I also get this after boot and uptime of about 5-30min: lock order reversal 1st 0xc0738200 UMA lock (UMA lock) @ /usr/src/sys/vm/uma_core.c:1494 2nd 0xc1062144 system map (system map) @ /usr/src/sys/vm/vm_kern.c:295 KDB: stack backtrace: kdb_backtrace(0,ffffffff,c06ec840,c06ec980,c06b4524) at kdb_backtrace+0x29 witness_checkorder(c1062144,9,c06916cd,127) at witness_checkorder+0x564 _mtx_lock_flags(c1062144,0,c06916cd,127) at _mtx_lock_flags+0x5b _vm_map_lock(c10620c0,c06916cd,127) at _vm_map_lock+0x26 kmem_malloc(c10620c0,2000,1,e9a70c08,c05fe1c3) at kmem_malloc+0x32 page_alloc(0,2000,e9a70bfb,1,267e76b) at page_alloc+0x1a uma_large_malloc(2000,1,c1046468,e9a70c74,2000) at uma_large_malloc+0x3b malloc(2000,c06c7760,1,44d,c1046460) at malloc+0xf1 hash_alloc(e9a70c74,c1046468,0,c0690986,1ab) at hash_alloc+0x29 zone_timeout(c1044b40) at zone_timeout+0x7e zone_foreach(c05fb68c,e9a70ce8,c04f3705,0,c05fb658) at zone_foreach+0x37 uma_timeout(0) at uma_timeout+0x12 softclock(0) at softclock+0x211 ithread_loop(c571e480,e9a70d38,c571e480,c04d5ab8,0) at ithread_loop+0x144 fork_exit(c04d5ab8,c571e480,e9a70d38) at fork_exit+0xa0 fork_trampoline() at fork_trampoline+0x8 --- trap 0x1, eip = 0, esp = 0xe9a70d6c, ebp = 0 ---