Panic from a recentish kernel: panic: Exit: Single threading fouled up

While trying to murder Mozilla and gwenview alongside compiling world and
perl, something went wrong...
Unfortunately, I'd updated my sources just prior to the event, so any listing
is probably highly suspect. Most things should be using libthr via libmap.
Apologies for the lack of info, I'll see if I can reproduce it and get
something more concrete (without losing 868 buffers this time, hopefully)

panic: Exit: Single threading fouled up

syncing disks, buffers remaining... 1384 1384 1384 1384 1384 1384 1384 1384
138
 1384 1384 1384 1384 1384 1384 1384 1384 1384 1384 1384 
giving up on 868 buffers
Uptime: 3h23m8s
Dumping 127 MB
 16 32 48 64[CTRL-C to abort] [CTRL-C to abort] [CTRL-C to abort]  80 96 112
---
Reading symbols from
/usr/obj/usr/src/sys/URIEL/modules/usr/src/sys/modules/lin
x/linux.ko.debug...done.
Loaded symbols for
/usr/obj/usr/src/sys/URIEL/modules/usr/src/sys/modules/linux
linux.ko.debug
Reading symbols from /boot/kernel/ng_ubt.ko...done.
Loaded symbols for /boot/kernel/ng_ubt.ko
Reading symbols from /boot/kernel/netgraph.ko...done.
Loaded symbols for /boot/kernel/netgraph.ko
Reading symbols from
/usr/obj/usr/src/sys/URIEL/modules/usr/src/sys/modules/acp
/acpi.ko.debug...done.
Loaded symbols for
/usr/obj/usr/src/sys/URIEL/modules/usr/src/sys/modules/acpi/
cpi.ko.debug
Reading symbols from
/usr/obj/usr/src/sys/URIEL/modules/usr/src/sys/modules/ntf
/ntfs.ko.debug...done.
Loaded symbols for
/usr/obj/usr/src/sys/URIEL/modules/usr/src/sys/modules/ntfs/
tfs.ko.debug
Reading symbols from
/usr/obj/usr/src/sys/URIEL/modules/usr/src/sys/modules/lin
rocfs/linprocfs.ko.debug...done.
Loaded symbols for
/usr/obj/usr/src/sys/URIEL/modules/usr/src/sys/modules/linpr
cfs/linprocfs.ko.debug
Reading symbols from
/usr/obj/usr/src/sys/URIEL/modules/usr/src/sys/modules/ipf
/ipfw.ko.debug...done.
Loaded symbols for
/usr/obj/usr/src/sys/URIEL/modules/usr/src/sys/modules/ipfw/
pfw.ko.debug
Reading symbols from /boot/kernel/logo_saver.ko...done.
Loaded symbols for /boot/kernel/logo_saver.ko
#0  doadump () at /usr/src/sys/kern/kern_shutdown.c:240
240             dumping++;
(kgdb) bt
#0  doadump () at /usr/src/sys/kern/kern_shutdown.c:240
#1  0xc0540e28 in boot (howto=256) at /usr/src/sys/kern/kern_shutdown.c:372
#2  0xc05411b7 in panic () at /usr/src/sys/kern/kern_shutdown.c:550
#3  0xc0529511 in exit1 (td=0xc2d04be0, rv=1536)
    at /usr/src/sys/kern/kern_exit.c:233
#4  0xc0528fe1 in sys_exit () at /usr/src/sys/kern/kern_exit.c:102
#5  0xc06a4430 in syscall (frame=
      {tf_fs = 47, tf_es = 47, tf_ds = 47, tf_edi = -1077944160, tf_esi = 6,
tf
ebp = -1077945032, tf_isp = -820667020, tf_ebx = 691275236, tf_edx =
691276208,
tf_ecx = 23, tf_eax = 1, tf_trapno = 12, tf_err = 2, tf_eip = 676497947, tf_cs 
 31, tf_eflags = 582, tf_esp = -1077945060, tf_ss = 47})
    at /usr/src/sys/i386/i386/trap.c:1012
#6  0xc069468d in Xint0x80_syscall () at {standard input}:144
---Can't read userspace from dump, or kernel process---

(kgdb) up 3
#3  0xc0529511 in exit1 (td=0xc2d04be0, rv=1536)
    at /usr/src/sys/kern/kern_exit.c:233
233                         ("realtime timer is still armed"));
(kgdb) l
228             if (timevalisset(&p->p_realtimer.it_value) &&
229                 callout_stop(&p->p_itcallout) == 0) {
230                     timevalclear(&p->p_realtimer.it_interval);
231                     msleep(&p->p_itcallout, &p->p_mtx, PWAIT, "ritwait",
0)
232                     KASSERT(!timevalisset(&p->p_realtimer.it_value),
233                         ("realtime timer is still armed"));
234             }
235             PROC_UNLOCK(p);
236
237             /*
(kgdb) up 1
#4  0xc0528fe1 in sys_exit () at /usr/src/sys/kern/kern_exit.c:102
102             exit1(td, W_EXITCODE(uap->rval, 0));
(kgdb) l
97      void
98      sys_exit(struct thread *td, struct sys_exit_args *uap)
99      {
100
101             mtx_lock(&Giant);
102             exit1(td, W_EXITCODE(uap->rval, 0));
103             /* NOTREACHED */
104     }
105
106     /*
(kgdb) up 1
#5  0xc06a4430 in syscall (frame=
      {tf_fs = 47, tf_es = 47, tf_ds = 47, tf_edi = -1077944160, tf_esi = 6,
tf
ebp = -1077945032, tf_isp = -820667020, tf_ebx = 691275236, tf_edx =
691276208,
tf_ecx = 23, tf_eax = 1, tf_trapno = 12, tf_err = 2, tf_eip = 676497947, tf_cs 
 31, tf_eflags = 582, tf_esp = -1077945060, tf_ss = 47})
    at /usr/src/sys/i386/i386/trap.c:1012
1012                    error = (*callp->sy_call)(td, args);
(kgdb) l
1007
1008                    STOPEVENT(p, S_SCE, narg);
1009
1010                    PTRACESTOP_SC(p, td, S_PT_SCE);
1011
1012                    error = (*callp->sy_call)(td, args);
1013            }
1014
1015            switch (error) {
1016            case 0:
(kgdb) 

-- 
Michael McGoldrick: michael_at_mcgoldrick.org