locked vnode / nfs... requires kill -9 in ddb
John Baldwin
jhb at freebsd.org
Fri Oct 20 19:13:49 UTC 2006
On Friday 20 October 2006 12:05, John E Hein wrote:
> John Baldwin wrote at 10:44 -0400 on Oct 19, 2006:
> > On Thursday 19 October 2006 06:04, Kostik Belousov wrote:
> > > On Wed, Oct 18, 2006 at 10:01:45AM -0600, John E Hein wrote:
> > > > 6.2-PRERELEASE from 20061016 RELENG_6 sources.
> > > > Locked vnodes
> > > >
> > > > 0xc6b7bdd0: tag nfs, type VDIR
> > > > usecount 2, writecount 0, refcount 8 mountedhere 0
> > > > flags (VV_ROOT)
> > > > v_object 0xc9d84108 ref 0 pages 0
> > > > lock type nfs: EXCL (count 1) by thread 0xc8adac00 (pid 50746)
with 5
> > pending
> > > > fileid 8 fsid 0x300ff06
> > > >
> > > > 50746 50000 49999 600 T+ sh
> > > > .
> > > > .
> > > > db>db> trace 50746
> > > > Tracing pid 50746 tid 100231 td 0xc8adac00
> > > > sched_switch(c8adac00,0,2) at 0xc05ce0cb = sched_switch+0x173
> > > > mi_switch(2,0) at 0xc05c2b0a = mi_switch+0x1ba
> > > > thread_suspend_check(1,c079e04c,c8adac00,c9206b80,1,...) at
0xc05c722d =
> > thread_suspend_check+0x191
> > > > sleepq_catch_signals(c9206b80) at 0xc05db93f =
sleepq_catch_signals+0x103
> > > > sleepq_wait_sig(c9206b80) at 0xc05dbd96 = sleepq_wait_sig+0xe
> > > > msleep(c9206b80,c08a6a40,153,c0813379,0) at 0xc05c2652 = msleep+0x25a
> > > > nfs_reply(c9206b80,0,c8adac00,4,c7ea7100,...) at 0xc06c33ac =
> > nfs_reply+0x244
> > > >
> >
nfs_request(c6b7bdd0,c6ae2d00,1,c8adac00,c7815280,e8f3488c,e8f34890,e8f34894,c8adac00,e8f348a0)
> > at 0xc06c40a5 = nfs_request+0x3c1
> > > > nfs_getattr(e8f348dc) at 0xc06c912b = nfs_getattr+0x11f
> > > > VOP_GETATTR_APV(c086c700,e8f348dc) at 0xc07b260c =
VOP_GETATTR_APV+0x38
> > > > nfsspec_access(e8f34a8c,c6bf7c94,0,e8f349a4,c060ca26,...) at
0xc06cebf1 =
> > nfsspec_access+0x85
> > > > nfs_access(e8f34a8c) at 0xc06c8b7a = nfs_access+0x122
> > > > VOP_ACCESS_APV(c086c700,e8f34a8c) at 0xc07b25b0 = VOP_ACCESS_APV+0x38
> > > > nfs_lookup(e8f34b18) at 0xc06c96ff = nfs_lookup+0xd3
> > > > VOP_LOOKUP_APV(c086c700,e8f34b18) at 0xc07b22f7 = VOP_LOOKUP_APV+0x43
> > > > lookup(e8f34c00) at 0xc060ee79 = lookup+0x4c1
> > > > namei(e8f34c00) at 0xc060e71a = namei+0x39a
> > > > kern_stat(c8adac00,806712c,0,e8f34c74) at 0xc061d3cd = kern_stat+0x35
> > > > stat(c8adac00,e8f34d04) at 0xc061d37b = stat+0x1b
> > > > syscall(3b,3b,3b,1,80670ec,...) at 0xc07a9363 = syscall+0x2bf
> > > > Xint0x80_syscall() at 0xc079456f = Xint0x80_syscall+0x1f
> > > > --- syscall (188, FreeBSD ELF32, stat), eip = 0x28196477, esp =
> > 0xbfbfdc1c, ebp = 0xbfbfdcb8 ---
> > > > db> kill 9 50746
> > > > db> c
> > >
> > > The nfs_reply is sleeping with the PCATCH set. The question is why
SIGTSTP
> > > does not cause msleep to return with EINTR.
> >
> > The problem is in thread_suspend_check(), not the sleepq code.
>
>
> It happened again (triggered by ctrl-z).
> INVARIANTS & WITNESS provided no help.
>
> Is the problem in thread_suspend_check() known?
> MFC-able from HEAD?
>
> I see this diff. I'm not sure it will help, but is there any reason
> not to try it in 6 (David Xu CC'd since he made this change)?
>
> Index: kern_thread.c
> ===================================================================
> RCS file: /base/FreeBSD-CVS/src/sys/kern/kern_thread.c,v
> retrieving revision 1.216.2.6
> retrieving revision 1.235
> diff -u -p -r1.216.2.6 -r1.235
> --- kern_thread.c 2 Sep 2006 17:29:57 -0000 1.216.2.6
> +++ kern_thread.c 28 Aug 2006 04:24:51 -0000 1.235
> @@ -910,6 +926,10 @@ thread_suspend_check(int return_instead)
> (p->p_flag & P_SINGLE_BOUNDARY) && return_instead)
> return (ERESTART);
>
> + /* If thread will exit, flush its pending signals */
> + if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td))
> + sigqueue_flush(&td->td_sigqueue);
> +
> mtx_lock_spin(&sched_lock);
> thread_stopped(p);
> /*
This change is not applicable to 6.x. The bug is likely in both 6.x and HEAD
in thread_suspend_check().
--
John Baldwin
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