[LTP] [PATCH V4 3/6] swapon01: Improving test with memory limits and swap reporting

Li Wang
2024-01-24T04:47:05Z

This is target to create a more robust and controlled environment to test
the swapon system call. By introducing memory limits through cgroups and
filling memory with a known pattern, the test can better assess swapon
behavior when the system experiences memory pressure.

Additionally, the reporting of "SwapCached" memory before turning off the
swap file provides a clearer understanding of the swap system's state in
response to the test conditions.

Signed-off-by: Li Wang <liwang@redhat.com>
---
testcases/kernel/syscalls/swapon/swapon01.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/testcases/kernel/syscalls/swapon/swapon01.c b/testcases/kernel/syscalls/swapon/swapon01.c
index e1fe50459..a74a5171e 100644
--- a/testcases/kernel/syscalls/swapon/swapon01.c
+++ b/testcases/kernel/syscalls/swapon/swapon01.c
@@ -20,11 +20,15 @@

#define MNTPOINT "mntpoint"
#define SWAP_FILE MNTPOINT"/swapfile01"
+#define TESTMEM (1UL<<30)

static void verify_swapon(void)
{
TST_EXP_PASS(tst_syscall(__NR_swapon, SWAP_FILE, 0));

+ tst_pollute_memory(TESTMEM, 0x41);
+ tst_res(TINFO, "SwapCached: %ld Kb", SAFE_READ_MEMINFO("SwapCached:"));
+
if (TST_PASS && tst_syscall(__NR_swapoff, SWAP_FILE) != 0) {
tst_brk(TBROK | TERRNO,
"Failed to turn off swapfile, system reboot recommended");
@@ -35,6 +39,9 @@ static void setup(void)
{
is_swap_supported(SWAP_FILE);
make_swapfile(SWAP_FILE, 0);
+
+ SAFE_CG_PRINTF(tst_cg, "cgroup.procs", "%d", getpid());
+ SAFE_CG_PRINTF(tst_cg, "memory.max", "%lu", TESTMEM);
}

static struct tst_test test = {
@@ -42,6 +49,7 @@ static struct tst_test test = {
.mount_device = 1,
.needs_root = 1,
.all_filesystems = 1,
+ .needs_cgroup_ctrls = (const char *const []){ "memory", NULL },
.test_all = verify_swapon,
.setup = setup
};
--
2.40.1