[LTP] [PATCH] controllers/cgroup_regression_test.sh: mitigate potential mount error

[Cyril Hrubis]

Hi!
> > There is always better solution than sprinking the code with sleeps,
> > here we can retry the mount instead, which would be faster and more
> 
> thanks for your kind reply!
> 
> retry mount cannot help here(at least for the current kernel), because 
> `umount cgroup/` **immediately** after `rmdir cgroup/0` corrupts the 
> cgroup_root refcnt, and it will always cause the subsequent remount 
> failure(s) whenever remounting overlapping controllers later.
> 
> so I simply put a sleep between between `umount cgroup/` and `rmdir 
> cgroup/0` to synchronize them.  <- any good idea to this point?
> 
> and attach the related kernel issue again:
> https://marc.info/?t=155021167400005&r=1&w=2

We are not working around kernel bugs in tests.

Too bad that it seems that nobody is interested in fixing the v1 cgroup
API. I guess this is a signal that we should stop using it as fast as
possible and migrate to v2.

-- 
Cyril Hrubis
chrubis@suse.cz