[LTP] [PATCH] Migrating the libhugetlbfs/testcases/quota.c - v2

[Pavithra <pavrampu@linux.ibm.com>]

Test hugetlbfs quota accounting with filesystem size limits to check
for regressions in quota handling for MAP_PRIVATE and MAP_SHARED pages.

Signed-off-by: Pavithra <pavrampu@linux.ibm.com>
---
 runtest/hugetlb                               |   1 +
 testcases/kernel/mem/.gitignore               |   1 +
 .../kernel/mem/hugetlb/hugemmap/hugemmap33.c  | 273 ++++++++++++++++++
 3 files changed, 275 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap33.c

diff --git a/runtest/hugetlb b/runtest/hugetlb
index 0896d3c94..24fa717ec 100644
--- a/runtest/hugetlb
+++ b/runtest/hugetlb
@@ -35,6 +35,7 @@ hugemmap29 hugemmap29
 hugemmap30 hugemmap30
 hugemmap31 hugemmap31
 hugemmap32 hugemmap32
+hugemmap33 hugemmap33
 hugemmap34 hugemmap34
 hugemmap05_1 hugemmap05 -m
 hugemmap05_2 hugemmap05 -s
diff --git a/testcases/kernel/mem/.gitignore b/testcases/kernel/mem/.gitignore
index b4455de51..7f1bcd4e7 100644
--- a/testcases/kernel/mem/.gitignore
+++ b/testcases/kernel/mem/.gitignore
@@ -35,6 +35,7 @@
 /hugetlb/hugemmap/hugemmap30
 /hugetlb/hugemmap/hugemmap31
 /hugetlb/hugemmap/hugemmap32
+/hugetlb/hugemmap/hugemmap33
 /hugetlb/hugemmap/hugemmap34
 /hugetlb/hugeshmat/hugeshmat01
 /hugetlb/hugeshmat/hugeshmat02
diff --git a/testcases/kernel/mem/hugetlb/hugemmap/hugemmap33.c b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap33.c
new file mode 100644
index 000000000..75ecf5796
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap33.c
@@ -0,0 +1,273 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/*
+ * Copyright (C) 2005-2007 David Gibson & Adam Litke, IBM Corporation.
+ * Copyright (c) Linux Test Project, 2024
+ * Copyright (C) 2025-2026 Naveed & Pavithra, IBM Corporation.
+ * Assisted with AI tools
+ */
+
+/*\
+ * Test hugetlbfs quota accounting with filesystem size limits.
+ *
+ * The number of global huge pages available to a mounted hugetlbfs filesystem
+ * can be limited using a quota mechanism by setting the size attribute at
+ * mount time. Older kernels did not properly handle quota accounting in a
+ * number of cases (e.g., for MAP_PRIVATE pages, and with MAP_SHARED reservation).
+ *
+ * This test replays some scenarios on a privately mounted filesystem with
+ * quota to check for regressions in hugetlbfs quota accounting.
+ */
+
+#define _GNU_SOURCE
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/vfs.h>
+#include <sys/statfs.h>
+#include <sys/mount.h>
+
+#include "hugetlb.h"
+
+#define MNTPOINT "hugetlbfs/"
+
+static long hpage_size;
+static int private_resv;
+static char quota_mnt[PATH_MAX];
+static int quota_mounted;
+
+/* map action flags */
+#define ACTION_COW		0x0001
+#define ACTION_TOUCH		0x0002
+
+/* Test result expectations */
+#define EXPECT_SUCCESS	0
+#define EXPECT_SIGNAL	1
+#define EXPECT_FAILURE	2
+
+static void verify_quota_stat(long tot, long free, long avail)
+{
+	struct statfs s;
+
+	SAFE_STATFS(quota_mnt, &s);
+
+	if ((long)s.f_blocks != tot || (long)s.f_bfree != free || (long)s.f_bavail != avail) {
+		tst_res(TFAIL,
+			"Bad quota counters: total=%li (expected %li), "
+			"free=%li (expected %li), avail=%li (expected %li)",
+			(long)s.f_blocks, tot, (long)s.f_bfree, free,
+			(long)s.f_bavail, avail);
+	}
+}
+
+static void do_map(unsigned long size, int mmap_flags, int action_flags)
+{
+	int fd;
+	char *a = MAP_FAILED, *b, *c = MAP_FAILED;
+	char path[PATH_MAX + 32];
+
+	snprintf(path, sizeof(path), "%s/test_file_%d", quota_mnt, getpid());
+	fd = SAFE_OPEN(path, O_CREAT | O_RDWR, 0600);
+	SAFE_UNLINK(path);
+
+	a = mmap(NULL, size, PROT_READ | PROT_WRITE, mmap_flags, fd, 0);
+	if (a == MAP_FAILED) {
+		if (errno == ENOMEM || errno == ENOSPC) {
+			tst_res(TINFO | TERRNO, "mmap failed as expected due to quota");
+			goto cleanup_fd;
+		}
+		tst_brk(TBROK | TERRNO, "mmap failed unexpectedly");
+	}
+
+	if (action_flags & ACTION_TOUCH) {
+		for (b = a; b < a + size; b += hpage_size)
+			*b = 1;
+	}
+
+	if (action_flags & ACTION_COW) {
+		c = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+		if (c == MAP_FAILED) {
+			if (errno == ENOMEM || errno == ENOSPC) {
+				tst_res(TINFO | TERRNO, "COW mapping failed as expected due to quota");
+				goto cleanup_a;
+			}
+			tst_brk(TBROK | TERRNO, "COW mapping failed unexpectedly");
+		}
+
+		if (*c != 1) {
+			tst_res(TINFO, "Data mismatch when setting up COW");
+			goto cleanup_c;
+		}
+		*c = 0;
+		SAFE_MUNMAP(c, size);
+	}
+
+	SAFE_MUNMAP(a, size);
+	SAFE_CLOSE(fd);
+	return;
+
+cleanup_c:
+	SAFE_MUNMAP(c, size);
+cleanup_a:
+	SAFE_MUNMAP(a, size);
+cleanup_fd:
+	SAFE_CLOSE(fd);
+	exit(1);
+}
+
+static void run_quota_test(int expected_result,
+			   unsigned long size, int mmap_flags,
+			   int action_flags)
+{
+	pid_t pid;
+	int status;
+	int actual_result;
+
+	pid = SAFE_FORK();
+	if (pid == 0) {
+		do_map(size, mmap_flags, action_flags);
+		exit(0);
+	}
+
+	SAFE_WAITPID(pid, &status, 0);
+
+	if (WIFEXITED(status)) {
+		if (WEXITSTATUS(status) == 0)
+			actual_result = EXPECT_SUCCESS;
+		else
+			actual_result = EXPECT_FAILURE;
+	} else {
+		actual_result = EXPECT_SIGNAL;
+	}
+
+	if (actual_result != expected_result) {
+		static const char * const result_names[] = {"success", "signal", "failure"};
+
+		tst_res(TFAIL,
+			"Unexpected result: expected %s, got %s",
+			result_names[expected_result],
+			result_names[actual_result]);
+	} else {
+		tst_res(TPASS, "Quota test passed as expected");
+	}
+}
+
+static int kernel_has_private_reservations(void)
+{
+	int fd;
+	long t, f, r, s;
+	long nt, nf, nr, ns;
+	void *p;
+	char path[PATH_MAX];
+
+	t = SAFE_READ_MEMINFO(MEMINFO_HPAGE_TOTAL);
+	f = SAFE_READ_MEMINFO(MEMINFO_HPAGE_FREE);
+	r = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+	s = SAFE_READ_MEMINFO(MEMINFO_HPAGE_SURP);
+
+	snprintf(path, sizeof(path), "%s/test_priv_resv", MNTPOINT);
+	fd = SAFE_OPEN(path, O_CREAT | O_RDWR, 0600);
+	SAFE_UNLINK(path);
+
+	p = SAFE_MMAP(NULL, hpage_size, PROT_READ | PROT_WRITE,
+		      MAP_PRIVATE, fd, 0);
+
+	nt = SAFE_READ_MEMINFO(MEMINFO_HPAGE_TOTAL);
+	nf = SAFE_READ_MEMINFO(MEMINFO_HPAGE_FREE);
+	nr = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+	ns = SAFE_READ_MEMINFO(MEMINFO_HPAGE_SURP);
+
+	SAFE_MUNMAP(p, hpage_size);
+	SAFE_CLOSE(fd);
+
+	/* Check if reservation was created for private mapping */
+	if ((nt == t + 1) && (nf == f + 1) && (ns == s + 1) && (nr == r + 1))
+		return 1;
+	else if ((nt == t) && (nf == f) && (ns == s)) {
+		if (nr == r + 1)
+			return 1;
+		else if (nr == r)
+			return 0;
+	}
+
+	tst_brk(TCONF, "Unexpected counter state - "
+		"T:%li F:%li R:%li S:%li -> T:%li F:%li R:%li S:%li",
+		t, f, r, s, nt, nf, nr, ns);
+	return -1;
+}
+
+static void run_test(void)
+{
+	int bad_priv_resv = private_resv ? EXPECT_FAILURE : EXPECT_SIGNAL;
+
+	tst_res(TINFO, "Testing unused quota cleanup for untouched mappings");
+	run_quota_test(EXPECT_SUCCESS, hpage_size, MAP_PRIVATE, 0);
+	verify_quota_stat(1, 1, 1);
+	run_quota_test(EXPECT_SUCCESS, hpage_size, MAP_SHARED, 0);
+	verify_quota_stat(1, 1, 1);
+
+	tst_res(TINFO, "Testing page instantiation within quota limits");
+	run_quota_test(EXPECT_SUCCESS, hpage_size, MAP_PRIVATE, ACTION_TOUCH);
+	run_quota_test(EXPECT_SUCCESS, hpage_size, MAP_SHARED, ACTION_TOUCH);
+
+	tst_res(TINFO, "Testing page instantiation over quota");
+	run_quota_test(EXPECT_FAILURE, 2 * hpage_size, MAP_SHARED, ACTION_TOUCH);
+
+	tst_res(TINFO, "Testing private mapping quota check");
+	run_quota_test(bad_priv_resv, 2 * hpage_size, MAP_PRIVATE, ACTION_TOUCH);
+
+	tst_res(TINFO, "Testing COW over quota");
+	run_quota_test(bad_priv_resv, hpage_size, MAP_SHARED,
+		       ACTION_TOUCH | ACTION_COW);
+	run_quota_test(bad_priv_resv, hpage_size, MAP_PRIVATE,
+		       ACTION_TOUCH | ACTION_COW);
+
+	tst_res(TINFO, "Testing operations within quota after failures");
+	run_quota_test(EXPECT_SUCCESS, hpage_size, MAP_SHARED, ACTION_TOUCH);
+	run_quota_test(EXPECT_SUCCESS, hpage_size, MAP_PRIVATE, ACTION_TOUCH);
+}
+
+static void setup(void)
+{
+	char mount_opts[BUFSIZ];
+
+	hpage_size = tst_get_hugepage_size();
+
+	/* Create a quota-limited hugetlbfs mount */
+	snprintf(quota_mnt, sizeof(quota_mnt), "%s/quota_test", MNTPOINT);
+	SAFE_MKDIR(quota_mnt, 0755);
+
+	snprintf(mount_opts, sizeof(mount_opts), "size=%luK",
+		 hpage_size / 1024);
+
+	if (mount("none", quota_mnt, "hugetlbfs", 0, mount_opts) == -1) {
+		if (errno == ENODEV)
+			tst_brk(TCONF, "hugetlbfs not supported");
+		tst_brk(TBROK | TERRNO, "mount() failed");
+	}
+	quota_mounted = 1;
+
+	tst_res(TINFO, "Mounted hugetlbfs with quota at %s (size=%luK)",
+		quota_mnt, hpage_size / 1024);
+
+	private_resv = kernel_has_private_reservations();
+	tst_res(TINFO, "Kernel %s private reservations",
+		private_resv ? "has" : "does not have");
+}
+
+static void cleanup(void)
+{
+	if (quota_mounted) {
+		SAFE_UMOUNT(quota_mnt);
+		SAFE_RMDIR(quota_mnt);
+	}
+}
+
+static struct tst_test test = {
+	.needs_root = 1,
+	.mntpoint = MNTPOINT,
+	.needs_hugetlbfs = 1,
+	.forks_child = 1,
+	.setup = setup,
+	.cleanup = cleanup,
+	.test_all = run_test,
+	.hugepages = {2, TST_NEEDS},
+};
-- 
2.53.0


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