[LTP] [PATCH v2] memcontrol03: Using clean page cache to avoid dependency on IO rate

[Wei Gao]

Bad IO situation(storage bandwidth ~10MB/sec) will lead background
writeback has uncertain progress for dirty page. So system can not
reclaim enough memory for new process and finally lead a unexpected
OOM.

memcontrol03.c:218: TPASS: Expect: (A/B/E memory.current=0) ~= 0
memcontrol03.c:116: TPASS: Child 1918 killed by OOM
memcontrol03.c:224: TPASS: Expect: (A/B memory.current=52588544) ~= 52428800
memcontrol03.c:129: TFAIL: Expected child 1944 to exit(0), but instead killed by SIGKILL

Signed-off-by: Wei Gao <wegao@suse.com>
---
 testcases/kernel/controllers/memcg/memcontrol03.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/testcases/kernel/controllers/memcg/memcontrol03.c b/testcases/kernel/controllers/memcg/memcontrol03.c
index 9c6c808e0..e2fc85cc8 100644
--- a/testcases/kernel/controllers/memcg/memcontrol03.c
+++ b/testcases/kernel/controllers/memcg/memcontrol03.c
@@ -144,6 +144,7 @@ static void alloc_pagecache_in_child(const struct tst_cg_group *const cg,
 	tst_res(TINFO, "Child %d in %s: Allocating pagecache: %"PRIdPTR,
 		getpid(), tst_cg_group_name(cg), size);
 	alloc_pagecache(fd, size);
+	SAFE_FSYNC(fd);
 
 	TST_CHECKPOINT_WAKE(CHILD_IDLE);
 	TST_CHECKPOINT_WAIT(TEST_DONE);
-- 
2.35.3