Date: Wed, 7 Apr 2010 15:15:21 -0700 (PDT)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Rik van Riel <riel@redhat.com>
cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
       Borislav Petkov <bp@alien8.de>,
       Andrew Morton <akpm@linux-foundation.org>,
       Minchan Kim <minchan.kim@gmail.com>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Lee Schermerhorn <Lee.Schermerhorn@hp.com>,
       Nick Piggin <npiggin@suse.de>, Andrea Arcangeli <aarcange@redhat.com>,
       Hugh Dickins <hugh.dickins@tiscali.co.uk>, sgunderson@bigfoot.com,
       hannes@cmpxchg.org
Subject: Re: [PATCH -v2] rmap: make anon_vma_prepare link in all the anon_vmas
 of a mergeable VMA
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On Wed, 7 Apr 2010, Linus Torvalds wrote:
> 
> In the long run, it would be nicer to actually return an error from the 
> mmap() that fails, but that's more complicated, and as mentioned, it's not 
> what the old code used to do either (since the failure point was always at 
> the page fault stage).

Put another way: I'm not proud of it, but the new code isn't any worse 
than what we used to have, and I think the new code is _fixable_.

The easiest way to do that would likely be to pre-allocate the anon_vma 
struct (and anon_vma_chain), and pass it down to anon_vma_prepare. That 
way anon_vma_prepare() itself can never fail, and all we need to do is a 
simple allocation earlier in the call-chain.

			Linus
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