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From: Tejun Heo <tj@kernel.org>
To: "Michal Koutný" <mkoutny@suse.com>
Cc: cgroups@vger.kernel.org, Johannes Weiner <hannes@cmpxchg.org>,
	Li Zefan <lizefan@huawei.com>,
	alex.shi@linux.alibaba.com, guro@fb.com, kernel-team@android.com,
	linger.lee@mediatek.com, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	linux-mediatek@lists.infradead.org, matthias.bgg@gmail.com,
	shuah@kernel.org, tomcherry@google.com
Subject: Re: [PATCH 2/3] cgroup: Iterate tasks that did not finish do_exit()
Date: Fri, 17 Jan 2020 09:28:06 -0800	[thread overview]
Message-ID: <20200117172806.GK2677547@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <20200117151533.12381-3-mkoutny@suse.com>

On Fri, Jan 17, 2020 at 04:15:32PM +0100, Michal Koutný wrote:
> PF_EXITING is set earlier than actual removal from css_set when a task
> is exitting. This can confuse cgroup.procs readers who see no PF_EXITING
> tasks, however, rmdir is checking against css_set membership so it can
> transitionally fail with EBUSY.
> 
> Fix this by listing tasks that weren't unlinked from css_set active
> lists.
> It may happen that other users of the task iterator (without
> CSS_TASK_ITER_PROCS) spot a PF_EXITING task before cgroup_exit(). This
> is equal to the state before commit c03cd7738a83 ("cgroup: Include dying
> leaders with live threads in PROCS iterations") but it may be reviewed
> later.

Yeah, this looks fine to me.  Any chance you can order this before the
clean up so that we can mark it for -stable.

Thanks.

-- 
tejun

  reply	other threads:[~2020-01-17 17:28 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-16  4:36 [PATCH 1/2] cgroup: allow deletion of cgroups containing only dying processes Suren Baghdasaryan
2020-01-16  4:36 ` [PATCH 2/2] kselftest/cgroup: add cgroup destruction test Suren Baghdasaryan
2020-01-17 15:15 ` [PATCH 0/3] cgroup: Iterate tasks that did not finish do_exit() Michal Koutný
2020-01-17 15:15   ` [PATCH 1/3] cgroup: Unify css_set task lists Michal Koutný
2020-01-17 16:59     ` Tejun Heo
2020-01-17 15:15   ` [PATCH 2/3] cgroup: Iterate tasks that did not finish do_exit() Michal Koutný
2020-01-17 17:28     ` Tejun Heo [this message]
2020-01-17 18:41       ` Suren Baghdasaryan
2020-01-20 14:56         ` Michal Koutný
2020-01-24 11:40           ` [PATCH v2 0/3] " Michal Koutný
2020-01-24 11:40             ` [PATCH v2 1/3] " Michal Koutný
2020-01-24 22:56               ` Suren Baghdasaryan
2020-02-05 17:27                 ` Suren Baghdasaryan
2020-02-12 22:03               ` Tejun Heo
2020-01-24 11:40             ` [PATCH v2 2/3] cgroup: Clean up css_set task traversal Michal Koutný
2020-01-24 11:40             ` [PATCH v2 3/3] kselftest/cgroup: add cgroup destruction test Michal Koutný
2020-02-12 22:10               ` Tejun Heo
2020-01-17 15:15   ` [PATCH " Michal Koutný
2020-01-17 17:30   ` [PATCH 0/3] cgroup: Iterate tasks that did not finish do_exit() Suren Baghdasaryan

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