panic in range_tree_seg64_compare()

Yet another issue I'm seeing after last update (currently running 
r364870), hit it 2 times today:

Fatal trap 12: page fault while in kernel mode
cpuid = 19; apic id = 0d
fault virtual address   = 0xfffff819e2ecdc40
fault code              = supervisor read data, page not present
instruction pointer     = 0x20:0xffffffff8277fa64
stack pointer           = 0x28:0xfffffe01f9ff2d90
frame pointer           = 0x28:0xfffffe01f9ff2d90
code segment            = base 0x0, limit 0xfffff, type 0x1b
                         = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 48792 (blk-3:0-0)
trap number             = 12
panic: page fault
cpuid = 19
time = 1598577675
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 
0xfffffe01f9ff2a40
vpanic() at vpanic+0x182/frame 0xfffffe01f9ff2a90
panic() at panic+0x43/frame 0xfffffe01f9ff2af0
trap_fatal() at trap_fatal+0x387/frame 0xfffffe01f9ff2b50
trap_pfault() at trap_pfault+0x97/frame 0xfffffe01f9ff2bb0
trap() at trap+0x2ab/frame 0xfffffe01f9ff2cc0
calltrap() at calltrap+0x8/frame 0xfffffe01f9ff2cc0
--- trap 0xc, rip = 0xffffffff8277fa64, rsp = 0xfffffe01f9ff2d90, rbp = 
0xfffffe01f9ff2d90 ---
range_tree_seg64_compare() at range_tree_seg64_compare+0x4/frame 
0xfffffe01f9ff2d90
zfs_btree_find() at zfs_btree_find+0x1bd/frame 0xfffffe01f9ff2df0
range_tree_find_impl() at range_tree_find_impl+0x6e/frame 0xfffffe01f9ff2e30
range_tree_find() at range_tree_find+0x1c/frame 0xfffffe01f9ff2e70
range_tree_contains() at range_tree_contains+0x9/frame 0xfffffe01f9ff2e80
dnode_block_freed() at dnode_block_freed+0x11d/frame 0xfffffe01f9ff2eb0
dbuf_read() at dbuf_read+0x70c/frame 0xfffffe01f9ff2fc0
dmu_buf_hold_array_by_dnode() at dmu_buf_hold_array_by_dnode+0x164/frame 
0xfffffe01f9ff3030
dmu_read_impl() at dmu_read_impl+0xce/frame 0xfffffe01f9ff30c0
dmu_read() at dmu_read+0x45/frame 0xfffffe01f9ff3100
zvol_geom_bio_strategy() at zvol_geom_bio_strategy+0x2aa/frame 
0xfffffe01f9ff3180
g_io_request() at g_io_request+0x2df/frame 0xfffffe01f9ff31b0
g_dev_strategy() at g_dev_strategy+0x155/frame 0xfffffe01f9ff31e0
physio() at physio+0x4f8/frame 0xfffffe01f9ff3270
devfs_read_f() at devfs_read_f+0xde/frame 0xfffffe01f9ff32d0
dofileread() at dofileread+0x81/frame 0xfffffe01f9ff3320
kern_preadv() at kern_preadv+0x62/frame 0xfffffe01f9ff3360
sys_preadv() at sys_preadv+0x39/frame 0xfffffe01f9ff3390
amd64_syscall() at amd64_syscall+0x140/frame 0xfffffe01f9ff34b0
fast_syscall_common() at fast_syscall_common+0xf8/frame 0xfffffe01f9ff34b0
--- syscall (289, FreeBSD ELF64, sys_preadv), rip = 0x8006fd89a, rsp = 
0x7fffdfdfcf18, rbp = 0x7fffdfdfcfc0 ---
Uptime: 4h13m43s

Guessing on zvol_geom_bio_strategy(), it's volmode=dev zvol I'm using 
for bhyve VM.  Anything known?