sysctl -a causes kernel trap 12

Henri Hennebert hlh at
Wed Feb 13 16:41:20 UTC 2013

On 02/12/2013 12:22, Henri Hennebert wrote:
> On 01/19/2013 06:58, Brandon Gooch wrote:
>> On Fri, Jan 18, 2013 at 2:56 PM, Xin Li <delphij at> wrote:
>>> Hash: SHA512
>>> On 01/18/13 12:50, Brandon Gooch wrote:
>>>> On Thu, Jan 10, 2013 at 4:25 PM, Xin Li <delphij at
>>>> <mailto:delphij at>> wrote:
>>>> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256
>>>> To all: this became more and more hard to replicate lately.  I've
>>>> tried these options and the most important progress is that it's
>>>> possible to get a crashdump when debug.debugger_on_panic=0 and I
>>>> managed to get a backtrace which indicates the panic occur when
>>>> trying to do mtx_lock(&Giant) -> __mtx_lock_sleep -> turnstile_wait
>>>> -> propagate_priority, but after I've added some instruments to
>>>> the surrounding code and enabled INVARIANT and/or WITNESS, it
>>>> mysteriously went away.
>>>> Reverting my instruments code and update to latest svn makes the
>>>> issue disappear for one day.  I've hit it again today but
>>>> unfortunately didn't get a successful dump and after reboot I can't
>>>> reproduce it again :(
>>>> Still trying...
>>>> Any updates Xin?
>>> No, it mysteriously disappeared for now.  According to my
>>> understanding to recent svn commits, I didn't see anybody committing
>>> something that fixes it but I can no longer panic my system, with or
>>> without debugging code :(
>>>> I was actually hitting what I believe to be exactly the same issue
>>>> as you on one of my systems, and, as you've seen, adding any extra
>>>> debugging or diagnostics seemed to eliminate the issue.
>>>> I was able to generate quite a few vmcores and still have these
>>>> sitting around in my filesystem (along with the kernels that helped
>>>> produce them).
>>>> I can recreate this crash on my system by compiling the NVIDIA
>>>> driver with clang at -01 and above. Although it's been noted that
>>>> this issue has been seen in scenarios without an NIVIDIA driver in
>>>> the mix, whatever is happening in the kernel to cause the panic is
>>>> somehow triggered by this, at least on my system.
>>> I'm not sure if this is the same problem.  Could you please try using
>>> gcc to compile the nVIdia driver and see if that "fixes" the problem?
>>> Cheers,
>>> - --
>>> Xin LI <delphij at>
>>> FreeBSD - The Power to Serve!           Live free or die
>> Indeed, a gcc compiled NVIDIA module eliminates the issue, sorry if I
>> hadn't mentioned this earlier.
>> What was happening to me at first was that my system would just hang while
>> booting. I was able to figure out that it was during /etc/rc.d/initrandom.
>> I actually got to a point where I removed the call to sysctl -a from
>> 'better_than_nothing()' in /etc/rc.d/initrandom to have a booting system. I
>> finally had a situation where I could get a panic by adding SW_WATCHDOG to
>> my kernel and running watchdogd(8).
>> For me, this panic would come and go seemingly at random as well, and I
>> couldn't fumble my way around in the debugger to learn much of anythingfreebsd-current at
>> when I first started seeing it. I just started a process of modularizing
>> everything I could in my kernel config, then loading modules 1-by-1 and
>> booting over-and-over until I finally found what appeared to be the
>> problem, which was the NVIDIA module compiled with clang.
>> Oh, another thing: at times it seemed as though it was the number of
>> modules loaded, as I could get the hang with 41 modules loaded, but not 40
>> or 42?! I admit, when I was seeing that behavior, I hadn't eliminated the
>> NVIDIA driver from my loaded modules. I need to revisit the panic situation
>> to confirm this particular strangeness.
>> Here's the last panic I had:
>> Unread portion of the kernel message buffer:
>>                         = DPL 0, pres 1, long 1, def32 0, gran 1
>> processor eflags        = interrupt enabled, resume, IOPL = 0
>> current process         = 1175 (sysctl)
>> (kgdb) bt
>> #0  doadump (textdump=1694704112) at pcpu.h:229
>> #1  0xffffffff802fab82 in db_fncall (dummy1=<value optimized out>,
>> dummy2=<value optimized out>, dummy3=<value optimized out>, dummy4=<value
>> optimized out>) at /usr/src/sys/ddb/db_command.c:578
>> #2  0xffffffff802fa85a in db_command (last_cmdp=<value optimized out>,
>> cmd_table=<value optimized out>, dopager=1) at
>> /usr/src/sys/ddb/db_command.c:449
>> #3  0xffffffff802fa612 in db_command_loop () at
>> /usr/src/sys/ddb/db_command.c:502
>> #4  0xffffffff802fcf60 in db_trap (type=<value optimized out>, code=0) at
>> /usr/src/sys/ddb/db_main.c:231
>> #5  0xffffffff804a7b93 in kdb_trap (type=12, code=0, tf=<value optimized
>> out>) at /usr/src/sys/kern/subr_kdb.c:654
>> #6  0xffffffff807157c5 in trap_fatal (frame=0xffffff8865032670, eva=<value
>> optimized out>) at /usr/src/sys/amd64/amd64/trap.c:867
>> #7  0xffffffff80715adb in trap_pfault (frame=0x0, usermode=0) at
>> /usr/src/sys/amd64/amd64/trap.c:698
>> #8  0xffffffff8071529b in trap (frame=0xffffff8865032670) at
>> /usr/src/sys/amd64/amd64/trap.c:463
>> #9  0xffffffff806ff382 in calltrap () at exception.S:228
>> #10 0xffffffff8047bd50 in sysctl_sysctl_next_ls (lsp=<value optimized out>,
>> name=0xffffff8865032a80, namelen=<value optimized out>,
>> next=0xffffff8865032898, len=0xffffff8865032904, level=3) at
>> /usr/src/sys/kern/kern_sysctl.c:759
>> #11 0xffffffff8047be5e in sysctl_sysctl_next_ls (lsp=0xfffffe000d3f0080,
>> name=0xffffff8865032a7c, namelen=<value optimized out>,
>> next=0xffffff8865032894, len=0xffffff8865032904, level=2) at
>> /usr/src/sys/kern/kern_sysctl.c:786
>> #12 0xffffffff8047be5e in sysctl_sysctl_next_ls (lsp=0xfffffe000d3f0080,
>> name=0xffffff8865032a78, namelen=<value optimized out>,
>> next=0xffffff8865032890, len=0xffffff8865032904, level=1) at
>> /usr/src/sys/kern/kern_sysctl.c:786
>> #13 0xffffffff8047bca3 in sysctl_sysctl_next (oidp=<value optimized out>,
>> arg1=0xffffff8865032a78, arg2=4, req=0xffffff88650329a8) at
>> /usr/src/sys/kern/kern_sysctl.c:808
>> #14 0xffffffff8047b03f in sysctl_root (arg1=<value optimized out>,
>> arg2=<value optimized out>) at /usr/src/sys/kern/kern_sysctl.c:1513
>> #15 0xffffffff8047b5d8 in userland_sysctl (td=<value optimized out>,
>> name=0xffffff8865032a70, namelen=<value optimized out>, old=<value
>> optimized out>, oldlenp=<value optimized out>, inkernel=<value optimized
>> out>, new=<value optimized out>, newlen=<value optimized out>,
>>     retval=<value optimized out>, flags=1694706064) at
>> /usr/src/sys/kern/kern_sysctl.c:1623
>> #16 0xffffffff8047b3c4 in sys___sysctl (td=0xfffffe001e2d4900,
>> uap=0xffffff8865032b80) at /usr/src/sys/kern/kern_sysctl.c:1549
>> #17 0xffffffff807160f7 in amd64_syscall (td=0xfffffe001e2d4900, traced=0)
>> at subr_syscall.c:135
>> #18 0xffffffff806ff66b in Xfast_syscall () at exception.S:387
>> #19 0x000000080093697a in ?? ()
>> Previous frame inner to this frame (corrupt stack?)
>> Current language:  auto; currently minimal
>> Any ideas on where to look through this vmcore?
>> -Brandon
> Just going from 9.1-STABLE r245423M to 9.1-STABLE #0 r246457M trigger
> this problem.
> I drop sysctl -a from /etc/rc.d/initrandom and all is back to normal.
> I have nvidia-driver-304.64 compiled with gcc as for all my ports.
> Henri

Just a follow up:

sysctl hw.nvidia generate a page fault:

morzine.restart.bel dumped core - see /var/crash/vmcore.86

Wed Feb 13 17:29:14 CET 2013

FreeBSD morzine.restart.bel 9.1-STABLE FreeBSD 9.1-STABLE #0 r246457M:
Thu Feb  7 15:09:16 CET 2013
root at morzine.restart.bel:/usr/obj/usr/src/sys/MORZINE  i386

panic: page fault

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Unread portion of the kernel message buffer:
kernel trap 12 with interrupts disabled

Fatal trap 12: page fault while in kernel mode
cpuid = 1; apic id = 01
fault virtual address   = 0x14
fault code              = supervisor read, page not present
instruction pointer     = 0x20:0xa07647d4
stack pointer           = 0x28:0xfd1f0ac8
frame pointer           = 0x28:0xfd1f0aec
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, def32 1, gran 1
processor eflags        = resume, IOPL = 0
current process         = 2369 (sysctl)
trap number             = 12
panic: page fault
cpuid = 1
KDB: stack backtrace:
db_trace_self_wrapper(a0a44a64,0,70617200,46,fc,...) at
db_trace_self_wrapper+0x2d/frame 0xfd1f07c0
kdb_backtrace(a0a760c5,1,a0a0bc3c,fd1f087c,1,...) at
kdb_backtrace+0x30/frame 0xfd1f0828
panic(a0a0bc3c,a0a76eaf,cfcb0d74,1,1,...) at panic+0x1bb/frame 0xfd1f0870
trap_fatal(fd1f0900,a09d2ee1,a0b17130,b5592000,0,...) at
trap_fatal+0x33a/frame 0xfd1f08c0
trap_pfault(14,c,1,ffffffff,fd1f0994,...) at trap_pfault+0x31d/frame
trap(fd1f0a88) at trap+0x4ef/frame 0xfd1f0a7c
calltrap() at calltrap+0x6/frame 0xfd1f0a7c
--- trap 0xc, eip = 0xa07647d4, esp = 0xfd1f0ac8, ebp = 0xfd1f0aec ---
turnstile_broadcast(0,0,a7b80b40,0,fd1f0b38,...) at
turnstile_broadcast+0xa4/frame 0xfd1f0aec
_mtx_unlock_sleep(a0b6a00c,0,0,0,fd1f0b58,...) at
_mtx_unlock_sleep+0x57/frame 0xfd1f0b04
sysctl_root(fd1f0b58,fd1f0b64,4,a09c87fe,bfc0d450,...) at
sysctl_root+0x248/frame 0xfd1f0b38
userland_sysctl(cfcb0bc0,fd1f0bd4,5,0,9fbfca2c,...) at
userland_sysctl+0x1da/frame 0xfd1f0b9c
sys___sysctl(cfcb0bc0,fd1f0cc8,1,fd1f0cb0,0,...) at
sys___sysctl+0x95/frame 0xfd1f0c40
syscall(fd1f0d08) at syscall+0x452/frame 0xfd1f0cfc
Xint0x80_syscall() at Xint0x80_syscall+0x21/frame 0xfd1f0cfc
--- syscall (202, FreeBSD ELF32, sys___sysctl), eip = 0x33d65f6b, esp =
0x9fbfc9e4, ebp = 0x9fbfd2ac ---
Uptime: 5h45m16s
Physical memory: 3046 MB


(kgdb) #0  doadump (textdump=1) at pcpu.h:249
#1  0xa071b78a in kern_reboot (howto=260)
    at /usr/src/sys/kern/kern_shutdown.c:448
#2  0xa071bc17 in panic (fmt=<value optimized out>)
    at /usr/src/sys/kern/kern_shutdown.c:636
#3  0xa09cc21a in trap_fatal (frame=<value optimized out>, eva=20)
    at /usr/src/sys/i386/i386/trap.c:1043
#4  0xa09cc54d in trap_pfault (frame=0x0, usermode=<value optimized out>,
    eva=0) at /usr/src/sys/i386/i386/trap.c:858
#5  0xa09cbb3f in trap (frame=0xfd1f0a88) at
#6  0xa09b5c0c in calltrap () at exception.s:169
#7  0xa07647d4 in turnstile_broadcast (ts=0x0, queue=0)
    at /usr/src/sys/kern/subr_turnstile.c:837
#8  0xa0707217 in _mtx_unlock_sleep (m=0xa0b6a00c, opts=-48297228,
    file=0xfd1f0af4 "", line=-48297228) at
#9  0xa0728418 in sysctl_root (arg1=<value optimized out>,
    arg2=<value optimized out>) at /usr/src/sys/kern/kern_sysctl.c:1515
#10 0xa072899a in userland_sysctl (td=0x4, old=<value optimized out>,
    oldlenp=<value optimized out>, inkernel=<value optimized out>,
    new=<value optimized out>, newlen=<value optimized out>,
    retval=<value optimized out>, flags=-1603107360)
    at /usr/src/sys/kern/kern_sysctl.c:1623
#11 0xa0728785 in sys___sysctl (uap=0xfd1f0cc8)
    at /usr/src/sys/kern/kern_sysctl.c:1549
#12 0xa09ccc22 in syscall (frame=<value optimized out>) at
#13 0xa09b5ca1 in Xint0x80_syscall () at exception.s:267
#14 0x00000033 in ?? ()
Previous frame inner to this frame (corrupt stack?)
Current language:  auto; currently minimal


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