On Fri, Apr 24, 2026 at 12:00:52PM +0800, Li Wang <li.wang@linux.dev> wrote:
> 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 <li.wang@linux.dev>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Michal Hocko <mhocko@kernel.org>
> Cc: Michal Koutný <mkoutny@suse.com>
> Cc: Muchun Song <muchun.song@linux.dev>
> Cc: Nhat Pham <nphamcs@gmail.com>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Roman Gushchin <roman.gushchin@linux.dev>
> Cc: Shakeel Butt <shakeel.butt@linux.dev>
> Cc: Yosry Ahmed <yosryahmed@google.com>
> Acked-by: Yosry Ahmed <yosry@kernel.org>
> Acked-by: Nhat Pham <nphamcs@gmail.com>
> ---
>  tools/testing/selftests/cgroup/test_zswap.c | 19 +++++++++++++++----
>  1 file changed, 15 insertions(+), 4 deletions(-)

Reviewed-by: Michal Koutný <mkoutny@suse.com>