From: Tejun Heo <tj@kernel.org>
To: Waiman Long <longman@redhat.com>
Cc: Li Zefan <lizefan@huawei.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com, pjt@google.com, luto@amacapital.net,
efault@gmx.de, torvalds@linux-foundation.org, guro@fb.com
Subject: Re: [PATCH] cgroup: remove unnecessary empty check when enabling threaded mode
Date: Tue, 25 Jul 2017 13:16:08 -0400 [thread overview]
Message-ID: <20170725171607.GC3216015@devbig577.frc2.facebook.com> (raw)
In-Reply-To: <20170723121826.GC1498614@devbig577.frc2.facebook.com>
On Sun, Jul 23, 2017 at 08:18:26AM -0400, Tejun Heo wrote:
> cgroup_enable_threaded() checks that the cgroup doesn't have any tasks
> or children and fails the operation if so. This test is unnecessary
> because the first part is already checked by
> cgroup_can_be_thread_root() and the latter is unnecessary. The latter
> actually cause a behavioral oddity. Please consider the following
> hierarchy. All cgroups are domains.
>
> A
> / \
> B C
> \
> D
>
> If B is made threaded, C and D becomes invalid domains. Due to the no
> children restriction, threaded mode can't be enabled on C. For C and
> D, the only thing the user can do is removal.
>
> There is no reason for this restriction. Remove it.
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Cc: Waiman Long <longman@redhat.com>
Applied to cgroup/for-4.14 with Waiman's ack.
Thanks.
--
tejun
next prev parent reply other threads:[~2017-07-25 17:16 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-21 20:34 [PATCH v2 0/4] cgroup: Introducing bypass mode Waiman Long
2017-07-21 20:34 ` [PATCH v2 1/4] cgroup: Child cgroup creation not allowed on invalid domain Waiman Long
2017-07-22 13:43 ` Tejun Heo
2017-07-23 12:18 ` [PATCH] cgroup: remove unnecessary empty check when enabling threaded mode Tejun Heo
2017-07-24 19:14 ` Waiman Long
2017-07-25 17:22 ` [PATCH cgroup/for-4.14] cgroup: add comment to cgroup_enable_threaded() Tejun Heo
2017-07-25 17:16 ` Tejun Heo [this message]
2017-07-24 17:48 ` [PATCH v2 1/4] cgroup: Child cgroup creation not allowed on invalid domain Waiman Long
2017-07-21 20:34 ` [PATCH v2 2/4] cgroup: Allow bypass mode in subtree_control Waiman Long
2017-07-22 13:50 ` Tejun Heo
2017-07-24 18:20 ` Waiman Long
2017-07-25 17:13 ` Tejun Heo
2017-07-25 19:10 ` Waiman Long
2017-08-01 14:29 ` Waiman Long
2017-07-21 20:34 ` [PATCH v2 3/4] cgroup: Allow reenabling of controller in bypass mode Waiman Long
2017-07-21 20:34 ` [PATCH v2 4/4] cgroup: Make debug controller report new controller masks Waiman Long
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