# uname -a
FreeBSD leader.local 11.1-STABLE FreeBSD 11.1-STABLE #0 r325311: Fri Nov
3 03:31:50 ACDT 2017 root at leader.local:/usr/obj/usr/src/sys/GENERIC amd64
mounting a nullfs mount point causes a lock violation when running a
debug kernel (enabling witness, invariants etc)
After starting the system with the debug kernel I logged in as root and
ran `mount_nullfs /var/crash /home/shane/test/crash` to get the following -
Full core.txt at
http://shaneware.biz/freebsddebugdata/core.txt-2017-11-25-13-19
http://shaneware.biz/freebsddebugdata/dmesg.boot
Unread portion of the kernel message buffer:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame
0xfffffe0468cf4560
assert_vop_locked() at assert_vop_locked+0x77/frame 0xfffffe0468cf4590
VOP_UNLOCK_APV() at VOP_UNLOCK_APV+0xad/frame 0xfffffe0468cf45c0
nullfs_mount() at nullfs_mount+0x25f/frame 0xfffffe0468cf4700
vfs_donmount() at vfs_donmount+0xf6d/frame 0xfffffe0468cf4940
sys_nmount() at sys_nmount+0x72/frame 0xfffffe0468cf4980
amd64_syscall() at amd64_syscall+0x7a8/frame 0xfffffe0468cf4ab0
Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe0468cf4ab0
--- syscall (378, FreeBSD ELF64, sys_nmount), rip = 0x80086de6a, rsp
0x7fffffffe048, rbp = 0x7fffffffe990 ---
vnode 0xfffff80209c00000: tag nullfs, type VNON
usecount 1, writecount 0, refcount 1 mountedhere 0
flags (VI_ACTIVE)
lock type nullfs: UNLOCKED
vp=0xfffff80209c00000, lowervp=0xfffff80059f81c30
VOP_UNLOCK: 0xfffff80209c00000 is not locked but should be
KDB: enter: lock violation
panic: mtx_lock() of spin mutex (null) @
/usr/src/sys/fs/nullfs/null_vnops.c:720
cpuid = 1
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame
0xfffffe0468cf4400
vpanic() at vpanic+0x186/frame 0xfffffe0468cf4480
kassert_panic() at kassert_panic+0x126/frame 0xfffffe0468cf44f0
__mtx_lock_flags() at __mtx_lock_flags+0x158/frame 0xfffffe0468cf4540
null_unlock() at null_unlock+0x5d/frame 0xfffffe0468cf4590
VOP_UNLOCK_APV() at VOP_UNLOCK_APV+0xe8/frame 0xfffffe0468cf45c0
nullfs_mount() at nullfs_mount+0x25f/frame 0xfffffe0468cf4700
vfs_donmount() at vfs_donmount+0xf6d/frame 0xfffffe0468cf4940
sys_nmount() at sys_nmount+0x72/frame 0xfffffe0468cf4980
amd64_syscall() at amd64_syscall+0x7a8/frame 0xfffffe0468cf4ab0
Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe0468cf4ab0
--- syscall (378, FreeBSD ELF64, sys_nmount), rip = 0x80086de6a, rsp
0x7fffffffe048, rbp = 0x7fffffffe990 ---
KDB: enter: panic
Uptime: 9m25s
Dumping 1053 out of 16295
MB:..2%..11%..22%..31%..41%..51%..61%..72%..81%..92%
--
FreeBSD - the place to B...Spinning Destruction ;)
Shane Ambler