On 2020-06-22 05:27, Luis Chamberlain wrote:

Note: this will bring you sanity if you try to figure out *why* we still
get:

[235530.144343] debugfs: Directory 'loop0' with parent 'block' already present!
[235530.149477] blktrace: debugfs_dir not present for loop0 so skipping
[235530.232328] debugfs: Directory 'loop0' with parent 'block' already present!
[235530.238962] blktrace: debugfs_dir not present for loop0 so skipping

If you run run_0004.sh from break-blktrace [0]. Even with all my patches
merged we still run into this. And so the bug lies within the block
layer or on the driver. I haven't been able to find the issue yet.

[0] https://github.com/mcgrof/break-blktrace

Thanks Luis for having shared this information. If I can find the time I
will have a look into this myself.

Bart.