`tail -F somefile` and ZFS weirdness

Hey all,

I just noticed this in a bhyve VM running HardenedBSD 16-CURRENT. My
`uname -a` aligns with FreeBSD commit b76b05c04cc9ed2cd053c7b367c92628447ede6f.

(so pretend the git commit has in my `uname -a` is FreeBSD's
b76b05c04cc9ed2cd053c7b367c92628447ede6f commit.)

I don't recall seeing this message before, so I suspect it might have
been introduced relatively recently.

==== BEGIN LOG ====
$ uname -a
FreeBSD hbsd-current-02 16.0-CURRENT FreeBSD 16.0-CURRENT #5  hardened/current/master-n196117-464cdf02df98-dirty: Wed May 13 01:12:14 UTC 2026     shawn@hbsd-current-02:/usr/obj/usr/src/amd64.amd64/sys/HARDENEDBSD amd64

$ tail -n 21 /var/log/messages
rms_rlock with the following non-sleepable locks held:
exclusive sleep mutex kqueue (kqueue) r = 0 (0xfffff80001d0b400) locked @ /usr/src/sys/kern/kern_event.c:2586
stack backtrace:
#0 0xffffffff80c921dc at witness_debugger+0x6c
#1 0xffffffff80c93adc at witness_warn+0x4bc
#2 0xffffffff80c0e10f at rms_rlock+0x1f
#3 0xffffffff82799a6b at zfs_freebsd_getattr+0x11b
#4 0xffffffff8127dba7 at VOP_GETATTR_APV+0x57
#5 0xffffffff80d2a7db at vn_getsize_locked+0x7b
#6 0xffffffff80d30b6d at filt_vfsread+0x8d
#7 0xffffffff80bb4d06 at knote+0xd6
#8 0xffffffff80d28a48 at vop_read_post+0x48
#9 0xffffffff8127e07a at VOP_READ_APV+0x9a
#10 0xffffffff80d450f2 at vn_read+0x242
#11 0xffffffff80d44df5 at vn_io_fault_doio+0x55
#12 0xffffffff80d3ff2f at vn_io_fault1+0x19f
#13 0xffffffff80d3d040 at vn_io_fault+0x190
#14 0xffffffff80c97e95 at dofileread+0x85
#15 0xffffffff80c97852 at sys_read+0x132
#16 0xffffffff811a7974 at amd64_syscall+0x184
#17 0xffffffff81175f0b at fast_syscall_common+0xf8
==== END LOG ====

Thanks,

-- 
Shawn Webb
Cofounder / Security Engineer
HardenedBSD

Signal Username:  shawn_webb.74
Tor-ified Signal: +1 303-901-1600 / shawn_webb_opsec.50
https://git.hardenedbsd.org/hardenedbsd/pubkeys/-/raw/master/Shawn_Webb/03A4CBEBB82EA5A67D9F3853FF2E67A277F8E1FA.pub.asc