I will not claim to have any kernel locking foo, however it seems odd to me that this machine has lots of processes waiting on "allproc" but "show alllocks" doesn't show any process having the allproc lock. Is this correct? db> show alllocks Process 89731 (perform_ca) thread 0xffffff0128c9fbe0 (100232) exclusive sx proctree r = 0 (0xffffffff8070dde0) locked @ kern/kern_exit.c:602 Process 85077 (ph_ thread 0xffffff012e83bbe0 (100182) exclusive sleep mutex process lock r = 0 (0xffffff01205c1418) locked @kern/subr_trap.c:88 Process 85077 (ph) thread 0xffffff01142e0000 (100133) exclusive sleep mutex so_rcv r = 0 (0xffffff0126948338) locked @ kern/uipc_socket.c:2037 exclusive sleep mutex so_snd r = 0 (0xffffff0126948408) locked @ kern/uipc_socket.c:2036 Process 837 (sendmail) thread 0xffffff012efa3260 (100035) exclusive sx sysctl lock r = 0 (0xffffffff8070e580) locked @ kern/kern_sysctl.c:1375 db> show sleepchain 843 thread 100055 (pid 843, sendmail) blocked on sx "sysctl lock" XLOCK thread 100035 (pid 837, sendmail) blocked on lk "allproc" EXCL (count 0) db> where 89792 Tracing pid 89792 tid 100199 td 0xffffff01251a24c0 sched_switch() at sched_switch+0x13a mi_switch() at mi_switch+0x1d2 critical_exit() at critical_exit+0xb0 spinlock_exit() at spinlock_exit+0x17 turnstile_unpend() at turnstile_unpend+0x249 vmspace_exit() at vmspace_exit+0x9a exit1() at exit1+0x38f sys_exit() at sys_exit+0xe syscall() at syscall+0x4d1 Xfast_syscall() at Xfast_syscall+0xa8 --- syscall (1, FreeBSD ELF64, sys_exit), rip = 0x48b46c, rsp = 0x7fffffffeae8, rbp = 0x5fa000 ---