I have two machines where shutdown -r just failed to actually reboot. Both were recently updated from 6.1 to 8.1, my impression is that it worked before. Both display "syncing disks...1 done" and then hang. On both, I'm able to enter ddb.
On the first one, the backtrace (minus the interrupt) is mutex_enter ffs_sync VFS_SYNC sched_sync which strikes me as odd since the sync has claimed to finish. entering "reboot" in ddb then actually reboots. On the second one, the backtrace is x86_stihlt acpicpu_cstate_idle_entry acpicpu_cstate_idle idle_loop and entering "reboot" doesn't actually reboot. Both machines were wedged with mst probably the vnode lock on the root of an NFS import held, but that appears unrelated to me. Any clues?
