test_zswap currently only checks whether zswap is present by testing /sys/module/zswap. This misses the runtime global state exposed in /sys/module/zswap/parameters/enabled.
When zswap is built/loaded but globally disabled, the zswap cgroup selftests run in an invalid environment and may fail spuriously. Check the runtime enabled state before running the tests: - skip if zswap is not configured, - fail if the enabled knob cannot be read, - skip if zswap is globally disabled. Also print a hint in the skip message on how to enable zswap. Signed-off-by: Li Wang <[email protected]> Cc: Johannes Weiner <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Michal Koutný <[email protected]> Cc: Muchun Song <[email protected]> Cc: Nhat Pham <[email protected]> Cc: Tejun Heo <[email protected]> Cc: Roman Gushchin <[email protected]> Cc: Shakeel Butt <[email protected]> Cc: Yosry Ahmed <[email protected]> --- Notes: v3: - Replace tri-state zswap_enabled() with check_zswap_enabled() for clearer flow. - Move skip/fail decisions into the helper instead of branching in main(). - Make read failure reporting more explicit by naming `/sys/module/zswap/parameters/enabled`. - Keep skip hint for enabling zswap: `echo 1 > /sys/module/zswap/parameters/enabled`. v2: - remove enable/disable_zswap functions - skip the test if zswap is not enabled - reporting fail when zswap_enabled return -1 tools/testing/selftests/cgroup/test_zswap.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/cgroup/test_zswap.c b/tools/testing/selftests/cgroup/test_zswap.c index 64ebc3f3f203..e69d845d3592 100644 --- a/tools/testing/selftests/cgroup/test_zswap.c +++ b/tools/testing/selftests/cgroup/test_zswap.c @@ -589,9 +589,21 @@ struct zswap_test { }; #undef T -static bool zswap_configured(void) +static void check_zswap_enabled(void) { - return access("/sys/module/zswap", F_OK) == 0; + char value[2]; + + if (access("/sys/module/zswap", F_OK)) + ksft_exit_skip("zswap isn't configured\n"); + + if (read_text("/sys/module/zswap/parameters/enabled", value, + sizeof(value)) <= 0) + ksft_exit_fail_msg("Failed to read " + "/sys/module/zswap/parameters/enabled\n"); + + if (value[0] == 'N') + ksft_exit_skip("zswap is disabled (hint: echo 1 > " + "/sys/module/zswap/parameters/enabled)\n"); } int main(int argc, char **argv) @@ -604,8 +616,7 @@ int main(int argc, char **argv) if (cg_find_unified_root(root, sizeof(root), NULL)) ksft_exit_skip("cgroup v2 isn't mounted\n"); - if (!zswap_configured()) - ksft_exit_skip("zswap isn't configured\n"); + check_zswap_enabled(); /* * Check that memory controller is available: -- 2.53.0
