Re: Panic: vrelel: bad ref count (9.99.54)

[Andrew Doran <ad%netbsd.org@localhost>]

On Mon, May 04, 2020 at 03:54:57PM +0200, Leonardo Taccari wrote:
> Hello Yorick and Andrew,
> 
> Yorick Hardy writes:
> > > > > [...]
> > > > > 
> > > > >   Crash version 9.99.55, image version 9.99.55.
> > > > >   crash: _kvm_kvatop(0)
> > > > >   Kernel compiled without options LOCKDEBUG.
> > > > >   System panicked: vrelel: bad ref count
> > > > >   Backtrace from time of crash is available.
> > > > >   crash> bt
> > > > >   _KERNEL_OPT_NAGR() at 0
> > > > >   ?() at 7f7ff7ecf000
> > > > >   sys_reboot() at sys_reboot
> > > > >   vpanic() at vpanic+0x181
> > > > >   vtryrele() at vtryrele
> > > > >   vcache_dealloc() at vcache_dealloc
> > > > >   uvm_unmap_detach() at uvm_unmap_detach+0x76
> > > > >   uvm_unmap1() at uvm_unmap1+0x4e
> > > > >   uvm_mremap() at uvm_mremap+0x36b
> > > > >   sys_mremap() at sys_mremap+0x68
> > > > >   syscall() at syscall+0x227
> > > > >   --- syscall (number 411) ---
> > > > >   797459842e9a:
> > > > >   crash>
> > > > 
> > > > The same just happened on 9.99.56 while fetching (POP) mail using mail/fdm.
> > > 
> > > Could you file a PR please?  If this panics again could you please run the
> > > "dmesg" command in crash and find out what it printed about the vnode?  That
> > > would be very useful.
> > > 
> > > Thanks,
> > > Andrew
> >
> > I will do so (... perhaps only this weekend).
> > [...]
> 
> I was able to reproduce it too with a yesterday evening NetBSD/amd64
> -current when using mail/fdm and I will try to prepare a minimal
> reproducer using mail/fdm and file a PR if noone beat me.
> 
> In the meantime here the information from dmesg:
> 
> [ 6107.6380323] vnode 0xffffa95219747d40 flags 0x418<MAPPED,MPSAFE,WRMAP>
> [ 6107.6380323]    tag VT_TMPFS(25) type VREG(1) mount 0xffffa951f6d89000 typedata 0xffffa95255e32c90
> [ 6107.6380323]    usecount 1 writecount 1 holdcount 0
> [ 6107.6380323]    size 18000 writesize 18000 numoutput 0
> [ 6107.6380323]    data 0xffffa952583304a0 lock 0xffffa95219747f00
> [ 6107.6380323]    state LOADED key(0xffffa951f6d89000 8) a0 04 33 58 52 a9 ff ff
> [ 6107.6380323]    lrulisthd 0xffffffff816b5ed0
> [ 6107.6380323]    tag VT_TMPFS, tmpfs_node 0xffffa952583304a0, flags 0x0, links 1
> [ 6107.6380323]    mode 0600, owner 1000, group 0, size 98304
> [ 6107.6380323] panic: vrelel: bad ref count
> [ 6107.6380323] cpu0: Begin traceback...
> [ 6107.6380323] vpanic() at netbsd:vpanic+0x178
> [ 6107.6480364] vnpanic() at netbsd:vnpanic+0x49
> [ 6107.6480364] vrelel() at netbsd:vrelel+0x5b6
> [ 6107.6480364] uvm_unmap_detach() at netbsd:uvm_unmap_detach+0x8e
> [ 6107.6480364] sys_munmap() at netbsd:sys_munmap+0x85
> [ 6107.6480364] syscall() at netbsd:syscall+0x2a0
> [ 6107.6480364] --- syscall (number 73) ---
> [ 6107.6480364] 7c1e5d18414a:
> [ 6107.6480364] cpu0: End traceback...
> [ 6107.6480364] fatal breakpoint trap in supervisor mode
> [ 6107.6480364] trap type 1 code 0 rip 0xffffffff802219fd cs 0x8 rflags 0x202 cr2 0x7f7ff7ee5000 ilevel 0 rsp 0xffffc100c227ae20
> [ 6107.6480364] curlwp 0xffffa9521e1b1600 pid 20756.20756 lowest kstack 0xffffc100c22772c0
> [ 6107.6480364] dumping to dev 0,1 (offset=276847, size=2062664):
> [ 6107.6480364] dump
> 
> If any possible further information is needed do not hesitate to
> contact me!
> 
> 
> Thanks!

Thank you.  I opened PR 55237 to track so I don't forget.

Andrew