Date: Wed, 27 Jul 2011 15:08:50 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: Rick Macklem <rmacklem@uoguelph.ca> Cc: rmacklem@freebsd.org, Herve Boulouis <amon@aelita.org>, freebsd-stable@freebsd.org Subject: Re: Sleeping thread owns a nonsleepable lock panic (& lor) Message-ID: <20110727120850.GT17489@deviant.kiev.zoral.com.ua> In-Reply-To: <132828699.1045046.1311721943354.JavaMail.root@erie.cs.uoguelph.ca> References: <20110726093258.GF17489@deviant.kiev.zoral.com.ua> <132828699.1045046.1311721943354.JavaMail.root@erie.cs.uoguelph.ca>
next in thread | previous in thread | raw e-mail | index | archive | help
--Ro3o5bxpeh65nwUH Content-Type: text/plain; charset=koi8-r Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jul 26, 2011 at 07:12:23PM -0400, Rick Macklem wrote: > Kostik Belousov wrote: > > On Tue, Jul 26, 2011 at 01:17:52PM +0200, Herve Boulouis wrote: > > > Le 26/07/2011 12:06, Kostik Belousov a =E9crit: > > > > On Tue, Jul 26, 2011 at 11:49:13AM +0200, Herve Boulouis wrote: > > > > > Le 25/07/2011 11:59, Kostik Belousov a ?crit: > > > > > > > > > > Ok the patched server crashed this morning strangely : all httpd > > > > > processes were stuck in nfs or vmopar > > > > > and were unkillable. Below is the full ps. > > > > > > > > Please see the > > > > http://www.freebsd.org/doc/en_US.ISO8859-1/books/developers-handboo= k/kerneldebug-deadlocks.html > > > > for information required to debug the deadlocks. > > > > > > the box was not stricly deadlocked since I was able to interact with > > > it but I suppose you want me to > > > break into debugger when the symptoms appears again and report all > > > the commands listed in the handbook > > > deadlock section ? > >=20 > > Exactly. > >=20 > > I think everything was hung that accessed an nfs mount point. > > From the usermode, procstat -kk could catch some interesting > > information, > > but it is redundant if ddb output is captured. >=20 > Would it be worth considering reverting r223054? > (Note that I don't understand the VM side, so this may be completely > wrong:-) >=20 > The sleeps on vmopar could be happening because a dirty page is busy > and r223054 changes the VM_PAGER_xx value set a couple of ways. > 1 - When it returns VM_PAGER_ERROR instead of VM_PAGER_AGAIN, the > return value of "runlen" from vm_pageout_flush() changes. > 2 - I'm not sure, but I think the pre-r223054 code marked a partially > written page as VM_PAGER_OK instead of VM_PAGER_AGAIN? > (I'm wondering about this one, since the problem seems to happen > when the file's size has been truncated.) >=20 > Herve Boulouis, if you want to see what r223054 changes, just go to > http://svn.freebsd.org/viewvc/stable/8/sys/nfsclient > and then click on nfs_bio.c. > (The changes are small and could easily be reverted with a manual > edit.) >=20 > Since r223054 went into stable/8 on Jun 13, it seems a possible > explanation? rick I doubt it. The ps output makes it not very inplausible that the reporter got the LOR between vnode lock and page busy flag. The correct order is vnode lock -> busy bit. vmopar is a wait for the busy page state. Mentioned revision does not change the lock order. Anyway, this is only a speculation, until the requested data is provided. --Ro3o5bxpeh65nwUH Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (FreeBSD) iEYEARECAAYFAk4v/9IACgkQC3+MBN1Mb4g1wwCdHVz5RdsVMC8sia2S5qw36Czi TH0Anj9y7UxYNzmvj80NZAdIxfvTNB20 =pguu -----END PGP SIGNATURE----- --Ro3o5bxpeh65nwUH--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20110727120850.GT17489>