From mboxrd@z Thu Jan  1 00:00:00 1970
From: dann frazier <dannf@dannf.org>
Date: Wed, 21 Jul 2010 03:06:29 +0000
Subject: Re: ia64 hang/mca running gdb 'make check'
Message-Id: <20100721030629.GA9987@lackof.org>
List-Id: <linux-ia64.vger.kernel.org>
References: <20100720173512.GF26783@ldl.fc.hp.com> <20100721105136.9d4440de.kamezawa.hiroyu@jp.fujitsu.com>
In-Reply-To: <20100721105136.9d4440de.kamezawa.hiroyu@jp.fujitsu.com>
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To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, Hugh Dickins <hugh.dickins@tiscali.co.uk>, Rik van Riel <riel@redhat.com>, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, Nick Piggin <npiggin@suse.de>, Mel Gorman <mel@csn.ul.ie>, Minchan Kim <minchan.kim@gmail.com>, Ralf Baechle <ralf@linux-mips.org>

On Wed, Jul 21, 2010 at 10:51:36AM +0900, KAMEZAWA Hiroyuki wrote:
> On Tue, 20 Jul 2010 11:35:12 -0600
> dann frazier <dannf@debian.org> 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?bugX8574
> > 
> > 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 <hugh.dickins@tiscali.co.uk>
> >   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