[PATCH v6 13/15] selftests/vm: add MADV_COLLAPSE collapse context to selftests

["Zach O'Keefe" <zokeefe@xxxxxxxxxx>]

Add madvise collapse context to hugepage collapse selftests.  This
context is tested with /sys/kernel/mm/transparent_hugepage/enabled set
to "never" in order to avoid unwanted interaction with khugepaged during
testing.

Signed-off-by: Zach O'Keefe <zokeefe@xxxxxxxxxx>
---
 tools/testing/selftests/vm/khugepaged.c | 55 +++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/tools/testing/selftests/vm/khugepaged.c b/tools/testing/selftests/vm/khugepaged.c
index 24a8715363be..5207930b34a4 100644
--- a/tools/testing/selftests/vm/khugepaged.c
+++ b/tools/testing/selftests/vm/khugepaged.c
@@ -14,6 +14,9 @@
 #ifndef MADV_PAGEOUT
 #define MADV_PAGEOUT 21
 #endif
+#ifndef MADV_COLLAPSE
+#define MADV_COLLAPSE 25
+#endif
 
 #define BASE_ADDR ((void *)(1UL << 30))
 static unsigned long hpage_pmd_size;
@@ -108,6 +111,7 @@ static struct settings default_settings = {
 };
 
 static struct settings saved_settings;
+static struct settings current_settings;
 static bool skip_settings_restore;
 
 static int exit_status;
@@ -282,6 +286,8 @@ static void write_settings(struct settings *settings)
 	write_num("khugepaged/max_ptes_swap", khugepaged->max_ptes_swap);
 	write_num("khugepaged/max_ptes_shared", khugepaged->max_ptes_shared);
 	write_num("khugepaged/pages_to_scan", khugepaged->pages_to_scan);
+
+	current_settings = *settings;
 }
 
 static void restore_settings(int sig)
@@ -912,6 +918,38 @@ static void collapse_max_ptes_shared(struct collapse_context *c)
 	munmap(p, hpage_pmd_size);
 }
 
+static void madvise_collapse(const char *msg, char *p, bool expect)
+{
+	int ret;
+	struct settings old_settings = current_settings;
+	struct settings settings = old_settings;
+
+	printf("%s...", msg);
+	/* Sanity check */
+	if (check_huge(p)) {
+		printf("Unexpected huge page\n");
+		exit(EXIT_FAILURE);
+	}
+
+	/*
+	 * Prevent khugepaged interference and tests that MADV_COLLAPSE
+	 * ignores /sys/kernel/mm/transparent_hugepage/enabled
+	 */
+	settings.thp_enabled = THP_NEVER;
+	write_settings(&settings);
+
+	madvise(p, hpage_pmd_size, MADV_HUGEPAGE);
+	ret = madvise(p, hpage_pmd_size, MADV_COLLAPSE);
+	if (((bool)ret) == expect)
+		fail("Fail: Bad return value");
+	else if (check_huge(p) != expect)
+		fail("Fail: check_huge()");
+	else
+		success("OK");
+
+	write_settings(&old_settings);
+}
+
 #define TICK 500000
 static bool wait_for_scan(const char *msg, char *p)
 {
@@ -996,5 +1034,22 @@ int main(void)
 	collapse_fork_compound(&c);
 	collapse_max_ptes_shared(&c);
 
+	printf("\n*** Testing context: madvise ***\n");
+	c.collapse = &madvise_collapse;
+	c.enforce_pte_scan_limits = false;
+
+	collapse_full(&c);
+	collapse_empty(&c);
+	collapse_single_pte_entry(&c);
+	collapse_max_ptes_none(&c);
+	collapse_swapin_single_pte(&c);
+	collapse_max_ptes_swap(&c);
+	collapse_single_pte_entry_compound(&c);
+	collapse_full_of_compound(&c);
+	collapse_compound_extreme(&c);
+	collapse_fork(&c);
+	collapse_fork_compound(&c);
+	collapse_max_ptes_shared(&c);
+
 	restore_settings(0);
 }
-- 
2.36.1.255.ge46751e96f-goog