Bug#1111670: ext4 regression in 6.16.1

[Ben Hutchings <ben@decadent.org.uk>]

Source: linux
Version: 6.16.1-1~exp1
Severity: serious
Tags: upstream

systemd's CI detected a regression in ext4 in 6.16.1, that is reported
to be easily reproducible:
<https://lore.kernel.org/all/3d7f77d2-b1f8-4d49-b36a-927a943efc2f@heusel.eu/>.

As discussed in today's meeting
<https://salsa.debian.org/kernel-team/meetings/-/wikis/20250820>, this
seems to be a blocker for uploading 6.16.x to unstable.

Ben.

-- System Information:
Debian Release: forky/sid
  APT prefers unstable-debug
  APT policy: (500, 'unstable-debug'), (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 6.12.38+deb13-amd64 (SMP w/12 CPU threads; PREEMPT)
Kernel taint flags: TAINT_WARN
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled