public inbox for linux-kernel@vger.kernel.org
 help / color / mirror / Atom feed
* [PATCH 1/5] selftests/cgroup: detect and handle global zswap state in test_zswap
@ 2026-03-11 11:05 Li Wang
  2026-03-11 11:05 ` [PATCH 2/5] selftests/cgroup: avoid OOM in test_swapin_nozswap Li Wang
                   ` (5 more replies)
  0 siblings, 6 replies; 19+ messages in thread
From: Li Wang @ 2026-03-11 11:05 UTC (permalink / raw)
  To: linux-kselftest, linux-kernel, akpm
  Cc: Johannes Weiner, Michal Hocko, Michal Koutný, Muchun Song,
	Nhat Pham, Tejun Heo, Roman Gushchin, Shakeel Butt, Yosry Ahmed

test_zswap currently checks only for zswap presence via /sys/module/zswap,
but does not account for the global runtime state in
/sys/module/zswap/parameters/enabled.

If zswap is configured but globally disabled, zswap cgroup tests may run in
an invalid environment and fail spuriously.

Add helpers to:
  - detect the runtime zswap enabled state,
  - enable zswap when it is initially disabled,
  - restore the original state after tests complete.

Skip the test when zswap state cannot be determined (e.g. unsupported or
unreadable), and keep existing behavior when zswap is already enabled.

This makes test_zswap more robust across systems where zswap is built but
disabled by default.

Signed-off-by: Li Wang <liwang@redhat.com>
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>
---
 tools/testing/selftests/cgroup/test_zswap.c | 77 ++++++++++++++++++++-
 1 file changed, 75 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/cgroup/test_zswap.c b/tools/testing/selftests/cgroup/test_zswap.c
index 64ebc3f3f203..1c80f4af9683 100644
--- a/tools/testing/selftests/cgroup/test_zswap.c
+++ b/tools/testing/selftests/cgroup/test_zswap.c
@@ -594,18 +594,88 @@ static bool zswap_configured(void)
 	return access("/sys/module/zswap", F_OK) == 0;
 }
 
+static int zswap_enabled_state(void)
+{
+	char buf[16];
+	ssize_t n;
+
+	if (!zswap_configured())
+		return -1;
+
+	n = read_text("/sys/module/zswap/parameters/enabled", buf, sizeof(buf));
+	if (n < 0 || n == 0)
+		return -1;
+
+	switch (buf[0]) {
+	case 'Y':
+	case 'y':
+	case '1':
+		return 1;
+	case 'N':
+	case 'n':
+	case '0':
+		return 0;
+	default:
+		return -1;
+	}
+}
+
+static bool enable_zswap(void)
+{
+	int st;
+	char y[] = "Y\n";
+
+	st = zswap_enabled_state();
+	if (st == 1)
+		return true;
+	if (st < 0)
+		return false;
+
+	if (write_text("/sys/module/zswap/parameters/enabled", y, strlen(y)) >= 0) {
+		if (zswap_enabled_state() == 1)
+			return true;
+	}
+
+	ksft_print_msg("Failed to enable zswap\n");
+	return false;
+}
+
+static bool disable_zswap(void)
+{
+	int st;
+	char n[] = "N\n";
+
+	st = zswap_enabled_state();
+	if (st == 0)
+		return true;
+	if (st < 0)
+		return false;
+
+	if (write_text("/sys/module/zswap/parameters/enabled", n, strlen(n)) >= 0) {
+		if (zswap_enabled_state() == 0)
+			return true;
+	}
+
+	ksft_print_msg("Failed to disable zswap\n");
+	return false;
+}
+
 int main(int argc, char **argv)
 {
 	char root[PATH_MAX];
-	int i;
+	int i, orig_zswap_state;
 
 	ksft_print_header();
 	ksft_set_plan(ARRAY_SIZE(tests));
 	if (cg_find_unified_root(root, sizeof(root), NULL))
 		ksft_exit_skip("cgroup v2 isn't mounted\n");
 
-	if (!zswap_configured())
+	orig_zswap_state = zswap_enabled_state();
+
+	if (orig_zswap_state == -1)
 		ksft_exit_skip("zswap isn't configured\n");
+	else if (orig_zswap_state == 0 && !enable_zswap())
+		ksft_exit_skip("zswap is disabled and cannot be enabled\n");
 
 	/*
 	 * Check that memory controller is available:
@@ -632,5 +702,8 @@ int main(int argc, char **argv)
 		}
 	}
 
+	if (orig_zswap_state == 0)
+		disable_zswap();
+
 	ksft_finished();
 }
-- 
2.53.0


^ permalink raw reply related	[flat|nested] 19+ messages in thread
end of thread, other threads:[~2026-03-13  2:59 UTC | newest]

Thread overview: 19+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-03-11 11:05 [PATCH 1/5] selftests/cgroup: detect and handle global zswap state in test_zswap Li Wang
2026-03-11 11:05 ` [PATCH 2/5] selftests/cgroup: avoid OOM in test_swapin_nozswap Li Wang
2026-03-11 18:50   ` Yosry Ahmed
2026-03-12  4:01     ` Li Wang
2026-03-12 17:09       ` Nhat Pham
2026-03-13  2:59         ` Li Wang
2026-03-11 11:05 ` [PATCH 3/5] selftests/cgroup: use runtime page size for zswpin check Li Wang
2026-03-11 18:56   ` Yosry Ahmed
2026-03-12  2:35     ` Li Wang
2026-03-11 11:05 ` [PATCH 4/5] selftest/cgroup: fix zswap test_no_invasive_cgroup_shrink on 64K pagesize system Li Wang
2026-03-11 19:01   ` Yosry Ahmed
2026-03-12  2:36     ` Li Wang
2026-03-11 11:05 ` [PATCH 5/5] selftest/cgroup: fix zswap attempt_writeback() " Li Wang
2026-03-11 18:58   ` Yosry Ahmed
2026-03-12  2:38     ` Li Wang
2026-03-11 13:20 ` [PATCH 1/5] selftests/cgroup: detect and handle global zswap state in test_zswap Michal Koutný
2026-03-11 18:41   ` Yosry Ahmed
2026-03-11 18:47 ` Yosry Ahmed
2026-03-12  1:41   ` Li Wang

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox