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From: Daniel Bristot de Oliveira <daolivei@redhat.com>
To: Tejun Heo <tj@kernel.org>,
	Daniel Bristot de Oliveira <daolivei@redhat.com>
Cc: linux-kernel@vger.kernel.org, Rik van Riel <riel@redhat.com>,
	"Luis Claudio R. Goncalves" <lgoncalv@redhat.com>,
	Li Zefan <lizefan@huawei.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Juri Lelli <juri.lelli@arm.com>,
	cgroups@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH v2] cgroup: disable irqs while holding css_set_lock
Date: Thu, 16 Jun 2016 21:12:32 -0300	[thread overview]
Message-ID: <cf514889-8a4d-1ef4-cf4a-fd1a9b9bcb1d@redhat.com> (raw)
In-Reply-To: <20160616221434.GI3262@mtj.duckdns.org>

On 06/16/2016 07:14 PM, Tejun Heo wrote:
> Except that the patch seems to use irqsave/restore instead of plain
> irq ones in places.  Care to update those?

Hi Tejun,

The use of the irq spin_(un)lock_irq() assumes that the code is always
called with IRQs enabled. But that is not always true in this case, as
we call cgroup_free() in the hard IRQ context, and unconditionally
enable IRQ in this context is a problem. So we need to use irqsave/restore.

Discussing with rostedt, we figured that this needs to be IRQ safe
(using irqsave/restore) in the PREEMPT RT too, so I need to code a v3 of
this patch using raw_spin_*() functions to avoid this problem in the -rt
kernel as well.

Do you see any problems on this?

Thanks! -- Daniel

  reply	other threads:[~2016-06-17  0:12 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-07 18:51 Daniel Bristot de Oliveira
2016-06-07 19:30 ` Tejun Heo
2016-06-07 20:05   ` Daniel Bristot de Oliveira
2016-06-16 21:48     ` Daniel Bristot de Oliveira
2016-06-16 22:03       ` Tejun Heo
2016-06-16 22:14         ` Tejun Heo
2016-06-17  0:12           ` Daniel Bristot de Oliveira [this message]
2016-06-17  5:36             ` Tejun Heo
2016-06-17 19:59               ` Daniel Bristot de Oliveira
2016-06-22 20:00                 ` Daniel Bristot de Oliveira

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