The test allocates dcache inside a cgroup, then destroys the cgroups and then checks the sanity of numbers on the parent level. 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 completing the cgroup creation/deletions. This should be good enough, assuming that machines running those tests are otherwise not very busy. This commit is directly inspired by Johannes over at the link below. Link: https://lore.kernel.org/all/20230801135632.1768830-1-hannes@xxxxxxxxxxx/ Signed-off-by: Lucas Karpinski <lkarpins@xxxxxxxxxx> --- tools/testing/selftests/cgroup/test_kmem.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/tools/testing/selftests/cgroup/test_kmem.c b/tools/testing/selftests/cgroup/test_kmem.c index 67cc0182058d..7ac384bbfdd5 100644 --- a/tools/testing/selftests/cgroup/test_kmem.c +++ b/tools/testing/selftests/cgroup/test_kmem.c @@ -183,6 +183,9 @@ static int test_kmem_memcg_deletion(const char *root) if (cg_run_in_subcgroups(parent, alloc_kmem_smp, NULL, 100)) goto cleanup; + /* wait for RCU freeing */ + sleep(1); + current = cg_read_long(parent, "memory.current"); slab = cg_read_key_long(parent, "memory.stat", "slab "); anon = cg_read_key_long(parent, "memory.stat", "anon "); -- 2.41.0
