Hi, Apart from the traces already reported, my amd64 machine finds this one while running regress.
acquiring duplicate lock of same type: "&mp->mnt_lock" 1st vfslock @ /usr/src/sys/kern/vfs_subr.c:191 2nd vfslock @ /usr/src/sys/kern/vfs_subr.c:191 Starting stack trace... witness_checkorder(9,ffffffff81ac7b98,bf,ffff8000006c7c40,21) at witness_checkorder+0x63d _rw_enter(0,ffff8000006c7c40,ffff8000006c7c00,80000) at _rw_enter+0x56 vfs_busy(ffff8000ffa57460,ffff8000006c9800) at vfs_busy+0x66 dounmount(ffff8000ffa57460,ffff8000ffa77790,1) at dounmount+0x8a sys_unmount(160,ffff8000ffa77790,16) at sys_unmount+0xba syscall(7f7fffff2450) at syscall+0x31d Xsyscall_untramp(6,0,0,0,0,16) at Xsyscall_untramp+0xc0 end of kernel end trace frame: 0x7f7fffff2890, count: 250 End of stack trace. Full dmesg is here: http://bluhm.genua.de/regress/results/2018-06-02T06:17:01Z/dmesg-ot6.txt bluhm
