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Date: Wed, 20 Mar 2013 15:02:48 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: "Hampson, Steven T" <steven.t.hampson@intel.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH} mm: Merging memory blocks resets mempolicy
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On Mon, 18 Mar 2013 06:13:42 +0000 "Hampson, Steven T" <steven.t.hampson@intel.com> wrote:

> Using mbind to change the mempolicy to MPOL_BIND on several adjacent
> mmapped blocks
> may result in a reset of the mempolicy to MPOL_DEFAULT in vma_adjust.
> 
> ...
>
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -820,7 +820,7 @@ again:			remove_next = 1 + (end > next->vm_end);
>  		if (next->anon_vma)
>  			anon_vma_merge(vma, next);
>  		mm->map_count--;
> -		mpol_put(vma_policy(next));
> +		vma_set_policy(vma, vma_policy(next));
>  		kmem_cache_free(vm_area_cachep, next);
>  		/*
>  		 * In mprotect's case 6 (see comments on vma_merge),

Is this missing an mpol_put(vma_policy(vma))?