Date: Wed, 29 Apr 2009 21:56:17 -0400 From: Ben Kelly <ben@wanderview.com> To: Lawrence Stewart <lstewart@freebsd.org> Cc: current@freebsd.org Subject: Re: [patch] zfs livelock and thread priorities Message-ID: <38E0E938-68DA-4D2E-8191-3CEC836A82E9@wanderview.com> In-Reply-To: <49F8E71B.2020102@freebsd.org> References: <AC3C4C3F-40C6-4AF9-BAF3-2C4D1E444839@wanderview.com> <ed91d4a80904142135n429dea52o672abf51116fa707@mail.gmail.com> <ed91d4a80904241816r28531a04r2dc70fa8960d430e@mail.gmail.com> <bc2d970904241947r50576efbgc93164a9e4dd297d@mail.gmail.com> <ed91d4a80904242059n3642a40aud55df6d1b6a1695@mail.gmail.com> <FC83DB1E-6C08-4BD4-8BC9-437D714FEE9E@wanderview.com> <ed91d4a80904271839l49420c8rbcfd52dd6e72eb83@mail.gmail.com> <ed91d4a80904281111q3b9a3c45vc9fcf129dde8c10d@mail.gmail.com> <F86D3461-3ABD-4A56-B9A6-36857364DF4B@wanderview.com> <4D8E4457-89AA-4F19-9960-E090D3B8E319@wanderview.com> <20090429064303.GA2189@a91-153-125-115.elisa-laajakaista.fi> <A83EA714-1EB5-41C1-91E2-FD031FD0DE0E@wanderview.com> <DA5E47A7-8D3C-4D79-A36E-4460ADC9E3F3@wanderview.com> <49F8E71B.2020102@freebsd.org>
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On Apr 29, 2009, at 7:47 PM, Lawrence Stewart wrote: > Ben Kelly wrote: >> On Apr 29, 2009, at 7:58 AM, Ben Kelly wrote: >>> On Apr 29, 2009, at 2:43 AM, Jaakko Heinonen wrote: >>>> On 2009-04-28, Ben Kelly wrote: >>>>>> http://www.wanderview.com/svn/public/misc/zfs/zfs_zinactive_deadlock.diff >>>>> >>>>> The patch is updated in the same location above. >>>> >>>> There's a fatal typo in the patch: >>>> >>>> - ZFS_OBJ_HOLD_ENTER(zfsvfs, z_id); >>>> + locked == ZFS_OBJ_HOLD_TRYENTER(zfsvfs, z_id); >>>> ^^^^ >>> >>> Yikes! Thanks for catching this! >>> >>> The patch has been updated at the same URL. If anyone has patched >>> their system please grab the new version. Sorry for the confusion. >> Argh! The patch was still broken even after this fix. >> Apparently when I tested my taskqueue solution I forgot to do a >> make installkernel. For some reason the taskqueue approach >> deadlocks my server at home under normal conditions. Therefore I >> have reverted the patch to use the simple return. I still don't >> think this is the right solution, but I don't have time to >> completely figure out what is going on right now. >> Again, sorry for the mess! > > As far as I can tell, one of the developers is working on a patch to > address the same issue you're discussing in this thread. He ran into > it on his SSD ZFS installation and the symptoms sound likely to be > the same as what you're discussing. I believe he's testing a patch > which is inspired by the one the opensolaris guys used to fix the > bug, which you can look at here: > > http://people.freebsd.org/~pjd/patches/vn_rele_hang.patch > > The open solaris one has major incompatibilities with FreeBSD so > can't be applied directly. > > As soon as it's ready I think he'll be making it available for wider > testing so stay tuned. > > Cheers, > Lawrence > > PS Apologies if the issue you're working on is not the same as the > one addressed by the opensolaris patch above. Thank you! This does appear to be the same issue and I look forward to seeing the final fix. For now I've gone ahead and updated my patch with a naive adaptation of the opensolaris diff. It seems more correct than what I had and I was worried people would waste time testing my broken approach. I've only been able to test it on my i386, non-SMP server however. Thanks again. - Ben
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