From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e31.co.us.ibm.com (e31.co.us.ibm.com [32.97.110.149]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e31.co.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTP id B2640DE03A for ; Thu, 19 Jul 2007 02:28:58 +1000 (EST) Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e31.co.us.ibm.com (8.13.8/8.13.8) with ESMTP id l6IGSnFa030258 for ; Wed, 18 Jul 2007 12:28:49 -0400 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v8.4) with ESMTP id l6IGSnpi173428 for ; Wed, 18 Jul 2007 10:28:49 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l6IGSmp1004757 for ; Wed, 18 Jul 2007 10:28:49 -0600 Subject: Re: [Bugme-new] [Bug 8778] New: Ocotea board: kernel reports access of bad area during boot with DEBUG_SLAB=y From: Josh Boyer To: Eugene Surovegin In-Reply-To: <20070718155940.GB29722@gate.ebshome.net> References: <20070718005253.942f0464.akpm@linux-foundation.org> <20070718083425.GA29722@gate.ebshome.net> <1184766070.3699.2.camel@zod.rchland.ibm.com> <20070718155940.GB29722@gate.ebshome.net> Content-Type: text/plain Date: Wed, 18 Jul 2007 11:28:47 -0500 Message-Id: <1184776127.16299.22.camel@weaponx.rchland.ibm.com> Mime-Version: 1.0 Cc: bart.vanassche@gmail.com, netdev@vger.kernel.org, Andrew Morton , "bugme-daemon@kernel-bugs.osdl.org" , linuxppc-embedded@ozlabs.org List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2007-07-18 at 08:59 -0700, Eugene Surovegin wrote: > On Wed, Jul 18, 2007 at 08:41:10AM -0500, Josh Boyer wrote: > > On Wed, 2007-07-18 at 01:34 -0700, Eugene Surovegin wrote: > > > On Wed, Jul 18, 2007 at 12:52:53AM -0700, Andrew Morton wrote: > > > > On Wed, 18 Jul 2007 00:07:50 -0700 (PDT) bugme-daemon@bugzilla.kernel.org wrote: > > > > > > > > > http://bugzilla.kernel.org/show_bug.cgi?id=8778 > > > > > > > > > > Summary: Ocotea board: kernel reports access of bad area during > > > > > boot with DEBUG_SLAB=y > > > > > > Slab debugging is probably the culprit here. I had similar problem > > > couple of years ago, not sure something has changed since then, > > > haven't checked. > > > > > > When slab debugging was enabled it made memory allocations non L1 > > > cache line aligned. This is very bad for DMA on non-coherent cache > > > arches (PPC440 is one of those archs). > > > > > > I have a hack for EMAC which tries to "workaround" this problem: > > > http://kernel.ebshome.net/emac_slab_debug.diff > > > which might help. > > > > Would you be opposed to including that patch in mainline? > > Yes. I don't think it's the right way to fix this issue. IMO, the > right one is to fix slab allocator. You cannot change all drivers to > do this kind of cache flushing, and yes, I saw the same problem with > PCI based NIC I tried on Ocotea at the time. Hm... good point. I'd still like to see if your patch works around the reporter's problem. josh