[PATCH 3/5] selftests/cgroup: use runtime page size for zswpin check

[Li Wang]

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 <liwang@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Michal Koutný <mkoutny@xxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Nhat Pham <nphamcs@xxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Cc: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Cc: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
---
 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 ccfa6d42a3a3..af21fa4f5b7b 100644
--- a/tools/testing/selftests/cgroup/test_zswap.c
+++ b/tools/testing/selftests/cgroup/test_zswap.c
@@ -235,7 +235,7 @@ 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