freebsd stable - Aug 2016 - 1-BETA3 Panic: __lockmgr_args: downgrade a recursed lockmgr nfs @ /usr/local/share/deploy-tools/RELENG_11/src/sys/fs/unionfs/union_vnops.c:1905

Hello,

I had another crash which I'm quite sure was triggered by mount_unionfs:

Unread portion of the kernel message buffer:
panic: __lockmgr_args: downgrade a recursed lockmgr nfs @
/usr/local/share/deploy-tools/RELENG_11/src/sys/fs/unionfs/union_vnops.c:1905

cpuid = 3
KDB: stack backtrace:
#0 0xffffffff80b2d887 at kdb_backtrace+0x67
#1 0xffffffff80ae5332 at vpanic+0x182
#2 0xffffffff80ae51a3 at panic+0x43
#3 0xffffffff80ab6987 at __lockmgr_args+0xe87
#4 0xffffffff80ba3c7c at vop_stdlock+0x3c
#5 0xffffffff811112cd at VOP_LOCK1_APV+0x8d
#6 0xffffffff80a17c1c at unionfs_lock+0x48c
#7 0xffffffff811112cd at VOP_LOCK1_APV+0x8d
#8 0xffffffff80bc8703 at _vn_lock+0x43
#9 0xffffffff80a17380 at unionfs_readdir+0x140
#10 0xffffffff81110e6f at VOP_READDIR_APV+0x8f
#11 0xffffffff80bc59ab at kern_getdirentries+0x21b
#12 0xffffffff80bc5768 at sys_getdirentries+0x28
#13 0xffffffff80fab6ae at amd64_syscall+0x4ce
#14 0xffffffff80f8dc0b at Xfast_syscall+0xfb
Uptime: 44m36s
Dumping 337 out of 2002 MB:..5%..15%..24%..34%..43%..53%..62%..72%..81%..91%

#0  doadump (textdump=<value optimized out>) at pcpu.h:221
221     pcpu.h: Permission denied.
        in pcpu.h
(kgdb) backtrace
#0  doadump (textdump=<value optimized out>) at pcpu.h:221
#1  0xffffffff80ae4db9 in kern_reboot (howto=260) at
/usr/local/share/deploy-tools/RELENG_11/src/sys/kern/kern_shutdown.c:366
#2  0xffffffff80ae536b in vpanic (fmt=<value optimized out>, ap=<value
optimized out>)
    at
/usr/local/share/deploy-tools/RELENG_11/src/sys/kern/kern_shutdown.c:759
#3  0xffffffff80ae51a3 in panic (fmt=0x0) at
/usr/local/share/deploy-tools/RELENG_11/src/sys/kern/kern_shutdown.c:690
#4  0xffffffff80ab6987 in __lockmgr_args (lk=<value optimized out>,
flags=<value optimized out>, ilk=<value optimized out>,
wmesg=<value
optimized out>,
    pri=<value optimized out>, timo=<value optimized out>,
file=<value
optimized out>, line=<value optimized out>)
    at /usr/local/share/deploy-tools/RELENG_11/src/sys/kern/kern_lock.c:992
#5  0xffffffff80ba3c7c in vop_stdlock (ap=<value optimized out>) at
lockmgr.h:98
#6  0xffffffff811112cd in VOP_LOCK1_APV (vop=<value optimized out>,
a=<value optimized out>) at vnode_if.c:2087
#7  0xffffffff80a17c1c in unionfs_lock (ap=0xfffffe00002296a0) at
vnode_if.h:859
#8  0xffffffff811112cd in VOP_LOCK1_APV (vop=<value optimized out>,
a=<value optimized out>) at vnode_if.c:2087
#9  0xffffffff80bc8703 in _vn_lock (vp=<value optimized out>,
flags=66560, file=<value optimized out>, line=<value optimized out>)
at
vnode_if.h:859
#10 0xffffffff80a17380 in unionfs_readdir (ap=<value optimized out>) at
/usr/local/share/deploy-tools/RELENG_11/src/sys/fs/unionfs/union_vnops.c:1531
#11 0xffffffff81110e6f in VOP_READDIR_APV (vop=<value optimized out>,
a=<value optimized out>) at vnode_if.c:1822
#12 0xffffffff80bc59ab in kern_getdirentries (td=<value optimized out>,
fd=<value optimized out>, buf=0x800a35000 <Address 0x800a35000 out of
bounds>,
    count=<value optimized out>, basep=0xfffffe0000229980, residp=0x0)
at vnode_if.h:758
#13 0xffffffff80bc5768 in sys_getdirentries (td=0x0,
uap=0xfffffe0000229a40) at
/usr/local/share/deploy-tools/RELENG_11/src/sys/kern/vfs_syscalls.c:3940
#14 0xffffffff80fab6ae in amd64_syscall (td=<value optimized out>,
traced=0) at subr_syscall.c:135
#15 0xffffffff80f8dc0b in Xfast_syscall () at
/usr/local/share/deploy-tools/RELENG_11/src/sys/amd64/amd64/exception.S:396
#16 0x000000000045da4a in ?? ()
Previous frame inner to this frame (corrupt stack?)
Current language:  auto; currently minimal

Analyzing is out of my scope, sorry.
But I hope somebody else can before 11-RELEASE ships with this problem.

Thanks,

-Harry

Harry Schmalzbauer wrote:
> Hello,
>
> I had another crash which I'm quite sure was triggered by
mount_unionfs:
Just in case you are not already aware, unionfs is always broken. Read the BUGS
section at the end of "man mount_unionfs". If it were easy to fix,
someone would
have done so long ago. Yes, some use it successfully, but if not...

Sorry, but I suspect that is how it will remain, rick

Unread portion of the kernel message buffer:
panic: __lockmgr_args: downgrade a recursed lockmgr nfs @
/usr/local/share/deploy-tools/RELENG_11/src/sys/fs/unionfs/union_vnops.c:1905
- Crash info deleted for brevity.