Date: Fri, 20 Oct 2006 15:13:54 -0400 From: John Baldwin <jhb@freebsd.org> To: John E Hein <jhein@timing.com> Cc: Kostik Belousov <kostikbel@gmail.com>, stable@freebsd.org, davidxu@freebsd.org Subject: Re: locked vnode / nfs... requires kill -9 in ddb Message-ID: <200610201513.55539.jhb@freebsd.org> In-Reply-To: <17720.62415.274270.378426@gromit.timing.com> References: <17718.20457.799395.602805@gromit.timing.com> <17719.56453.21278.746053@gromit.timing.com> <17720.62415.274270.378426@gromit.timing.com>
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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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