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From: Dave Hansen <dave@linux.vnet.ibm.com>
To: David Rientjes <rientjes@google.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Nazarewicz <mina86@mina86.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 1/2] break out page allocation warning code
Date: Mon, 18 Apr 2011 14:03:14 -0700	[thread overview]
Message-ID: <1303160594.9887.309.camel@nimitz> (raw)
In-Reply-To: <alpine.DEB.2.00.1104181321480.31186@chino.kir.corp.google.com>

On Mon, 2011-04-18 at 13:25 -0700, David Rientjes wrote:
>  - provide a statically-allocated buffer to use for get_task_comm() and 
>    copy current->comm over before printing it, or
> 
>  - take task_lock(current) to protect against /proc/pid/comm.
> 
> The latter probably isn't safe because we could potentially already be 
> holding task_lock(current) during a GFP_ATOMIC page allocation. 

I'm not sure get_task_comm() is suitable, either.  It takes the task
lock:

char *get_task_comm(char *buf, struct task_struct *tsk)
{
        /* buf must be at least sizeof(tsk->comm) in size */
        task_lock(tsk);
        strncpy(buf, tsk->comm, sizeof(tsk->comm));
        task_unlock(tsk);
        return buf;
}

-- Dave


WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave@linux.vnet.ibm.com>
To: David Rientjes <rientjes@google.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Nazarewicz <mina86@mina86.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 1/2] break out page allocation warning code
Date: Mon, 18 Apr 2011 14:03:14 -0700	[thread overview]
Message-ID: <1303160594.9887.309.camel@nimitz> (raw)
In-Reply-To: <alpine.DEB.2.00.1104181321480.31186@chino.kir.corp.google.com>

On Mon, 2011-04-18 at 13:25 -0700, David Rientjes wrote:
>  - provide a statically-allocated buffer to use for get_task_comm() and 
>    copy current->comm over before printing it, or
> 
>  - take task_lock(current) to protect against /proc/pid/comm.
> 
> The latter probably isn't safe because we could potentially already be 
> holding task_lock(current) during a GFP_ATOMIC page allocation. 

I'm not sure get_task_comm() is suitable, either.  It takes the task
lock:

char *get_task_comm(char *buf, struct task_struct *tsk)
{
        /* buf must be at least sizeof(tsk->comm) in size */
        task_lock(tsk);
        strncpy(buf, tsk->comm, sizeof(tsk->comm));
        task_unlock(tsk);
        return buf;
}

-- Dave

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  parent reply	other threads:[~2011-04-18 21:03 UTC|newest]

Thread overview: 79+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-15 17:04 [PATCH 1/2] break out page allocation warning code Dave Hansen
2011-04-15 17:04 ` Dave Hansen
2011-04-15 17:04 ` [PATCH 2/2] print vmalloc() state after allocation failures Dave Hansen
2011-04-15 17:04   ` Dave Hansen
2011-04-15 17:20   ` Michal Nazarewicz
2011-04-15 17:20     ` Michal Nazarewicz
2011-04-15 17:44     ` Dave Hansen
2011-04-15 17:44       ` Dave Hansen
2011-04-17  0:03       ` David Rientjes
2011-04-17  0:03         ` David Rientjes
2011-04-18 15:21         ` Dave Hansen
2011-04-18 15:21           ` Dave Hansen
2011-04-17  0:02 ` [PATCH 1/2] break out page allocation warning code David Rientjes
2011-04-17  0:02   ` David Rientjes
2011-04-18 15:10   ` Dave Hansen
2011-04-18 15:10     ` Dave Hansen
2011-04-18 20:25     ` David Rientjes
2011-04-18 20:25       ` David Rientjes
2011-04-18 20:57       ` Dave Hansen
2011-04-18 20:57         ` Dave Hansen
2011-04-19 21:23         ` David Rientjes
2011-04-19 21:23           ` David Rientjes
2011-04-18 21:03       ` Dave Hansen [this message]
2011-04-18 21:03         ` Dave Hansen
2011-04-18 21:22       ` Dave Hansen
2011-04-18 21:22         ` Dave Hansen
2011-04-19  0:44         ` KOSAKI Motohiro
2011-04-19  0:44           ` KOSAKI Motohiro
2011-04-19 21:21           ` David Rientjes
2011-04-19 21:21             ` David Rientjes
2011-04-20  0:39             ` KOSAKI Motohiro
2011-04-20  0:39               ` KOSAKI Motohiro
2011-04-20 20:24               ` David Rientjes
2011-04-20 20:24                 ` David Rientjes
2011-04-20 20:34                 ` john stultz
2011-04-20 20:34                   ` john stultz
2011-04-21  1:29                   ` KOSAKI Motohiro
2011-04-21  1:29                     ` KOSAKI Motohiro
2011-04-25  4:21                     ` KOSAKI Motohiro
2011-04-25  4:21                       ` KOSAKI Motohiro
2011-04-26 19:27                     ` john stultz
2011-04-26 19:27                       ` john stultz
2011-04-27 23:51                       ` David Rientjes
2011-04-27 23:51                         ` David Rientjes
2011-04-28  0:32                         ` john stultz
2011-04-28  0:32                           ` john stultz
2011-04-28  1:29                           ` john stultz
2011-04-28  1:29                             ` john stultz
2011-04-28 22:48                             ` David Rientjes
2011-04-28 22:48                               ` David Rientjes
2011-04-28 23:48                               ` john stultz
2011-04-28 23:48                                 ` john stultz
2011-04-29  0:04                                 ` john stultz
2011-04-29  0:04                                   ` john stultz
2011-04-26 21:25                     ` john stultz
2011-04-26 21:25                       ` john stultz
2011-04-28  3:05                       ` KOSAKI Motohiro
2011-04-28  3:05                         ` KOSAKI Motohiro
2011-04-20  1:41             ` Dave Hansen
2011-04-20  1:41               ` Dave Hansen
2011-04-20  1:50               ` KOSAKI Motohiro
2011-04-20  1:50                 ` KOSAKI Motohiro
2011-04-20  2:19                 ` KOSAKI Motohiro
2011-04-20  2:19                   ` KOSAKI Motohiro
2011-04-20  2:46                   ` Dave Hansen
2011-04-20  2:46                     ` Dave Hansen
  -- strict thread matches above, loose matches on Subject: below --
2011-04-19 16:21 Dave Hansen
2011-04-19 16:21 ` Dave Hansen
2011-04-08 20:22 Dave Hansen
2011-04-08 20:22 ` Dave Hansen
2011-04-08 20:37 ` David Rientjes
2011-04-08 20:37   ` David Rientjes
2011-04-08 20:43   ` Dave Hansen
2011-04-08 20:43     ` Dave Hansen
2011-04-08 20:54 ` Michał Nazarewicz
2011-04-08 21:02   ` Dave Hansen
2011-04-08 21:02     ` Dave Hansen
2011-04-11 10:20     ` Michal Nazarewicz
2011-04-11 10:20       ` Michal Nazarewicz

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