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From: Tejun Heo <tj@kernel.org>
To: Jan Kara <jack@suse.cz>
Cc: "Michal Koutný" <mkoutny@suse.com>,
	"Paolo Valente" <paolo.valente@linaro.org>,
	linux-block@vger.kernel.org, fvogdt@suse.de,
	cgroups@vger.kernel.org
Subject: Re: Use after free with BFQ and cgroups
Date: Tue, 30 Nov 2021 06:22:13 -1000	[thread overview]
Message-ID: <YaZPtZcdMKwhzzy/@slm.duckdns.org> (raw)
In-Reply-To: <20211130115010.GF7174@quack2.suse.cz>

Hello,

On Tue, Nov 30, 2021 at 12:50:10PM +0100, Jan Kara wrote:
> The problem is bfq_queue associated with a task effectively holds a
> reference to the potentially dead cgroup and the reference can stay there
> until the task (that itself got reparented to the root cgroup) exits. So I
> think we need to reparent these bfq_queue structures as well to avoid
> holding cgroup in zombie state excessively long.

Ah, I see. Yeah, that's not great. Agree that it'd be better to reparent
(probably just punt to the root cgroup).

Thanks.

-- 
tejun

WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>
Cc: "Michal Koutný" <mkoutny-IBi9RG/b67k@public.gmane.org>,
	"Paolo Valente"
	<paolo.valente-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
	linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	fvogdt-l3A5Bk7waGM@public.gmane.org,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: Use after free with BFQ and cgroups
Date: Tue, 30 Nov 2021 06:22:13 -1000	[thread overview]
Message-ID: <YaZPtZcdMKwhzzy/@slm.duckdns.org> (raw)
In-Reply-To: <20211130115010.GF7174-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>

Hello,

On Tue, Nov 30, 2021 at 12:50:10PM +0100, Jan Kara wrote:
> The problem is bfq_queue associated with a task effectively holds a
> reference to the potentially dead cgroup and the reference can stay there
> until the task (that itself got reparented to the root cgroup) exits. So I
> think we need to reparent these bfq_queue structures as well to avoid
> holding cgroup in zombie state excessively long.

Ah, I see. Yeah, that's not great. Agree that it'd be better to reparent
(probably just punt to the root cgroup).

Thanks.

-- 
tejun

  reply	other threads:[~2021-11-30 16:22 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-25 17:28 Use after free with BFQ and cgroups Jan Kara
2021-11-26 14:47 ` Michal Koutný
2021-11-26 14:47   ` Michal Koutný
2021-11-29 17:11   ` Jan Kara
2021-11-29 17:11     ` Jan Kara
2021-12-09  2:23     ` yukuai (C)
2021-12-09  2:23       ` yukuai (C)
2021-12-09 15:33       ` Paolo Valente
2021-12-09 15:33         ` Paolo Valente
2021-12-13 17:33       ` Jan Kara
2021-12-14  1:24         ` yukuai (C)
2021-12-14  1:24           ` yukuai (C)
2021-12-20 18:38           ` Jan Kara
2021-12-20 18:38             ` Jan Kara
2021-12-22 15:21       ` Jan Kara
2021-12-22 15:21         ` Jan Kara
2021-12-23  1:02         ` yukuai (C)
2021-12-23  1:02           ` yukuai (C)
2021-12-23 17:13           ` Jan Kara
2021-12-23 17:13             ` Jan Kara
2021-11-29 17:12   ` Tejun Heo
2021-11-30 11:50     ` Jan Kara
2021-11-30 16:22       ` Tejun Heo [this message]
2021-11-30 16:22         ` Tejun Heo

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