Re: r269147: NULL mp in getnewvnode() via kern_proc_filedesc_out()

On Wed, Aug 06, 2014 at 09:15:12PM +0300, Konstantin Belousov wrote:
> On Wed, Aug 06, 2014 at 12:48:28PM -0500, Bryan Drewery wrote:
> > On 8/5/2014 10:56 PM, Bryan Drewery wrote:
> > > On 8/5/2014 10:19 PM, Konstantin Belousov wrote:
> > >> On Tue, Aug 05, 2014 at 09:47:57PM -0500, Bryan Drewery wrote:
> > >>> Has anyone else encountered this? Got it while running poudriere.
> > >>>
> > >>>> NULL mp in getnewvnode()
> > >>>> [...]
> > >>>> vn_fullpath1() at vn_fullpath1+0x19d/frame 0xfffffe1247d8e540
> > >>>> vn_fullpath() at vn_fullpath+0xc1/frame 0xfffffe1247d8e590
> > >>>> export_fd_to_sb() at export_fd_to_sb+0x489/frame 0xfffffe1247d8e7c0
> > >>>> kern_proc_filedesc_out() at kern_proc_filedesc_out+0x234/frame
> > >>>> 0xfffffe1247d8e840
> > >>>> sysctl_kern_proc_filedesc() at sysctl_kern_proc_filedesc+0x84/frame
> > >>>> 0xfffffe1247d8e900
> > >>>> sysctl_root_handler_locked() at
> > >>>> sysctl_root_handler_locked+0x68/frame 0xfffffe1247d8e940
> > >>>> sysctl_root() at sysctl_root+0x18e/frame 0xfffffe1247d8e990
> > >>>> userland_sysctl() at userland_sysctl+0x192/frame 0xfffffe1247d8ea30
> > >>>> sys___sysctl() at sys___sysctl+0x74/frame 0xfffffe1247d8eae0
> > >>>> amd64_syscall() at amd64_syscall+0x25a/frame 0xfffffe1247d8ebf0
> > >>>> Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe1247d8ebf0
> > >>>
> > >>> Unfortunately I have no dump as the kmem was too large compared to my
> > >>> swap, and I didn't get to the console before some of the text was
> > >>> overwritten. Perhaps it will hit it again soon after reboot and I'll get
> > >>> a core.
> > >>
> > >> "NULL mp in getnewvnode()" is only the printf(), it is not a panic or
> > >> KASSERT.  The event does not stop the machine, nor it prints the
> > >> backtrace.
> > >>
> > >> You mentioned that you was unable to dump, so did the system paniced ?
> > >> Without full log of the panic messages and backtrace, it is impossible
> > >> to start guessing what the problem is.
> > >>
> > >> That said, the printf seemingly outlived its usefulness.
> > >>
> > > 
> > > Got it. I've set debug.debugger_on_panic=1 to not auto reboot on panic
> > > next time this happens. I had it at 0 which was causing the lack of
> > > information in these.
> > 
> > Here is the full trace:
> > 
> > 
> > > NULL mp in getnewvnode()
> > > VNASSERT failed
> > > 0xfffff806071dc760: tag null, type VDIR
> > >     usecount 1, writecount 0, refcount 1 mountedhere 0
> > >     flags ()
> > >     lock type zfs: EXCL by thread 0xfffff8009a53f490 (pid 1028, tmux, tid 100881)
> > >         vp=0xfffff806071dc760, lowervp=0xfffff8013157f588
> > > panic: Don't call insmntque(foo, NULL)
> > > cpuid = 5
> > > KDB: stack backtrace:
> > > db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe1247e76b50
> > > kdb_backtrace() at kdb_backtrace+0x39/frame 0xfffffe1247e76c00
> > > vpanic() at vpanic+0x126/frame 0xfffffe1247e76c40
> > > kassert_panic() at kassert_panic+0x139/frame 0xfffffe1247e76cb0
> > > insmntque1() at insmntque1+0x230/frame 0xfffffe1247e76cf0
> > > null_nodeget() at null_nodeget+0x158/frame 0xfffffe1247e76d60
> > > null_lookup() at null_lookup+0xeb/frame 0xfffffe1247e76dd0
> > > VOP_LOOKUP_APV() at VOP_LOOKUP_APV+0xf1/frame 0xfffffe1247e76e00
> > > lookup() at lookup+0x5ad/frame 0xfffffe1247e76e90
> > > namei() at namei+0x4e4/frame 0xfffffe1247e76f50
> > > vn_open_cred() at vn_open_cred+0x27a/frame 0xfffffe1247e770a0
> > > vop_stdvptocnp() at vop_stdvptocnp+0x161/frame 0xfffffe1247e773e0
> > > null_vptocnp() at null_vptocnp+0x2b/frame 0xfffffe1247e77440
> > > VOP_VPTOCNP_APV() at VOP_VPTOCNP_APV+0xf7/frame 0xfffffe1247e77470
> > > vn_vptocnp_locked() at vn_vptocnp_locked+0x118/frame 0xfffffe1247e774e0
> > > vn_fullpath1() at vn_fullpath1+0x19d/frame 0xfffffe1247e77540
> > > vn_fullpath() at vn_fullpath+0xc1/frame 0xfffffe1247e77590
> > > export_fd_to_sb() at export_fd_to_sb+0x489/frame 0xfffffe1247e777c0
> > > kern_proc_filedesc_out() at kern_proc_filedesc_out+0x234/frame 0xfffffe1247e77840
> > > sysctl_kern_proc_filedesc() at sysctl_kern_proc_filedesc+0x84/frame 0xfffffe1247e77900
> > > sysctl_root_handler_locked() at sysctl_root_handler_locked+0x68/frame 0xfffffe1247e77940
> > > sysctl_root() at sysctl_root+0x18e/frame 0xfffffe1247e77990
> > > userland_sysctl() at userland_sysctl+0x192/frame 0xfffffe1247e77a30
> > > sys___sysctl() at sys___sysctl+0x74/frame 0xfffffe1247e77ae0
> > > amd64_syscall() at amd64_syscall+0x25a/frame 0xfffffe1247e77bf0
> > > Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe1247e77bf0
> > > --- syscall (202, FreeBSD ELF64, sys___sysctl), rip = 0x801041fca, rsp = 0x7fffffffd878, rbp = 0x7fffffffd8b0 ---
> > > KDB: enter: panic
> > > [ thread pid 1028 tid 100881 ]
> > > Stopped at      kdb_enter+0x3e: movq    $0,kdb_why
> > > db> call doadump()
> > > 
> > > Dump failed. Partition too small.
> > > = 0
> > 
> 
> Try this.
> 
> diff --git a/sys/fs/nullfs/null_vnops.c b/sys/fs/nullfs/null_vnops.c
> index 481644c..e803c24 100644
> --- a/sys/fs/nullfs/null_vnops.c

With this patch I get a 
panic: Lock (lockmgr) null not locked _at_ kern/vfs_default.c:523.

Details _at_ http://people.freebsd.org/~pho/stress/log/kostik698.txt

- Peter