannes Weiner
2012-11-14 13:59           ` Michal Hocko
2012-11-14 18:33             ` Johannes Weiner
2012-10-26 11:37 ` [PATCH v3 4/6] cgroups: forbid pre_destroy callback to fail Michal Hocko
2012-10-29 14:04   ` Glauber Costa
2012-10-29 14:06     ` Glauber Costa
2012-10-29 14:17       ` Michal Hocko
2012-11-13 21:13   ` Johannes Weiner
2012-10-26 11:37 ` [PATCH v3 5/6] memcg: make mem_cgroup_reparent_charges non failing Michal Hocko
2012-10-29 14:07   ` Glauber Costa
2012-10-26 11:37 ` [PATCH v3 6/6] hugetlb: do not fail in hugetlb_cgroup_pre_destroy Michal Hocko
2012-10-29 14:08   ` Glauber Costa
2012-10-29 23:26 ` memcg/cgroup: do not fail fail on pre_destroy callbacks Tejun Heo
2012-10-30 23:37   ` Michal Hocko

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