59 files changed, 908 insertions, 33 deletions

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 0ebd9cce49b9..13a6837a0c6b 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -86,7 +86,7 @@ TARGETS += tmpfs
 TARGETS += tpm2
 TARGETS += user
 TARGETS += vDSO
-TARGETS += vm
+TARGETS += mm
 TARGETS += x86
 TARGETS += zram
 #Please keep the TARGETS list alphabetically sorted
diff --git a/tools/testing/selftests/damon/debugfs_rm_non_contexts.sh b/tools/testing/selftests/damon/debugfs_rm_non_contexts.sh
index 48b7af6b022c..f3ffeb1343cf 100644
--- a/tools/testing/selftests/damon/debugfs_rm_non_contexts.sh
+++ b/tools/testing/selftests/damon/debugfs_rm_non_contexts.sh
@@ -10,7 +10,7 @@ dmesg -C
 
 for file in "$DBGFS/"*
 do
-	echo "$(basename "$f")" > "$DBGFS/rm_contexts"
+	(echo "$(basename "$f")" > "$DBGFS/rm_contexts") &> /dev/null
 	if dmesg | grep -q BUG
 	then
 		dmesg
diff --git a/tools/testing/selftests/damon/sysfs.sh b/tools/testing/selftests/damon/sysfs.sh
index db4942383a50..bcd4734ca094 100644
--- a/tools/testing/selftests/damon/sysfs.sh
+++ b/tools/testing/selftests/damon/sysfs.sh
@@ -24,7 +24,7 @@ ensure_write_fail()
 	content=$2
 	reason=$3
 
-	if echo "$content" > "$file"
+	if (echo "$content" > "$file") 2> /dev/null
 	then
 		echo "writing $content to $file succeed ($fail_reason)"
 		echo "expected failure because $reason"
@@ -96,6 +96,34 @@ test_stats()
 	done
 }
 
+test_filter()
+{
+	filter_dir=$1
+	ensure_file "$filter_dir/type" "exist" "600"
+	ensure_write_succ "$filter_dir/type" "anon" "valid input"
+	ensure_write_succ "$filter_dir/type" "memcg" "valid input"
+	ensure_write_fail "$filter_dir/type" "foo" "invalid input"
+	ensure_file "$filter_dir/matching" "exist" "600"
+	ensure_file "$filter_dir/memcg_path" "exist" "600"
+}
+
+test_filters()
+{
+	filters_dir=$1
+	ensure_dir "$filters_dir" "exist"
+	ensure_file "$filters_dir/nr_filters" "exist" "600"
+	ensure_write_succ  "$filters_dir/nr_filters" "1" "valid input"
+	test_filter "$filters_dir/0"
+
+	ensure_write_succ  "$filters_dir/nr_filters" "2" "valid input"
+	test_filter "$filters_dir/0"
+	test_filter "$filters_dir/1"
+
+	ensure_write_succ "$filters_dir/nr_filters" "0" "valid input"
+	ensure_dir "$filters_dir/0" "not_exist"
+	ensure_dir "$filters_dir/1" "not_exist"
+}
+
 test_watermarks()
 {
 	watermarks_dir=$1
@@ -143,6 +171,7 @@ test_scheme()
 	test_access_pattern "$scheme_dir/access_pattern"
 	test_quotas "$scheme_dir/quotas"
 	test_watermarks "$scheme_dir/watermarks"
+	test_filters "$scheme_dir/filters"
 	test_stats "$scheme_dir/stats"
 	test_tried_regions "$scheme_dir/tried_regions"
 }
diff --git a/tools/testing/selftests/kselftest_deps.sh b/tools/testing/selftests/kselftest_deps.sh
index 7424a1f5babc..4bc14d9e8ff1 100755
--- a/tools/testing/selftests/kselftest_deps.sh
+++ b/tools/testing/selftests/kselftest_deps.sh
@@ -12,9 +12,9 @@ usage()
 
 echo -e "Usage: $0 -[p] <compiler> [test_name]\n"
 echo -e "\tkselftest_deps.sh [-p] gcc"
-echo -e "\tkselftest_deps.sh [-p] gcc vm"
+echo -e "\tkselftest_deps.sh [-p] gcc mm"
 echo -e "\tkselftest_deps.sh [-p] aarch64-linux-gnu-gcc"
-echo -e "\tkselftest_deps.sh [-p] aarch64-linux-gnu-gcc vm\n"
+echo -e "\tkselftest_deps.sh [-p] aarch64-linux-gnu-gcc mm\n"
 echo "- Should be run in selftests directory in the kernel repo."
 echo "- Checks if Kselftests can be built/cross-built on a system."
 echo "- Parses all test/sub-test Makefile to find library dependencies."
@@ -120,7 +120,7 @@ l1_tests=$(grep -r --include=Makefile "^LDLIBS" | \
 # Level 2
 # Some tests have multiple valid LDLIBS lines for individual sub-tests
 # that need dependency checks. Find them and append them to the tests
-# e.g: vm/Makefile:$(OUTPUT)/userfaultfd: LDLIBS += -lpthread
+# e.g: mm/Makefile:$(OUTPUT)/userfaultfd: LDLIBS += -lpthread
 # Filter out VAR_LDLIBS to discard the following:
 # 	memfd/Makefile:$(OUTPUT)/fuse_mnt: LDLIBS += $(VAR_LDLIBS)
 # Append space at the end of the list to append more tests.
diff --git a/tools/testing/selftests/memfd/fuse_test.c b/tools/testing/selftests/memfd/fuse_test.c
index be675002f918..93798c8c5d54 100644
--- a/tools/testing/selftests/memfd/fuse_test.c
+++ b/tools/testing/selftests/memfd/fuse_test.c
@@ -22,6 +22,7 @@
 #include <linux/falloc.h>
 #include <fcntl.h>
 #include <linux/memfd.h>
+#include <linux/types.h>
 #include <sched.h>
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c
index 94df2692e6e4..ae71f15f790d 100644
--- a/tools/testing/selftests/memfd/memfd_test.c
+++ b/tools/testing/selftests/memfd/memfd_test.c
@@ -28,12 +28,46 @@
 #define MFD_DEF_SIZE 8192
 #define STACK_SIZE 65536
 
+#define F_SEAL_EXEC	0x0020
+
+#define F_WX_SEALS (F_SEAL_SHRINK | \
+		    F_SEAL_GROW | \
+		    F_SEAL_WRITE | \
+		    F_SEAL_FUTURE_WRITE | \
+		    F_SEAL_EXEC)
+
+#define MFD_NOEXEC_SEAL	0x0008U
+
 /*
  * Default is not to test hugetlbfs
  */
 static size_t mfd_def_size = MFD_DEF_SIZE;
 static const char *memfd_str = MEMFD_STR;
 
+static ssize_t fd2name(int fd, char *buf, size_t bufsize)
+{
+	char buf1[PATH_MAX];
+	int size;
+	ssize_t nbytes;
+
+	size = snprintf(buf1, PATH_MAX, "/proc/self/fd/%d", fd);
+	if (size < 0) {
+		printf("snprintf(%d) failed on %m\n", fd);
+		abort();
+	}
+
+	/*
+	 * reserver one byte for string termination.
+	 */
+	nbytes = readlink(buf1, buf, bufsize-1);
+	if (nbytes == -1) {
+		printf("readlink(%s) failed %m\n", buf1);
+		abort();
+	}
+	buf[nbytes] = '\0';
+	return nbytes;
+}
+
 static int mfd_assert_new(const char *name, loff_t sz, unsigned int flags)
 {
 	int r, fd;
@@ -54,6 +88,37 @@ static int mfd_assert_new(const char *name, loff_t sz, unsigned int flags)
 	return fd;
 }
 
+static void sysctl_assert_write(const char *val)
+{
+	int fd = open("/proc/sys/vm/memfd_noexec", O_WRONLY | O_CLOEXEC);
+
+	if (fd < 0) {
+		printf("open sysctl failed\n");
+		abort();
+	}
+
+	if (write(fd, val, strlen(val)) < 0) {
+		printf("write sysctl failed\n");
+		abort();
+	}
+}
+
+static void sysctl_fail_write(const char *val)
+{
+	int fd = open("/proc/sys/vm/memfd_noexec", O_WRONLY | O_CLOEXEC);
+
+	if (fd < 0) {
+		printf("open sysctl failed\n");
+		abort();
+	}
+
+	if (write(fd, val, strlen(val)) >= 0) {
+		printf("write sysctl %s succeeded, but failure expected\n",
+				val);
+		abort();
+	}
+}
+
 static int mfd_assert_reopen_fd(int fd_in)
 {
 	int fd;
@@ -98,11 +163,14 @@ static unsigned int mfd_assert_get_seals(int fd)
 
 static void mfd_assert_has_seals(int fd, unsigned int seals)
 {
+	char buf[PATH_MAX];
+	int nbytes;
 	unsigned int s;
+	fd2name(fd, buf, PATH_MAX);
 
 	s = mfd_assert_get_seals(fd);
 	if (s != seals) {
-		printf("%u != %u = GET_SEALS(%d)\n", seals, s, fd);
+		printf("%u != %u = GET_SEALS(%s)\n", seals, s, buf);
 		abort();
 	}
 }
@@ -594,6 +662,64 @@ static void mfd_fail_grow_write(int fd)
 	}
 }
 
+static void mfd_assert_mode(int fd, int mode)
+{
+	struct stat st;
+	char buf[PATH_MAX];
+	int nbytes;
+
+	fd2name(fd, buf, PATH_MAX);
+
+	if (fstat(fd, &st) < 0) {
+		printf("fstat(%s) failed: %m\n", buf);
+		abort();
+	}
+
+	if ((st.st_mode & 07777) != mode) {
+		printf("fstat(%s) wrong file mode 0%04o, but expected 0%04o\n",
+		       buf, (int)st.st_mode & 07777, mode);
+		abort();
+	}
+}
+
+static void mfd_assert_chmod(int fd, int mode)
+{
+	char buf[PATH_MAX];
+	int nbytes;
+
+	fd2name(fd, buf, PATH_MAX);
+
+	if (fchmod(fd, mode) < 0) {
+		printf("fchmod(%s, 0%04o) failed: %m\n", buf, mode);
+		abort();
+	}
+
+	mfd_assert_mode(fd, mode);
+}
+
+static void mfd_fail_chmod(int fd, int mode)
+{
+	struct stat st;
+	char buf[PATH_MAX];
+	int nbytes;
+
+	fd2name(fd, buf, PATH_MAX);
+
+	if (fstat(fd, &st) < 0) {
+		printf("fstat(%s) failed: %m\n", buf);
+		abort();
+	}
+
+	if (fchmod(fd, mode) == 0) {
+		printf("fchmod(%s, 0%04o) didn't fail as expected\n",
+		       buf, mode);
+		abort();
+	}
+
+	/* verify that file mode bits did not change */
+	mfd_assert_mode(fd, st.st_mode & 07777);
+}
+
 static int idle_thread_fn(void *arg)
 {
 	sigset_t set;
@@ -671,6 +797,9 @@ static void test_create(void)
 	mfd_fail_new("", ~0);
 	mfd_fail_new("", 0x80000000U);
 
+	/* verify EXEC and NOEXEC_SEAL can't both be set */
+	mfd_fail_new("", MFD_EXEC | MFD_NOEXEC_SEAL);
+
 	/* verify MFD_CLOEXEC is allowed */
 	fd = mfd_assert_new("", 0, MFD_CLOEXEC);
 	close(fd);
@@ -881,6 +1010,211 @@ static void test_seal_resize(void)
 }
 
 /*
+ * Test SEAL_EXEC
+ * Test fd is created with exec and allow sealing.
+ * chmod() cannot change x bits after sealing.
+ */
+static void test_exec_seal(void)
+{
+	int fd;
+
+	printf("%s SEAL-EXEC\n", memfd_str);
+
+	printf("%s	Apply SEAL_EXEC\n", memfd_str);
+	fd = mfd_assert_new("kern_memfd_seal_exec",
+			    mfd_def_size,
+			    MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_EXEC);
+
+	mfd_assert_mode(fd, 0777);
+	mfd_assert_chmod(fd, 0644);
+
+	mfd_assert_has_seals(fd, 0);
+	mfd_assert_add_seals(fd, F_SEAL_EXEC);
+	mfd_assert_has_seals(fd, F_SEAL_EXEC);
+
+	mfd_assert_chmod(fd, 0600);
+	mfd_fail_chmod(fd, 0777);
+	mfd_fail_chmod(fd, 0670);
+	mfd_fail_chmod(fd, 0605);
+	mfd_fail_chmod(fd, 0700);
+	mfd_fail_chmod(fd, 0100);
+	mfd_assert_chmod(fd, 0666);
+	mfd_assert_write(fd);
+	close(fd);
+
+	printf("%s	Apply ALL_SEALS\n", memfd_str);
+	fd = mfd_assert_new("kern_memfd_seal_exec",
+			    mfd_def_size,
+			    MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_EXEC);
+
+	mfd_assert_mode(fd, 0777);
+	mfd_assert_chmod(fd, 0700);
+
+	mfd_assert_has_seals(fd, 0);
+	mfd_assert_add_seals(fd, F_SEAL_EXEC);
+	mfd_assert_has_seals(fd, F_WX_SEALS);
+
+	mfd_fail_chmod(fd, 0711);
+	mfd_fail_chmod(fd, 0600);
+	mfd_fail_write(fd);
+	close(fd);
+}
+
+/*
+ * Test EXEC_NO_SEAL
+ * Test fd is created with exec and not allow sealing.
+ */
+static void test_exec_no_seal(void)
+{
+	int fd;
+
+	printf("%s EXEC_NO_SEAL\n", memfd_str);
+
+	/* Create with EXEC but without ALLOW_SEALING */
+	fd = mfd_assert_new("kern_memfd_exec_no_sealing",
+			    mfd_def_size,
+			    MFD_CLOEXEC | MFD_EXEC);
+	mfd_assert_mode(fd, 0777);
+	mfd_assert_has_seals(fd, F_SEAL_SEAL);
+	mfd_assert_chmod(fd, 0666);
+	close(fd);
+}
+
+/*
+ * Test memfd_create with MFD_NOEXEC flag
+ */
+static void test_noexec_seal(void)
+{
+	int fd;
+
+	printf("%s NOEXEC_SEAL\n", memfd_str);
+
+	/* Create with NOEXEC and ALLOW_SEALING */
+	fd = mfd_assert_new("kern_memfd_noexec",
+			    mfd_def_size,
+			    MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_NOEXEC_SEAL);
+	mfd_assert_mode(fd, 0666);
+	mfd_assert_has_seals(fd, F_SEAL_EXEC);
+	mfd_fail_chmod(fd, 0777);
+	close(fd);
+
+	/* Create with NOEXEC but without ALLOW_SEALING */
+	fd = mfd_assert_new("kern_memfd_noexec",
+			    mfd_def_size,
+			    MFD_CLOEXEC | MFD_NOEXEC_SEAL);
+	mfd_assert_mode(fd, 0666);
+	mfd_assert_has_seals(fd, F_SEAL_EXEC);
+	mfd_fail_chmod(fd, 0777);
+	close(fd);
+}
+
+static void test_sysctl_child(void)
+{
+	int fd;
+
+	printf("%s sysctl 0\n", memfd_str);
+	sysctl_assert_write("0");
+	fd = mfd_assert_new("kern_memfd_sysctl_0",
+			    mfd_def_size,
+			    MFD_CLOEXEC | MFD_ALLOW_SEALING);
+
+	mfd_assert_mode(fd, 0777);
+	mfd_assert_has_seals(fd, 0);
+	mfd_assert_chmod(fd, 0644);
+	close(fd);
+
+	printf("%s sysctl 1\n", memfd_str);
+	sysctl_assert_write("1");
+	fd = mfd_assert_new("kern_memfd_sysctl_1",
+			    mfd_def_size,
+			    MFD_CLOEXEC | MFD_ALLOW_SEALING);
+
+	mfd_assert_mode(fd, 0666);
+	mfd_assert_has_seals(fd, F_SEAL_EXEC);
+	mfd_fail_chmod(fd, 0777);
+	sysctl_fail_write("0");
+	close(fd);
+
+	printf("%s sysctl 2\n", memfd_str);
+	sysctl_assert_write("2");
+	mfd_fail_new("kern_memfd_sysctl_2",
+		MFD_CLOEXEC | MFD_ALLOW_SEALING);
+	sysctl_fail_write("0");
+	sysctl_fail_write("1");
+}
+
+static int newpid_thread_fn(void *arg)
+{
+	test_sysctl_child();
+	return 0;
+}
+
+static void test_sysctl_child2(void)
+{
+	int fd;
+
+	sysctl_fail_write("0");
+	fd = mfd_assert_new("kern_memfd_sysctl_1",
+			    mfd_def_size,
+			    MFD_CLOEXEC | MFD_ALLOW_SEALING);
+
+	mfd_assert_mode(fd, 0666);
+	mfd_assert_has_seals(fd, F_SEAL_EXEC);
+	mfd_fail_chmod(fd, 0777);
+	close(fd);
+}
+
+static int newpid_thread_fn2(void *arg)
+{
+	test_sysctl_child2();
+	return 0;
+}
+static pid_t spawn_newpid_thread(unsigned int flags, int (*fn)(void *))
+{
+	uint8_t *stack;
+	pid_t pid;
+
+	stack = malloc(STACK_SIZE);
+	if (!stack) {
+		printf("malloc(STACK_SIZE) failed: %m\n");
+		abort();
+	}
+
+	pid = clone(fn,
+		    stack + STACK_SIZE,
+		    SIGCHLD | flags,
+		    NULL);
+	if (pid < 0) {
+		printf("clone() failed: %m\n");
+		abort();
+	}
+
+	return pid;
+}
+
+static void join_newpid_thread(pid_t pid)
+{
+	waitpid(pid, NULL, 0);
+}
+
+/*
+ * Test sysctl
+ * A very basic sealing test to see whether setting/retrieving seals works.
+ */
+static void test_sysctl(void)
+{
+	int pid = spawn_newpid_thread(CLONE_NEWPID, newpid_thread_fn);
+
+	join_newpid_thread(pid);
+
+	printf("%s child ns\n", memfd_str);
+	sysctl_assert_write("1");
+
+	pid = spawn_newpid_thread(CLONE_NEWPID, newpid_thread_fn2);
+	join_newpid_thread(pid);
+}
+
+/*
  * Test sharing via dup()
  * Test that seals are shared between dupped FDs and they're all equal.
  */
@@ -1053,6 +1387,9 @@ int main(int argc, char **argv)
 
 	test_create();
 	test_basic();
+	test_exec_seal();
+	test_exec_no_seal();
+	test_noexec_seal();
 
 	test_seal_write();
 	test_seal_future_write();
@@ -1074,6 +1411,8 @@ int main(int argc, char **argv)
 	test_share_fork("SHARE-FORK", SHARED_FT_STR);
 	join_idle_thread(pid);
 
+	test_sysctl();
+
 	printf("memfd: DONE\n");
 
 	return 0;
diff --git a/tools/testing/selftests/vm/.gitignore b/tools/testing/selftests/mm/.gitignore
index 1f8c36a9fa10..1f8c36a9fa10 100644
--- a/tools/testing/selftests/vm/.gitignore
+++ b/tools/testing/selftests/mm/.gitignore
diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/mm/Makefile
index ac9366065fd2..c31d952cff68 100644
--- a/tools/testing/selftests/vm/Makefile
+++ b/tools/testing/selftests/mm/Makefile
@@ -1,11 +1,15 @@
 # SPDX-License-Identifier: GPL-2.0
-# Makefile for vm selftests
+# Makefile for mm selftests
 
-LOCAL_HDRS += $(selfdir)/vm/local_config.h $(top_srcdir)/mm/gup_test.h
+LOCAL_HDRS += $(selfdir)/mm/local_config.h $(top_srcdir)/mm/gup_test.h
 
 include local_config.mk
 
+ifeq ($(CROSS_COMPILE),)
 uname_M := $(shell uname -m 2>/dev/null || echo not)
+else
+uname_M := $(shell echo $(CROSS_COMPILE) | grep -o '^[a-z0-9]\+')
+endif
 MACHINE ?= $(shell echo $(uname_M) | sed -e 's/aarch64.*/arm64/' -e 's/ppc64.*/ppc64/')
 
 # Without this, failed build products remain, with up-to-date timestamps,
@@ -56,6 +60,7 @@ TEST_GEN_PROGS += soft-dirty
 TEST_GEN_PROGS += split_huge_page_test
 TEST_GEN_FILES += ksm_tests
 TEST_GEN_PROGS += ksm_functional_tests
+TEST_GEN_PROGS += mdwe_test
 
 ifeq ($(MACHINE),x86_64)
 CAN_BUILD_I386 := $(shell ./../x86/check_cc.sh "$(CC)" ../x86/trivial_32bit_program.c -m32)
diff --git a/tools/testing/selftests/vm/charge_reserved_hugetlb.sh b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
index a5cb4b09a46c..a5cb4b09a46c 100644
--- a/tools/testing/selftests/vm/charge_reserved_hugetlb.sh
+++ b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
diff --git a/tools/testing/selftests/vm/check_config.sh b/tools/testing/selftests/mm/check_config.sh
index bcba3af0acea..bcba3af0acea 100644
--- a/tools/testing/selftests/vm/check_config.sh
+++ b/tools/testing/selftests/mm/check_config.sh
diff --git a/tools/testing/selftests/vm/compaction_test.c b/tools/testing/selftests/mm/compaction_test.c
index 9b420140ba2b..9b420140ba2b 100644
--- a/tools/testing/selftests/vm/compaction_test.c
+++ b/tools/testing/selftests/mm/compaction_test.c
diff --git a/tools/testing/selftests/vm/config b/tools/testing/selftests/mm/config
index be087c4bc396..be087c4bc396 100644
--- a/tools/testing/selftests/vm/config
+++ b/tools/testing/selftests/mm/config
diff --git a/tools/testing/selftests/vm/cow.c b/tools/testing/selftests/mm/cow.c
index 26f6ea3079e2..0eb2e8180aa5 100644
--- a/tools/testing/selftests/vm/cow.c
+++ b/tools/testing/selftests/mm/cow.c
@@ -30,6 +30,13 @@
 #include "../kselftest.h"
 #include "vm_util.h"
 
+#ifndef MADV_PAGEOUT
+#define MADV_PAGEOUT 21
+#endif
+#ifndef MADV_COLLAPSE
+#define MADV_COLLAPSE 25
+#endif
+
 static size_t pagesize;
 static int pagemap_fd;
 static size_t thpsize;
@@ -1178,6 +1185,228 @@ static int tests_per_anon_test_case(void)
 	return tests;
 }
 
+enum anon_thp_collapse_test {
+	ANON_THP_COLLAPSE_UNSHARED,
+	ANON_THP_COLLAPSE_FULLY_SHARED,
+	ANON_THP_COLLAPSE_LOWER_SHARED,
+	ANON_THP_COLLAPSE_UPPER_SHARED,
+};
+
+static void do_test_anon_thp_collapse(char *mem, size_t size,
+				      enum anon_thp_collapse_test test)
+{
+	struct comm_pipes comm_pipes;
+	char buf;
+	int ret;
+
+	ret = setup_comm_pipes(&comm_pipes);
+	if (ret) {
+		ksft_test_result_fail("pipe() failed\n");
+		return;
+	}
+
+	/*
+	 * Trigger PTE-mapping the THP by temporarily mapping a single subpage
+	 * R/O, such that we can try collapsing it later.
+	 */
+	ret = mprotect(mem + pagesize, pagesize, PROT_READ);
+	if (ret) {
+		ksft_test_result_fail("mprotect() failed\n");
+		goto close_comm_pipes;
+	}
+	ret = mprotect(mem + pagesize, pagesize, PROT_READ | PROT_WRITE);
+	if (ret) {
+		ksft_test_result_fail("mprotect() failed\n");
+		goto close_comm_pipes;
+	}
+
+	switch (test) {
+	case ANON_THP_COLLAPSE_UNSHARED:
+		/* Collapse before actually COW-sharing the page. */
+		ret = madvise(mem, size, MADV_COLLAPSE);
+		if (ret) {
+			ksft_test_result_skip("MADV_COLLAPSE failed: %s\n",
+					      strerror(errno));
+			goto close_comm_pipes;
+		}
+		break;
+	case ANON_THP_COLLAPSE_FULLY_SHARED:
+		/* COW-share the full PTE-mapped THP. */
+		break;
+	case ANON_THP_COLLAPSE_LOWER_SHARED:
+		/* Don't COW-share the upper part of the THP. */
+		ret = madvise(mem + size / 2, size / 2, MADV_DONTFORK);
+		if (ret) {
+			ksft_test_result_fail("MADV_DONTFORK failed\n");
+			goto close_comm_pipes;
+		}
+		break;
+	case ANON_THP_COLLAPSE_UPPER_SHARED:
+		/* Don't COW-share the lower part of the THP. */
+		ret = madvise(mem, size / 2, MADV_DONTFORK);
+		if (ret) {
+			ksft_test_result_fail("MADV_DONTFORK failed\n");
+			goto close_comm_pipes;
+		}
+		break;
+	default:
+		assert(false);
+	}
+
+	ret = fork();
+	if (ret < 0) {
+		ksft_test_result_fail("fork() failed\n");
+		goto close_comm_pipes;
+	} else if (!ret) {
+		switch (test) {
+		case ANON_THP_COLLAPSE_UNSHARED:
+		case ANON_THP_COLLAPSE_FULLY_SHARED:
+			exit(child_memcmp_fn(mem, size, &comm_pipes));
+			break;
+		case ANON_THP_COLLAPSE_LOWER_SHARED:
+			exit(child_memcmp_fn(mem, size / 2, &comm_pipes));
+			break;
+		case ANON_THP_COLLAPSE_UPPER_SHARED:
+			exit(child_memcmp_fn(mem + size / 2, size / 2,
+					     &comm_pipes));
+			break;
+		default:
+			assert(false);
+		}
+	}
+
+	while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
+		;
+
+	switch (test) {
+	case ANON_THP_COLLAPSE_UNSHARED:
+		break;
+	case ANON_THP_COLLAPSE_UPPER_SHARED:
+	case ANON_THP_COLLAPSE_LOWER_SHARED:
+		/*
+		 * Revert MADV_DONTFORK such that we merge the VMAs and are
+		 * able to actually collapse.
+		 */
+		ret = madvise(mem, size, MADV_DOFORK);
+		if (ret) {
+			ksft_test_result_fail("MADV_DOFORK failed\n");
+			write(comm_pipes.parent_ready[1], "0", 1);
+			wait(&ret);
+			goto close_comm_pipes;
+		}
+		/* FALLTHROUGH */
+	case ANON_THP_COLLAPSE_FULLY_SHARED:
+		/* Collapse before anyone modified the COW-shared page. */
+		ret = madvise(mem, size, MADV_COLLAPSE);
+		if (ret) {
+			ksft_test_result_skip("MADV_COLLAPSE failed: %s\n",
+					      strerror(errno));
+			write(comm_pipes.parent_ready[1], "0", 1);
+			wait(&ret);
+			goto close_comm_pipes;
+		}
+		break;
+	default:
+		assert(false);
+	}
+
+	/* Modify the page. */
+	memset(mem, 0xff, size);
+	write(comm_pipes.parent_ready[1], "0", 1);
+
+	wait(&ret);
+	if (WIFEXITED(ret))
+		ret = WEXITSTATUS(ret);
+	else
+		ret = -EINVAL;
+
+	ksft_test_result(!ret, "No leak from parent into child\n");
+close_comm_pipes:
+	close_comm_pipes(&comm_pipes);
+}
+
+static void test_anon_thp_collapse_unshared(char *mem, size_t size)
+{
+	do_test_anon_thp_collapse(mem, size, ANON_THP_COLLAPSE_UNSHARED);
+}
+
+static void test_anon_thp_collapse_fully_shared(char *mem, size_t size)
+{
+	do_test_anon_thp_collapse(mem, size, ANON_THP_COLLAPSE_FULLY_SHARED);
+}
+
+static void test_anon_thp_collapse_lower_shared(char *mem, size_t size)
+{
+	do_test_anon_thp_collapse(mem, size, ANON_THP_COLLAPSE_LOWER_SHARED);
+}
+
+static void test_anon_thp_collapse_upper_shared(char *mem, size_t size)
+{
+	do_test_anon_thp_collapse(mem, size, ANON_THP_COLLAPSE_UPPER_SHARED);
+}
+
+/*
+ * Test cases that are specific to anonymous THP: pages in private mappings
+ * that may get shared via COW during fork().
+ */
+static const struct test_case anon_thp_test_cases[] = {
+	/*
+	 * Basic COW test for fork() without any GUP when collapsing a THP
+	 * before fork().
+	 *
+	 * Re-mapping a PTE-mapped anon THP using a single PMD ("in-place
+	 * collapse") might easily get COW handling wrong when not collapsing
+	 * exclusivity information properly.
+	 */
+	{
+		"Basic COW after fork() when collapsing before fork()",
+		test_anon_thp_collapse_unshared,
+	},
+	/* Basic COW test, but collapse after COW-sharing a full THP. */
+	{
+		"Basic COW after fork() when collapsing after fork() (fully shared)",
+		test_anon_thp_collapse_fully_shared,
+	},
+	/*
+	 * Basic COW test, but collapse after COW-sharing the lower half of a
+	 * THP.
+	 */
+	{
+		"Basic COW after fork() when collapsing after fork() (lower shared)",
+		test_anon_thp_collapse_lower_shared,
+	},
+	/*
+	 * Basic COW test, but collapse after COW-sharing the upper half of a
+	 * THP.
+	 */
+	{
+		"Basic COW after fork() when collapsing after fork() (upper shared)",
+		test_anon_thp_collapse_upper_shared,
+	},
+};
+
+static void run_anon_thp_test_cases(void)
+{
+	int i;
+
+	if (!thpsize)
+		return;
+
+	ksft_print_msg("[INFO] Anonymous THP tests\n");
+
+	for (i = 0; i < ARRAY_SIZE(anon_thp_test_cases); i++) {
+		struct test_case const *test_case = &anon_thp_test_cases[i];
+
+		ksft_print_msg("[RUN] %s\n", test_case->desc);
+		do_run_with_thp(test_case->fn, THP_RUN_PMD);
+	}
+}
+
+static int tests_per_anon_thp_test_case(void)
+{
+	return thpsize ? 1 : 0;
+}
+
 typedef void (*non_anon_test_fn)(char *mem, const char *smem, size_t size);
 
 static void test_cow(char *mem, const char *smem, size_t size)
@@ -1518,6 +1747,7 @@ int main(int argc, char **argv)
 
 	ksft_print_header();
 	ksft_set_plan(ARRAY_SIZE(anon_test_cases) * tests_per_anon_test_case() +
+		      ARRAY_SIZE(anon_thp_test_cases) * tests_per_anon_thp_test_case() +
 		      ARRAY_SIZE(non_anon_test_cases) * tests_per_non_anon_test_case());
 
 	gup_fd = open("/sys/kernel/debug/gup_test", O_RDWR);
@@ -1526,6 +1756,7 @@ int main(int argc, char **argv)
 		ksft_exit_fail_msg("opening pagemap failed\n");
 
 	run_anon_test_cases();
+	run_anon_thp_test_cases();
 	run_non_anon_test_cases();
 
 	err = ksft_get_fail_cnt();
diff --git a/tools/testing/selftests/vm/gup_test.c b/tools/testing/selftests/mm/gup_test.c
index e43879291dac..e43879291dac 100644
--- a/tools/testing/selftests/vm/gup_test.c
+++ b/tools/testing/selftests/mm/gup_test.c
diff --git a/tools/testing/selftests/vm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c
index 4adaad1b822f..4adaad1b822f 100644
--- a/tools/testing/selftests/vm/hmm-tests.c
+++ b/tools/testing/selftests/mm/hmm-tests.c
diff --git a/tools/testing/selftests/vm/hugepage-mmap.c b/tools/testing/selftests/mm/hugepage-mmap.c
index 955ef87f382c..955ef87f382c 100644
--- a/tools/testing/selftests/vm/hugepage-mmap.c
+++ b/tools/testing/selftests/mm/hugepage-mmap.c
diff --git a/tools/testing/selftests/vm/hugepage-mremap.c b/tools/testing/selftests/mm/hugepage-mremap.c
index e53b5eaa8fce..e53b5eaa8fce 100644
--- a/tools/testing/selftests/vm/hugepage-mremap.c
+++ b/tools/testing/selftests/mm/hugepage-mremap.c
diff --git a/tools/testing/selftests/vm/hugepage-shm.c b/tools/testing/selftests/mm/hugepage-shm.c
index e2527f32005b..e2527f32005b 100644
--- a/tools/testing/selftests/vm/hugepage-shm.c
+++ b/tools/testing/selftests/mm/hugepage-shm.c
diff --git a/tools/testing/selftests/vm/hugepage-vmemmap.c b/tools/testing/selftests/mm/hugepage-vmemmap.c
index 557bdbd4f87e..557bdbd4f87e 100644
--- a/tools/testing/selftests/vm/hugepage-vmemmap.c
+++ b/tools/testing/selftests/mm/hugepage-vmemmap.c
diff --git a/tools/testing/selftests/vm/hugetlb-madvise.c b/tools/testing/selftests/mm/hugetlb-madvise.c
index 9a127a8fe176..9a127a8fe176 100644
--- a/tools/testing/selftests/vm/hugetlb-madvise.c
+++ b/tools/testing/selftests/mm/hugetlb-madvise.c
diff --git a/tools/testing/selftests/vm/hugetlb_reparenting_test.sh b/tools/testing/selftests/mm/hugetlb_reparenting_test.sh
index bf2d2a684edf..bf2d2a684edf 100644
--- a/tools/testing/selftests/vm/hugetlb_reparenting_test.sh
+++ b/tools/testing/selftests/mm/hugetlb_reparenting_test.sh
diff --git a/tools/testing/selftests/vm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
index 64126c8cd561..64126c8cd561 100644
--- a/tools/testing/selftests/vm/khugepaged.c
+++ b/tools/testing/selftests/mm/khugepaged.c
diff --git a/tools/testing/selftests/vm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c
index b11b7e5115dc..d8b5b4930412 100644
--- a/tools/testing/selftests/vm/ksm_functional_tests.c
+++ b/tools/testing/selftests/mm/ksm_functional_tests.c
@@ -37,7 +37,7 @@ static bool range_maps_duplicates(char *addr, unsigned long size)
 	/*
 	 * There is no easy way to check if there are KSM pages mapped into
 	 * this range. We only check that the range does not map the same PFN
-	 * twice by comaring each pair of mapped pages.
+	 * twice by comparing each pair of mapped pages.
 	 */
 	for (offs_a = 0; offs_a < size; offs_a += pagesize) {
 		pfn_a = pagemap_get_pfn(pagemap_fd, addr + offs_a);
diff --git a/tools/testing/selftests/vm/ksm_tests.c b/tools/testing/selftests/mm/ksm_tests.c
index f9eb4d67e0dd..f9eb4d67e0dd 100644
--- a/tools/testing/selftests/vm/ksm_tests.c
+++ b/tools/testing/selftests/mm/ksm_tests.c
diff --git a/tools/testing/selftests/vm/madv_populate.c b/tools/testing/selftests/mm/madv_populate.c
index 262eae6b58f2..262eae6b58f2 100644
--- a/tools/testing/selftests/vm/madv_populate.c
+++ b/tools/testing/selftests/mm/madv_populate.c
diff --git a/tools/testing/selftests/vm/map_fixed_noreplace.c b/tools/testing/selftests/mm/map_fixed_noreplace.c
index eed44322d1a6..eed44322d1a6 100644
--- a/tools/testing/selftests/vm/map_fixed_noreplace.c
+++ b/tools/testing/selftests/mm/map_fixed_noreplace.c
diff --git a/tools/testing/selftests/vm/map_hugetlb.c b/tools/testing/selftests/mm/map_hugetlb.c
index 312889edb84a..312889edb84a 100644
--- a/tools/testing/selftests/vm/map_hugetlb.c
+++ b/tools/testing/selftests/mm/map_hugetlb.c
diff --git a/tools/testing/selftests/vm/map_populate.c b/tools/testing/selftests/mm/map_populate.c
index 6b8aeaa0bf7a..6b8aeaa0bf7a 100644
--- a/tools/testing/selftests/vm/map_populate.c
+++ b/tools/testing/selftests/mm/map_populate.c
diff --git a/tools/testing/selftests/mm/mdwe_test.c b/tools/testing/selftests/mm/mdwe_test.c
new file mode 100644
index 000000000000..f466a099f1bf
--- /dev/null
+++ b/tools/testing/selftests/mm/mdwe_test.c
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#ifdef __aarch64__
+#include <asm/hwcap.h>
+#endif
+
+#include <linux/mman.h>
+#include <linux/prctl.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/auxv.h>
+#include <sys/prctl.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "../kselftest_harness.h"
+
+#ifndef __aarch64__
+# define PROT_BTI	0
+#endif
+
+TEST(prctl_flags)
+{
+	EXPECT_LT(prctl(PR_SET_MDWE, 7L, 0L, 0L, 0L), 0);
+	EXPECT_LT(prctl(PR_SET_MDWE, 0L, 7L, 0L, 0L), 0);
+	EXPECT_LT(prctl(PR_SET_MDWE, 0L, 0L, 7L, 0L), 0);
+	EXPECT_LT(prctl(PR_SET_MDWE, 0L, 0L, 0L, 7L), 0);
+
+	EXPECT_LT(prctl(PR_GET_MDWE, 7L, 0L, 0L, 0L), 0);
+	EXPECT_LT(prctl(PR_GET_MDWE, 0L, 7L, 0L, 0L), 0);
+	EXPECT_LT(prctl(PR_GET_MDWE, 0L, 0L, 7L, 0L), 0);
+	EXPECT_LT(prctl(PR_GET_MDWE, 0L, 0L, 0L, 7L), 0);
+}
+
+FIXTURE(mdwe)
+{
+	void *p;
+	int flags;
+	size_t size;
+	pid_t pid;
+};
+
+FIXTURE_VARIANT(mdwe)
+{
+	bool enabled;
+	bool forked;
+};
+
+FIXTURE_VARIANT_ADD(mdwe, stock)
+{
+        .enabled = false,
+	.forked = false,
+};
+
+FIXTURE_VARIANT_ADD(mdwe, enabled)
+{
+        .enabled = true,
+	.forked = false,
+};
+
+FIXTURE_VARIANT_ADD(mdwe, forked)
+{
+        .enabled = true,
+	.forked = true,
+};
+
+FIXTURE_SETUP(mdwe)
+{
+	int ret, status;
+
+	self->p = NULL;
+	self->flags = MAP_SHARED | MAP_ANONYMOUS;
+	self->size = getpagesize();
+
+	if (!variant->enabled)
+		return;
+
+	ret = prctl(PR_SET_MDWE, PR_MDWE_REFUSE_EXEC_GAIN, 0L, 0L, 0L);
+	ASSERT_EQ(ret, 0) {
+		TH_LOG("PR_SET_MDWE failed or unsupported");
+	}
+
+	ret = prctl(PR_GET_MDWE, 0L, 0L, 0L, 0L);
+	ASSERT_EQ(ret, 1);
+
+	if (variant->forked) {
+		self->pid = fork();
+		ASSERT_GE(self->pid, 0) {
+			TH_LOG("fork failed\n");
+		}
+
+		if (self->pid > 0) {
+			ret = waitpid(self->pid, &status, 0);
+			ASSERT_TRUE(WIFEXITED(status));
+			exit(WEXITSTATUS(status));
+		}
+	}
+}
+
+FIXTURE_TEARDOWN(mdwe)
+{
+	if (self->p && self->p != MAP_FAILED)
+		munmap(self->p, self->size);
+}
+
+TEST_F(mdwe, mmap_READ_EXEC)
+{
+	self->p = mmap(NULL, self->size, PROT_READ | PROT_EXEC, self->flags, 0, 0);
+	EXPECT_NE(self->p, MAP_FAILED);
+}
+
+TEST_F(mdwe, mmap_WRITE_EXEC)
+{
+	self->p = mmap(NULL, self->size, PROT_WRITE | PROT_EXEC, self->flags, 0, 0);
+	if (variant->enabled) {
+		EXPECT_EQ(self->p, MAP_FAILED);
+	} else {
+		EXPECT_NE(self->p, MAP_FAILED);
+	}
+}
+
+TEST_F(mdwe, mprotect_stay_EXEC)
+{
+	int ret;
+
+	self->p = mmap(NULL, self->size, PROT_READ | PROT_EXEC, self->flags, 0, 0);
+	ASSERT_NE(self->p, MAP_FAILED);
+
+	ret = mprotect(self->p, self->size, PROT_READ | PROT_EXEC);
+	EXPECT_EQ(ret, 0);
+}
+
+TEST_F(mdwe, mprotect_add_EXEC)
+{
+	int ret;
+
+	self->p = mmap(NULL, self->size, PROT_READ, self->flags, 0, 0);
+	ASSERT_NE(self->p, MAP_FAILED);
+
+	ret = mprotect(self->p, self->size, PROT_READ | PROT_EXEC);
+	if (variant->enabled) {
+		EXPECT_LT(ret, 0);
+	} else {
+		EXPECT_EQ(ret, 0);
+	}
+}
+
+TEST_F(mdwe, mprotect_WRITE_EXEC)
+{
+	int ret;
+
+	self->p = mmap(NULL, self->size, PROT_WRITE, self->flags, 0, 0);
+	ASSERT_NE(self->p, MAP_FAILED);
+
+	ret = mprotect(self->p, self->size, PROT_WRITE | PROT_EXEC);
+	if (variant->enabled) {
+		EXPECT_LT(ret, 0);
+	} else {
+		EXPECT_EQ(ret, 0);
+	}
+}
+
+TEST_F(mdwe, mmap_FIXED)
+{
+	void *p, *p2;
+
+	p2 = mmap(NULL, self->size, PROT_READ | PROT_EXEC, self->flags, 0, 0);
+	self->p = mmap(NULL, self->size, PROT_READ, self->flags, 0, 0);
+	ASSERT_NE(self->p, MAP_FAILED);
+
+	p = mmap(self->p + self->size, self->size, PROT_READ | PROT_EXEC,
+		 self->flags | MAP_FIXED, 0, 0);
+	if (variant->enabled) {
+		EXPECT_EQ(p, MAP_FAILED);
+	} else {
+		EXPECT_EQ(p, self->p);
+	}
+}
+
+TEST_F(mdwe, arm64_BTI)
+{
+	int ret;
+
+#ifdef __aarch64__
+	if (!(getauxval(AT_HWCAP2) & HWCAP2_BTI))
+#endif
+		SKIP(return, "HWCAP2_BTI not supported");
+
+	self->p = mmap(NULL, self->size, PROT_EXEC, self->flags, 0, 0);
+	ASSERT_NE(self->p, MAP_FAILED);
+
+	ret = mprotect(self->p, self->size, PROT_EXEC | PROT_BTI);
+	EXPECT_EQ(ret, 0);
+}
+
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/vm/memfd_secret.c b/tools/testing/selftests/mm/memfd_secret.c
index 957b9e18c729..957b9e18c729 100644
--- a/tools/testing/selftests/vm/memfd_secret.c
+++ b/tools/testing/selftests/mm/memfd_secret.c
diff --git a/tools/testing/selftests/vm/migration.c b/tools/testing/selftests/mm/migration.c
index 1cec8425e3ca..1cec8425e3ca 100644
--- a/tools/testing/selftests/vm/migration.c
+++ b/tools/testing/selftests/mm/migration.c
diff --git a/tools/testing/selftests/vm/mlock-random-test.c b/tools/testing/selftests/mm/mlock-random-test.c
index 782ea94dee2f..782ea94dee2f 100644
--- a/tools/testing/selftests/vm/mlock-random-test.c
+++ b/tools/testing/selftests/mm/mlock-random-test.c
diff --git a/tools/testing/selftests/vm/mlock2-tests.c b/tools/testing/selftests/mm/mlock2-tests.c
index 11b2301f3aa3..11b2301f3aa3 100644
--- a/tools/testing/selftests/vm/mlock2-tests.c
+++ b/tools/testing/selftests/mm/mlock2-tests.c
diff --git a/tools/testing/selftests/vm/mlock2.h b/tools/testing/selftests/mm/mlock2.h
index 2a6e76c226bc..2a6e76c226bc 100644
--- a/tools/testing/selftests/vm/mlock2.h
+++ b/tools/testing/selftests/mm/mlock2.h
diff --git a/tools/testing/selftests/vm/mrelease_test.c b/tools/testing/selftests/mm/mrelease_test.c
index 6c62966ab5db..6c62966ab5db 100644
--- a/tools/testing/selftests/vm/mrelease_test.c
+++ b/tools/testing/selftests/mm/mrelease_test.c
diff --git a/tools/testing/selftests/vm/mremap_dontunmap.c b/tools/testing/selftests/mm/mremap_dontunmap.c
index f01dc4a85b0b..f01dc4a85b0b 100644
--- a/tools/testing/selftests/vm/mremap_dontunmap.c
+++ b/tools/testing/selftests/mm/mremap_dontunmap.c
diff --git a/tools/testing/selftests/vm/mremap_test.c b/tools/testing/selftests/mm/mremap_test.c
index 9496346973d4..5c3773de9f0f 100644
--- a/tools/testing/selftests/vm/mremap_test.c
+++ b/tools/testing/selftests/mm/mremap_test.c
@@ -119,47 +119,109 @@ static unsigned long long get_mmap_min_addr(void)
 }
 
 /*
- * This test validates that merge is called when expanding a mapping.
- * Mapping containing three pages is created, middle page is unmapped
- * and then the mapping containing the first page is expanded so that
- * it fills the created hole. The two parts should merge creating
- * single mapping with three pages.
+ * Using /proc/self/maps, assert that the specified address range is contained
+ * within a single mapping.
  */
-static void mremap_expand_merge(unsigned long page_size)
+static bool is_range_mapped(FILE *maps_fp, void *start, void *end)
 {
-	char *test_name = "mremap expand merge";
-	FILE *fp;
 	char *line = NULL;
 	size_t len = 0;
 	bool success = false;
-	char *start = mmap(NULL, 3 * page_size, PROT_READ | PROT_WRITE,
-			   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
-
-	munmap(start + page_size, page_size);
-	mremap(start, page_size, 2 * page_size, 0);
 
-	fp = fopen("/proc/self/maps", "r");
-	if (fp == NULL) {
-		ksft_test_result_fail("%s\n", test_name);
-		return;
-	}
+	rewind(maps_fp);
 
-	while (getline(&line, &len, fp) != -1) {
+	while (getline(&line, &len, maps_fp) != -1) {
 		char *first = strtok(line, "- ");
 		void *first_val = (void *)strtol(first, NULL, 16);
 		char *second = strtok(NULL, "- ");
 		void *second_val = (void *) strtol(second, NULL, 16);
 
-		if (first_val == start && second_val == start + 3 * page_size) {
+		if (first_val <= start && second_val >= end) {
 			success = true;
 			break;
 		}
 	}
+
+	return success;
+}
+
+/*
+ * This test validates that merge is called when expanding a mapping.
+ * Mapping containing three pages is created, middle page is unmapped
+ * and then the mapping containing the first page is expanded so that
+ * it fills the created hole. The two parts should merge creating
+ * single mapping with three pages.
+ */
+static void mremap_expand_merge(FILE *maps_fp, unsigned long page_size)
+{
+	char *test_name = "mremap expand merge";
+	bool success = false;
+	char *remap, *start;
+
+	start = mmap(NULL, 3 * page_size, PROT_READ | PROT_WRITE,
+		     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+	if (start == MAP_FAILED) {
+		ksft_print_msg("mmap failed: %s\n", strerror(errno));
+		goto out;
+	}
+
+	munmap(start + page_size, page_size);
+	remap = mremap(start, page_size, 2 * page_size, 0);
+	if (remap == MAP_FAILED) {
+		ksft_print_msg("mremap failed: %s\n", strerror(errno));
+		munmap(start, page_size);
+		munmap(start + 2 * page_size, page_size);
+		goto out;
+	}
+
+	success = is_range_mapped(maps_fp, start, start + 3 * page_size);
+	munmap(start, 3 * page_size);
+
+out:
+	if (success)
+		ksft_test_result_pass("%s\n", test_name);
+	else
+		ksft_test_result_fail("%s\n", test_name);
+}
+
+/*
+ * Similar to mremap_expand_merge() except instead of removing the middle page,
+ * we remove the last then attempt to remap offset from the second page. This
+ * should result in the mapping being restored to its former state.
+ */
+static void mremap_expand_merge_offset(FILE *maps_fp, unsigned long page_size)
+{
+
+	char *test_name = "mremap expand merge offset";
+	bool success = false;
+	char *remap, *start;
+
+	start = mmap(NULL, 3 * page_size, PROT_READ | PROT_WRITE,
+		     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+	if (start == MAP_FAILED) {
+		ksft_print_msg("mmap failed: %s\n", strerror(errno));
+		goto out;
+	}
+
+	/* Unmap final page to ensure we have space to expand. */
+	munmap(start + 2 * page_size, page_size);
+	remap = mremap(start + page_size, page_size, 2 * page_size, 0);
+	if (remap == MAP_FAILED) {
+		ksft_print_msg("mremap failed: %s\n", strerror(errno));
+		munmap(start, 2 * page_size);
+		goto out;
+	}
+
+	success = is_range_mapped(maps_fp, start, start + 3 * page_size);
+	munmap(start, 3 * page_size);
+
+out:
 	if (success)
 		ksft_test_result_pass("%s\n", test_name);
 	else
 		ksft_test_result_fail("%s\n", test_name);
-	fclose(fp);
 }
 
 /*
@@ -380,11 +442,12 @@ int main(int argc, char **argv)
 	int i, run_perf_tests;
 	unsigned int threshold_mb = VALIDATION_DEFAULT_THRESHOLD;
 	unsigned int pattern_seed;
-	int num_expand_tests = 1;
+	int num_expand_tests = 2;
 	struct test test_cases[MAX_TEST];
 	struct test perf_test_cases[MAX_PERF_TEST];
 	int page_size;
 	time_t t;
+	FILE *maps_fp;
 
 	pattern_seed = (unsigned int) time(&t);
 
@@ -458,7 +521,17 @@ int main(int argc, char **argv)
 		run_mremap_test_case(test_cases[i], &failures, threshold_mb,
 				     pattern_seed);
 
-	mremap_expand_merge(page_size);
+	maps_fp = fopen("/proc/self/maps", "r");
+
+	if (maps_fp == NULL) {
+		ksft_print_msg("Failed to read /proc/self/maps: %s\n", strerror(errno));
+		exit(KSFT_FAIL);
+	}
+
+	mremap_expand_merge(maps_fp, page_size);
+	mremap_expand_merge_offset(maps_fp, page_size);
+
+	fclose(maps_fp);
 
 	if (run_perf_tests) {
 		ksft_print_msg("\n%s\n",
diff --git a/tools/testing/selftests/vm/on-fault-limit.c b/tools/testing/selftests/mm/on-fault-limit.c
index 634d87dfb2a4..634d87dfb2a4 100644
--- a/tools/testing/selftests/vm/on-fault-limit.c
+++ b/tools/testing/selftests/mm/on-fault-limit.c
diff --git a/tools/testing/selftests/vm/pkey-helpers.h b/tools/testing/selftests/mm/pkey-helpers.h
index 92f3be3dd8e5..92f3be3dd8e5 100644
--- a/tools/testing/selftests/vm/pkey-helpers.h
+++ b/tools/testing/selftests/mm/pkey-helpers.h
diff --git a/tools/testing/selftests/vm/pkey-powerpc.h b/tools/testing/selftests/mm/pkey-powerpc.h
index 1ebb586b2fbc..1ebb586b2fbc 100644
--- a/tools/testing/selftests/vm/pkey-powerpc.h
+++ b/tools/testing/selftests/mm/pkey-powerpc.h
diff --git a/tools/testing/selftests/vm/pkey-x86.h b/tools/testing/selftests/mm/pkey-x86.h
index 72c14cd3ddc7..72c14cd3ddc7 100644
--- a/tools/testing/selftests/vm/pkey-x86.h
+++ b/tools/testing/selftests/mm/pkey-x86.h
diff --git a/tools/testing/selftests/vm/protection_keys.c b/tools/testing/selftests/mm/protection_keys.c
index 95f403a0c46d..95f403a0c46d 100644
--- a/tools/testing/selftests/vm/protection_keys.c
+++ b/tools/testing/selftests/mm/protection_keys.c
diff --git a/tools/testing/selftests/vm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
index 8984e0bb58c7..8984e0bb58c7 100755..100644
--- a/tools/testing/selftests/vm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
diff --git a/tools/testing/selftests/vm/settings b/tools/testing/selftests/mm/settings
index 9abfc60e9e6f..9abfc60e9e6f 100644
--- a/tools/testing/selftests/vm/settings
+++ b/tools/testing/selftests/mm/settings
diff --git a/tools/testing/selftests/vm/soft-dirty.c b/tools/testing/selftests/mm/soft-dirty.c
index 21d8830c5f24..21d8830c5f24 100644
--- a/tools/testing/selftests/vm/soft-dirty.c
+++ b/tools/testing/selftests/mm/soft-dirty.c
diff --git a/tools/testing/selftests/vm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index 76e1c36dd9e5..76e1c36dd9e5 100644
--- a/tools/testing/selftests/vm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
diff --git a/tools/testing/selftests/vm/test_hmm.sh b/tools/testing/selftests/mm/test_hmm.sh
index 46e19b5d648d..46e19b5d648d 100755..100644
--- a/tools/testing/selftests/vm/test_hmm.sh
+++ b/tools/testing/selftests/mm/test_hmm.sh
diff --git a/tools/testing/selftests/vm/test_vmalloc.sh b/tools/testing/selftests/mm/test_vmalloc.sh
index d73b846736f1..d73b846736f1 100755..100644
--- a/tools/testing/selftests/vm/test_vmalloc.sh
+++ b/tools/testing/selftests/mm/test_vmalloc.sh
diff --git a/tools/testing/selftests/vm/thuge-gen.c b/tools/testing/selftests/mm/thuge-gen.c
index 361ef7192cc6..361ef7192cc6 100644
--- a/tools/testing/selftests/vm/thuge-gen.c
+++ b/tools/testing/selftests/mm/thuge-gen.c
diff --git a/tools/testing/selftests/vm/transhuge-stress.c b/tools/testing/selftests/mm/transhuge-stress.c
index e3f00adb1b82..e3f00adb1b82 100644
--- a/tools/testing/selftests/vm/transhuge-stress.c
+++ b/tools/testing/selftests/mm/transhuge-stress.c
diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/mm/userfaultfd.c
index 7f22844ed704..7f22844ed704 100644
--- a/tools/testing/selftests/vm/userfaultfd.c
+++ b/tools/testing/selftests/mm/userfaultfd.c
diff --git a/tools/testing/selftests/vm/util.h b/tools/testing/selftests/mm/util.h
index b27d26199334..b27d26199334 100644
--- a/tools/testing/selftests/vm/util.h
+++ b/tools/testing/selftests/mm/util.h
diff --git a/tools/testing/selftests/vm/va_128TBswitch.c b/tools/testing/selftests/mm/va_128TBswitch.c
index 1d2068989883..1d2068989883 100644
--- a/tools/testing/selftests/vm/va_128TBswitch.c
+++ b/tools/testing/selftests/mm/va_128TBswitch.c
diff --git a/tools/testing/selftests/vm/va_128TBswitch.sh b/tools/testing/selftests/mm/va_128TBswitch.sh
index 41580751dc51..41580751dc51 100755..100644
--- a/tools/testing/selftests/vm/va_128TBswitch.sh
+++ b/tools/testing/selftests/mm/va_128TBswitch.sh
diff --git a/tools/testing/selftests/vm/virtual_address_range.c b/tools/testing/selftests/mm/virtual_address_range.c
index c0592646ed93..c0592646ed93 100644
--- a/tools/testing/selftests/vm/virtual_address_range.c
+++ b/tools/testing/selftests/mm/virtual_address_range.c
diff --git a/tools/testing/selftests/vm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index 40e795624ff3..40e795624ff3 100644
--- a/tools/testing/selftests/vm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
diff --git a/tools/testing/selftests/vm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
index 1995ee911ef2..1995ee911ef2 100644
--- a/tools/testing/selftests/vm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
diff --git a/tools/testing/selftests/vm/write_hugetlb_memory.sh b/tools/testing/selftests/mm/write_hugetlb_memory.sh
index 70a02301f4c2..70a02301f4c2 100644
--- a/tools/testing/selftests/vm/write_hugetlb_memory.sh
+++ b/tools/testing/selftests/mm/write_hugetlb_memory.sh
diff --git a/tools/testing/selftests/vm/write_to_hugetlbfs.c b/tools/testing/selftests/mm/write_to_hugetlbfs.c
index 6a2caba19ee1..6a2caba19ee1 100644
--- a/tools/testing/selftests/vm/write_to_hugetlbfs.c
+++ b/tools/testing/selftests/mm/write_to_hugetlbfs.c