Re: panic td->td_lock == NULL in scheduler(), csup'd 2011-02-19

Hi,

 it looks similar to
http://lists.freebsd.org/pipermail/freebsd-current/2011-March/023829.html

   Svata

On Wed, Jun 13, 2012 at 1:11 AM, Benjamin Kaduk <kaduk_at_mit.edu> wrote:
> 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 _at_ %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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