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Date:      Mon, 20 Feb 2012 16:13:42 -0500
From:      Paul Mather <paul@gromit.dlib.vt.edu>
To:        Konstantin Belousov <kostikbel@gmail.com>
Cc:        stable@freebsd.org
Subject:   Re: ZFS + nullfs + Linuxulator = panic?
Message-ID:  <D5490F82-1F80-4A2A-8168-92F5BD79598F@gromit.dlib.vt.edu>
In-Reply-To: <20120218012746.GA3283@deviant.kiev.zoral.com.ua>
References:  <CB455B5A-0583-4DFB-9712-6FFCC8B67AAB@gromit.dlib.vt.edu> <20120215004753.GQ3283@deviant.kiev.zoral.com.ua> <8F48D496-59BD-431D-B7F1-962A79C7ACC5@gromit.dlib.vt.edu> <20120216154932.GM3283@deviant.kiev.zoral.com.ua> <CDADA8EF-2642-45E8-92D1-358778A0FF40@gromit.dlib.vt.edu> <20120218012746.GA3283@deviant.kiev.zoral.com.ua>

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On Feb 17, 2012, at 8:27 PM, Konstantin Belousov wrote:

> On Thu, Feb 16, 2012 at 12:07:46PM -0500, Paul Mather wrote:
>> On Feb 16, 2012, at 10:49 AM, Konstantin Belousov wrote:
>>=20
>>> On Thu, Feb 16, 2012 at 10:09:27AM -0500, Paul Mather wrote:
>>>> On Feb 14, 2012, at 7:47 PM, Konstantin Belousov wrote:
>>>>=20
>>>>> On Tue, Feb 14, 2012 at 09:38:18AM -0500, Paul Mather wrote:
>>>>>> I have a problem with RELENG_8 (FreeBSD/amd64 running a GENERIC =
kernel, last built 2012-02-08).  It will panic during the daily periodic =
scripts that run at 3am.  Here is the most recent panic message:
>>>>>>=20
>>>>>> Fatal trap 9: general protection fault while in kernel mode
>>>>>> cpuid =3D 0; apic id =3D 00
>>>>>> instruction pointer     =3D 0x20:0xffffffff8069d266
>>>>>> stack pointer           =3D 0x28:0xffffff8094b90390
>>>>>> frame pointer           =3D 0x28:0xffffff8094b903a0
>>>>>> code segment            =3D base 0x0, limit 0xfffff, type 0x1b
>>>>>>                      =3D DPL 0, pres 1, long 1, def32 0, gran 1
>>>>>> processor eflags        =3D resume, IOPL =3D 0
>>>>>> current process         =3D 72566 (ps)
>>>>>> trap number             =3D 9
>>>>>> panic: general protection fault
>>>>>> cpuid =3D 0
>>>>>> KDB: stack backtrace:
>>>>>> #0 0xffffffff8062cf8e at kdb_backtrace+0x5e
>>>>>> #1 0xffffffff805facd3 at panic+0x183
>>>>>> #2 0xffffffff808e6c20 at trap_fatal+0x290
>>>>>> #3 0xffffffff808e715a at trap+0x10a
>>>>>> #4 0xffffffff808cec64 at calltrap+0x8
>>>>>> #5 0xffffffff805ee034 at fill_kinfo_thread+0x54
>>>>>> #6 0xffffffff805eee76 at fill_kinfo_proc+0x586
>>>>>> #7 0xffffffff805f22b8 at sysctl_out_proc+0x48
>>>>>> #8 0xffffffff805f26c8 at sysctl_kern_proc+0x278
>>>>>> #9 0xffffffff8060473f at sysctl_root+0x14f
>>>>>> #10 0xffffffff80604a2a at userland_sysctl+0x14a
>>>>>> #11 0xffffffff80604f1a at __sysctl+0xaa
>>>>>> #12 0xffffffff808e62d4 at amd64_syscall+0x1f4
>>>>>> #13 0xffffffff808cef5c at Xfast_syscall+0xfc
>>>>>=20
>>>>> Please look up the line number for the fill_kinfo_thread+0x54.
>>>>=20
>>>>=20
>>>> Is there a way for me to do this from the above information? As
>>>> I said in the original message, I failed to get a crash dump after
>>>> reboot (because, it turns out, I hadn't set up my gmirror swap =
device
>>>> properly). Alas, with the latest panic, it appears to have hung[1]
>>>> during the "Dumping" phase, so it looks like I won't get a saved =
crash
>>>> dump this time, either. :-(
>>>=20
>>> Load the kernel.debug into kgdb, and from there do
>>> "list *fill_kinfo_thread+0x54".
>>=20
>>=20
>> gromit# kgdb /usr/obj/usr/src/sys/GENERIC/kernel.debug
>> GNU gdb 6.1.1 [FreeBSD]
>> Copyright 2004 Free Software Foundation, Inc.
>> GDB is free software, covered by the GNU General Public License, and =
you are
>> welcome to change it and/or distribute copies of it under certain =
conditions.
>> Type "show copying" to see the conditions.
>> There is absolutely no warranty for GDB.  Type "show warranty" for =
details.
>> This GDB was configured as "amd64-marcel-freebsd"...
>> (kgdb) list *fill_kinfo_thread+0x54
>> 0xffffffff805ee034 is in fill_kinfo_thread =
(/usr/src/sys/kern/kern_proc.c:854).
>> 849             thread_lock(td);
>> 850             if (td->td_wmesg !=3D NULL)
>> 851                     strlcpy(kp->ki_wmesg, td->td_wmesg, =
sizeof(kp->ki_wmesg));
>> 852             else
>> 853                     bzero(kp->ki_wmesg, sizeof(kp->ki_wmesg));
>> 854             strlcpy(kp->ki_ocomm, td->td_name, =
sizeof(kp->ki_ocomm));
>> 855             if (TD_ON_LOCK(td)) {
>> 856                     kp->ki_kiflag |=3D KI_LOCKBLOCK;
>> 857                     strlcpy(kp->ki_lockname, td->td_lockname,
>> 858                         sizeof(kp->ki_lockname));
>> (kgdb)=20
>=20
> This is indeed strange. It can only occur if td pointer is damaged.
>=20
> Please, try to get a core and at least print the content of *td in =
this case.


Hopefully, I will be able to get a crash dump tonight.  I disabled the =
Tivoli "dsmc schedule" job over the weekend, because I don't have ready =
physical access to the machine and prefer it not to be down for very =
extended periods of time.  (As I reported previously, for some reason =
the system seems to get stuck saving the crash dump.  If this persists, =
maybe it might be better to get the system to drop into the debugger on =
panic instead of hoping forlornly for a successful crash dump.)

Cheers,

Paul.




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