Re: panic: process 839(xmms):1 holds process lock but isn't blocked ona lock

On Wed, 8 Dec 2004, Wilkinson, Alex wrote:

:Hi all,
:
:I got this panic today on a:
:FreeBSD 5.3-STABLE #13: Mon Nov 29 09:49:10 CST 2004
:
:This panic is reproduceable via two methods:
:
:1.  # kldload snd_ich
:
:2.  add snd_ich_load="YES" to /boot/loader.conf; reboot;
:    # kldunload snd_ich
:

For what it's worth, on recent -CURRENt, I've had 'kdload snd_ich' hang my
machine... as in full lock up.  kldload snd_driver I've had varied
success... I booted yesterday AM's -CURRENT and after boot kldload'd
snd_Driver and had a hang... but after reb ooting, starting X, su'ing to
root, and loading.. it worked.  Random :-)

:I have a kernel with debugging symbols and a vmcore if anyone is
:interested.
:
:db> trace
:kdb_enter(c068735f,c06df360,c068a355,e3744c64,c266c320) at
:kdb_enter+0x32
:panic(c068a355,347,c3020698,1,c0686981) at panic+0x14b
:turnstile_wait(c2ef6600,c06ddec0,c3021e10,220,c06ddec0) at
:turnstile_wait+0x5ec
:_mtx_lock_sleep(c06ddec0,c266c320,0,c0684ceb,222) at
:_mtx_lock_sleep+0xb0
:_mtx_lock_flags(c06ddec0,0,c0684ceb,222,0) at _mtx_lock_flags+0xaf
:ithread_loop(c2661480,e3744d48,c0684acc,323,c2661480) at
:ithread_loop+0x1ea
:fork_exit(c04de759,c2661480,e3744d48) at fork_exit+0xa6
:fork_trampoline() at fork_trampoline+0x8
:--- trap 0x1, eip = 0, esp = 0xe3744d7c, ebp = 0 ---
:db> show pcpu
:cpuid        = 0
:curthread    = 0xc266c320: pid 28 "irq18: uhci2 bt0++"
:curpcb       = 0xe3744da0
:fpcurthread  = none
:idlethread   = 0xc26644b0: pid 11 "idle"
:APIC ID      = 0
:currentldt   = 0x28
:spin locks held:
:db> show lockedvnods
:Locked vnodes
:db>
:
: (850)-08.12.2004 hostname-{17:26}-[/var/crash]->sudo kldunload snd_ich
:Password:
:lock order reversal
: 1st 0xc2781a40 pcm0 (sound cdev) _at_
:/usr/src/sys/modules/sound/sound/../../../dev/sound/pcm/sound.c:706
: 2nd 0xc07c6a20 sndstat (sndstat) _at_
:/usr/src/sys/modules/sound/sound/../../../dev/sound/pcm/sndstat.c:257
:KDB: stack backtrace:
:witness_checkorder(c07c6a20,9,c07c1a3d,101,0) at
:witness_checkorder+0x5fa
:_sx_xlock(c07c6a20,c07c1a3d,101,0,c2738e00) at _sx_xlock+0x5c
:sndstat_unregister(c2753800,8,c07c1b35,2c2,c2753800) at
:sndstat_unregister+0x27
:pcm_unregister(c2753800,c06a5f7c,c2753800,e75e2bfc,c2753800) at
:pcm_unregister+0x1f5
:ich_pci_detach(c2753800,c26fd850,c06a5f7c,c07a88f1,3) at
:ich_pci_detach+0x13
:device_detach(c2753800,c07a8909,c26e2000,1,c26aed80) at
:device_detach+0x6b
:
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--
Andrew R. Reiter
arr_at_watson.org
arr_at_FreeBSD.org