linux-kernel - Re: [PATCH -v2] rmap: make anon_vma_prepare link in all the anon

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Message-ID: <alpine.LFD.2.00.1004101123540.3558@i5.linux-foundation.org>
Date:	Sat, 10 Apr 2010 11:26:58 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Borislav Petkov <bp@...en8.de>
cc:	Johannes Weiner <hannes@...xchg.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Rik van Riel <riel@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Minchan Kim <minchan.kim@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	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 -v2] rmap: make anon_vma_prepare link in all the anon_vmas
 of a mergeable VMA

On Sat, 10 Apr 2010, Linus Torvalds wrote:
> 
> I dunno. Does the above sound at all sane? Or am I just raving?
> 
> Something hacky like the above might fix it if I'm not just raving. I 
> really might be missing something here.

Btw, if this turns out to be accurate, the real fix is to probably just 
have a separate phase at the very end to actually release all the vma's, 
rather than do it in "free_page_tables()". We don't want to make the 
tlb-gather any more atomic than it already is. In fact, Nick is trying to 
make it preemptible.

So the patch included in that mail was meant very much as a "let's test my 
crazy theory" patch, rather than as the real solution.

The patch is also untested. Maybe it doesn't work at all and introduces 
new bugs. Caveat emptor.

			Linus
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