[LTP] [PATCH v2 27/31] testcases: sysfs: Add sys_hugepages01

A test for /sys/kernel/mm/hugepages/hugepages-*/* files.

Signed-off-by: Cyril Hrubis <[email protected]>
---
 runtest/sysfs                                 |   1 +
 testcases/kernel/sysfs/kernel/mm/Makefile     |   7 +
 .../sysfs/kernel/mm/hugepages/.gitignore      |   1 +
 .../kernel/sysfs/kernel/mm/hugepages/Makefile |   7 +
 .../kernel/mm/hugepages/sys_hugepages01.c     | 133 ++++++++++++++++++
 5 files changed, 149 insertions(+)
 create mode 100644 testcases/kernel/sysfs/kernel/mm/Makefile
 create mode 100644 testcases/kernel/sysfs/kernel/mm/hugepages/.gitignore
 create mode 100644 testcases/kernel/sysfs/kernel/mm/hugepages/Makefile
 create mode 100644 testcases/kernel/sysfs/kernel/mm/hugepages/sys_hugepages01.c

diff --git a/runtest/sysfs b/runtest/sysfs
index 46593b82f..a81fbc12e 100644
--- a/runtest/sysfs
+++ b/runtest/sysfs
@@ -22,3 +22,4 @@ sys_net04 sys_net04
 sys_block_loop01 sys_block_loop01
 sys_block_queue01 sys_block_queue01
 sys_block_size01 sys_block_size01
+sys_hugepages01 sys_hugepages01
diff --git a/testcases/kernel/sysfs/kernel/mm/Makefile b/testcases/kernel/sysfs/kernel/mm/Makefile
new file mode 100644
index 000000000..9bc26552c
--- /dev/null
+++ b/testcases/kernel/sysfs/kernel/mm/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (c) 2026 Cyril Hrubis <[email protected]>
+
+top_srcdir		?= ../../../../..
+
+include $(top_srcdir)/include/mk/env_pre.mk
+include $(top_srcdir)/include/mk/generic_trunk_target.mk
diff --git a/testcases/kernel/sysfs/kernel/mm/hugepages/.gitignore b/testcases/kernel/sysfs/kernel/mm/hugepages/.gitignore
new file mode 100644
index 000000000..1c66028fb
--- /dev/null
+++ b/testcases/kernel/sysfs/kernel/mm/hugepages/.gitignore
@@ -0,0 +1 @@
+/sys_hugepages01
diff --git a/testcases/kernel/sysfs/kernel/mm/hugepages/Makefile b/testcases/kernel/sysfs/kernel/mm/hugepages/Makefile
new file mode 100644
index 000000000..781865569
--- /dev/null
+++ b/testcases/kernel/sysfs/kernel/mm/hugepages/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (c) 2026 Cyril Hrubis <[email protected]>
+
+top_srcdir		?= ../../../../../..
+
+include $(top_srcdir)/include/mk/testcases.mk
+include $(top_srcdir)/include/mk/generic_leaf_target.mk
diff --git a/testcases/kernel/sysfs/kernel/mm/hugepages/sys_hugepages01.c b/testcases/kernel/sysfs/kernel/mm/hugepages/sys_hugepages01.c
new file mode 100644
index 000000000..13bcec3fc
--- /dev/null
+++ b/testcases/kernel/sysfs/kernel/mm/hugepages/sys_hugepages01.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2026 Cyril Hrubis <[email protected]>
+ */
+
+/*\
+ * Sanity checks for the hugepage pool attributes exported under
+ * /sys/kernel/mm/hugepages/.
+ *
+ * Each supported hugepage size has its own hugepages-<size>kB directory with a
+ * set of counters describing its pool. For each such directory the test
+ * verifies that:
+ *
+ * - the size encoded in the directory name is a power of two (in kB)
+ * - nr_hugepages, free_hugepages, resv_hugepages and surplus_hugepages are
+ *   all non-negative
+ * - free_hugepages <= nr_hugepages + surplus_hugepages (the free count cannot
+ *   exceed the total pool)
+ * - resv_hugepages <= free_hugepages (reserved pages are a subset of free)
+ *
+ * All checks skip gracefully with TCONF when a particular attribute is not
+ * present.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <dirent.h>
+#include <limits.h>
+#include "tst_test.h"
+#include "tst_sysfs_assert.h"
+
+#define HUGEPAGES "/sys/kernel/mm/hugepages"
+
+static int read_count(const char *dir, const char *attr, long *val)
+{
+	char path[PATH_MAX];
+
+	snprintf(path, sizeof(path), HUGEPAGES "/%s/%s", dir, attr);
+
+	if (access(path, F_OK))
+		return 1;
+
+	if (FILE_SCANF(path, "%ld", val))
+		return 1;
+
+	return 0;
+}
+
+static void check_size(const char *dir)
+{
+	long size;
+
+	if (sscanf(dir, "hugepages-%ldkB", &size) != 1) {
+		tst_res(TFAIL, "Malformed hugepage directory name '%s'", dir);
+		return;
+	}
+
+	if (size > 0 && !(size & (size - 1))) {
+		tst_res(TPASS, "%s: size %ld kB is a power of two", dir, size);
+	} else {
+		tst_res(TFAIL, "%s: size %ld kB is not a power of two",
+			dir, size);
+	}
+}
+
+static void check_counts(const char *dir)
+{
+	long nr, free, resv, surplus;
+
+	TST_SYSFS_ASSERT_RANGELL(0, LONG_MAX, HUGEPAGES "/%s/nr_hugepages", dir);
+	TST_SYSFS_ASSERT_RANGELL(0, LONG_MAX, HUGEPAGES "/%s/free_hugepages", dir);
+	TST_SYSFS_ASSERT_RANGELL(0, LONG_MAX, HUGEPAGES "/%s/resv_hugepages", dir);
+	TST_SYSFS_ASSERT_RANGELL(0, LONG_MAX,
+			       HUGEPAGES "/%s/surplus_hugepages", dir);
+
+	if (read_count(dir, "nr_hugepages", &nr) ||
+	    read_count(dir, "free_hugepages", &free) ||
+	    read_count(dir, "surplus_hugepages", &surplus))
+		return;
+
+	if (free <= nr + surplus) {
+		tst_res(TPASS,
+			"%s: free_hugepages (%ld) <= nr_hugepages (%ld) + surplus_hugepages (%ld)",
+			dir, free, nr, surplus);
+	} else {
+		tst_res(TFAIL,
+			"%s: free_hugepages (%ld) > nr_hugepages (%ld) + surplus_hugepages (%ld)",
+			dir, free, nr, surplus);
+	}
+
+	if (read_count(dir, "resv_hugepages", &resv))
+		return;
+
+	if (resv <= free) {
+		tst_res(TPASS, "%s: resv_hugepages (%ld) <= free_hugepages (%ld)",
+			dir, resv, free);
+	} else {
+		tst_res(TFAIL, "%s: resv_hugepages (%ld) > free_hugepages (%ld)",
+			dir, resv, free);
+	}
+}
+
+static void run(void)
+{
+	DIR *d;
+	struct dirent *ent;
+	int found = 0;
+
+	d = SAFE_OPENDIR(HUGEPAGES);
+
+	while ((ent = SAFE_READDIR(d))) {
+		if (strncmp(ent->d_name, "hugepages-", 10))
+			continue;
+
+		found = 1;
+		tst_res(TINFO, "Checking hugepage pool '%s'", ent->d_name);
+		check_size(ent->d_name);
+		check_counts(ent->d_name);
+	}
+
+	SAFE_CLOSEDIR(d);
+
+	if (!found)
+		tst_res(TCONF, "No hugepage pools found");
+}
+
+static struct tst_test test = {
+	.test_all = run,
+	.needs_kconfigs = (const char *const[]){
+		"CONFIG_HUGETLBFS=y",
+		NULL
+	},
+};
-- 
2.54.0


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