* [LTP] [PATCH v9] mremap07.c: New test for mremap() with MREMAP_DONTUNMAP
2026-04-17 12:27 [LTP] [PATCH v8] " Wei Gao via ltp
@ 2026-04-22 2:30 ` Wei Gao via ltp
0 siblings, 0 replies; 2+ messages in thread
From: Wei Gao via ltp @ 2026-04-22 2:30 UTC (permalink / raw)
To: ltp
This test verifies the mremap() syscall with the MREMAP_DONTUNMAP flag.
It uses userfaultfd to verify that accessing the old memory region
correctly triggers a page fault after the mapping has been moved.
MREMAP_DONTUNMAP behavior with userfaultfd was not covered by existing
mremap tests. This test provides coverage for the feature requested in
the linked issue.
Closes: https://github.com/linux-test-project/ltp/issues/1168
Signed-off-by: Wei Gao <wegao@suse.com>
---
v8->v9:
- Removed `MREMAP_DONTUNMAP` check from `configure.ac` and moved fallback to `include/lapi/mmap.h`.
- Renamed address variables to `old_addr` and `new_addr` for clarity.
- Replaced hardcoded strings with `TEST_STRING_A` and `TEST_STRING_B` macros.
- Improved code formatting and indentation.
- Removed `.min_kver = "5.7"` in favor of dynamic feature detection.
- Added runtime `EINVAL` check to trigger `TCONF` on unsupported kernels.
- Added verification logic for data content at `new_addr`.
- Fixed stability issues for multiple test iterations (`-i` option).
include/lapi/mmap.h | 4 +
runtest/syscalls | 1 +
testcases/kernel/syscalls/mremap/.gitignore | 1 +
testcases/kernel/syscalls/mremap/Makefile | 1 +
testcases/kernel/syscalls/mremap/mremap07.c | 164 ++++++++++++++++++++
5 files changed, 171 insertions(+)
create mode 100644 testcases/kernel/syscalls/mremap/mremap07.c
diff --git a/include/lapi/mmap.h b/include/lapi/mmap.h
index 248b64564..3908310f4 100644
--- a/include/lapi/mmap.h
+++ b/include/lapi/mmap.h
@@ -91,6 +91,10 @@
# define MAP_DROPPABLE 0x08
#endif
+#ifndef MREMAP_DONTUNMAP
+# define MREMAP_DONTUNMAP 4
+#endif
+
#ifndef MAP_FIXED_NOREPLACE
#ifdef __alpha__
diff --git a/runtest/syscalls b/runtest/syscalls
index 5025b259f..df5dc02b5 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -927,6 +927,7 @@ mremap03 mremap03
mremap04 mremap04
mremap05 mremap05
mremap06 mremap06
+mremap07 mremap07
mseal01 mseal01
mseal02 mseal02
diff --git a/testcases/kernel/syscalls/mremap/.gitignore b/testcases/kernel/syscalls/mremap/.gitignore
index ec15a19cd..292899e03 100644
--- a/testcases/kernel/syscalls/mremap/.gitignore
+++ b/testcases/kernel/syscalls/mremap/.gitignore
@@ -4,3 +4,4 @@
/mremap04
/mremap05
/mremap06
+/mremap07
diff --git a/testcases/kernel/syscalls/mremap/Makefile b/testcases/kernel/syscalls/mremap/Makefile
index 9f5aca9ec..8811b887e 100644
--- a/testcases/kernel/syscalls/mremap/Makefile
+++ b/testcases/kernel/syscalls/mremap/Makefile
@@ -8,5 +8,6 @@ LTPLIBS = ipc
include $(top_srcdir)/include/mk/testcases.mk
mremap04: LTPLDLIBS = -lltpipc
+mremap07: LDLIBS += -lpthread
include $(top_srcdir)/include/mk/generic_leaf_target.mk
diff --git a/testcases/kernel/syscalls/mremap/mremap07.c b/testcases/kernel/syscalls/mremap/mremap07.c
new file mode 100644
index 000000000..ecd8319f9
--- /dev/null
+++ b/testcases/kernel/syscalls/mremap/mremap07.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2026 Wei Gao <wegao@suse.com>
+ */
+
+/*\
+ * LTP test case for mremap() with MREMAP_DONTUNMAP and userfaultfd.
+ *
+ * Test mremap() with MREMAP_DONTUNMAP and verify that accessing the
+ * old memory region triggers a page fault, which is then correctly
+ * handled by a userfaultfd handler.
+ */
+
+#define _GNU_SOURCE
+#include <poll.h>
+#include <pthread.h>
+
+#include "tst_test.h"
+#include "tst_safe_pthread.h"
+#include "lapi/userfaultfd.h"
+#include "lapi/mmap.h"
+#include "config.h"
+
+static int page_size;
+static int uffd = -1;
+static char *old_addr;
+static char *new_addr;
+
+#define TEST_STRING_A "ABCD"
+#define TEST_STRING_B "EFGH"
+
+static void *fault_handler_thread(void *arg LTP_ATTRIBUTE_UNUSED)
+{
+ struct uffd_msg msg;
+ struct uffdio_copy uffdio_copy;
+
+ TST_CHECKPOINT_WAIT(0);
+
+ struct pollfd pollfd;
+
+ pollfd.fd = uffd;
+ pollfd.events = POLLIN;
+
+ int nready = poll(&pollfd, 1, -1);
+
+ if (nready == -1)
+ tst_brk(TBROK | TERRNO, "poll() failed");
+
+ if (nready == 0)
+ tst_brk(TBROK, "poll() timed out unexpectedly");
+
+ SAFE_READ(1, uffd, &msg, sizeof(msg));
+
+ if (msg.event != UFFD_EVENT_PAGEFAULT)
+ tst_brk(TBROK, "Received unexpected UFFD_EVENT: %d", msg.event);
+
+ if ((char *)msg.arg.pagefault.address != old_addr)
+ tst_brk(TBROK, "Page fault on unexpected address: %p",
+ (void *)msg.arg.pagefault.address);
+
+ tst_res(TINFO, "Userfaultfd handler caught a page fault at %p",
+ (void *)msg.arg.pagefault.address);
+
+ uffdio_copy.src = (unsigned long)new_addr;
+ uffdio_copy.dst = (unsigned long)old_addr;
+ uffdio_copy.len = page_size;
+ uffdio_copy.mode = 0;
+ uffdio_copy.copy = 0;
+
+ SAFE_IOCTL(uffd, UFFDIO_COPY, &uffdio_copy);
+ tst_res(TPASS, "Userfaultfd handler successfully handled the fault");
+
+ return NULL;
+}
+
+static void setup(void)
+{
+ struct uffdio_api uffdio_api;
+ struct uffdio_register uffdio_register;
+
+ page_size = getpagesize();
+ uffd = SAFE_USERFAULTFD(O_CLOEXEC | O_NONBLOCK, true);
+
+ uffdio_api.api = UFFD_API;
+ uffdio_api.features = 0;
+ SAFE_IOCTL(uffd, UFFDIO_API, &uffdio_api);
+
+ old_addr = SAFE_MMAP(NULL, page_size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS,
+ -1, 0);
+
+ tst_res(TINFO, "Original mapping created at %p", (void *)old_addr);
+
+ strcpy(old_addr, TEST_STRING_A);
+
+ uffdio_register.range.start = (unsigned long)old_addr;
+ uffdio_register.range.len = page_size;
+ uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
+ SAFE_IOCTL(uffd, UFFDIO_REGISTER, &uffdio_register);
+}
+
+static void cleanup(void)
+{
+ if (new_addr && new_addr != MAP_FAILED)
+ SAFE_MUNMAP(new_addr, page_size);
+
+ if (old_addr && old_addr != MAP_FAILED)
+ SAFE_MUNMAP(old_addr, page_size);
+
+ if (uffd != -1)
+ SAFE_CLOSE(uffd);
+}
+
+static void run(void)
+{
+ new_addr = NULL;
+ pthread_t handler_thread;
+
+ SAFE_PTHREAD_CREATE(&handler_thread, NULL,
+ fault_handler_thread, NULL);
+
+ new_addr = mremap(old_addr, page_size, page_size,
+ MREMAP_DONTUNMAP | MREMAP_MAYMOVE, NULL);
+
+ if (new_addr == MAP_FAILED) {
+ if (errno == EINVAL) {
+ tst_brk(TCONF | TERRNO,
+ "mremap with MREMAP_DONTUNMAP not supported?");
+ }
+ tst_brk(TBROK | TERRNO, "mremap failed");
+ }
+
+ tst_res(TINFO, "New mapping created at %p", (void *)new_addr);
+
+ TST_EXP_EQ_STR(new_addr, TEST_STRING_A);
+ strcpy(new_addr, TEST_STRING_B);
+
+ TST_CHECKPOINT_WAKE(0);
+
+ tst_res(TINFO, "Main thread accessing old address %p to trigger fault",
+ (void *)old_addr);
+
+ (void)*(volatile char *)old_addr;
+
+ SAFE_PTHREAD_JOIN(handler_thread, NULL);
+
+ TST_EXP_EQ_STR(old_addr, TEST_STRING_B);
+
+ SAFE_MUNMAP(new_addr, page_size);
+ new_addr = NULL;
+ strcpy(old_addr, TEST_STRING_A);
+}
+
+static struct tst_test test = {
+ .test_all = run,
+ .setup = setup,
+ .needs_checkpoints = 1,
+ .cleanup = cleanup,
+ .needs_kconfigs = (const char *[]) {
+ "CONFIG_USERFAULTFD=y",
+ NULL,
+ },
+};
--
2.52.0
--
Mailing list info: https://lists.linux.it/listinfo/ltp
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [LTP] [PATCH v9] mremap07.c: New test for mremap() with MREMAP_DONTUNMAP
@ 2026-04-22 5:14 Li Wang
0 siblings, 0 replies; 2+ messages in thread
From: Li Wang @ 2026-04-22 5:14 UTC (permalink / raw)
To: Wei Gao; +Cc: ltp
Hi Wei,
Wei Gao wrote:
> This test verifies the mremap() syscall with the MREMAP_DONTUNMAP flag.
> It uses userfaultfd to verify that accessing the old memory region
> correctly triggers a page fault after the mapping has been moved.
>
> MREMAP_DONTUNMAP behavior with userfaultfd was not covered by existing
> mremap tests. This test provides coverage for the feature requested in
> the linked issue.
>
> Closes: https://github.com/linux-test-project/ltp/issues/1168
> Signed-off-by: Wei Gao <wegao@suse.com>
> ---
> v8->v9:
> - Removed `MREMAP_DONTUNMAP` check from `configure.ac` and moved fallback to `include/lapi/mmap.h`.
> - Renamed address variables to `old_addr` and `new_addr` for clarity.
> - Replaced hardcoded strings with `TEST_STRING_A` and `TEST_STRING_B` macros.
> - Improved code formatting and indentation.
> - Removed `.min_kver = "5.7"` in favor of dynamic feature detection.
> - Added runtime `EINVAL` check to trigger `TCONF` on unsupported kernels.
> - Added verification logic for data content at `new_addr`.
> - Fixed stability issues for multiple test iterations (`-i` option).
Patch merged with some improvements (for better readability and reliability):
--- a/testcases/kernel/syscalls/mremap/mremap07.c
+++ b/testcases/kernel/syscalls/mremap/mremap07.c
@@ -19,7 +19,6 @@
#include "tst_safe_pthread.h"
#include "lapi/userfaultfd.h"
#include "lapi/mmap.h"
-#include "config.h"
static int page_size;
static int uffd = -1;
@@ -33,33 +32,24 @@ static void *fault_handler_thread(void *arg LTP_ATTRIBUTE_UNUSED)
{
struct uffd_msg msg;
struct uffdio_copy uffdio_copy;
+ struct pollfd pollfd = { .fd = uffd, .events = POLLIN };
TST_CHECKPOINT_WAIT(0);
- struct pollfd pollfd;
-
- pollfd.fd = uffd;
- pollfd.events = POLLIN;
-
- int nready = poll(&pollfd, 1, -1);
-
- if (nready == -1)
+ if (poll(&pollfd, 1, -1) == -1)
tst_brk(TBROK | TERRNO, "poll() failed");
- if (nready == 0)
- tst_brk(TBROK, "poll() timed out unexpectedly");
-
SAFE_READ(1, uffd, &msg, sizeof(msg));
if (msg.event != UFFD_EVENT_PAGEFAULT)
tst_brk(TBROK, "Received unexpected UFFD_EVENT: %d", msg.event);
- if ((char *)msg.arg.pagefault.address != old_addr)
+ if (msg.arg.pagefault.address != (unsigned long)old_addr)
tst_brk(TBROK, "Page fault on unexpected address: %p",
- (void *)msg.arg.pagefault.address);
+ (void *)msg.arg.pagefault.address);
tst_res(TINFO, "Userfaultfd handler caught a page fault at %p",
- (void *)msg.arg.pagefault.address);
+ (void *)msg.arg.pagefault.address);
uffdio_copy.src = (unsigned long)new_addr;
uffdio_copy.dst = (unsigned long)old_addr;
@@ -73,12 +63,32 @@ static void *fault_handler_thread(void *arg LTP_ATTRIBUTE_UNUSED)
return NULL;
}
+static void check_mremap_dontunmap(void)
+{
+ char *test = SAFE_MMAP(NULL, page_size, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+ char *tmp = mremap(test, page_size, page_size,
+ MREMAP_DONTUNMAP | MREMAP_MAYMOVE, NULL);
+
+ if (tmp == MAP_FAILED) {
+ if (errno == EINVAL)
+ tst_brk(TCONF | TERRNO,
+ "MREMAP_DONTUNMAP not supported");
+ tst_brk(TBROK | TERRNO, "mremap failed");
+ }
+
+ SAFE_MUNMAP(tmp, page_size);
+ SAFE_MUNMAP(test, page_size);
+}
+
static void setup(void)
{
struct uffdio_api uffdio_api;
struct uffdio_register uffdio_register;
page_size = getpagesize();
+ check_mremap_dontunmap();
uffd = SAFE_USERFAULTFD(O_CLOEXEC | O_NONBLOCK, true);
uffdio_api.api = UFFD_API;
@@ -92,7 +102,7 @@ static void setup(void)
tst_res(TINFO, "Original mapping created at %p", (void *)old_addr);
- strcpy(old_addr, TEST_STRING_A);
+ memcpy(old_addr, TEST_STRING_A, sizeof(TEST_STRING_A));
uffdio_register.range.start = (unsigned long)old_addr;
uffdio_register.range.len = page_size;
@@ -118,23 +128,17 @@ static void run(void)
pthread_t handler_thread;
SAFE_PTHREAD_CREATE(&handler_thread, NULL,
- fault_handler_thread, NULL);
+ fault_handler_thread, NULL);
new_addr = mremap(old_addr, page_size, page_size,
- MREMAP_DONTUNMAP | MREMAP_MAYMOVE, NULL);
-
- if (new_addr == MAP_FAILED) {
- if (errno == EINVAL) {
- tst_brk(TCONF | TERRNO,
- "mremap with MREMAP_DONTUNMAP not supported?");
- }
+ MREMAP_DONTUNMAP | MREMAP_MAYMOVE, NULL);
+ if (new_addr == MAP_FAILED)
tst_brk(TBROK | TERRNO, "mremap failed");
- }
tst_res(TINFO, "New mapping created at %p", (void *)new_addr);
TST_EXP_EQ_STR(new_addr, TEST_STRING_A);
- strcpy(new_addr, TEST_STRING_B);
+ memcpy(new_addr, TEST_STRING_B, sizeof(TEST_STRING_B));
TST_CHECKPOINT_WAKE(0);
@@ -148,8 +152,7 @@ static void run(void)
TST_EXP_EQ_STR(old_addr, TEST_STRING_B);
SAFE_MUNMAP(new_addr, page_size);
- new_addr = NULL;
- strcpy(old_addr, TEST_STRING_A);
+ memcpy(old_addr, TEST_STRING_A, sizeof(TEST_STRING_A));
}
static struct tst_test test = {
--
Regards,
Li Wang
--
Mailing list info: https://lists.linux.it/listinfo/ltp
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2026-04-17 12:27 [LTP] [PATCH v8] " Wei Gao via ltp
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