Advice on kernel panics

Raimo Niskanen raimo+freebsd at
Mon May 29 09:20:48 UTC 2017

Hello list.

I have a server that panics about every 3 days and need some advice on how
to handle that.

It currently has 7 dumps in /var/crash/, head of the latest core.txt.4
looks like this:

======= dumped core - see /var/crash/vmcore.4

Mon May 29 03:15:32 CEST 2017

FreeBSD 10.3-RELEASE-p18 FreeBSD 10.3-RELEASE-p18
#0: Tue Apr 11 10:31:00 UTC 2017
root at  amd64

panic: page fault

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This GDB was configured as "amd64-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   = 0x0
fault code              = supervisor write data, page not present
instruction pointer     = 0x20:0xffffffff809fb017
stack pointer           = 0x28:0xfffffe04673a18c0
frame pointer           = 0x28:0xfffffe04673a1900
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 18 (syncer)
trap number             = 12
panic: page fault
cpuid = 0
KDB: stack backtrace:
#0 0xffffffff8098e7e0 at kdb_backtrace+0x60
#1 0xffffffff809514b6 at vpanic+0x126
#2 0xffffffff80951383 at panic+0x43
#3 0xffffffff80d5646b at trap_fatal+0x36b
#4 0xffffffff80d5676d at trap_pfault+0x2ed
#5 0xffffffff80d55dea at trap+0x47a
#6 0xffffffff80d3bdb2 at calltrap+0x8
#7 0xffffffff809f9b23 at vfs_msync+0x203
#8 0xffffffff809fb858 at sync_fsync+0x108
#9 0xffffffff80e81ed7 at VOP_FSYNC_APV+0xa7
#10 0xffffffff809fc27b at sched_sync+0x3ab
#11 0xffffffff8091a93a at fork_exit+0x9a
#12 0xffffffff80d3c2ee at fork_trampoline+0xe
Uptime: 2d19h53m15s

What sticks out later in core.txt.4 is the fstat section that contains a
lot of errors, but I can not tell if that is just a secondary symptom...

Looks like this:

fstat: can't read file 1 at 0x200007fffffffff
fstat: can't read file 2 at 0x4000000001fffff
fstat: can't read znode_phys at 0x1
fstat: can't read znode_phys at 0x1
fstat: can't read znode_phys at 0x1
USER     CMD          PID   FD MOUNT      INUM MODE         SZ|DV R/W
root     sed        78401 root -         -       error    -
root     sed        78401   wd -         -       error    -
root     sed        78401 text -         -       error    -
root     sed        78401    0* pipe fffff8001800f000 <-> fffff8001800f160
   0 rw
root     grep       78400 root -         -       error    -
root     grep       78400   wd -         -       error    -
root     grep       78400 text -         -       error    -

To me the other core.txt.? files does not look exactly the same.  All have
an fstat section with many errors, though.

Does anyone have some advice on how to proceed?

/ Raimo Niskanen, Erlang/OTP, Ericsson AB

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