kern/133902: [tun] Killing tun0 iface ssh tunnel causes Panic String: page fault

Mikolaj Golub at
Thu Apr 23 14:42:13 UTC 2009

I have asked Leonardo to provide more info and backtrace.

So here is backtrace:

cobra4# kgdb /boot/kernel/kernel.symbols /var/crash/vmcore.0
[GDB will not be able to debug user-mode threads:
/usr/lib/ Undefined symbol "ps_pglobal_lookup"]
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This GDB was configured as "i386-marcel-freebsd".

Unread portion of the kernel message buffer:

Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address   = 0x65656c7b
fault code              = supervisor write, page not present
instruction pointer     = 0x20:0xc0786e00
stack pointer           = 0x28:0xe958fac4
frame pointer           = 0x28:0xe958fac4
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, def32 1, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 66873 (ssh)
trap number             = 12
panic: page fault
cpuid = 1
Uptime: 54d11h21m54s
Physical memory: 2023 MB
Dumping 277 MB: 262 246 230 214 198 182 166 150 134 118 102 86 70 54 38 22 6

#0  doadump () at pcpu.h:195
195     pcpu.h: No such file or directory.
        in pcpu.h
(kgdb) backtrace
#0  doadump () at pcpu.h:195
#1  0xc0754457 in boot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:409
#2  0xc0754719 in panic (fmt=Variable "fmt" is not available.
) at /usr/src/sys/kern/kern_shutdown.c:563
#3  0xc0a4905c in trap_fatal (frame=0xe958fa84, eva=1701145723) at
#4  0xc0a492e0 in trap_pfault (frame=0xe958fa84, usermode=0,
eva=1701145723) at /usr/src/sys/i386/i386/trap.c:812
#5  0xc0a49c8c in trap (frame=0xe958fa84) at /usr/src/sys/i386/i386/trap.c:490
#6  0xc0a2fc0b in calltrap () at /usr/src/sys/i386/i386/exception.s:139
#7  0xc0786e00 in clear_selinfo_list (td=0xca3fc840) at
#8  0xc0788efc in kern_select (td=0xca3fc840, nd=8, fd_in=0x284010b8,
fd_ou=0x284010bc, fd_ex=0x0, tvp=0x0) at
#9  0xc07890de in select (td=0xca3fc840, uap=0xe958fcfc) at
#10 0xc0a49635 in syscall (frame=0xe958fd38) at
#11 0xc0a2fc70 in Xint0x80_syscall () at /usr/src/sys/i386/i386/exception.s:196
#12 0x00000033 in ?? ()
Previous frame inner to this frame (corrupt stack?)

The system panics on

ifconfig tun0 destroy

This issue is related to kern/116837.

Leonardo, you can try the patch attached to that pr.

Mikolaj Golub

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