linux-kernel - Re: [PATCH 1/2] vmevent: Should not grab mutex in the atomic context

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Date:	Wed, 18 Apr 2012 23:01:58 +0300 (EEST)
From:	Pekka Enberg <penberg@...nel.org>
To:	Anton Vorontsov <anton.vorontsov@...aro.org>
cc:	Leonid Moiseichuk <leonid.moiseichuk@...ia.com>,
	John Stultz <john.stultz@...aro.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, linaro-kernel@...ts.linaro.org,
	patches@...aro.org
Subject: Re: [PATCH 1/2] vmevent: Should not grab mutex in the atomic
 context

On Wed, 18 Apr 2012, Anton Vorontsov wrote:
> vmevent grabs a mutex in the atomic context, and so this pops up:
> 
> BUG: sleeping function called from invalid context at kernel/mutex.c:271
> in_atomic(): 1, irqs_disabled(): 0, pid: 0, name: swapper/0
> 1 lock held by swapper/0/0:
>  #0:  (&watch->timer){+.-...}, at: [<ffffffff8103eb80>] call_timer_fn+0x0/0xf0
> Pid: 0, comm: swapper/0 Not tainted 3.2.0+ #6
> Call Trace:
>  <IRQ>  [<ffffffff8102f5da>] __might_sleep+0x12a/0x1e0
>  [<ffffffff810bd990>] ? vmevent_match+0xe0/0xe0
>  [<ffffffff81321f2c>] mutex_lock_nested+0x3c/0x340
>  [<ffffffff81064b33>] ? lock_acquire+0xa3/0xc0
>  [<ffffffff8103eb80>] ? internal_add_timer+0x110/0x110
>  [<ffffffff810bd990>] ? vmevent_match+0xe0/0xe0
>  [<ffffffff810bda21>] vmevent_timer_fn+0x91/0xf0
>  [<ffffffff810bd990>] ? vmevent_match+0xe0/0xe0
>  [<ffffffff8103ebf5>] call_timer_fn+0x75/0xf0
>  [<ffffffff8103eb80>] ? internal_add_timer+0x110/0x110
>  [<ffffffff81062fdd>] ? trace_hardirqs_on_caller+0x7d/0x120
>  [<ffffffff8103ee9f>] run_timer_softirq+0x10f/0x1e0
>  [<ffffffff810bd990>] ? vmevent_match+0xe0/0xe0
>  [<ffffffff81038d90>] __do_softirq+0xb0/0x160
>  [<ffffffff8105eb0f>] ? tick_program_event+0x1f/0x30
>  [<ffffffff8132642c>] call_softirq+0x1c/0x26
>  [<ffffffff810036d5>] do_softirq+0x85/0xc0
> 
> This patch fixes the issue by removing the mutex and making the logic
> lock-free.
> 
> Signed-off-by: Anton Vorontsov <anton.vorontsov@...aro.org>

Applied, thanks!
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