[LTP] [PATCH v3 28/31] testcases: sysfs: Add sys_hugepages02

[Cyril Hrubis]

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

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
---
 runtest/sysfs                                 |  1 +
 .../sysfs/kernel/mm/hugepages/.gitignore      |  1 +
 .../kernel/mm/hugepages/sys_hugepages02.c     | 84 +++++++++++++++++++
 3 files changed, 86 insertions(+)
 create mode 100644 testcases/kernel/sysfs/kernel/mm/hugepages/sys_hugepages02.c

diff --git a/runtest/sysfs b/runtest/sysfs
index a81fbc12e..ec38d8b44 100644
--- a/runtest/sysfs
+++ b/runtest/sysfs
@@ -23,3 +23,4 @@ sys_block_loop01 sys_block_loop01
 sys_block_queue01 sys_block_queue01
 sys_block_size01 sys_block_size01
 sys_hugepages01 sys_hugepages01
+sys_hugepages02 sys_hugepages02
diff --git a/testcases/kernel/sysfs/kernel/mm/hugepages/.gitignore b/testcases/kernel/sysfs/kernel/mm/hugepages/.gitignore
index 1c66028fb..1bebeb2c0 100644
--- a/testcases/kernel/sysfs/kernel/mm/hugepages/.gitignore
+++ b/testcases/kernel/sysfs/kernel/mm/hugepages/.gitignore
@@ -1 +1,2 @@
 /sys_hugepages01
+/sys_hugepages02
diff --git a/testcases/kernel/sysfs/kernel/mm/hugepages/sys_hugepages02.c b/testcases/kernel/sysfs/kernel/mm/hugepages/sys_hugepages02.c
new file mode 100644
index 000000000..29d89d491
--- /dev/null
+++ b/testcases/kernel/sysfs/kernel/mm/hugepages/sys_hugepages02.c
@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2026 Cyril Hrubis <chrubis@suse.cz>
+ */
+
+/*\
+ * Cross-checks the default hugepage pool in sysfs against /proc/meminfo.
+ *
+ * /proc/meminfo describes the default hugepage size pool, which corresponds to
+ * one of the hugepages-<size>kB directories under /sys/kernel/mm/hugepages/.
+ * The test verifies that for the default pool:
+ *
+ * - Hugepagesize in /proc/meminfo matches the default pool directory size
+ * - HugePages_Total matches nr_hugepages
+ * - HugePages_Free matches free_hugepages
+ * - HugePages_Rsvd matches resv_hugepages
+ * - HugePages_Surp matches surplus_hugepages
+ *
+ * The test skips with TCONF when hugepages are not available.
+ */
+
+#include <stdio.h>
+#include <limits.h>
+#include "tst_test.h"
+#include "tst_sysfs_assert.h"
+
+#define HUGEPAGES "/sys/kernel/mm/hugepages"
+
+static void compare(const char *what, const char *meminfo_key, const char *attr,
+		    long hugepagesize)
+{
+	char path[PATH_MAX];
+	long meminfo_val, sysfs_val;
+
+	SAFE_FILE_LINES_SCANF("/proc/meminfo", meminfo_key, &meminfo_val);
+
+	snprintf(path, sizeof(path), HUGEPAGES "/hugepages-%ldkB/%s",
+		 hugepagesize, attr);
+	SAFE_FILE_SCANF(path, "%ld", &sysfs_val);
+
+	if (meminfo_val == sysfs_val) {
+		tst_res(TPASS, "%s: /proc/meminfo (%ld) == %s (%ld)",
+			what, meminfo_val, attr, sysfs_val);
+	} else {
+		tst_res(TFAIL, "%s: /proc/meminfo (%ld) != %s (%ld)",
+			what, meminfo_val, attr, sysfs_val);
+	}
+}
+
+static void do_test(void)
+{
+	long hugepagesize;
+
+	SAFE_FILE_LINES_SCANF("/proc/meminfo", "Hugepagesize: %ld",
+			      &hugepagesize);
+
+	if (!tst_sysfs_exists(HUGEPAGES "/hugepages-%ldkB", hugepagesize)) {
+		tst_res(TCONF,
+			"Default hugepage pool hugepages-%ldkB not found in sysfs",
+			hugepagesize);
+		return;
+	}
+
+	tst_res(TPASS,
+		"/proc/meminfo Hugepagesize (%ld kB) has a matching sysfs pool",
+		hugepagesize);
+
+	compare("HugePages_Total", "HugePages_Total: %ld",
+		"nr_hugepages", hugepagesize);
+	compare("HugePages_Free", "HugePages_Free: %ld",
+		"free_hugepages", hugepagesize);
+	compare("HugePages_Rsvd", "HugePages_Rsvd: %ld",
+		"resv_hugepages", hugepagesize);
+	compare("HugePages_Surp", "HugePages_Surp: %ld",
+		"surplus_hugepages", hugepagesize);
+}
+
+static struct tst_test test = {
+	.test_all = do_test,
+	.needs_kconfigs = (const char *const[]){
+		"CONFIG_HUGETLBFS=y",
+		NULL
+	},
+};
-- 
2.51.0