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From: Tejun Heo <tj@kernel.org>
To: "Michal Koutný" <mkoutny@suse.com>
Cc: Tadeusz Struk <tadeusz.struk@linaro.org>,
	cgroups@vger.kernel.org, Zefan Li <lizefan.x@bytedance.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Christian Brauner <brauner@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	stable@vger.kernel.org, linux-kernel@vger.kernel.org,
	syzbot+e42ae441c3b10acf9e9d@syzkaller.appspotmail.com
Subject: Re: [PATCH] cgroup: don't queue css_release_work if one already pending
Date: Thu, 21 Apr 2022 14:00:56 -1000	[thread overview]
Message-ID: <YmHwOAdGY2Lwl+M3@slm.duckdns.org> (raw)
In-Reply-To: <20220414164409.GA5404@blackbody.suse.cz>

On Thu, Apr 14, 2022 at 06:44:09PM +0200, Michal Koutný wrote:
> I suspect the double-queuing is a result of the fact that there exists
> only the single reference to the css->refcnt. I.e. it's
> percpu_ref_kill_and_confirm()'d and released both at the same time.
> 
> (Normally (when not killing the last reference), css->destroy_work reuse
> is not a problem because of the sequenced chain
> css_killed_work_fn()->css_put()->css_release().)

If this is the case, we need to hold an extra reference to be put by the
css_killed_work_fn(), right?

Thanks.

-- 
tejun

  parent reply	other threads:[~2022-04-22  0:00 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-12 19:24 [PATCH] cgroup: don't queue css_release_work if one already pending Tadeusz Struk
     [not found] ` <20220412192459.227740-1-tadeusz.struk-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
2022-04-14 16:44   ` Michal Koutný
     [not found]     ` <20220414164409.GA5404-9OudH3eul5jcvrawFnH+a6VXKuFTiq87@public.gmane.org>
2022-04-14 17:51       ` Tadeusz Struk
     [not found]         ` <584183e2-2473-6185-e07d-f478da118b87-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
2022-04-21 23:43           ` Tejun Heo
2022-04-22  0:00     ` Tejun Heo [this message]
2022-04-22 11:05       ` Michal Koutný
2022-05-18 16:48         ` Tadeusz Struk
2022-05-23 21:27 ` [PATCH v2] cgroups: separate destroy_work into two separate wq Tadeusz Struk

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