FreeBSD-9.1: machine reboots during snapshot creation, LORs found

Fri Jul 12 06:01:18 UTC 2013

On Fri, Jul 12, 2013 at 07:24:40AM +0200, Andre Albsmeier wrote:
> On Thu, 04-Jul-2013 at 19:25:28 +0200, Konstantin Belousov wrote:
> > On Thu, Jul 04, 2013 at 04:29:19PM +0200, Andre Albsmeier wrote:
> > > OK, patch is applied. I will reboot the machine later
> > > and see what happens tomorrow in the morning. However,
> > > it might take a few days since the last 2 weeks all was
> > > fine.
> > > 
> > > BTW, should this patch be used in general or is it just
> > > for debugging? My understanding is that it is something
> > > which could stay in the code...
> > 
> > Patch is to improve debugging.
> > 
> > I probably commit it after the issue is closed.  Arguments against
> > the commit is that the change imposes small performance penalty
> > due to save and restore of the %ebp (I doubt that this is measureable
> > by any means).  Also, arguably, such change should be done for all
> > functions in support.s, but bcopy() is the hot spot.
> 
> Got a new one, 2 hours old ;-)
> 
> GNU gdb 6.1.1 [FreeBSD]
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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
> fault virtual address   = 0xcd5ec000
> fault code              = supervisor write, page not present
> instruction pointer     = 0x20:0xc07cb2fe
> stack pointer           = 0x28:0xd82e45cc
> frame pointer           = 0x28:0xd82e45d4
> 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         = 18714 (mksnap_ffs)
> trap number             = 12
> panic: page fault
> KDB: stack backtrace:
> db_trace_self_wrapper(c08207eb,d82e4418,c05fdfc9,c081df13,c08a82e0,...) at db_trace_self_wrapper+0x26/frame 0xd82e43e8
> kdb_backtrace(c081df13,c08a82e0,c0801bfa,d82e4424,d82e4424,...) at kdb_backtrace+0x29/frame 0xd82e43f4
> panic(c0801bfa,c0845a01,c2b067d4,1,1,...) at panic+0xc9/frame 0xd82e4418
> trap_fatal(c0ff6000,cd5ec000,2,0,c08b6bf4,...) at trap_fatal+0x353/frame 0xd82e4458
> trap_pfault(baa8454b,21510,0,c2b06620,c08b6bf0,...) at trap_pfault+0x2d7/frame 0xd82e44a0
> trap(d82e458c) at trap+0x41a/frame 0xd82e4580
> calltrap() at calltrap+0x6/frame 0xd82e4580
> --- trap 0xc, eip = 0xc07cb2fe, esp = 0xd82e45cc, ebp = 0xd82e45d4 ---
> bcopy(c36ed000,cd5e6000,8000,8000,c281b980,...) at bcopy+0x1a/frame 0xd82e45d4
> ffs_snapshot(c2b35a90,c2ed0400,0,0,0,...) at ffs_snapshot+0x2933/frame 0xd82e490c
> ffs_mount(c2b35a90,c322e200,ff,d82e4c08,c2ccbc8c,...) at ffs_mount+0x15ee/frame 0xd82e4a3c
> vfs_donmount(c2b06620,10313108,0,c2b74d80,c2b74d80,...) at vfs_donmount+0x196b/frame 0xd82e4c2c
> sys_nmount(c2b06620,d82e4ccc,c2b06908,d82e4c6c,c0605015,...) at sys_nmount+0x63/frame 0xd82e4c50
> syscall(d82e4d08) at syscall+0x2ce/frame 0xd82e4cfc
> Xint0x80_syscall() at Xint0x80_syscall+0x21/frame 0xd82e4cfc
> --- syscall (378, FreeBSD ELF32, sys_nmount), eip = 0x180bdf37, esp = 0xbfbfd65c, ebp = 0xbfbfddd8 ---
> Uptime: 4d20h0m44s
> Physical memory: 503 MB
> Dumping 104 MB: 89 73 57 41 25 9
> 
> No symbol "stopped_cpus" in current context.
> No symbol "stoppcbs" in current context.
> #0  doadump (textdump=1) at pcpu.h:249
> 249     pcpu.h: No such file or directory.
>         in pcpu.h
> (kgdb) where
> #0  doadump (textdump=1) at pcpu.h:249
> #1  0xc05fdddd in kern_reboot (howto=260) at /src/src-9/sys/kern/kern_shutdown.c:449
> #2  0xc05fe028 in panic (fmt=<value optimized out>) at /src/src-9/sys/kern/kern_shutdown.c:637
> #3  0xc07cd1d3 in trap_fatal (frame=0xd82e458c, eva=3445538816)
>     at /src/src-9/sys/i386/i386/trap.c:1044
> #4  0xc07cd4b7 in trap_pfault (frame=0xd82e458c, usermode=0, eva=3445538816)
>     at /src/src-9/sys/i386/i386/trap.c:957
> #5  0xc07ce05a in trap (frame=0xd82e458c) at /src/src-9/sys/i386/i386/trap.c:555
> #6  0xc07ba88c in calltrap () at /src/src-9/sys/i386/i386/exception.s:170
> #7  0xc07cb2fe in bcopy () at /src/src-9/sys/i386/i386/support.s:198
> #8  0xc072be13 in ffs_snapshot (mp=0xc2b35a90, snapfile=0xc2ed0400 "s5-2013.07.12-03.15.01")
>     at /src/src-9/sys/ufs/ffs/ffs_snapshot.c:793
> #9  0xc0748e8e in ffs_mount (mp=0xc2b35a90) at /src/src-9/sys/ufs/ffs/ffs_vfsops.c:483
> #10 0xc068a72b in vfs_donmount (td=0xc2b06620, fsflags=271659272, fsoptions=0xc2b74d80)
>     at /src/src-9/sys/kern/vfs_mount.c:948
> #11 0xc068a8e3 in sys_nmount (td=0xc2b06620, uap=0xd82e4ccc) at /src/src-9/sys/kern/vfs_mount.c:417
> #12 0xc07cd7ae in syscall (frame=0xd82e4d08) at subr_syscall.c:135
> #13 0xc07ba8f1 in Xint0x80_syscall () at /src/src-9/sys/i386/i386/exception.s:270
> #14 0x00000033 in ?? ()
> Previous frame inner to this frame (corrupt stack?)

Please show me the first 100 lines of the output of dumpfs(8) on the
filesystem where snapshot creation caused the panic.
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