While working on a few config.txt issues on the RPi4B I noticed, that when you actual write to the file on the msdos partition the following LOR is reproducible be triggered. kernel: 1st 0xffffa000224349f8 msdosfs (msdosfs, lockmgr) @ /tank/nfs_public/tiny/src/sys/kern/vfs_syscal ls.c:3498 kernel: 2nd 0xffffa00022013628 devfs (devfs, lockmgr) @ /tank/nfs_public/tiny/src/sys/fs/msdosfs/msdosfs_ vnops.c:853 kernel: lock order msdosfs -> devfs attempted at: kernel: #0 0xffff0000004c5774 at witness_checkorder+0xc50 kernel: #1 0xffff0000004296fc at lockmgr_xlock+0x50 kernel: #2 0xffff00000054feb8 at _vn_lock+0x54 kernel: #3 0xffff000000313d4c at msdosfs_fsync+0x58 kernel: #4 0xffff00000054bb74 at kern_fsync+0x194 kernel: #5 0xffff00000079037c at do_el0_sync+0x7cc kernel: #6 0xffff00000076fa24 at handle_el0_sync+0x90
fixed in https://cgit.freebsd.org/src/commit?id=dbc689cdef0cc8ff11171642cdcf107dfbc3fb41