cgroup: account for memory_recursiveprot in test_memcg_low()

The test_memcg_low() testcase in test_memcontrol.c verifies the expected
behavior of groups using the memory.low knob.  Part of the testcase
verifies that a group with memory.low that experiences reclaim due to
memory pressure elsewhere in the system, observes memory.events.low events
as a result of that reclaim.

In commit 8a931f801340 ("mm: memcontrol: recursive memory.low
protection"), the memory controller was updated to propagate memory.low
and memory.min protection from a parent group to its children via a
configurable memory_recursiveprot mount option.  This unfortunately broke
the memcg tests, which asserts that a sibling that experienced reclaim but
had a memory.low value of 0, would not observe any memory.low events. 
This patch updates test_memcg_low() to account for the new behavior
introduced by memory_recursiveprot.

So as to make the test resilient to multiple configurations, the patch
also adds a new proc_mount_contains() helper that checks for a string in
/proc/mounts, and is used to toggle behavior based on whether the default
memory_recursiveprot was present.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Vernet <[email protected]>
Acked-by: Roman Gushchin <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Shakeel Butt <[email protected]>
Cc: Tejun Heo <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions