panic: witness_warn head/amd64 _at_r285741 on 1 of 2 machines

From: David Wolfskill <david_at_catwhisker.org>
Date: Tue, 21 Jul 2015 05:57:34 -0700
My laptop had no problems, but the build machine has a panic that
appears quite reproducible (4 "successes" out of 4 tries); here's a bit
from the core.txt file:

freebeast.catwhisker.org dumped core - see /var/crash/vmcore.1

Tue Jul 21 05:36:11 PDT 2015

FreeBSD freebeast.catwhisker.org 11.0-CURRENT FreeBSD 11.0-CURRENT #1787  r285741M/285741:1100077: Tue Jul 21 04:48:37 PDT 2015     root_at_freebeast.catwhisker.org:/common/S4/obj/usr/src/sys/GENERIC  amd64

panic: witness_warn

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Unread portion of the kernel message buffer:
panic: witness_warn
cpuid = 3
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe083b9c0860
vpanic() at vpanic+0x189/frame 0xfffffe083b9c08e0
kassert_panic() at kassert_panic+0x132/frame 0xfffffe083b9c0950
witness_warn() at witness_warn+0x498/frame 0xfffffe083b9c0a20
ithread_loop() at ithread_loop+0x165/frame 0xfffffe083b9c0a70
fork_exit() at fork_exit+0x84/frame 0xfffffe083b9c0ab0
fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe083b9c0ab0
--- trap 0, rip = 0, rsp = 0xfffffe083b9c0b70, rbp = 0 ---
...
(kgdb) #0  doadump (textdump=0) at pcpu.h:221
#1  0xffffffff80377dfe in db_dump (dummy=<value optimized out>, dummy2=false, 
    dummy3=0, dummy4=0x0) at /usr/src/sys/ddb/db_command.c:533
#2  0xffffffff80377971 in db_command (cmd_table=0x0)
    at /usr/src/sys/ddb/db_command.c:440
#3  0xffffffff80377604 in db_command_loop ()
    at /usr/src/sys/ddb/db_command.c:493
#4  0xffffffff8037a19b in db_trap (type=<value optimized out>, code=0)
    at /usr/src/sys/ddb/db_main.c:251
#5  0xffffffff80a56624 in kdb_trap (type=3, code=0, tf=<value optimized out>)
    at /usr/src/sys/kern/subr_kdb.c:654
#6  0xffffffff80e61bd1 in trap (frame=0xfffffe083b9c0790)
    at /usr/src/sys/amd64/amd64/trap.c:540
#7  0xffffffff80e41e02 in calltrap ()
    at /usr/src/sys/amd64/amd64/exception.S:235
#8  0xffffffff80a55cfe in kdb_enter (why=0xffffffff8136f098 "panic", 
    msg=0xffffffff80a5bee0 "UH\211<E5>AWAVATSH\203<EC>PI\211<F7>A\211<FE>H\213\004%<D0><C7><B8>\201H\211E<D8>\201<%x<D7><B8>\201") at cpufunc.h:63
#9  0xffffffff80a19739 in vpanic (fmt=<value optimized out>, 
    ap=<value optimized out>) at /usr/src/sys/kern/kern_shutdown.c:737
#10 0xffffffff80a19582 in kassert_panic (fmt=<value optimized out>)
    at /usr/src/sys/kern/kern_shutdown.c:634
#11 0xffffffff80a74908 in witness_warn (flags=2, lock=<value optimized out>, 
    fmt=0xffffffff81367827 "suspending ithread")
    at /usr/src/sys/kern/subr_witness.c:1757
#12 0xffffffff809e2985 in ithread_loop (arg=0xfffff8000770c820)
    at /usr/src/sys/kern/kern_intr.c:1345
#13 0xffffffff809df874 in fork_exit (
    callout=0xffffffff809e2820 <ithread_loop>, arg=0xfffff8000770c820, 
    frame=0xfffffe083b9c0ac0) at /usr/src/sys/kern/kern_fork.c:1006
#14 0xffffffff80e4233e in fork_trampoline ()
    at /usr/src/sys/amd64/amd64/exception.S:610
#15 0x0000000000000000 in ?? ()
Current language:  auto; currently minimal
(kgdb) 


On boot, it dropped into the debugger; it was on the most recent
instantiation that I manually issued a "dump" command from that
environment, then rebooted under the previous kernel:

FreeBSD freebeast.catwhisker.org 11.0-CURRENT FreeBSD 11.0-CURRENT #1786  r285715M/285715:1100077: Mon Jul 20 04:22:26 PDT 2015     root_at_freebeast.catwhisker.org:/common/S3/obj/usr/src/sys/GENERIC  amd64

(And yes, it runs an unmodified GENERIC kernel.)

The machine has been deployed only for a couple of months or so,
but has been building stable/10 and head daily during that time.
Until a couple of weeks ago, it was doing this for both i386 and
amd64; since then, I dropped i386 from my home infrastructure, so
it's been only amd64.

In the stable/10 environment, it also make use of a 3-spindle zraid for
running poudriere (to build the ports for my "production" machines), and
it's been doing that quite well, also.

Only other thing that I think of that's noteworthy is that its boot
drive is an SSD (where I have not yet enabled TRIM, as it's a Crucial
M500, and I need to be sure we don't try to use the queued TRIM commands
on it, as there are reports that queued TRIM commands on the M500 will
corrupt data).

OK; please see <http://www.catwhisker.org/~david/FreeBSD/head/> for the
dump(-related) files.  (It's on a residential ADSL, so it's going to be
slow.  Sorry; I have a limited amount of bandwidth.)

Peace,
david
-- 
David H. Wolfskill				david_at_catwhisker.org
Those who murder in the name of God or prophet are blasphemous cowards.

See http://www.catwhisker.org/~david/publickey.gpg for my public key.

Received on Tue Jul 21 2015 - 10:57:37 UTC

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