Date: Fri, 5 Nov 2010 17:16:04 -0400 (EDT) From: Rick Macklem <rmacklem@uoguelph.ca> To: Andriy Gapon <avg@freebsd.org> Cc: freebsd-fs@freebsd.org, freebsd-current@freebsd.org Subject: Re: processes stuck on a vnode lock Message-ID: <1090600565.181851.1288991764084.JavaMail.root@erie.cs.uoguelph.ca> In-Reply-To: <4CD3B4A0.6060207@freebsd.org>
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[-- Attachment #1 --] > on 04/11/2010 16:45 Andriy Gapon said the following: > > on 04/11/2010 09:49 Andriy Gapon said the following: > >> > >> I see a few processes stuck on the same vnode, trying to take or to > >> upgrade to > >> an exclusive lock on it, while the lock data suggests that it is > >> already > >> shared-locked. The vnode is a root vnode of one of ZFS filesystems > >> (it's not a > >> global root). > >> > >> I couldn't find any (other) threads that could actually hold the > >> vnode lock, but > >> lock shared count is suspiciously or coincidentally the same as > >> number of > >> threads in zfs_root call. > > > > BTW, I still have the system alive and online, so if anyone has > > ideas I can try them. > > > > The kernel is not live now, but I have saved it and vmcore of the > system. > > Kostik, > > just a pure guesswork here - could r214049 have something to do with > this? > I looked at the change and it looks completely correct - I don't think > that a > vnode lock can be leaked by that code. But, OTOH, it has some special > handling > for VV_ROOT, it's in NFS code and and it's in a right time-frame, so > just asking. > You could try the attached patch which seems to have worked for Josh Carroll, who had a similar problem with stable/8. rick [-- Attachment #2 --] --- nfs_serv.c.sav 2010-11-05 08:15:57.000000000 -0400 +++ nfs_serv.c 2010-11-05 08:18:40.000000000 -0400 @@ -3252,7 +3252,7 @@ nfhp->fh_fsid = nvp->v_mount->mnt_stat.f_fsid; if ((error1 = VOP_VPTOFH(nvp, &nfhp->fh_fid)) == 0) error1 = VOP_GETATTR(nvp, vap, cred); - if (vp == nvp) + if (usevget == 0 && vp == nvp) vunref(nvp); else vput(nvp);
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