On Fri, Mar 20, 2026 at 04:42:41PM -0400, Waiman Long wrote: > Although there is supposed to be a periodic and asynchronous flush of > stats every 2 seconds, the actual time lag between succesive runs can > actually vary quite a bit. In fact, I have seen time lag of up to 10s > of seconds in some cases. > > At the end of test_memcg_sock, it waits up to 3 seconds for the > "sock" attribute of memory.stat to go back down to 0. Obviously it > may occasionally fail especially when the kernel has large page size > (e.g. 64k). Treat this failure as an expected failure (XFAIL) to > distinguish it from the other failure cases. > > Signed-off-by: Waiman Long <[email protected]> > --- > tools/testing/selftests/cgroup/test_memcontrol.c | 14 +++++++++++++- > 1 file changed, 13 insertions(+), 1 deletion(-) > > diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c > b/tools/testing/selftests/cgroup/test_memcontrol.c > index 5336be5ed2f5..af3e8fe4e50e 100644 > --- a/tools/testing/selftests/cgroup/test_memcontrol.c > +++ b/tools/testing/selftests/cgroup/test_memcontrol.c > @@ -1486,12 +1486,21 @@ static int test_memcg_sock(const char *root) > * Poll memory.stat for up to 3 seconds (~FLUSH_TIME plus some > * scheduling slack) and require that the "sock " counter > * eventually drops to zero. > + * > + * The actual run-to-run elapse time between consecutive run > + * of asynchronous memcg rstat flush may varies quite a bit. > + * So the 3 seconds wait time may not be enough for the "sock" > + * counter to go down to 0. Treat it as a XFAIL instead of > + * a FAIL. > */ > sock_post = cg_read_key_long_poll(memcg, "memory.stat", "sock ", 0, > MEMCG_SOCKSTAT_WAIT_RETRIES, > DEFAULT_WAIT_INTERVAL_US); > - if (sock_post) > + if (sock_post) { > + if (sock_post > 0) > + ret = KSFT_XFAIL;
XFAIL means "expected failure" and is intended for known kernel bugs or unsupported features. A timing issue where the test simply doesn't wait long enough probably not an expected failure, it's a test that needs a longer timeout. I'm wondering can we just enlarge the MEMCG_SOCKSTAT_WAIT_RETRIES value? e.g. from 30 to 150 -- Regards, Li Wang
