From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Gibson Subject: Re: [powerpc] Next tree Nov 2 : kernel BUG at mm/mmap.c:2135! Date: Fri, 13 Nov 2009 13:10:48 +1100 Message-ID: <20091113021048.GA4865@yookeroo.seuss> References: <20091102173845.210d1c57.sfr@canb.auug.org.au> <4AEEA279.4040106@in.ibm.com> <4AF175D4.7030507@in.ibm.com> <20091105001650.GD3613@yookeroo.seuss> <4AFBEE98.2070208@in.ibm.com> <20091113013729.GB18848@yookeroo.seuss> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from e23smtp02.au.ibm.com ([202.81.31.144]:53496 "EHLO e23smtp02.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754821AbZKMCKu (ORCPT ); Thu, 12 Nov 2009 21:10:50 -0500 Received: from d23relay04.au.ibm.com (d23relay04.au.ibm.com [202.81.31.246]) by e23smtp02.au.ibm.com (8.14.3/8.13.1) with ESMTP id nAD28LTA007252 for ; Fri, 13 Nov 2009 13:08:21 +1100 Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by d23relay04.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id nAD27gjY1290286 for ; Fri, 13 Nov 2009 13:07:44 +1100 Received: from d23av02.au.ibm.com (loopback [127.0.0.1]) by d23av02.au.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id nAD2ArL5025661 for ; Fri, 13 Nov 2009 13:10:53 +1100 Content-Disposition: inline In-Reply-To: <20091113013729.GB18848@yookeroo.seuss> Sender: linux-next-owner@vger.kernel.org List-ID: To: Sachin Sant , Linux/PPC Development , Stephen Rothwell , linux-next@vger.kernel.org, Benjamin Herrenschmidt On Fri, Nov 13, 2009 at 12:37:29PM +1100, David Gibson wrote: > On Thu, Nov 12, 2009 at 04:46:40PM +0530, Sachin Sant wrote: > > David Gibson wrote: > > >On Wed, Nov 04, 2009 at 06:08:44PM +0530, Sachin Sant wrote: > > >>Sachin Sant wrote: > > >>>Today's next tree failed to boot on a POWER 6 box with : > > >>> > > >>>------------[ cut here ]------------ > > >>>kernel BUG at mm/mmap.c:2135! > > >>>Oops: Exception in kernel mode, sig: 5 [#2] > > >>>SMP NR_CPUS=1024 NUMA pSeries > > >>Problem exists with today's next as well. > > >> > > >>Likely cause for this problem seems to the following commit. > > >>If i revert this patch the machine boots fine. > > >> > > >>commit a0668cdc154e54bf0c85182e0535eea237d53146 > > >>powerpc/mm: Cleanup management of kmem_caches for pagetables > > > > > >Ugh. Ok, it's not at all obvious how my patch could cause this bug. > > >Can you send your .config? > > > > > Still present in today's next. > > Sorry, I've been sidetracked by other issues and have only managed to > look into this today. My initial attempts to reproduce the bug with > your config on both POWER6 and POWER5+ have failed though. > > Is it possible to get the complete boot log from this system - not > just the [cut here] section around the BUG()? This should help to > determine exactly when during boot the bug is being triggered. Also, could you try booting the kernel with the patch below, which should give a bit more information about the problem. Index: working-2.6/mm/mmap.c =================================================================== --- working-2.6.orig/mm/mmap.c 2009-11-13 13:08:29.000000000 +1100 +++ working-2.6/mm/mmap.c 2009-11-13 13:09:26.000000000 +1100 @@ -2136,6 +2136,8 @@ void exit_mmap(struct mm_struct *mm) while (vma) vma = remove_vma(vma); + if (nr_ptes != 0) + printk("exit_mmap(): mm %p nr_ptes %d\n", mm, mm->nr_ptes); BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); } -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson