From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 1/1] mm: mempolicy: fix mbind_range() && vma_adjust()
 interaction
Date: Tue, 9 Jul 2013 14:56:45 -0700
Message-ID: <20130709145645.bd48e31c1a7d9e83d521b845@linux-foundation.org>
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To: Oleg Nesterov <oleg@redhat.com>
Cc: Colin Cross <ccross@android.com>, Hugh Dickins <hughd@google.com>, Linus Torvalds <torvalds@linux-foundation.org>, "Hampson, Steven T" <steven.t.hampson@intel.com>, lkml <linux-kernel@vger.kernel.org>, Kyungmin Park <kmpark@infradead.org>, Christoph Hellwig <hch@infradead.org>, John Stultz <john.stultz@linaro.org>, Rob Landley <rob@landley.net>, Arnd Bergmann <arnd@arndb.de>, Cyrill Gorcunov <gorcunov@openvz.org>, David Rientjes <rientjes@google.com>, Davidlohr Bueso <dave@gnu.org>, Kees Cook <keescook@chromium.org>, Al Viro <viro@zeniv.linux.org.uk>, Mel Gorman <mgorman@suse.de>, Michel Lespinasse <walken@google.com>, Rik van Riel <riel@redhat.com>, Konstantin Khlebnikov <khlebnikov@openvz.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>, Rusty Russell <rusty@rustcorp.com.au>, "Eric W. Biederman" <ebiederm@xmission.com>, Srikar Dronamraju <srikar@linux.vnet.ibm.com>, KAMEZA
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On Mon, 8 Jul 2013 20:05:01 +0200 Oleg Nesterov <oleg@redhat.com> wrote:

> vma_adjust() does vma_set_policy(vma, vma_policy(next)) and this
> is doubly wrong:
> 
> 1. This leaks vma->vm_policy if it is not NULL and not equal to
>    next->vm_policy.
> 
>    This can happen if vma_merge() expands "area", not prev (case 8).
> 
> 2. This sets the wrong policy if vma_merge() joins prev and area,
>    area is the vma the caller needs to update and it still has the
>    old policy.
> 
> Revert 1444f92c "mm: merging memory blocks resets mempolicy" which
> introduced these problems.
> 
> Change mbind_range() to recheck mpol_equal() after vma_merge() to
> fix the problem 1444f92c tried to address.
> 

So I assume the kernel still passes Steven's testcase from the
1444f92c changelog?

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