Date: Tue, 10 Jul 2012 22:23:28 +0200 From: Andreas Tobler <andreast-list@fgznet.ch> To: alc@freebsd.org Cc: Alan Cox <alan.l.cox@gmail.com>, Justin Hibbits <chmeeedalf@gmail.com>, freebsd-ppc@freebsd.org, Alan Cox <alc@rice.edu> Subject: Re: Panic with latest pmap lock changes. Message-ID: <4FFC8F40.90505@fgznet.ch> In-Reply-To: <CAJUyCcPDLmNKaW8WTQWMMW9tx%2BL2ovYYtxj0MD94EAhT=Z2ZRQ@mail.gmail.com> References: <20120707102004.3e874201@narn.knownspace> <4FF87446.2090903@rice.edu> <4FF9F3CF.6050608@fgznet.ch> <CAJUyCcPDLmNKaW8WTQWMMW9tx%2BL2ovYYtxj0MD94EAhT=Z2ZRQ@mail.gmail.com>
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On 10.07.12 22:00, Alan Cox wrote: > On Sun, Jul 8, 2012 at 3:55 PM, Andreas Tobler <andreast-list@fgznet.ch > <mailto:andreast-list@fgznet.ch>> wrote: > > On 07.07.12 19:39, Alan Cox wrote: > > On 07/07/2012 09:20, Justin Hibbits wrote: > > Looks like I spoke too soon about the pmap lock changes > working on my > G4. After about 24 hours of uptime, it panicked with the > following: > > _rw_wlock_hard: recursing but non-recursive rw pmap pv global > @ /home/chmeee/freebsd/src/sys/__powerpc/aim/mmu_oea.c:2301 > > I think the attached patch should fix it (Untested, except for > compiling). > > > Ugh. Sorry. > > The attached patch eliminates the lock recursion. While I was doing > that, I noticed that the pmap_ts_referenced() implementations on > powerpc > have the wrong return type. Oddly, the comments in mmu_if.h > have the > return type correct, but the code two or three lines later has > it wrong. > > > Fyi, I'm building world with the patch mentioned in this thread and > the kernel updated to 238258. (G5-SMP 32-bit) > > So far it looks promising. > > Before 238258 I got reliable machine locks/freeze w/o any idea what > was happening. > > If I reverted mmu_oea.c back to 238158, one before the commit from > you Alan, I was able to get a successful full world/kernel build cycle. > Yes, I confirmed that it booted, but I was not able to run a full > world/kernel cycle since I lost my GEOM_APM config ;). > > Anyway, as said, it looks promising and it will take some hours to > complete. > > > Should I commit the patch? Hmmm, I had three successful world/kernel builds with this patch. All with a GENERIC kernel. But I also had one freeze, no info/panic nothing, with a kernel where I disabled the WITNESS/INVARIANTS stuff. I think the patch is an improvement. I need to figure why I do not get any info when the machine freezes/locks whatever. But this can be done with the committed patch. Maybe we get bigger testing audience when it is committed. Thanks, Andreas
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