linux-kernel - Re: [PATCH] hugetlb: release pages in the error path of hugetlb

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Date:	Tue, 15 Nov 2011 16:38:51 +0100
From:	Michal Hocko <mhocko@...e.cz>
To:	Hillf Danton <dhillf@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Hugh Dickins <hughd@...gle.com>,
	Johannes Weiner <jweiner@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org
Subject: Re: [PATCH] hugetlb: release pages in the error path of hugetlb_cow()

On Fri 11-11-11 21:01:20, Hillf Danton wrote:
> If fail to prepare anon_vma, {new, old}_page should be released, or they will
> escape the track and/or control of memory management.

Looks good (intrduced by in .36 by 0fe6e20b: hugetlb, rmap: add reverse
mapping for hugepage). The failure case is really not probable but I
guess this is still a candidate for stable kernel.

> 
> Thanks
> 
> Signed-off-by: Hillf Danton <dhillf@...il.com>

Reviewed-by: Michal Hocko <mhocko@...e.cz>

> ---
> 
> --- a/mm/hugetlb.c	Fri Nov 11 20:36:32 2011
> +++ b/mm/hugetlb.c	Fri Nov 11 20:43:06 2011
> @@ -2422,6 +2422,8 @@ retry_avoidcopy:
>  	 * anon_vma prepared.
>  	 */
>  	if (unlikely(anon_vma_prepare(vma))) {
> +		page_cache_release(new_page);
> +		page_cache_release(old_page);
>  		/* Caller expects lock to be held */
>  		spin_lock(&mm->page_table_lock);
>  		return VM_FAULT_OOM;
> 
> --
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-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic
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