Comment 0 for bug 1780137

We're seeing a very reproducible regression in the bionic kernel triggered by the stress-ng chdir test performed by the Ubuntu certification suite. Platform is a HiSilicon D05 arm64 server, but we don't have reason to believe it is platform specific at this time.

[Test Case]
$ sudo apt-add-repository -y ppa:hardware-certification/public
$ sudo apt install -y canonical-certification-server
$ sudo mkfs.ext4 /dev/sda1 (Obviously, this should not be your root disk!!)
$ sudo /usr/lib/plainbox-provider-checkbox/bin/disk_stress_ng sda --base-time 240 --really-run

This test runs a series of stress-ng tests against /dev/sda, and fails on the "chdir" test. To speed up reproduction, reduce the test list to just "chdir" in the disk_stress_ng script. Attempts to reproduce this directly with stress-ng have failed - presumably because of other environment setup that this script performs (e.g. setting aio-max-nr to 524288).

Our reproduction test is to use a non-root disk because it can lead to corruption, and mkfs.ext4'ing the partition just before running the test, to get to a pristine fs state.

I bisected this down to the following commit:

commit 555bc9b1421f10d94a1192c7eea4a59faca3e711
Author: Theodore Ts'o <email address hidden>
Date: Mon Feb 19 14:16:47 2018 -0500

    ext4: don't update checksum of new initialized bitmaps

    BugLink: http://bugs.launchpad.net/bugs/1773233

    commit 044e6e3d74a3d7103a0c8a9305dfd94d64000660 upstream.