Date: Mon, 29 Jun 2009 17:13:09 +0200 From: Attilio Rao <attilio@freebsd.org> To: pluknet <pluknet@gmail.com> Cc: freebsd-stable <freebsd-stable@freebsd.org> Subject: Re: [nfs] process locks in "bo_wwait" on 6.4 Message-ID: <3bbf2fe10906290813h731a94bcrb1142e6e094a9877@mail.gmail.com> In-Reply-To: <3bbf2fe10906290801l3ed2e04ey44dd5f40f541a714@mail.gmail.com> References: <a31046fc0906260944h68eed26bs256dcad1f29871ff@mail.gmail.com> <3bbf2fe10906290458v3d57441ar44c4ed8f36c957f@mail.gmail.com> <a31046fc0906290555ib9abf4fy90502eb01e2ef8d3@mail.gmail.com> <3bbf2fe10906290611j683a0ddawbd524e406e832d54@mail.gmail.com> <a31046fc0906290618r31e5bfb0h9e267fadef53408a@mail.gmail.com> <3bbf2fe10906290620r7005f47dtfef8becc7f439515@mail.gmail.com> <a31046fc0906290659t44d11818x21dfb560ee509b44@mail.gmail.com> <3bbf2fe10906290706q349211c1pe00cc57cc18a1315@mail.gmail.com> <a31046fc0906290756s4f83c2f6jee199dad54244253@mail.gmail.com> <3bbf2fe10906290801l3ed2e04ey44dd5f40f541a714@mail.gmail.com>
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2009/6/29 Attilio Rao <attilio@freebsd.org>: > 2009/6/29 pluknet <pluknet@gmail.com>: >> 2009/6/29 Attilio Rao <attilio@freebsd.org>: >>> 2009/6/29 pluknet <pluknet@gmail.com>: >>>> 2009/6/29 Attilio Rao <attilio@freebsd.org>: >>>>> 2009/6/29 pluknet <pluknet@gmail.com>: >>>>>> 2009/6/29 Attilio Rao <attilio@freebsd.org>: >>>>>>> 2009/6/29 pluknet <pluknet@gmail.com>: >>>>>>>> 2009/6/29 Attilio Rao <attilio@freebsd.org>: >>>>>>>>> 2009/6/29 pluknet <pluknet@gmail.com>: >>>>>>>>>> 2009/6/26 pluknet <pluknet@gmail.com>: >>>>>>>>>>> 2009/6/26 pluknet <pluknet@gmail.com>: >>>>>>>>>>>> Hello. >>>>>>>>>>>> >>>>>>>>>>>> While building a module on nfs mounted /usr/src >>>>>>>>>>>> I got an unkillable process waiting forever in bo_wwait. >>>>>>>>>>> >>>>>>>>>>> Small note: iface on NFS server has mtu changed from 1500 to 1450. >>>>>>>>>>> Can this be a source of the problem? >>>>>>>>>> >>>>>>>>>> This is 100% reproducible. Lock in the same place. Any hints? >>>>>>>>> >>>>>>>>> Can you also show the value of ps? >>>>>>>>> A precise map of what processes are doing would give an help. >>>>>>>>> Also would be useful to printout traces for other threads and not only >>>>>>>>> the stucked one. >>>>>>>>> >>>>>>>> >>>>>>>> >From another run: >>>>>>> >>>>>>> I'm unable to see who would be locking the buffer object in question. >>>>>>> Do you have INVARIANT_SUPPORT/INVARIANTS on? >>>>>> >>>>>> Yes, I do both. >>>>>> >>>>>>> What revision of /usr/src/sys/kern/vfs_bio.c are you running with? >>>>>>> >>>>>> >>>>>> As of 6.4-R: CVS rev 1.491.2.12.4.1 / SVN rev 183531. >>>>> >>>>> Please try this patch and report. >>>>> >>>>> Thanks, >>>>> Attilio >>>>> >>>>> --- src/sys/nfsclient/nfs_vnops.c 2008/02/13 20:44:18 1.281 >>>>> +++ src/sys/nfsclient/nfs_vnops.c 2008/03/22 09:15:15 1.282 >>>>> @@ -33,7 +33,7 @@ >>>>> */ >>>>> >>>>> #include <sys/cdefs.h> >>>>> -__FBSDID("$FreeBSD: >>>>> /usr/local/www/cvsroot/FreeBSD/src/sys/nfsclient/nfs_vnops.c,v 1.281 >>>>> 2008/02/13 20:44:18 attilio Exp $"); >>>>> +__FBSDID("$FreeBSD: >>>>> /usr/local/www/cvsroot/FreeBSD/src/sys/nfsclient/nfs_vnops.c,v 1.282 >>>>> 2008/03/22 09:15:15 jeff Exp $"); >>>>> >>>> >>>> Do you refer to the whole svn r177493, or is its nfs part will be enough? >>>> This only vfs_vnops.c diff seems not applicable without underneath >>>> kernel part changes. >>>> >>>> I'll try. Thanks. >>> >>> The NFS part should be enough, though I don't understand why it >>> doesn't trigger a panic on STABLE_6 as long as, at least in my >>> revision, there is an assert for the buffer object lock to be held in >>> bufobj_wwait(). What's your sys/kern/vfs_bio.c rev? >>> >> >> As of 6.4-R. >> $FreeBSD: src/sys/kern/vfs_bio.c,v 1.491.2.12.4.1 2008/10/02 02:57:24 >> kensmith Exp $ > > That's it, the revision doesn't have the assert. > If it does fix the problem for you, I will let you test a more > comprehensive patch as there is also at least another fix I want to > bring in along with this one (and the relative asserts). Uhm, wait, after better looking at the code I don't think this patch can fix your problem. I will let you know with a bit of more time to study the deadlock. Thanks, Attilio -- Peace can only be achieved by understanding - A. Einstein
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