From: Tejun Heo <tj@kernel.org>
To: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"cgroups@vger.kernel.org" <cgroups@vger.kernel.org>,
Michal Hocko <mhocko@suse.cz>,
Johannes Weiner <hannes@cmpxchg.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Glauber Costa <glommer@parallels.com>,
Han Ying <yinghan@google.com>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC][PATCH 8/9 v2] cgroup: avoid creating new cgroup under a cgroup being destroyed
Date: Sat, 28 Apr 2012 14:31:51 -0700 [thread overview]
Message-ID: <20120428213151.GA4586@mtj.dyndns.org> (raw)
In-Reply-To: <CABEgKgpPXPu3L6oS6+2+dZmcPS=t-ZR7PnCvm0mo8UFeXPHDog@mail.gmail.com>
Hello, KAME.
On Sat, Apr 28, 2012 at 06:31:38PM +0900, Hiroyuki Kamezawa wrote:
> > So, IMHO, just making pre_destroy() clean up its own charges and
> > always returning 0 is enough. There's no need to fix up old
> > non-critical race condition at this point in the patch stream. cgroup
> > rmdir simplification will make them disappear anyway.
>
> So, hmm, ok. I'll drop patch 7 & 8. memcg may return -EBUSY in very very
> race case but users will not see it in the most case.
> I'll fix limit, move-charge and use_hierarchy problem first.
IIUC, memcg can just return 0 when child creation races against
pre_destroy(). cgroup will retry if child exists after pre_destroy()
completion. If child comes and goes before cgroup checks its
existence, some charges may be lost but that race already exists and
it will be gone once the retry logic is removed. Also, returning
-errno will trigger WARN_ON() w/o the legacy behavior flag.
Thank you very much.
--
tejun
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next prev parent reply other threads:[~2012-04-28 21:31 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-27 5:45 [RFC][PATCH 0/7 v2] memcg: prevent failure in pre_destroy() KAMEZAWA Hiroyuki
2012-04-27 5:49 ` [RFC][PATCH 1/7 v2] temporal compile-fix in linux-next KAMEZAWA Hiroyuki
2012-04-30 8:47 ` Aneesh Kumar K.V
2012-04-27 5:51 ` [RFC][PATCH 2/7 v2] memcg: fix error code in hugetlb_force_memcg_empty() KAMEZAWA Hiroyuki
2012-04-30 8:49 ` Aneesh Kumar K.V
2012-04-27 5:53 ` [RFC][PATCH 3/7 v2] res_counter: add res_counter_uncharge_until() KAMEZAWA Hiroyuki
2012-04-27 17:08 ` Glauber Costa
2012-04-27 23:51 ` Hiroyuki Kamezawa
2012-04-27 18:18 ` Tejun Heo
2012-04-27 23:51 ` Hiroyuki Kamezawa
2012-04-27 5:54 ` [RFC][PATCH 4/7 v2] memcg: use res_counter_uncharge_until in move_parent KAMEZAWA Hiroyuki
2012-04-27 17:16 ` Glauber Costa
2012-04-27 18:26 ` Ying Han
2012-04-27 20:11 ` Glauber Costa
2012-04-27 23:58 ` Hiroyuki Kamezawa
2012-04-27 18:20 ` Tejun Heo
2012-04-27 23:59 ` Hiroyuki Kamezawa
2012-04-30 9:00 ` Aneesh Kumar K.V
2012-04-27 5:58 ` [RFC][PATCH 5/9 v2] move charges to root at rmdir if use_hierarchy is unset KAMEZAWA Hiroyuki
2012-04-27 19:12 ` Ying Han
2012-04-28 0:01 ` Hiroyuki Kamezawa
2012-04-30 9:07 ` Aneesh Kumar K.V
2012-04-27 6:00 ` [RFC][PATCH 6/9 v2] memcg: don't uncharge in mem_cgroup_move_account KAMEZAWA Hiroyuki
2012-04-27 6:02 ` [RFC][PATCH 7/9 v2] cgroup: avoid attaching task to a cgroup under rmdir() KAMEZAWA Hiroyuki
2012-04-27 10:39 ` Frederic Weisbecker
2012-04-28 0:06 ` Hiroyuki Kamezawa
2012-04-27 20:31 ` Tejun Heo
2012-04-27 20:33 ` Tejun Heo
2012-04-27 6:04 ` [RFC][PATCH 8/9 v2] cgroup: avoid creating new cgroup under a cgroup being destroyed KAMEZAWA Hiroyuki
2012-04-27 17:18 ` Glauber Costa
2012-04-27 20:40 ` Tejun Heo
2012-04-27 20:41 ` Tejun Heo
2012-04-28 0:20 ` Hiroyuki Kamezawa
2012-04-28 2:00 ` Tejun Heo
2012-04-28 9:31 ` Hiroyuki Kamezawa
2012-04-28 21:31 ` Tejun Heo [this message]
2012-04-27 6:06 ` [RFC][PATCH 9/9 v2] memcg: never return error at pre_destroy() KAMEZAWA Hiroyuki
2012-04-27 21:28 ` Ying Han
2012-04-28 0:25 ` Hiroyuki Kamezawa
2012-04-30 17:02 ` Ying Han
2012-05-01 22:28 ` Suleiman Souhlal
2012-05-02 3:34 ` Hiroyuki Kamezawa
2012-04-27 18:16 ` [RFC][PATCH 0/7 v2] memcg: prevent failure in pre_destroy() Tejun Heo
2012-04-27 23:48 ` Hiroyuki Kamezawa
2012-04-28 16:13 ` Michal Hocko
2012-04-29 6:03 ` Michal Hocko
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