[LTP] [PATCH v10] hugetlb/hugefallocate: Add hugefallocate03 to stress test fallocate on hugetlbfs

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

Stress test fallocate() on hugetlbfs with three concurrent threads:
one continuously punches and fills holes, one faults in hugepages,
and one continuously mmaps and munmaps the same file range.
Verify no hugepage leak occurs after the stress run.

Signed-off-by: Pavithra <pavrampu@linux.ibm.com>
---
v9 -> v10:
- Save the original SIGBUS handler in thread_fault() and restore it before
  the thread exits.
- Replace pthread_cancel()/pthread_testcancel() and the cleanup handler with
  a volatile "run" flag.
- Drop the unused thread return value variables and the global
  fault_mmap_addr.
Link to v9: https://lore.kernel.org/ltp/20260923080150.44934-1-pavrampu@linux.ibm.com/
---
 runtest/hugetlb                               |   1 +
 testcases/kernel/mem/.gitignore               |   1 +
 .../hugetlb/hugefallocate/hugefallocate03.c   | 200 ++++++++++++++++++
 3 files changed, 202 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugefallocate/hugefallocate03.c

diff --git a/runtest/hugetlb b/runtest/hugetlb
index fd687a14e..2e7bd1779 100644
--- a/runtest/hugetlb
+++ b/runtest/hugetlb
@@ -1,5 +1,6 @@
 hugefallocate01 hugefallocate01
 hugefallocate02 hugefallocate02
+hugefallocate03 hugefallocate03
 
 hugefork01 hugefork01
 hugefork02 hugefork02
diff --git a/testcases/kernel/mem/.gitignore b/testcases/kernel/mem/.gitignore
index 763f134dd..f4d5a6dae 100644
--- a/testcases/kernel/mem/.gitignore
+++ b/testcases/kernel/mem/.gitignore
@@ -2,6 +2,7 @@
 /cpuset/cpuset02
 /hugetlb/hugefallocate/hugefallocate01
 /hugetlb/hugefallocate/hugefallocate02
+/hugetlb/hugefallocate/hugefallocate03
 /hugetlb/hugefork/hugefork01
 /hugetlb/hugefork/hugefork02
 /hugetlb/hugemmap/hugemmap01
diff --git a/testcases/kernel/mem/hugetlb/hugefallocate/hugefallocate03.c b/testcases/kernel/mem/hugetlb/hugefallocate/hugefallocate03.c
new file mode 100644
index 000000000..a63fa2f8f
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugefallocate/hugefallocate03.c
@@ -0,0 +1,200 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2026 Pavithra <pavrampu@linux.ibm.com>
+ */
+
+/*\
+ * Stress test :manpage:`fallocate(2)`. This test starts three threads:
+ *
+ * - Thread one will continually punch/fill holes via :manpage:`fallocate(2)`.
+ * - Thread two will continually fault in those same pages.
+ * - Thread three will continually :manpage:`mmap(2)` / :manpage:`munmap(2)` that page range.
+ *
+ * Requires root to mount hugetlbfs.
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <sys/mount.h>
+#include <limits.h>
+#include <sys/param.h>
+#include <sys/types.h>
+#include <pthread.h>
+#include <signal.h>
+#include <setjmp.h>
+#include <time.h>
+
+#include "hugetlb.h"
+#include "lapi/fallocate.h"
+#include "tst_safe_pthread.h"
+
+#define MNTPOINT "hugetlbfs/"
+#define MAX_PAGES_TO_USE 100
+#define FALLOCATE_ITERATIONS 100000
+
+static int fd = -1;
+static unsigned long max_hpages;
+static long hpage_size;
+static void *thread_fallocate(void *arg)
+{
+	int i, err;
+	long tpage;
+
+	(void)arg;
+
+	for (i = 0; i < FALLOCATE_ITERATIONS; i++) {
+		tpage = ((long long)random()) % (max_hpages);
+		err = fallocate(fd,
+				FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+				tpage * hpage_size, hpage_size);
+		if (err) {
+			tst_res(TFAIL | TERRNO, "fallocate(PUNCH_HOLE) failed at page %ld", tpage);
+			return NULL;
+		}
+		err = fallocate(fd, 0, tpage * hpage_size, hpage_size);
+		if (err) {
+			tst_res(TFAIL | TERRNO, "fallocate(fill) failed at page %ld", tpage);
+			return NULL;
+		}
+	}
+	return NULL;
+}
+
+static volatile int run;
+static sigjmp_buf fault_jmp;
+
+static void sigbus_handler(int signum LTP_ATTRIBUTE_UNUSED)
+{
+	siglongjmp(fault_jmp, 1);
+}
+
+static void *thread_fault(void *arg)
+{
+	long tpage;
+	char foo;
+	void *addr;
+	struct sigaction sa = {
+		.sa_handler = sigbus_handler,
+	};
+	struct sigaction old_sa;
+
+	(void)arg;
+
+	SAFE_SIGACTION(SIGBUS, &sa, &old_sa);
+
+	addr = SAFE_MMAP(NULL, max_hpages * hpage_size,
+			PROT_READ | PROT_WRITE, MAP_SHARED,
+			fd, 0);
+
+	while (run) {
+		tpage = ((long long)random()) % (max_hpages);
+
+		if (sigsetjmp(fault_jmp, 1) == 0) {
+			foo = *((char *)(addr + (tpage * hpage_size)));
+			*((volatile char *)(addr + (tpage * hpage_size))) = foo;
+		}
+	}
+
+	SAFE_MUNMAP(addr, max_hpages * hpage_size);
+
+	/* fault_jmp is no longer valid once this thread exits */
+	SAFE_SIGACTION(SIGBUS, &old_sa, NULL);
+
+	return NULL;
+}
+
+static void *thread_mmap_munmap(void *arg)
+{
+	void *addr;
+
+	(void)arg;
+
+	while (run) {
+		addr = mmap(NULL, max_hpages * hpage_size,
+				PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+		if (addr != MAP_FAILED)
+			SAFE_MUNMAP(addr, max_hpages * hpage_size);
+	}
+
+	return NULL;
+}
+
+static void run_test(void)
+{
+	int err;
+	long nr_hpages_free;
+	unsigned long free_before, free_after;
+	unsigned long rsvd_before, rsvd_after;
+	pthread_t falloc_th, fault_th, mmap_munmap_th;
+
+	fd = tst_creat_unlinked(MNTPOINT, 0, 0600);
+
+	unsigned int seed = (unsigned int)getpid() * time(NULL);
+
+	srandom(seed);
+	tst_res(TINFO, "Seed = %u", seed);
+	nr_hpages_free = SAFE_READ_MEMINFO(MEMINFO_HPAGE_FREE);
+	max_hpages = MIN(nr_hpages_free, MAX_PAGES_TO_USE);
+	free_before = nr_hpages_free;
+	rsvd_before = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+
+	/* First preallocate file with max_hpages pages */
+	err = fallocate(fd, 0, 0, hpage_size * max_hpages);
+	if (err) {
+		if (errno == EOPNOTSUPP)
+			tst_brk(TCONF, "fallocate() Operation is not supported");
+		tst_brk(TBROK | TERRNO, "fallocate() failed to preallocate");
+	}
+
+	free_after = SAFE_READ_MEMINFO(MEMINFO_HPAGE_FREE);
+	if (free_before - free_after != max_hpages) {
+		tst_brk(TBROK, "fallocate did not preallocate %lu huge pages",
+				max_hpages);
+	}
+
+	run = 1;
+
+	SAFE_PTHREAD_CREATE(&falloc_th, NULL, thread_fallocate, NULL);
+
+	SAFE_PTHREAD_CREATE(&fault_th, NULL, thread_fault, NULL);
+
+	SAFE_PTHREAD_CREATE(&mmap_munmap_th, NULL, thread_mmap_munmap, NULL);
+
+	SAFE_PTHREAD_JOIN(falloc_th, NULL);
+
+	run = 0;
+
+	SAFE_PTHREAD_JOIN(fault_th, NULL);
+
+	SAFE_PTHREAD_JOIN(mmap_munmap_th, NULL);
+
+	SAFE_CLOSE(fd);
+
+	free_after = SAFE_READ_MEMINFO(MEMINFO_HPAGE_FREE);
+	rsvd_after = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+
+	TST_EXP_EQ_LU(free_after, free_before);
+	TST_EXP_EQ_LU(rsvd_after, rsvd_before);
+}
+
+static void setup(void)
+{
+	hpage_size = tst_get_hugepage_size();
+}
+
+static void cleanup(void)
+{
+	if (fd != -1)
+		SAFE_CLOSE(fd);
+}
+
+static struct tst_test test = {
+	.needs_root = 1,
+	.mntpoint = MNTPOINT,
+	.needs_hugetlbfs = 1,
+	.needs_tmpdir = 1,
+	.setup = setup,
+	.cleanup = cleanup,
+	.test_all = run_test,
+	.hugepages = {MAX_PAGES_TO_USE, TST_REQUEST},
+};
-- 
2.56.0


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