Fatal LOR: PV ENTRY (UMA zone) _at_ /home2/src/sys/vm/uma_core.c:2033

Running on amd64:

lock order reversal
 1st 0xffffff007fed7c10 PV ENTRY (UMA zone) _at_ /home2/src/sys/vm/uma_core.c:2033
 2nd 0xffffffff8063dce0 UMA pcpu (UMA pcpu) _at_ /home2/src/sys/vm/uma_core.c:2015
KDB: stack backtrace:
kdb_backtrace() at kdb_backtrace+0x34
witness_checkorder() at witness_checkorder+0x613
_mtx_lock_flags() at _mtx_lock_flags+0x68
uma_zfree_arg() at uma_zfree_arg+0x80
namei() at namei+0x15c
vn_open_cred() at vn_open_cred+0x285
vn_open() at vn_open+0x17
kern_open() at kern_open+0x101
open() at open+0x18
syscall() at syscall+0x330
Xfast_syscall() at Xfast_syscall+0xa8
--- syscall (5, FreeBSD ELF64, open), rip = 0x76d75c, rsp = 0x7fffffffe088, rbp
= 0x7fffffffe0c0 ---

And right followed by....

panic: lock (sleep mutex) Giant not locked _at_ /home2/src/sys/kern/vfs_syscalls.c:
959
cpuid = 0;
KDB: stack backtrace:
kdb_backtrace() at kdb_backtrace+0x34
panic() at panic+0x1d2
witness_unlock() at witness_unlock+0xdd
_mtx_unlock_flags() at _mtx_unlock_flags+0x68
kern_open() at kern_open+0x128
open() at open+0x18
syscall() at syscall+0x330
Xfast_syscall() at Xfast_syscall+0xa8
--- syscall (5, FreeBSD ELF64, open), rip = 0x76d75c, rsp = 0x7fffffffe088, rbp
= 0x7fffffffe0c0 ---
KDB: enter: panic
[thread 100316]
Stopped at      kdb_enter+0x2e: nop

--WjW