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From: Steven Rostedt <rostedt@goodmis.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-mm@kvack.org, Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>,
	Christoph Lameter <cl@linux.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] slub/memcg: Cure the brainless abuse of sysfs attributes
Date: Sat, 20 May 2017 10:25:50 -0400	[thread overview]
Message-ID: <20170520102550.2f793194@gandalf.local.home> (raw)
In-Reply-To: <20170520131645.GA5058@infradead.org>

On Sat, 20 May 2017 06:16:45 -0700
Christoph Hellwig <hch@infradead.org> wrote:

> On Sat, May 20, 2017 at 12:52:03PM +0200, Thomas Gleixner wrote:
> > This should be rewritten proper by adding a propagate() callback to those
> > slub_attributes which must be propagated and avoid that insane conversion
> > to and from ASCII
> 
> Exactly..
> 
> >, but that's too large for a hot fix.
> 
> What made this such a hot fix?  Looks like this crap has been in
> for quite a while.

It can cause a deadlock with get_online_cpus() that has been uncovered
by recent cpu hotplug and lockdep changes that Thomas and Peter have
been doing.

[  102.567308]  Possible unsafe locking scenario:
[  102.567308] 
[  102.574846]        CPU0                    CPU1
[  102.580148]        ----                    ----
[  102.585421]   lock(cpu_hotplug.lock);
[  102.589808]                                lock(slab_mutex);
[  102.596166]                                lock(cpu_hotplug.lock);
[  102.603028]   lock(slab_mutex);
[  102.606846] 
[  102.606846]  *** DEADLOCK ***

-- Steve

WARNING: multiple messages have this Message-ID
From: Steven Rostedt <rostedt@goodmis.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-mm@kvack.org, Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>,
	Christoph Lameter <cl@linux.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] slub/memcg: Cure the brainless abuse of sysfs attributes
Date: Sat, 20 May 2017 10:25:50 -0400	[thread overview]
Message-ID: <20170520102550.2f793194@gandalf.local.home> (raw)
In-Reply-To: <20170520131645.GA5058@infradead.org>

On Sat, 20 May 2017 06:16:45 -0700
Christoph Hellwig <hch@infradead.org> wrote:

> On Sat, May 20, 2017 at 12:52:03PM +0200, Thomas Gleixner wrote:
> > This should be rewritten proper by adding a propagate() callback to those
> > slub_attributes which must be propagated and avoid that insane conversion
> > to and from ASCII
> 
> Exactly..
> 
> >, but that's too large for a hot fix.
> 
> What made this such a hot fix?  Looks like this crap has been in
> for quite a while.

It can cause a deadlock with get_online_cpus() that has been uncovered
by recent cpu hotplug and lockdep changes that Thomas and Peter have
been doing.

[  102.567308]  Possible unsafe locking scenario:
[  102.567308] 
[  102.574846]        CPU0                    CPU1
[  102.580148]        ----                    ----
[  102.585421]   lock(cpu_hotplug.lock);
[  102.589808]                                lock(slab_mutex);
[  102.596166]                                lock(cpu_hotplug.lock);
[  102.603028]   lock(slab_mutex);
[  102.606846] 
[  102.606846]  *** DEADLOCK ***

-- Steve

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  reply	other threads:[~2017-05-20 14:25 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-20 10:52 Thomas Gleixner
2017-05-20 10:52 ` Thomas Gleixner
2017-05-20 13:16 ` Christoph Hellwig
2017-05-20 13:16   ` Christoph Hellwig
2017-05-20 14:25   ` Steven Rostedt [this message]
2017-05-20 14:25     ` Steven Rostedt
2017-05-21 20:01   ` Thomas Gleixner
2017-05-21 20:01     ` Thomas Gleixner
2017-05-22  1:25 ` David Rientjes
2017-05-22  1:25   ` David Rientjes

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