On Tue, 30 Jan 2024 at 21:33, Steven Rostedt [off-list ref] wrote:

With even the last patch included, without the d_invalidate() I get errors
with simply doing:

 # cd /sys/kernel/tracing
 # mkdir instances/foo
 # ls instances/foo/events
 # rmdir instances/foo

As the rmdir calls tracefs_remove() that calls simple_recursive_removal()
that then walks into the "events" directory. Without that d_invalidate, it
walks beyond just the top directory and then splats on the dentries that
are cached.

Ugh.

This is only an issue for that "events" dir, right? The one that has a
proper refcount on the dentry in 'ei->events_dir'?

Because yes, then doing d_invalidate() looks like the right thing.

           Linus