From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Mundt Date: Mon, 10 Nov 2008 08:11:59 +0000 Subject: Re: repeated oops under load on SH4 system Message-Id: <20081110081159.GC13734@linux-sh.org> List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-sh@vger.kernel.org On Mon, Nov 10, 2008 at 05:06:23PM +0900, Paul Mundt wrote: > On Tue, Nov 04, 2008 at 09:31:44PM +0900, CHIKAMA Masaki wrote: > > Hello all. > > > > I've got repeated oops message under a load on kernel 2.6.26.7. > > It happens once or twice per a week with the below message. > > > > >Unable to handle kernel paging request at virtual address dfff0700 > > >Unable to handle kernel paging request at virtual address dfff1000 > > >Unable to handle kernel paging request at virtual address dfff0a00 > > > > I have been gotten this message from around kernel 2.6.23. I didn't > > test before it. > > My hardware is mach-landisk with attached .config. > > The root file system is on nfs server. > > Please let me know if you need more information to investigating the problem. > > Could somebody give me a hint to resolve the issue ? > > > > Thanks in advance. > > > This suggests you are getting a TLB miss on various fixmap entries. Based > on your call chain, these are related to the cache colouring in the page > copying. update_mmu_cache() specifically faults the translation in, so > you should not be making it all the way up to the TLB miss handler in the > first place. This points to something evicting the entry from the TLB > during your copy, which while it is not something I have seen in > practice, is interesting to know that it remains a possibility under > other workloads. A simple but expensive fix for this would be blowing out > the TLB and speculatively bumping up the UTLB replace boundary prior to > pre-faulting the fixmap translation. I'll look at this some more over the > next couple days and send you a patch for testing. Now I remember where I saw this before.. try this patch: http://marc.info/?l=linux-sh&m0400865707505&w=2 There was never any feedback on it, and I was not able to reproduce the issues.