RE: lockmgr panic on shutdown

On Sat, 1 Nov 2003, Doug White wrote:

> For giggles I'm rolling back vfs_default.c back to 1.87 since its along
> the backtrace path.

This didn't work so -CURRENT is fully broke.

I'd suggest staying on 10/30 not before 4PM PST if you want to not crash
on shutdown.

>
> I suspect I'll need to back up the whole thing to before the commit for
> the struct mount locking until jeff & kan can straighten things out.
>
> On Sun, 2 Nov 2003 peter.edwards_at_openet-telecom.com wrote:
>
> >
> >
> > >I can confirm the lockmgr panic on shutdown reported by someone else
> > >earlier (whose message I mistakenly deleted).
> > >
> > >It looks like swapper is trying to undo a lock from pagedaemon and runs
> > >into trouble. This is probably related to the Giant pushdown of
> > >vm_pageout() that alc did last week.
> > >
> > >I'm building with INVARIANTS to see if that will catch more info.  Will
> > >report back soon.
> >
> > Just happened me too. I think I see the problem:
> >
> > When boot() calls sync(), it passes &thread0 as the thread argument.
> > This gets propgated up to ffs_sync, which:
> >
> >   calls vget(), which takes a thread argument.
> >   does some stuff
> >   calls vput(), which does _not_ take a thread argument
> >
> > The vget() is passed thread0, as passed from boot.
> > The vput() gets the current thread, which is the process calling boot.
> >
> > The unlocking in vput is asserting that the same thread that aquired
> > the lock is releasing it, which seems reasonable.
> >
> > The obvious solution might be to change line 1161 of ffs_vfsops to
> > pass vget() "curthread" rather than td. I assume there's a good
> > reason why "thread0" is passed from boot(), but I can't see why
> > that's of any use to the vnode locking.
> >
> > i.e.:
> > Index: ffs_vfsops.c
> > ===================================================================
> > RCS file: /usr/cvs/FreeBSD-CVS/src/sys/ufs/ffs/ffs_vfsops.c,v
> > retrieving revision 1.221
> > diff -u -r1.221 ffs_vfsops.c
> > --- ffs_vfsops.c        1 Nov 2003 05:51:54 -0000       1.221
> > +++ ffs_vfsops.c        2 Nov 2003 03:06:42 -0000
> > _at__at_ -1158,7 +1158,7 _at__at_
> >                         continue;
> >                 }
> >                 mtx_unlock(&mntvnode_mtx);
> > -               if ((error = vget(vp, lockreq, td)) != 0) {
> > +               if ((error = vget(vp, lockreq, curthread)) != 0) {
> >                         mtx_lock(&mntvnode_mtx);
> >                         if (error == ENOENT)
> >                                 goto loop;
> >
> >
> > How come tha parameters to vget and vput are lopsided like this?
> >
> > This might have something to do with the commit
> > of revision 1.218 of ffs_vfsops.c, but I'm not sure.
> >
> >
>
>

-- 
Doug White                    |  FreeBSD: The Power to Serve
dwhite_at_gumbysoft.com          |  www.FreeBSD.org