From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Fri, 29 Jan 2010 18:18:36 +0100 (CET) Received: from smtp2.caviumnetworks.com ([209.113.159.134]:13774 "EHLO smtp2.caviumnetworks.com" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S1492734Ab0A2RSc (ORCPT ); Fri, 29 Jan 2010 18:18:32 +0100 Received: from maexch1.caveonetworks.com (Not Verified[192.168.14.20]) by smtp2.caviumnetworks.com with MailMarshal (v6,5,4,7535) id ; Fri, 29 Jan 2010 12:13:03 -0500 Received: from caexch01.caveonetworks.com ([192.168.16.9]) by maexch1.caveonetworks.com with Microsoft SMTPSVC(6.0.3790.3959); Fri, 29 Jan 2010 12:18:30 -0500 Received: from caexch01.caveonetworks.com ([192.168.16.9]) by caexch01.caveonetworks.com with Microsoft SMTPSVC(6.0.3790.3959); Fri, 29 Jan 2010 09:11:47 -0800 Received: from dd1.caveonetworks.com ([12.108.191.236]) by caexch01.caveonetworks.com over TLS secured channel with Microsoft SMTPSVC(6.0.3790.3959); Fri, 29 Jan 2010 09:11:47 -0800 Message-ID: <4B6316D2.1060006@caviumnetworks.com> Date: Fri, 29 Jan 2010 09:11:46 -0800 From: David Daney User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: Guenter Roeck CC: Ralf Baechle , "linux-mips@linux-mips.org" Subject: Re: Kernel crash in 2.6.32.6 / bcm1480 with 16k page size References: <20100128155514.GA31611@ericsson.com> <20100129132406.GD5685@linux-mips.org> <20100129151220.GA3882@ericsson.com> In-Reply-To: <20100129151220.GA3882@ericsson.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 29 Jan 2010 17:11:47.0820 (UTC) FILETIME=[23EEAAC0:01CAA106] X-archive-position: 25739 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ddaney@caviumnetworks.com Precedence: bulk X-list: linux-mips Return-Path: X-Keywords: X-UID: 19005 Guenter Roeck wrote: > On Fri, Jan 29, 2010 at 08:24:07AM -0500, Ralf Baechle wrote: >> On Thu, Jan 28, 2010 at 07:55:14AM -0800, Guenter Roeck wrote: >>> I get the following kernel crash when running a 2.6.32.6 kernel on a bcm1480 cpu. >>> It only happens if I configure a page size of 16k or 64k; 4k page size is fine. >>> >>> A similar problem was recently fixed for ppc. It turned out to be a problem in ppc >>> specific memory management code, so that fix won't help here. >>> >>> Has anyone else seen this before ? Any idea where to start looking for the problem ? >> Supposedly this was working for SB1. I suggest you find an older kernel >> version that works for your with 16k pages then use git bisect to find >> the problem. >> > It used to work with 2.6.27. > > However, bisect won't work, because the code in question (per cpu memory allocation) was > completely rewritten since then. > > The new percpu code tries to allocate memory just below VMALLOC_END. This works on sb1 for > a page size of 4k, but not for a page size of 16k and 64k. The value of VMALLOC_END depends > on the page size. > > ppc had a similar problem. It had nothing to do with the new percpu memory allocation code, > but with memory alocation close to VMALLOC_END. In other words, it was a day-one bug which > was never noticed because allocating memory in that address space is highly unlikely. > > I suspect the same is the case here. I could write some code for 2.6.27, to test the same > memory allocation there, but I am quite sure the problem is going to show up there as well. > > So first question would be: Has anyone successfully loaded a 64 bit mips kernel with 2.6.32 > and a page size of 16k or 64k ? This would at least help me reducing the problem to sb1. > Yes, I routinely run with both 64K and 16K page sizes on 2.6.32 and 2.6.33-rc*. I have not seen any crashes that can not be easily explained. David Daney.