[PATCH v7 3/8] selftests/cgroup: use runtime page size for zswpin check

Li Wang
2026-04-24T04:01:52Z

test_zswapin compares memory.stat:zswpin (counted in pages) against a
byte threshold converted with PAGE_SIZE. In cgroup selftests, PAGE_SIZE
is hardcoded to 4096, which makes the conversion wrong on systems with
non-4K base pages (e.g. 64K).

As a result, the test requires too many pages to pass and fails
spuriously even when zswap is working.

Use sysconf(_SC_PAGESIZE) for the zswpin threshold conversion so the
check matches the actual system page size.

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>
Reviewed-by: Yosry Ahmed <yosry@kernel.org>
Acked-by: Nhat Pham <nphamcs@gmail.com>
---
tools/testing/selftests/cgroup/test_zswap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/cgroup/test_zswap.c b/tools/testing/selftests/cgroup/test_zswap.c
index 47709cbdcdf..37aa83c2f1b 100644
--- a/tools/testing/selftests/cgroup/test_zswap.c
+++ b/tools/testing/selftests/cgroup/test_zswap.c
@@ -245,7 +245,7 @@ static int test_zswapin(const char *root)
goto out;
}

- if (zswpin < MB(24) / PAGE_SIZE) {
+ if (zswpin < MB(24) / sysconf(_SC_PAGESIZE)) {
ksft_print_msg("at least 24MB should be brought back from zswap\n");
goto out;
}
--
2.53.0