Hi, I've got repeatable panics with gmirror and ufs. The test case is the following: # gmirror label -v test /dev/da1b # newfs /dev/mirror/test # while :; do gmirror label -v test /dev/da1b; mount /dev/mirror/test /mnt; dd if=/dev/zero of=/mnt/test count=100 bs=1m; umount -f /mnt; gmirror remove test da1b; done After a while I've got panic with such DDB backtrace: db:0:kdb.enter.default> bt Tracing pid 5240 tid 100075 td 0xfffffe0001e47460 _sx_xlock_hard() at _sx_xlock_hard+0xb3 g_mirror_access() at g_mirror_access+0x262 g_access() at g_access+0x162 g_vfs_open() at g_vfs_open+0xb3 ffs_mount() at ffs_mount+0xb4b vfs_donmount() at vfs_donmount+0x1072 sys_nmount() at sys_nmount+0x66 amd64_syscall() at amd64_syscall+0x5bf Xfast_syscall() at Xfast_syscall+0xf7 --- syscall (378, FreeBSD ELF64, sys_nmount), rip = 0x800a8746c, rsp 0x7fffffffcb58, rbp = 0x801008048 --- -- Andrey Zonov