watchdogd_flags followed by panic watchdog timeout, after reboot my rc.conf disappear

[Daniel Dvořák]

Hi all,
 
first of all, I´m sorry maybe for my bad English.
 
We have 2 routers which I maintain in our mesh wireless community network.
 
The Router 1 has 2 atheros adapters, ath0=wistron cm9, ath1=wistron cm10, of
course some sisX, fxpX and so on.
The Router 2 has 1 atheros adapter, ath0=wistron CM10.
 
My R1 panics and even more it freezes very often. Maybe the reason for
panicing and freezing is the same and maybe not.
 
This is not important now, this story is about R2.
 
I started to use "option SW_WATCHDOG" in both my custom kernels on the R1
and R2 recently in hope, it is some walkaround for freezing at least if not
for panicing.
 
In the /etc/defaults/rc.conf there are not "watchdogd_flags=""" option, but
I tried to wrote it to my /etc/rc.conf in this way:
 
watchdogd_enable="YES"
watchdogd_flags="-e ping 10.40.0.72 -s 2 -t 1"
 
I saved my rc.conf without any doubt.
 
I did so, because I wanted to instruct watchdogd to execute my command,
common pinging some IP address. I was not satisfied with a trivial file
system check instead.
 
After saving the rc.conf file, I restarted watchdogd deamon at once.
 
... and ... 2 seconds ... my ssh client was disconnected ... unexpected end
of ssh session. :)
 
Okay, maybe something wrong, maybe I did a mistake and it panicked.
 
I was waitting for 3 minutes, but R2 did not react at all.
 
So I went to R2 and I powered off and powered on ... but still it was the
same.
 
After I attached monitor and keyboard, I saw that ifconfig did not configure
any interfaces. Why ?
 
Answear: Because rc.conf had 0 Bytes !!!
 
-rw-r--r--  1 root  wheel      6174 Sep  1 XX:XX rc.conf , I do not remember
time of last modification of file.
 
So the content of rc.conf was completly gone !!!
 
Is it possible at all ?
 
Now I am scared that any modification rc.conf will be mean loss of content.
 
I have kernel dump and backtrace of panic.
 
It is in the attachment.
 
 
If I could help with this, I will do it.
 
And please explain me somebody, how I lost the content of rc.conf file. :-O
Thank you.
 
Daniel
 
P.S.: I am not currently subscribed in the freebsd-stable mailling list, so
use my e-mail address. I am ok with freebsd-current mailling list.
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# cd /usr/obj/usr/src/sys/mykernel/
# kgdb kernel.debug /var/crash/vmcore.0
[GDB will not be able to debug user-mode threads: /usr/lib/libthread_db.so: Unde                                                                             fined symbol "ps_pglobal_lookup"]
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 "i386-marcel-freebsd".

Unread portion of the kernel message buffer:
interrupt                   total
irq14: ata0                       325735
irq16: fxp1                            5
irq17: ath0                     50298459
irq18: wi0                       3904083
irq19: sis0 fxp0                20167051
cpu0: timer                    604044908
Total                   678740241
panic: watchdog timeout
Uptime: 3d11h53m45s
Dumping 223 MB (2 chunks)
  chunk 0: 1MB (159 pages) ... ok
  chunk 1: 223MB (57072 pages) 207 191 175 159 143 127 111 95 79 63 47 31 15

#0  doadump () at pcpu.h:165
165             __asm __volatile("movl %%fs:0,%0" : "=r" (td));
(kgdb) backtrace
#0  doadump () at pcpu.h:165
#1  0xc059c4ee in boot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:402
#2  0xc059c7a6 in panic (fmt=0xc081050d "watchdog timeout")
    at /usr/src/sys/kern/kern_shutdown.c:558
#3  0xc0571642 in watchdog_fire () at /usr/src/sys/kern/kern_clock.c:583
#4  0xc0571130 in hardclock (frame=0xc1f44780)
    at /usr/src/sys/kern/kern_clock.c:279
#5  0xc07a4631 in lapic_handle_timer (frame=
      {cf_vec = 0, cf_fs = 8, cf_es = 40, cf_ds = 40, cf_edi = -1040320488, cf_esi = -1040320512, cf_ebp = -890192676, cf_ebx = 0, cf_edx = 0, cf_ecx = -1041016416, cf_eax = 1000, cf_eip = -1063283195, cf_cs = 32, cf_eflags = 524818, cf_esp = -890192644, cf_ss = -1063305969}) at /usr/src/sys/i386/i386/local_apic.c:623
#6  0xc079eb30 in Xtimerint () at apic_vector.s:137
#7  0xc09f9605 in ?? ()
#8  0xcaf0bd04 in ?? ()
#9  0xc07a609f in cpu_idle () at /usr/src/sys/i386/i386/machdep.c:1134
Previous frame inner to this frame (corrupt stack?)
(kgdb) quit