This test fails routinely in our prod testing environment, and I can reproduce it locally as well. The test allocates dcache inside a cgroup, then drops the memory limit and checks that usage drops correspondingly. The reason it fails is because dentries are freed with an RCU delay - a debugging sleep shows that usage drops as expected shortly after. Insert a 1s sleep after dropping the limit. This should be good enough, assuming that machines running those tests are otherwise not very busy. Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> --- tools/testing/selftests/cgroup/test_kmem.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/tools/testing/selftests/cgroup/test_kmem.c b/tools/testing/selftests/cgroup/test_kmem.c index 258ddc565deb..1b2cec9d18a4 100644 --- a/tools/testing/selftests/cgroup/test_kmem.c +++ b/tools/testing/selftests/cgroup/test_kmem.c @@ -70,6 +70,10 @@ static int test_kmem_basic(const char *root) goto cleanup; cg_write(cg, "memory.high", "1M"); + + /* wait for RCU freeing */ + sleep(1); + slab1 = cg_read_key_long(cg, "memory.stat", "slab "); if (slab1 <= 0) goto cleanup; -- 2.41.0
