selftests: memcg: fix compilation

Patch series "memcontrol selftests fixups", v2.

Flushing the patches to make memcontrol selftests check the events
behavior we had consensus about (test_memcg_low fails).

(test_memcg_reclaim, test_memcg_swap_max fail for me now but it's present
even before the refactoring.)

The two bigger changes are:
- adjustment of the protected values to make tests succeed with the given
  tolerance,
- both test_memcg_low and test_memcg_min check protection of memory in
  populated cgroups (actually as per Documentation/admin-guide/cgroup-v2.rst
  memory.min should not apply to empty cgroups, which is not the case
  currently. Therefore I unified tests with the populated case in order to to
  bring more broken tests).


This patch (of 5):

This fixes mis-applied changes from commit 72b1e03a

 ("cgroup: account
for memory_localevents in test_memcg_oom_group_leaf_events()").

Link: https://lkml.kernel.org/r/20220518161859.21565-1-mkoutny@suse.com
Link: https://lkml.kernel.org/r/20220518161859.21565-2-mkoutny@suse.com
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: David Vernet <void@manifault.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Richard Palethorpe <rpalethorpe@suse.de>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>