dtrace ustack kernel panic

[maestro something]

On Sat, Jul 30, 2011 at 12:50 AM, Andriy Gapon <avg at freebsd.org> wrote:

> on 30/07/2011 00:27 maestro something said the following:
> > Hi,
> >
> > trying to do so I don't really find my way around. This is what I get
> when I run
> > kgdb
> >
> > On startup the assert frame is #7 and the probe frame is #8.
> >
> [snip]
> > kernel trap 12 with interrupts disabled
> >
>
> I am not quite sure.  Apparently there is some issue with either what
> information we store in a crash dump and how, or with how kgdb interprets
> that
> information, or with a combination of both...
> Perhaps this is a result of -O2 optimization and -O1 would improve the
> situation
>
>
I guess I have to recompile the kernel without -O then ... does that work
for freebsd (I remember linux has issues i.e., does not compile without any
-O)

How would I do that the in the most straight forward way?


> Meanwhile, there is something simple that you can do without much hassle:
> (kgdb) list *dtrace_probe+0x135c
>

True there was not a lot hassle involved. However the result is not really
satisfactory either :-)

(kgdb) list *dtrace_probe+0x135c
No source file for address 0xc10fb28c.

The address is in accordance with the stack-trace (i.e., frame #8)


> where the address is taken from the backtrace printed by panic(9).
>

 cheers
--m



>
>
> > On Tue, Jul 26, 2011 at 4:05 AM, Andriy Gapon <avg at freebsd.org
> > <mailto:avg at freebsd.org>> wrote:
> >
> >     on 26/07/2011 04:20 maestro something said the following:
> >     > Hi,
> >     >
> >     > when using the ustack action on the latest FreeBSD8.2 i386 the
> kernel
> >     > panics.
> >     >
> >     > Here is the information I could gather:
> >     >
> >     > let me know if I can provide more information. (i.e., i have the
> full crash
> >     > information 80+mbs handy)
> >
> >     Use kgdb on the crash dump, go to the dtrace_probe frame and see
> which exactly
> >     assert fails and why.
> >
> >     > Here is the backtrace:
> >     >
> >     > Fatal trap 12: page fault while in kernel mode
> >     > cpuid = 0; apic id = 00
> >     > fault virtual address   = 0x108
> >     > fault code              = supervisor write, page not present
> >     > instruction pointer     = 0x20:0xc11012d7
> >     > stack pointer           = 0x28:0xcd3ed9f4
> >     > frame pointer           = 0x28:0xcd3eda0c
> >     > code segment            = base 0x0, limit 0xfffff, type 0x1b
> >     >                         = DPL 0, pres 1, def32 1, gran 1
> >     > processor eflags        = resume, IOPL = 0
> >     > current process         = 1132 (nc)
> >     > trap number             = 12
> >     > panic: page fault
> >     > cpuid = 0
> >     > KDB: stack backtrace:
> >     > #0 0xc09036a7 at kdb_backtrace+0x47
> >     > #1 0xc08d1a07 at panic+0x117
> >     > #2 0xc0c158c3 at trap_fatal+0x323
> >     > #3 0xc0c15bc0 at trap_pfault+0x2f0
> >     > #4 0xc0c1612a at trap+0x48a
> >     > #5 0xc0bfc97c at calltrap+0x6
> >     > #6 0xc10e992b at dtrace_panic+0x1b
> >     > #7 0xc10e995d at dtrace_assfail+0x2d
> >     > #8 0xc10fb28c at dtrace_probe+0x135c
> >     > #9 0xc1237f72 at systrace_probe+0x62
> >     > #10 0xc090f63f at syscallenter+0x47f
> >     > #11 0xc0c15c14 at syscall+0x34
> >     > #12 0xc0bfca11 at Xint0x80_syscall+0x21
> >     > Uptime: 3m0s
> >     > Physical memory: 239 MB
> >     > Dumping 79 MB: 64 48 32 16
> >     >
> >     >
> >     > Steps To reproduce:
> >     >
> >     > the dtrace program (i.e., test.d) was:
> >     >
> >     > #!/usr/sbin/dtrace -s
> >     >
> >     > syscall::accept:return
> >     > / execname == "nc" /
> >     > {
> >     >     printf("%s accept:return\n", execname);
> >     >     ustack();
> >     > }
> >     >
> >     > % dtrace -s test.d
> >     >
> >     > then running
> >     > % nc -vl 8080
> >     > on one shell and
> >     > % nc localhost 8080
> >     > on another would make the kernel panic
>
>
> --
> Andriy Gapon
>