linux-kernel - Re: [PATCH] rmap: fix anon_vma

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Message-ID: <alpine.LFD.2.00.1004050824400.21313@i5.linux-foundation.org>
Date:	Mon, 5 Apr 2010 08:37:26 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Rik van Riel <riel@...hat.com>
cc:	Minchan Kim <minchan.kim@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Borislav Petkov <bp@...en8.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Lee Schermerhorn <Lee.Schermerhorn@...com>,
	Nick Piggin <npiggin@...e.de>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Hugh Dickins <hugh.dickins@...cali.co.uk>,
	sgunderson@...foot.com
Subject: Re: [PATCH] rmap: fix anon_vma_fork() memory leak



On Sun, 4 Apr 2010, Rik van Riel wrote:
>
> Fix a memory leak in anon_vma_fork(), where we fail to tear down the
> anon_vmas attached to the new VMA in case setting up the new anon_vma
> fails.
> 
> Reported-by: Minchan Kim <minchan.kim@...il.com>
> Signed-off-by: Rik van Riel <riel@...hat.com>
> Reviewed-by: Minchan Kim <minchan.kim@...il.com>
> ---
> 
> diff --git a/mm/rmap.c b/mm/rmap.c
> index fcd593c..fb7ce99 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -231,6 +231,7 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
>  
>   out_error_free_anon_vma:
>  	anon_vma_free(anon_vma);
> +	unlink_anon_vmas(vma);
>   out_error:
>  	return -ENOMEM;
>  }

This looks _very_ wrong to me.

Shouldn't the unlink_anon_vmas() be in the "out_error" case? IOW, we 
should do it even if the "anon_vma_alloc()" failed, nbot just if the 
"anon_vma_chain_alloc()" failed?

No?

What am I missing?

			Linus
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