linux-kernel - Re: [PATCH 1/2] tmpfs mempolicy: fix /proc/mounts corrupting memory

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Message-ID: <CA+55aFyH63agfbf+pYNRGHaprPqAJF=F19GR6ASP_RhoyDGLdA@mail.gmail.com>
Date:	Wed, 2 Jan 2013 09:24:37 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Christoph Lameter <cl@...ux.com>
Cc:	Hugh Dickins <hughd@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Lee Schermerhorn <lee.schermerhorn@...com>,
	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	David Rientjes <rientjes@...gle.com>,
	Mel Gorman <mgorman@...e.de>, Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>
Subject: Re: [PATCH 1/2] tmpfs mempolicy: fix /proc/mounts corrupting memory

On Wed, Jan 2, 2013 at 7:57 AM, Christoph Lameter <cl@...ux.com> wrote:
> On Wed, 2 Jan 2013, Hugh Dickins wrote:
>
>> @@ -2796,10 +2787,7 @@ int mpol_to_str(char *buffer, int maxlen
>>       case MPOL_BIND:
>>               /* Fall through */
>>       case MPOL_INTERLEAVE:
>> -             if (no_context)
>> -                     nodes = pol->w.user_nodemask;
>> -             else
>> -                     nodes = pol->v.nodes;
>> +             nodes = pol->v.nodes;
>>               break;
>>
>
> no_context was always true. Why is the code from the false branch kept?

no_context is zero in the caller in fs/proc/task_mmu.c, and one in the
mm/shmem.c caller. So it's not always true (for mpol_parse_str() there
is only one caller, and it's always true as Hugh said).

Anyway, I do not know why Hugh took the true case, but I don't really
imagine that it matters. So I'll take these two patches, but it would
be good if you double-checked this, Hugh.

Hugh?

                   Linus
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