[LTP] [PATCH] swapon01: swapon01: prevent OOM happening in swap process

[Li Wang]

Here we take many ways to prevent the OOM happening with
run the swapon test:

  * shrink the pollute memory size
  * increase swapfile size
  * setting swap max for Cgroup
  * setting test oom_score_adj to -1000

Reproted-by: Wei Gao <wegao@suse.com>
Signed-off-by: Li Wang <liwang@redhat.com>
---

Notes:
    Hi Wei,
    
       Could you please test this patch and post the output messages?
       Thanks!!

 testcases/kernel/syscalls/swapon/swapon01.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/testcases/kernel/syscalls/swapon/swapon01.c b/testcases/kernel/syscalls/swapon/swapon01.c
index d406e4bd9..b4fc02d6e 100644
--- a/testcases/kernel/syscalls/swapon/swapon01.c
+++ b/testcases/kernel/syscalls/swapon/swapon01.c
@@ -26,7 +26,7 @@ static void verify_swapon(void)
 {
 	TST_EXP_PASS(tst_syscall(__NR_swapon, SWAP_FILE, 0));
 
-	tst_pollute_memory(TESTMEM, 0x41);
+	tst_pollute_memory(TESTMEM * 9/10, 0x41);
 	tst_res(TINFO, "SwapCached: %ld Kb", SAFE_READ_MEMINFO("SwapCached:"));
 
 	if (TST_PASS && tst_syscall(__NR_swapoff, SWAP_FILE) != 0) {
@@ -37,11 +37,21 @@ static void verify_swapon(void)
 
 static void setup(void)
 {
+	tst_enable_oom_protection(0);
 	is_swap_supported(SWAP_FILE);
-	make_swapfile(SWAP_FILE, 10, 0);
+	make_swapfile(SWAP_FILE, 1024, 0);
 
 	SAFE_CG_PRINTF(tst_cg, "cgroup.procs", "%d", getpid());
 	SAFE_CG_PRINTF(tst_cg, "memory.max", "%lu", TESTMEM);
+	if (TST_CG_VER_IS_V1(tst_cg, "memory"))
+		SAFE_CG_PRINTF(tst_cg, "memory.swap.max", "%lu", ~0UL);
+	else
+		SAFE_CG_PRINT(tst_cg, "memory.swap.max", "max");
+}
+
+static void cleanup(void)
+{
+	tst_disable_oom_protection(0);
 }
 
 static struct tst_test test = {
@@ -51,5 +61,6 @@ static struct tst_test test = {
 	.all_filesystems = 1,
 	.needs_cgroup_ctrls = (const char *const []){ "memory", NULL },
 	.test_all = verify_swapon,
-	.setup = setup
+	.setup = setup,
+	.cleanup = cleanup
 };
-- 
2.40.1