-current lockup (how to diagnose?)

Jun Kuriyama kuriyama at imgsrc.co.jp
Wed Jan 7 15:12:17 PST 2004

Hi Robert,

At Tue, 2 Dec 2003 06:49:38 +0000 (UTC),
Robert Watson wrote:
> Could you try compiling in DEBUG_LOCKS into your kernel and doing "show
> lockedvnods" with that?  Unfortunately, someone removed the pid from the
> output of that command, but didn't add the thread pointer to the DDB ps
> output, so you'll probably need to modify the lockmgr_printinfo() function
> in vfs_subr.c to print out lkp->lk_lockholder->td_proc->p_pid as well for
> exclusive locks.  It looks like maybe something isn't releasing a vnode
> lock before returning to userspace.  I have some patches to assert that no
> lockmgr locks are held on the return to userspace, but I'll have to dig
> them up tomorrow and send them to you.  Basically, it adds a per-thread
> lockmgr lock count in a thread-local variable, incrementing for each lock,
> and decrementing for each release, and then KASSERT()'s in userret that
> the variable is 0.

Can I use these patches?  I still get this lockup almost everyday
(during nightly dump with snapshot).  I'd like to try any patches even
if they are half baked.

Jun Kuriyama <kuriyama at imgsrc.co.jp> // IMG SRC, Inc.
             <kuriyama at FreeBSD.org> // FreeBSD Project

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