Date: Tue, 12 Jun 2012 19:11:13 -0400 (EDT) From: Benjamin Kaduk <kaduk@MIT.EDU> To: freebsd-current@freebsd.org Subject: panic td->td_lock == NULL in scheduler(), csup'd 2011-02-19 Message-ID: <alpine.GSO.1.10.1206121910380.18441@multics.mit.edu>
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Hi all,
I know, I should update the machine, but I figured I would throw this out
for the archives anyway.
I saw the panic a few minutes after starting X, but I'm pretty sure I was
not actually swapping. In ddb (blind), I ran 'call doadump; show
alllocks; show lockedvnods; call doadump; reboot' ... I'm not sure whether
the two 'doadump's will cause any issues with the core.
Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address = 0x18
fault code = supervisor read data, page not present
instruction pointer = 0x20:0xffffffff806d7dce
stack pointer = 0x28:0xffffffff81381c40
frame pointer = 0x28:0xffffffff81381ca0
code segment = base 0x0, limit 0xfffff, type 0x1b
= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags = resume, IOPL = 0
current process = 0 (swapper)
#7 0xffffffff809e20a5 in trap (frame=0xffffffff81381b90)
at /usr/src/sys/amd64/amd64/trap.c:319
#8 0xffffffff809cc6ef in calltrap ()
at /usr/src/sys/amd64/amd64/exception.S:228
#9 0xffffffff806d7dce in _thread_lock_flags (td=0xfffffe003b14d8c0, opts=0,
file=0xffffffff80b4b720 "/usr/src/sys/vm/vm_glue.c", line=744)
at /usr/src/sys/kern/kern_mutex.c:560
#10 0xffffffff8094b395 in scheduler (dummy=Variable "dummy" is not available.
) at /usr/src/sys/vm/vm_glue.c:744
#11 0xffffffff8069f8c7 in mi_startup () at /usr/src/sys/kern/init_main.c:256
#12 0xffffffff80292f2c in btext () at /usr/src/sys/amd64/amd64/locore.S:81
#13 0x0000000000000000 in ?? ()
#14 0xffffffff80eff8a0 in cpu_top ()
#15 0xffffffff80eff900 in affinity ()
#16 0xfffffe00025f8000 in ?? ()
#17 0xffffffff81381b60 in ?? ()
#18 0xffffffff81381b08 in ?? ()
#19 0xffffffff80ee6030 in proc0 ()
#20 0xffffffff8070e5d2 in sched_switch (td=0x0, newtd=0x0, flags=Variable
"flags" is not available.
)
at /usr/src/sys/kern/sched_ule.c:1847
I verified that td->td_lock was null using kgdb on the coredump.
kern_mutex.c:
558 retry:
559 spinlock_enter();
560 m = td->td_lock;
561 KASSERT(m->mtx_lock != MTX_DESTROYED,
562 ("thread_lock() of destroyed mutex @ %s:%d", file, l
vm_glue.c:
738 FOREACH_THREAD_IN_PROC(p, td) {
739 /*
740 * An otherwise runnable thread of a process
741 * swapped out has only the TDI_SWAPPED bit set.
742 *
743 */
744 thread_lock(td);
745 if (td->td_inhibitors == TDI_SWAPPED) {
-Ben Kaduk
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