Backtrace:
Tracing pid 4 tid 100037 td 0xfffff80003b99000
kdb_enter() at kdb_enter+0x3b/frame 0xfffffe00f5b11fc0
vpanic() at vpanic+0x1a3/frame 0xfffffe00f5b12040
panic() at panic+0x43/frame 0xfffffe00f5b120a0
reassignbuf() at reassignbuf+0x27f/frame 0xfffffe00f5b120e0
bdirty() at bdirty+0x2e/frame 0xfffffe00f5b12100
brelse() at brelse+0x107/frame 0xfffffe00f5b12160
bufdone() at bufdone+0x80/frame 0xfffffe00f5b12180
g_io_deliver() at g_io_deliver+0x23f/frame 0xfffffe00f5b121e0
g_io_deliver() at g_io_deliver+0x23f/frame 0xfffffe00f5b12240
g_io_deliver() at g_io_deliver+0x23f/frame 0xfffffe00f5b122a0
g_disk_done() at g_disk_done+0x127/frame 0xfffffe00f5b122f0
bioq_flush() at bioq_flush+0x84/frame 0xfffffe00f5b12320
cam_iosched_flush() at cam_iosched_flush+0x18/frame 0xfffffe00f5b12350
adaoninvalidate() at adaoninvalidate+0x31/frame 0xfffffe00f5b12370
cam_periph_invalidate() at cam_periph_invalidate+0xaa/frame 0xfffffe00f5b12390
adaasync() at adaasync+0x229/frame 0xfffffe00f5b128b0
xpt_async_process_dev() at xpt_async_process_dev+0x1b2/frame 0xfffffe00f5b12900
xptdevicetraverse() at xptdevicetraverse+0x196/frame 0xfffffe00f5b12950
xpttargettraverse() at xpttargettraverse+0x13a/frame 0xfffffe00f5b129a0
xpt_async_process() at xpt_async_process+0x100/frame 0xfffffe00f5b129e0
xpt_done_process() at xpt_done_process+0x677/frame 0xfffffe00f5b12a20
xpt_done_td() at xpt_done_td+0x196/frame 0xfffffe00f5b12a70
fork_exit() at fork_exit+0x85/frame 0xfffffe00f5b12ab0
fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe00f5b12ab0
— trap 0, rip = 0, rsp = 0, rbp = 0 —