panic: malloc(M_WAITOK) with sleeping prohibited

H/W: Supermicro X9DRI-LN4F+, booting from IPMI Virtual CD-ROM using
FreeBSD-14.0-CURRENT-amd64-20210311-15565e0a217-257277-disc1.iso.

Root mount waiting for: usbus0
ugen0.4: <vendor 0x0ea0 product 0x2222> at usbus0
umass0 numa-domain 0 on uhub2
umass0: <vendor 0x0ea0 product 0x2222, class 0/0, rev 2.00/2.00, addr 4>
on usbus0
umass0: SCSI over Bulk-Only; quirks = 0xc101
umass0:7:0: Attached to scbus7
umass1 numa-domain 0 on uhub2
umass1: <vendor 0x0ea0 product 0x2222, class 0/0, rev 2.00/2.00, addr 4>
on usbus0
umass1: 8070i (ATAPI) over Bulk-Only; quirks = 0xc101
umass1:8:1: Attached to scbus8
panic: malloc(M_WAITOK) with sleeping prohibited
cpuid = 37
time = 9
KDB: stack backtrace:
db_trace_self_wrapper()
vpanic()
malloc_dbg()
malloc()
disk_alloc()
cdregister()
cam_periph_alloc()
cdasync()
xpt_async_process_dev()
xpt_async_process()
xpt_done_process()
xpt_done_td()
fork_exit()
fork_trampoline()
--- trap 0, rip = 0, rsp = 0, rbp =0 ---
KDB: enter: panic
[ thread pid 49 tid 100383 ]