[LTP] [PATCH v8] hugetlb/hugefallocate: Add hugefallocate03 to stress test fallocate on hugetlbfs
Pavithra
pavrampu@linux.ibm.com
Sun Sep 20 13:35:19 CEST 2026
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>
---
v7 -> v8:
- Document why root privileges are required in the test description.
- Format syscall names with Sphinx :manpage: roles and avoid abbreviations.
- Drop redundant mutexes (fault_addr_lock, mmap_munmap_lock) and make mmap_munmap_addr local.
- Add sigsetjmp/siglongjmp handler to safely recover from concurrent SIGBUS during page faults.
- Use non-fatal mmap() in thread_mmap_munmap to tolerate transient ENOMEM under stress.
- Cast write-back pointer to (volatile char *) to prevent compiler optimization.
- Replace nanosleep() with pthread_testcancel() for thread cancellation points.
- Abort with tst_brk(TBROK) on preallocation failure instead of jumping to cleanup.
- Use TST_EXP_EQ_LU() macros to report hugepage counter assertions.
- Fix format specifiers (%u for seed, %lu for max_hpages) and check (fd != -1) in cleanup().
Link to v7: https://lore.kernel.org/ltp/20260919174920.1078796-1-pavrampu@linux.ibm.com/
---
runtest/hugetlb | 1 +
testcases/kernel/mem/.gitignore | 1 +
.../hugetlb/hugefallocate/hugefallocate03.c | 220 ++++++++++++++++++
3 files changed, 222 insertions(+)
create mode 100644 testcases/kernel/mem/hugetlb/hugefallocate/hugefallocate03.c
diff --git a/runtest/hugetlb b/runtest/hugetlb
index 621c9718a..cd1c2794e 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 9e706e1c8..3086d1ac6 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..b5441428b
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugefallocate/hugefallocate03.c
@@ -0,0 +1,220 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2015 Oracle Corporation
+ * Author: Mike Kravetz
+ * 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 "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 volatile int thread_err;
+
+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);
+ thread_err = 1;
+ }
+ err = fallocate(fd, 0, tpage * hpage_size, hpage_size);
+ if (err) {
+ tst_res(TFAIL | TERRNO, "fallocate(fill) failed at page %ld:", tpage);
+ thread_err = 1;
+ }
+ }
+ return NULL;
+}
+
+static void *fault_mmap_addr;
+static sigjmp_buf fault_jmp;
+
+static void sigbus_handler(int signum LTP_ATTRIBUTE_UNUSED)
+{
+ siglongjmp(fault_jmp, 1);
+}
+
+static void thread_fault_cleanup(void *arg)
+{
+ (void)arg;
+
+ if (fault_mmap_addr) {
+ munmap(fault_mmap_addr, max_hpages * hpage_size);
+ fault_mmap_addr = NULL;
+ }
+}
+
+static void *thread_fault(void *arg)
+{
+ long tpage;
+ char foo;
+ struct sigaction sa = {
+ .sa_handler = sigbus_handler,
+ };
+
+ (void)arg;
+
+ SAFE_SIGACTION(SIGBUS, &sa, NULL);
+
+ fault_mmap_addr = SAFE_MMAP(NULL, max_hpages * hpage_size,
+ PROT_READ | PROT_WRITE, MAP_SHARED,
+ fd, 0);
+
+ pthread_cleanup_push(thread_fault_cleanup, NULL);
+
+ while (1) {
+ tpage = ((long long)random()) % (max_hpages);
+
+ if (sigsetjmp(fault_jmp, 1) == 0) {
+ foo = *((char *)(fault_mmap_addr + (tpage * hpage_size)));
+ *((volatile char *)(fault_mmap_addr + (tpage * hpage_size))) = foo;
+ }
+
+ pthread_testcancel();
+ }
+
+ pthread_cleanup_pop(1);
+
+ return NULL;
+}
+
+static void *thread_mmap_munmap(void *arg)
+{
+ void *addr;
+
+ (void)arg;
+
+ while (1) {
+ 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);
+
+ pthread_testcancel();
+ }
+
+ 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;
+ void *falloc_th_ret, *fault_th_ret, *mmap_munmap_th_ret;
+
+ 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 = SAFE_READ_MEMINFO(MEMINFO_HPAGE_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);
+ }
+
+ thread_err = 0;
+
+ 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, &falloc_th_ret);
+
+ SAFE_PTHREAD_CANCEL(fault_th);
+
+ SAFE_PTHREAD_JOIN(fault_th, &fault_th_ret);
+
+ SAFE_PTHREAD_CANCEL(mmap_munmap_th);
+
+ SAFE_PTHREAD_JOIN(mmap_munmap_th, &mmap_munmap_th_ret);
+
+ SAFE_CLOSE(fd);
+
+ free_after = SAFE_READ_MEMINFO(MEMINFO_HPAGE_FREE);
+ rsvd_after = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
+
+ if (thread_err)
+ tst_res(TFAIL, "fallocate() failed during stress, see above");
+
+ 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_NEEDS},
+};
--
2.55.0
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