Re: Interesting panic from the Yahoo builder (10-current)

On Sat, 2013-09-07 at 17:05 +0200, Davide Italiano wrote: 
> On Fri, Sep 6, 2013 at 6:00 PM, Sean Bruno <sean_bruno_at_yahoo.com> wrote:
> > Our "yBSD" builder needs to mount a disk image temporarily that has a
> > dos partition (for openstack-ish things) to put configs into it.  It
> > seems that under high stress, we can squeeze a panic out of it in
> > namei().
> >
> > Sean
> >
> >
> > Unread portion of the kernel message buffer:
> > panic: namei: nameiop contaminated with flags
> > cpuid = 8
> > KDB: stack backtrace:
> > db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe048d8e53b0
> > kdb_backtrace() at kdb_backtrace+0x39/frame 0xfffffe048d8e5460
> > vpanic() at vpanic+0x126/frame 0xfffffe048d8e54a0
> > kassert_panic() at kassert_panic+0x136/frame 0xfffffe048d8e5510
> > namei() at namei+0x2c8/frame 0xfffffe048d8e5600
> > msdosfs_mount() at msdosfs_mount+0x556/frame 0xfffffe048d8e57c0
> > vfs_donmount() at vfs_donmount+0xc35/frame 0xfffffe048d8e5aa0
> > sys_nmount() at sys_nmount+0x72/frame 0xfffffe048d8e5ae0
> > amd64_syscall() at amd64_syscall+0x223/frame 0xfffffe048d8e5bf0
> > Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe048d8e5bf0
> > --- syscall (378, FreeBSD ELF64, sys_nmount), rip = 0x8000a8b68a, rsp = 0x7fffffffd508, rbp = 0x7fffffffdb30 ---
> > Uptime: 34m55s
> > Dumping 1140 out of 16350 MB:..2%..12%..22%..31%..41%..51%..61%..71%..82%..92%
> >
> > Reading symbols from /boot/modules/msdosfs.ko...done.
> > Loaded symbols for /boot/modules/msdosfs.ko
> > #0  doadump (textdump=1) at pcpu.h:227
> > 227     pcpu.h: No such file or directory.
> >         in pcpu.h
> > (kgdb) Hangup detected on fd 0
> > error detected on stdin
> 
> Can you please print the value of cnp->cn_nameiop (or, even better,
> the whole struct) before the panic?
> 
> Thanks,
> 

Hrm ... tried to reproduce after recompiling the kernel (turning off
KDB_UNATTENDED) and its not happening now.  

I'll keep an eye out for it.

Sean