Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754595Ab1CQPkw (ORCPT ); Thu, 17 Mar 2011 11:40:52 -0400 Received: from mail-yw0-f46.google.com ([209.85.213.46]:49481 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754080Ab1CQPkt convert rfc822-to-8bit (ORCPT ); Thu, 17 Mar 2011 11:40:49 -0400 MIME-Version: 1.0 In-Reply-To: References: Date: Thu, 17 Mar 2011 16:40:47 +0100 Message-ID: Subject: Re: [PATCH] mm: fix possible cause of a page_mapped BUG From: =?UTF-8?B?Um9iZXJ0IMWad2nEmWNraQ==?= To: Hugh Dickins Cc: Andrew Morton , Linus Torvalds , Miklos Szeredi , linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2478 Lines: 66 Hi, On Tue, Mar 1, 2011 at 12:35 AM, Robert Święcki wrote: >> But rather than exporting the notion of restart_addr from memory.c, or >> converting to restart_pgoff throughout, simply reset vm_truncate_count >> to 0 to force a rescan if mremap move races with preempted truncation. >> >> We have no confirmation that this fixes Robert's BUG, >> but it is a fix that's worth making anyway. > > Hi, I don't have currently access to my rs232/console testing machine > (lame excuse but it helps a lot;), cause I'm working currently OOtO, > so I'll try to test it asap - which is probably Mar 15th or so. So, I compiled 2.6.38 and started fuzzing it. I'm bumping into other problems, and never seen anything about mremap in 2.6.38 (yet), as it had been happening in 2.6.37-rc2. The output goes to http://alt.swiecki.net/linux_kernel/ - I'm still trying. > Btw, the fuzzer is here: http://code.google.com/p/iknowthis/ > > I think i was trying it with this revision: > http://code.google.com/p/iknowthis/source/detail?r=11 (i386 mode, > newest 'iknowthis' supports x86-64 natively), so feel free to try it. > > It used to crash the machine (it's BUG_ON but the system became > unusable) in matter of hours. Btw, when I was testing it for the last > time it Ooopsed much more frequently in proc_readdir (I sent report in > one of earliet e-mails). > >> Signed-off-by: Hugh Dickins >> --- >> >>  mm/mremap.c |    4 +--- >>  1 file changed, 1 insertion(+), 3 deletions(-) >> >> --- 2.6.38-rc6/mm/mremap.c      2011-01-18 22:04:56.000000000 -0800 >> +++ linux/mm/mremap.c   2011-02-23 15:29:52.000000000 -0800 >> @@ -94,9 +94,7 @@ static void move_ptes(struct vm_area_str >>                 */ >>                mapping = vma->vm_file->f_mapping; >>                spin_lock(&mapping->i_mmap_lock); >> -               if (new_vma->vm_truncate_count && >> -                   new_vma->vm_truncate_count != vma->vm_truncate_count) >> -                       new_vma->vm_truncate_count = 0; >> +               new_vma->vm_truncate_count = 0; >>        } >> >>        /* >> > > > > -- > Robert Święcki > -- Robert Święcki -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/