[PATCH] selftests/mm: khugepaged: skip swap tests when no swap available

[Alexander Gordeev <agordeev@linux.ibm.com>]

When no swap is configured, swap-related tests fail because
madvise(MADV_PAGEOUT) does not swap out pages. Add a helper
function to detect swap availability and skip these tests.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
---
 tools/testing/selftests/mm/khugepaged.c | 33 +++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
index 10e8dedcb087..b254baf9e0b7 100644
--- a/tools/testing/selftests/mm/khugepaged.c
+++ b/tools/testing/selftests/mm/khugepaged.c
@@ -216,6 +216,25 @@ static bool check_swap(void *addr, unsigned long size)
 	return swap;
 }
 
+static bool is_swap_available(unsigned long size)
+{
+	unsigned long swap_total = 0;
+	char buffer[256];
+	FILE *fp;
+
+	fp = fopen("/proc/meminfo", "r");
+	if (!fp)
+		return false;
+
+	while (fgets(buffer, sizeof(buffer), fp)) {
+		if (sscanf(buffer, "SwapTotal: %lu kB", &swap_total) == 1)
+			break;
+	}
+	fclose(fp);
+
+	return swap_total >= (size / 1024);
+}
+
 static void *alloc_mapping(int nr)
 {
 	void *p;
@@ -734,6 +753,13 @@ static void collapse_swapin_single_pte(struct collapse_context *c, struct mem_op
 {
 	void *p;
 
+	if (!is_swap_available(page_size)) {
+		ksft_print_msg("No swap available...");
+		skip("Skip");
+		ksft_test_result_skip("%s\n", __func__);
+		return;
+	}
+
 	p = ops->setup_area(1);
 	ops->fault(p, 0, hpage_pmd_size);
 
@@ -760,6 +786,13 @@ static void collapse_max_ptes_swap(struct collapse_context *c, struct mem_ops *o
 	int max_ptes_swap = thp_read_num("khugepaged/max_ptes_swap");
 	void *p;
 
+	if (!is_swap_available((max_ptes_swap + 1) * page_size)) {
+		ksft_print_msg("No swap available...");
+		skip("Skip");
+		ksft_test_result_skip("%s\n", __func__);
+		return;
+	}
+
 	p = ops->setup_area(1);
 	ops->fault(p, 0, hpage_pmd_size);
 
-- 
2.55.0