linux-kernel - Re: [PATCH 6/6] mm: sigbus instead of abusing oom

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Date:	Wed, 11 Nov 2009 11:42:04 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	kosaki.motohiro@...fujitsu.com,
	Hugh Dickins <hugh.dickins@...cali.co.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Izik Eidus <ieidus@...hat.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Minchan Kim <minchan.kim@...il.com>,
	Andi Kleen <andi@...stfloor.org>,
	Wu Fengguang <fengguang.wu@...el.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 6/6] mm: sigbus instead of abusing oom

> On Tue, 10 Nov 2009 22:06:49 +0000 (GMT)
> Hugh Dickins <hugh.dickins@...cali.co.uk> wrote:
> 
> > When do_nonlinear_fault() realizes that the page table must have been
> > corrupted for it to have been called, it does print_bad_pte() and
> > returns ... VM_FAULT_OOM, which is hard to understand.
> > 
> > It made some sense when I did it for 2.6.15, when do_page_fault()
> > just killed the current process; but nowadays it lets the OOM killer
> > decide who to kill - so page table corruption in one process would
> > be liable to kill another.
> > 
> > Change it to return VM_FAULT_SIGBUS instead: that doesn't guarantee
> > that the process will be killed, but is good enough for such a rare
> > abnormality, accompanied as it is by the "BUG: Bad page map" message.
> > 
> > And recent HWPOISON work has copied that code into do_swap_page(),
> > when it finds an impossible swap entry: fix that to VM_FAULT_SIGBUS too.
> > 
> > Signed-off-by: Hugh Dickins <hugh.dickins@...cali.co.uk>
> 
> Thank you !
> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

Thank you, me too.

	Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>



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