Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751484Ab0GUEUV (ORCPT ); Wed, 21 Jul 2010 00:20:21 -0400 Received: from smtp-out.google.com ([74.125.121.35]:57578 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751331Ab0GUEUG (ORCPT ); Wed, 21 Jul 2010 00:20:06 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id: references:user-agent:mime-version:content-type:x-system-of-record; b=WyOnNn4PjyS0ewZTTmmqQxFFQDDTrypEUDu6VtZEjDoWuMhMTQ2aiGKULw2kKlpiI Ig6yP9gZtIkYy1ywtvpYg== Date: Tue, 20 Jul 2010 21:19:50 -0700 (PDT) From: Hugh Dickins X-X-Sender: hughd@tigran.mtv.corp.google.com To: dann frazier cc: KAMEZAWA Hiroyuki , linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, Rik van Riel , KOSAKI Motohiro , Nick Piggin , Mel Gorman , Minchan Kim , Ralf Baechle Subject: Re: ia64 hang/mca running gdb 'make check' In-Reply-To: <20100721030629.GA9987@lackof.org> Message-ID: References: <20100720173512.GF26783@ldl.fc.hp.com> <20100721105136.9d4440de.kamezawa.hiroyu@jp.fujitsu.com> <20100721030629.GA9987@lackof.org> User-Agent: Alpine 1.00 (DEB 882 2007-12-20) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2848 Lines: 64 On Tue, 20 Jul 2010, dann frazier wrote: > On Wed, Jul 21, 2010 at 10:51:36AM +0900, KAMEZAWA Hiroyuki wrote: > > On Tue, 20 Jul 2010 11:35:12 -0600 > > dann frazier wrote: > > > > > Debian's ia64 autobuilders have been experiencing system crashes while > > > trying to run the gdb test suite: > > > http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=588574 > > > > > > I was able to reproduce this w/ the latest git tree, and bisected it > > > down to this commit, introduced in 2.6.32: > > > > > > commit 62eede62dafb4a6633eae7ffbeb34c60dba5e7b1 > > > Author: Hugh Dickins > > > Date: Mon Sep 21 17:03:34 2009 -0700 > > > > > > mm: ZERO_PAGE without PTE_SPECIAL > > > > > > Reinstate anonymous use of ZERO_PAGE to all architectures, not just to > > > those which __HAVE_ARCH_PTE_SPECIAL: as suggested by Nick Piggin. > > > > > > Contrary to how I'd imagined it, there's nothing ugly about this, just a > > > zero_pfn test built into one or another block of vm_normal_page(). > > > > > > But the MIPS ZERO_PAGE-of-many-colours case demands is_zero_pfn() and > > > my_zero_pfn() inlines. Reinstate its mremap move_pte() shuffling of > > > ZERO_PAGEs we did from 2.6.17 to 2.6.19? Not unless someone shouts for > > > that: it would have to take vm_flags to weed out some cases. > > > > > > fyi, I found this to not be reproducible on SLES11 SP1 (which is > > > 2.6.32-based). I compared the .configs and found that the relevant > > > difference is the PAGE_SIZE. It does not fail w/ 64KB pages, but > > > reliably fails w/ 16KB pages. > > > > > > > Sorry, I have no idea... > > Hmm, what is the address of empty_zero_page[] on your debian(16kb-page) ? > > > dannf@krebs:~$ grep empty_zero_page /boot/System.map-2.6.32-5-mckinley > a0000001008784c0 d __ksymtab_empty_zero_page > a000000100882688 d __kcrctab_empty_zero_page > a000000100884ca4 r __kstrtab_empty_zero_page > a000000100974000 D empty_zero_page Thanks a lot for reporting this, but I too have no idea yet. It is likely that the bug is not to be found in that 62eede62, but rather in one of the preceding patches to mm/memory.c which 62eede62 was extending to ia64 and other architectures without PTE_SPECIAL. I wonder, from looking at that gdb testsuite log, is it plausible that all these hangs/crashes occurred when writing out a coredump? Is that something you could check for us? or rule out the possibility. I was rather proud of the get_dump_page() simplification, but perhaps there's something nasty lurking in there. Hugh -- 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/