linux-kernel - Re: [PATCH 1/2] break out page allocation warning code

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Message-ID: <1303160594.9887.309.camel@nimitz>
Date:	Mon, 18 Apr 2011 14:03:14 -0700
From:	Dave Hansen <dave@...ux.vnet.ibm.com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Nazarewicz <mina86@...a86.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/2] break out page allocation warning code

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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