[PATCH kselftest-next 1/2] kselftests: memcg: update the oom group leaf events test

[Roman Gushchin <guro@fb.com>]

Commit 9852ae3fe529 ("mm, memcg: consider subtrees in memory.events") made
memory.events recursive: all events are propagated upwards by the
tree. It was a change in semantics.

It broke the oom group leaf events test: it assumes that after
an OOM the oom_kill counter is zero on parent's level.

Let's adjust the test: it should have similar expectations
for the child and parent levels.

The test passes after this fix.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Chris Down <chris@chrisdown.name>
Cc: Johannes Weiner <hannes@cmpxchg.org>
---
 tools/testing/selftests/cgroup/test_memcontrol.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
index c19a97dd02d4..60bfe53c0289 100644
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -1002,7 +1002,8 @@ static int test_memcg_sock(const char *root)
 /*
  * This test disables swapping and tries to allocate anonymous memory
  * up to OOM with memory.group.oom set. Then it checks that all
- * processes in the leaf (but not the parent) were killed.
+ * processes in the leaf were killed. It also checks that oom_events
+ * were propagated to the parent level.
  */
 static int test_memcg_oom_group_leaf_events(const char *root)
 {
@@ -1045,7 +1046,7 @@ static int test_memcg_oom_group_leaf_events(const char *root)
 	if (cg_read_key_long(child, "memory.events", "oom_kill ") <= 0)
 		goto cleanup;
 
-	if (cg_read_key_long(parent, "memory.events", "oom_kill ") != 0)
+	if (cg_read_key_long(parent, "memory.events", "oom_kill ") <= 0)
 		goto cleanup;
 
 	ret = KSFT_PASS;
-- 
2.17.1