panic: mutex Giant not owned at /usr/src/sys/kern/tty_ttydisc.c:1127

Hi all.

Ed, can you look at this?

I triggered a double panic by an accident while in ddb> prompt by pressing
and unpressing a 'pause' key (to scroll up the first panic message).
Then my system unconditionally goes to reboot (after 15 seconds).

Backtrace initially posted by me in "nullfs: panic: vrele: negative ref cnt"
thread on -current and spammed here again for the reference.

Script started on Mon Mar  9 21:43:17 2009
c8-vb# kgdb /boot/ke rnel/ke rnel /var/crash/vm core.1

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This GDB was configured as "i386-marcel-freebsd"...

Unread portion of the kernel message buffer:
, FreeBSD ELF32, __getcwd), eip = 0x28154b2b, esp = 0xbfbfe71c, ebp =
0xbfbfe7d8 ---
null_hashget: 0xc4451560 is not locked but should be
KDB: enter: lock violation
panic: mutex Giant not owned at /usr/src/sys/kern/tty_ttydisc.c:1127
cpuid = 0
Uptime: 43m7s
Physical memory: 1015 MB
Dumping 51 MB: 36 20 4

Reading symbols from /boot/kernel/if_em.ko...Reading symbols from
/boot/kernel/if_em.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/if_em.ko
Reading symbols from /boot/kernel/nfsclient.ko...Reading symbols from
/boot/kernel/nfsclient.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/nfsclient.ko
#0  doadump () at pcpu.h:246
246     pcpu.h: No such file or directory.
       in pcpu.h
(kgdb) bt
#0  doadump () at pcpu.h:246
#1  0xc05c458e in boot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:420
#2  0xc05c4862 in panic (fmt=Variable "fmt" is not available.
) at /usr/src/sys/kern/kern_shutdown.c:576
#3  0xc05b4c77 in _mtx_assert (m=0xc08b6170, what=4,
   file=0xc0829baf "/usr/src/sys/kern/tty_ttydisc.c", line=1127)
   at /usr/src/sys/kern/kern_mutex.c:639
#4  0xc06197dd in ttydisc_getc (tp=0xc3dbf000, buf=0xe66bc7c0, len=128)
   at /usr/src/sys/kern/tty_ttydisc.c:1127
#5  0xc050daf4 in sctty_outwakeup (tp=0xc3dbf000)
   at /usr/src/sys/dev/syscons/syscons.c:323
#6  0xc050e05c in scgetc (sc=0xc0a73000, flags=3)
   at /usr/src/sys/dev/syscons/syscons.c:3281
#7  0xc050e680 in sc_cngetc (cd=0xc0863d20)
   at /usr/src/sys/dev/syscons/syscons.c:1607
#8  0xc058cd68 in cncheckc () at /usr/src/sys/kern/kern_cons.c:377
#9  0xc058cda6 in cngetc () at /usr/src/sys/kern/kern_cons.c:355
#10 0xc0480435 in db_readline (lstart=0xc08a0100 "", lsize=120)
   at /usr/src/sys/ddb/db_input.c:326
#11 0xc0480e0a in db_read_line () at /usr/src/sys/ddb/db_lex.c:56
#12 0xc047f0b6 in db_command_loop () at /usr/src/sys/ddb/db_command.c:496
#13 0xc0480f2d in db_trap (type=3, code=0) at /usr/src/sys/ddb/db_main.c:229
#14 0xc05f1d86 in kdb_trap (type=3, code=0, tf=0xe66bca34)
   at /usr/src/sys/kern/subr_kdb.c:534
#15 0xc07bc856 in trap (frame=0xe66bca34) at /usr/src/sys/i386/i386/trap.c:678
---Type <return> to continue, or q <return> to quit---
#16 0xc07a15bb in calltrap () at /usr/src/sys/i386/i386/exception.s:165
#17 0xc05f1f0a in kdb_enter (why=0xc082deeb "vfslock",
   msg=0xc082dedc "lock violation") at cpufunc.h:71
#18 0xc064a541 in vfs_badlock (msg=0xc082df39 "is not locked but should be",
   str=0xc08173c4 "null_hashget", vp=0xc4451560)
   at /usr/src/sys/kern/vfs_subr.c:3699
#19 0xc064ddf2 in assert_vop_locked (vp=0xc4451560,
   str=0xc08173c4 "null_hashget") at /usr/src/sys/kern/vfs_subr.c:3723
#20 0xc055c5df in null_nodeget (mp=0xc40152cc, lowervp=0xc4451560,
   vpp=0xe66bcbf0) at /usr/src/sys/fs/nullfs/null_subr.c:110
#21 0xc055d75a in null_bypass (ap=0xe66bcbdc)
   at /usr/src/sys/fs/nullfs/null_vnops.c:325
#22 0xc07c86a3 in VOP_VPTOCNP_APV (vop=0xc08688a0, a=0xe66bcbdc)
   at vnode_if.c:2871
#23 0xc063a749 in vn_vptocnp (vp=0xe66bcc24, bp=0xe66bcc28,
   buf=0xc3e15c00 'p' <repeats 200 times>..., buflen=0xe66bcc48)
   at vnode_if.h:1541
#24 0xc063aaca in vn_fullpath1 (td=Variable "td" is not available.
) at /usr/src/sys/kern/vfs_cache.c:1001
#25 0xc063ae60 in kern___getcwd (td=0xc4435000,
   buf=0xbfbfe8d4 <Address 0xbfbfe8d4 out of bounds>, bufseg=UIO_USERSPACE,
   buflen=1024) at /usr/src/sys/kern/vfs_cache.c:795
#26 0xc063b009 in __getcwd (td=0xc4435000, uap=0xe66bccf8)
   at /usr/src/sys/kern/vfs_cache.c:769
#27 0xc07bbfd4 in syscall (frame=0xe66bcd38)
---Type <return> to continue, or q <return> to quit---
   at /usr/src/sys/i386/i386/trap.c:1066
#28 0xc07a1620 in Xint0x80_syscall ()
   at /usr/src/sys/i386/i386/exception.s:261
#29 0x00000033 in ?? ()
Previous frame inner to this frame (corrupt stack?)
(kgdb) c8-vb#

c8-vb# ^D  exit

-- 
wbr,
pluknet