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

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Message-ID: <alpine.LFD.2.00.1004071929090.3586@i5.linux-foundation.org>
Date:	Wed, 7 Apr 2010 19:33:01 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
cc:	Rik van Riel <riel@...hat.com>, Borislav Petkov <bp@...en8.de>,
	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, hannes@...xchg.org
Subject: Re: [PATCH -v2] rmap: make anon_vma_prepare link in all the anon_vmas
 of a mergeable VMA



On Thu, 8 Apr 2010, KOSAKI Motohiro wrote:
> 
> Now pagefault don't insert anon_vma anymore, right? if so, SIGBUS is better.
> Now SIGBUS and VM_FAULT_OOM make different result.
> 
> SIGBUS       -> kill current task
> VM_FAULT_OOM -> invoke oom-killer (see pagefault_out_of_memory())

Yeah, maybe VM_FAULT_SIGBUS works ok instead of VM_FAULT_OOM. But the 
cause of it is the system having been oom when themappign was created, so 
I think either is fine.

> If current task can't recover proper anon_vma. we should just kill current
> instead random highest badness process. otherwise !anon_vma process continue
> to randomly invoke oom-killer.

Yes, that is a good point.

Anyway, I think it might be interesting to test my anon_vma_prepare() 
locking change patch together with Rik's _first_ version of his "fix 
anon_vma_prepare" thing (the one without the spinlock). They should apply 
independently of each other, and maybe it all even works together.

		Linus
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