reproducible panic with mount_smbfs

[Attilio Rao]

2008/11/2, Yuri Pankov <yuri.pankov at gmail.com>:
> On Sun, Nov 02, 2008 at 05:17:18PM +0100, Attilio Rao wrote:
>  > 2008/11/2, Attilio Rao <attilio at freebsd.org>:
>  > > 2008/11/2, Yuri Pankov <yuri.pankov at gmail.com>:
>  > >
>  > > > Hi,
>  > >  >
>  > >  >  Trying to mount nonexistent smb share with mount_smbfs leads to
>  > >  >  following panic:
>  > >  >
>  > >  >  # mount_smbfs //yuri at lifebane/blahblah /mnt
>  > >  >
>  > >  >  Unread portion of the kernel message buffer:
>  > >  >  smb_co_lock: recursive lock for object 1
>  > >  >  panic: Lock (lockmgr) smb_vc not locked @
>  > >  >  /usr/src/sys/modules/smbfs/../../netsmb/smb_conn.c:329.
>  > >  >  cpuid = 0
>  > >  >  KDB: stack backtrace:
>  > >  >  db_trace_self_wrapper() at db_trace_self_wrapper+0x2a
>  > >  >  panic() at panic+0x182
>  > >  >  witness_assert() at witness_assert+0x21a
>  > >  >  __lockmgr_args() at __lockmgr_args+0x17a
>  > >  >  smb_co_put() at smb_co_put+0x76
>  > >  >  smb_sm_lookup() at smb_sm_lookup+0xfe
>  > >  >  smb_usr_lookup() at smb_usr_lookup+0xcd
>  > >  >  nsmb_dev_ioctl() at nsmb_dev_ioctl+0x1f6
>  > >  >  giant_ioctl() at giant_ioctl+0x75
>  > >  >  devfs_ioctl_f() at devfs_ioctl_f+0x76
>  > >  >  kern_ioctl() at kern_ioctl+0x92
>  > >  >  ioctl() at ioctl+0xfd
>  > >  >  syscall() at syscall+0x1bf
>  > >  >  Xfast_syscall() at Xfast_syscall+0xab
>  > >  >  --- syscall (54, FreeBSD ELF64, ioctl), rip = 0x800939aec, rsp =
>  > >  >  0x7fffffffe038, rbp = 0x7fffffffe450 ---
>  > >  >  Uptime: 6m46s
>  > >  >  Physical memory: 2032 MB
>  > >
>  > >
>  > > So, what is happening here is that smb_co_lock() is AFU.
>  > >  Infact looking at the code:
>  > >  int
>  > >  smb_co_lock(struct smb_connobj *cp, int flags, struct thread *td)
>  > >  {
>  > >  ...
>  > >         if (smb_co_lockstatus(cp, td) == LK_EXCLUSIVE &&
>  > >             (flags & LK_CANRECURSE) == 0) {
>  > >                 SMBERROR("recursive lock for object %d\n", cp->co_level);
>  > >                 return 0;
>  > >         }
>  > >  ...
>  >
>  > Yuri,
>  > could you please test this fix:
>  > http://www.freebsd.org/~attilio/netsmb.diff
>  >
>  > and report if it works?
>  > You could get a KASSERT running but this is expected as I want to
>  > identify on the callers who passes a malformed request and fix it.
>  >
>  > Thanks,
>  > Attilio
>  >
>  >
>  > --
>  > Peace can only be achieved by understanding - A. Einstein
>
>
> Thanks, Attilio.
>
>  With this patch system doesn't panic anymore with nonexistent share
>  names (though I had to comment out smb_co_lockstatus prototype and
>  function to get rid of -Werror complaints). Still getting a LOR:
>
>  netsmb_dev: loaded
>  lock order reversal:
>   1st 0xffffff0021644008 smb_vc (smb_vc) @
>  /usr/src/sys/modules/smbfs/../../netsmb/smb_conn.c:332
>   2nd 0xffffffff81037368 smbsm (smbsm) @
>  /usr/src/sys/modules/smbfs/../../netsmb/smb_conn.c:348
>
> KDB: stack backtrace:
>  db_trace_self_wrapper() at db_trace_self_wrapper+0x2a
>
> _witness_debugger() at _witness_debugger+0x2e
>  witness_checkorder() at witness_checkorder+0x81e
>  __lockmgr_args() at __lockmgr_args+0xc2a
>  smb_co_lock() at smb_co_lock+0x38
>  smb_co_gone() at smb_co_gone+0x38
>
> smb_sm_lookup() at smb_sm_lookup+0xfe
>  smb_usr_lookup() at smb_usr_lookup+0xcd
>  nsmb_dev_ioctl() at nsmb_dev_ioctl+0x1f6
>  giant_ioctl() at giant_ioctl+0x75
>  devfs_ioctl_f() at devfs_ioctl_f+0x76
>  kern_ioctl() at kern_ioctl+0x92
>  ioctl() at ioctl+0xfd
>  syscall() at syscall+0x1bf
>  Xfast_syscall() at Xfast_syscall+0xab
>  --- syscall (54, FreeBSD ELF64, ioctl), rip = 0x800939aec, rsp =
>
> 0x7fffffffe048, rbp = 0x7fffffffe460 ---

I've updated the patch in order to fix smb_co_lockstatus problem.
Could you please stress test it while I investigate the LOR problem?

Are you running with INVARIANTS?

Thanks,
Attilio


-- 
Peace can only be achieved by understanding - A. Einstein