From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id EDB756B004D for ; Thu, 4 Jun 2009 00:26:14 -0400 (EDT) Date: Thu, 4 Jun 2009 12:26:03 +0800 From: Wu Fengguang Subject: Re: [PATCH] [6/16] HWPOISON: Add various poison checks in mm/memory.c Message-ID: <20090604042603.GA15682@localhost> References: <20090603846.816684333@firstfloor.org> <20090603184639.1933B1D028F@basil.firstfloor.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090603184639.1933B1D028F@basil.firstfloor.org> Sender: owner-linux-mm@kvack.org To: Andi Kleen Cc: "akpm@linux-foundation.org" , "npiggin@suse.de" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" List-ID: On Thu, Jun 04, 2009 at 02:46:38AM +0800, Andi Kleen wrote: > > Bail out early when hardware poisoned pages are found in page fault handling. I suspect this patch is also not absolutely necessary: the poisoned page will normally have been isolated already. > Since they are poisoned they should not be mapped freshly into processes, > because that would cause another (potentially deadly) machine check > > This is generally handled in the same way as OOM, just a different > error code is returned to the architecture code. > > Signed-off-by: Andi Kleen > > --- > mm/memory.c | 3 +++ > 1 file changed, 3 insertions(+) > > Index: linux/mm/memory.c > =================================================================== > --- linux.orig/mm/memory.c 2009-06-03 19:36:23.000000000 +0200 > +++ linux/mm/memory.c 2009-06-03 19:36:23.000000000 +0200 > @@ -2797,6 +2797,9 @@ > if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) > return ret; > > + if (unlikely(PageHWPoison(vmf.page))) > + return VM_FAULT_HWPOISON; > + Direct return with locked page could lockup someone later. Either drop this patch or fix it with this check? Thanks, Fengguang --- --- linux.orig/mm/memory.c +++ linux/mm/memory.c @@ -2658,8 +2658,11 @@ static int __do_fault(struct mm_struct * if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) return ret; - if (unlikely(PageHWPoison(vmf.page))) + if (unlikely(PageHWPoison(vmf.page))) { + if (ret & VM_FAULT_LOCKED) + unlock_page(vmf.page); return VM_FAULT_HWPOISON; + } /* * For consistency in subsequent calls, make the faulted page always -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org