Merge tag 'mm-stable-2022-12-13' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - More userfaultfs work from Peter Xu

 - Several convert-to-folios series from Sidhartha Kumar and Huang Ying

 - Some filemap cleanups from Vishal Moola

 - David Hildenbrand added the ability to selftest anon memory COW
   handling

 - Some cpuset simplifications from Liu Shixin

 - Addition of vmalloc tracing support by Uladzislau Rezki

 - Some pagecache folioifications and simplifications from Matthew
   Wilcox

 - A pagemap cleanup from Kefeng Wang: we have VM_ACCESS_FLAGS, so use
   it

 - Miguel Ojeda contributed some cleanups for our use of the
   __no_sanitize_thread__ gcc keyword.

   This series should have been in the non-MM tree, my bad

 - Naoya Horiguchi improved the interaction between memory poisoning and
   memory section removal for huge pages

 - DAMON cleanups and tuneups from SeongJae Park

 - Tony Luck fixed the handling of COW faults against poisoned pages

 - Peter Xu utilized the PTE marker code for handling swapin errors

 - Hugh Dickins reworked compound page mapcount handling, simplifying it
   and making it more efficient

 - Removal of the autonuma savedwrite infrastructure from Nadav Amit and
   David Hildenbrand

 - zram support for multiple compression streams from Sergey Senozhatsky

 - David Hildenbrand reworked the GUP code's R/O long-term pinning so
   that drivers no longer need to use the FOLL_FORCE workaround which
   didn't work very well anyway

 - Mel Gorman altered the page allocator so that local IRQs can remnain
   enabled during per-cpu page allocations

 - Vishal Moola removed the try_to_release_page() wrapper

 - Stefan Roesch added some per-BDI sysfs tunables which are used to
   prevent network block devices from dirtying excessive amounts of
   pagecache

 - David Hildenbrand did some cleanup and repair work on KSM COW
   breaking

 - Nhat Pham and Johannes Weiner have implemented writeback in zswap's
   zsmalloc backend

 - Brian Foster has fixed a longstanding corner-case oddity in
   file[map]_write_and_wait_range()

 - sparse-vmemmap changes for MIPS, LoongArch and NIOS2 from Feiyang
   Chen

 - Shiyang Ruan has done some work on fsdax, to make its reflink mode
   work better under xfstests. Better, but still not perfect

 - Christoph Hellwig has removed the .writepage() method from several
   filesystems. They only need .writepages()

 - Yosry Ahmed wrote a series which fixes the memcg reclaim target
   beancounting

 - David Hildenbrand has fixed some of our MM selftests for 32-bit
   machines

 - Many singleton patches, as usual

* tag 'mm-stable-2022-12-13' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (313 commits)
  mm/hugetlb: set head flag before setting compound_order in __prep_compound_gigantic_folio
  mm: mmu_gather: allow more than one batch of delayed rmaps
  mm: fix typo in struct pglist_data code comment
  kmsan: fix memcpy tests
  mm: add cond_resched() in swapin_walk_pmd_entry()
  mm: do not show fs mm pc for VM_LOCKONFAULT pages
  selftests/vm: ksm_functional_tests: fixes for 32bit
  selftests/vm: cow: fix compile warning on 32bit
  selftests/vm: madv_populate: fix missing MADV_POPULATE_(READ|WRITE) definitions
  mm/gup_test: fix PIN_LONGTERM_TEST_READ with highmem
  mm,thp,rmap: fix races between updates of subpages_mapcount
  mm: memcg: fix swapcached stat accounting
  mm: add nodes= arg to memory.reclaim
  mm: disable top-tier fallback to reclaim on proactive reclaim
  selftests: cgroup: make sure reclaim target memcg is unprotected
  selftests: cgroup: refactor proactive reclaim code to reclaim_until()
  mm: memcg: fix stale protection of reclaim target memcg
  mm/mmap: properly unaccount memory on mas_preallocate() failure
  omfs: remove ->writepage
  jfs: remove ->writepage
  ...

14 files changed, 2169 insertions, 156 deletions

diff --git a/tools/testing/selftests/vm/.gitignore b/tools/testing/selftests/vm/.gitignore
index a8fbf8548bc0..1f8c36a9fa10 100644
--- a/tools/testing/selftests/vm/.gitignore
+++ b/tools/testing/selftests/vm/.gitignore
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-only
+cow
 hugepage-mmap
 hugepage-mremap
 hugepage-shm
diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile
index 163c2fde3cb3..89c14e41bd43 100644
--- a/tools/testing/selftests/vm/Makefile
+++ b/tools/testing/selftests/vm/Makefile
@@ -1,7 +1,9 @@
 # SPDX-License-Identifier: GPL-2.0
 # Makefile for vm selftests
 
-LOCAL_HDRS += $(top_srcdir)/mm/gup_test.h
+LOCAL_HDRS += $(selfdir)/vm/local_config.h $(top_srcdir)/mm/gup_test.h
+
+include local_config.mk
 
 uname_M := $(shell uname -m 2>/dev/null || echo not)
 MACHINE ?= $(shell echo $(uname_M) | sed -e 's/aarch64.*/arm64/' -e 's/ppc64.*/ppc64/')
@@ -25,7 +27,8 @@ MAKEFLAGS += --no-builtin-rules
 
 CFLAGS = -Wall -I $(top_srcdir) -I $(top_srcdir)/usr/include $(EXTRA_CFLAGS) $(KHDR_INCLUDES)
 LDLIBS = -lrt -lpthread
-TEST_GEN_FILES = compaction_test
+TEST_GEN_FILES = cow
+TEST_GEN_FILES += compaction_test
 TEST_GEN_FILES += gup_test
 TEST_GEN_FILES += hmm-tests
 TEST_GEN_FILES += hugetlb-madvise
@@ -52,6 +55,7 @@ TEST_GEN_FILES += userfaultfd
 TEST_GEN_PROGS += soft-dirty
 TEST_GEN_PROGS += split_huge_page_test
 TEST_GEN_FILES += ksm_tests
+TEST_GEN_PROGS += ksm_functional_tests
 
 ifeq ($(MACHINE),x86_64)
 CAN_BUILD_I386 := $(shell ./../x86/check_cc.sh "$(CC)" ../x86/trivial_32bit_program.c -m32)
@@ -95,7 +99,9 @@ TEST_FILES += va_128TBswitch.sh
 
 include ../lib.mk
 
+$(OUTPUT)/cow: vm_util.c
 $(OUTPUT)/khugepaged: vm_util.c
+$(OUTPUT)/ksm_functional_tests: vm_util.c
 $(OUTPUT)/madv_populate: vm_util.c
 $(OUTPUT)/soft-dirty: vm_util.c
 $(OUTPUT)/split_huge_page_test: vm_util.c
@@ -150,8 +156,25 @@ warn_32bit_failure:
 endif
 endif
 
+# cow_EXTRA_LIBS may get set in local_config.mk, or it may be left empty.
+$(OUTPUT)/cow: LDLIBS += $(COW_EXTRA_LIBS)
+
 $(OUTPUT)/mlock-random-test $(OUTPUT)/memfd_secret: LDLIBS += -lcap
 
 $(OUTPUT)/ksm_tests: LDLIBS += -lnuma
 
 $(OUTPUT)/migration: LDLIBS += -lnuma
+
+local_config.mk local_config.h: check_config.sh
+	/bin/sh ./check_config.sh $(CC)
+
+EXTRA_CLEAN += local_config.mk local_config.h
+
+ifeq ($(COW_EXTRA_LIBS),)
+all: warn_missing_liburing
+
+warn_missing_liburing:
+	@echo ; \
+	echo "Warning: missing liburing support. Some COW tests will be skipped." ; \
+	echo
+endif
diff --git a/tools/testing/selftests/vm/check_config.sh b/tools/testing/selftests/vm/check_config.sh
new file mode 100644
index 000000000000..bcba3af0acea
--- /dev/null
+++ b/tools/testing/selftests/vm/check_config.sh
@@ -0,0 +1,31 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# Probe for libraries and create header files to record the results. Both C
+# header files and Makefile include fragments are created.
+
+OUTPUT_H_FILE=local_config.h
+OUTPUT_MKFILE=local_config.mk
+
+tmpname=$(mktemp)
+tmpfile_c=${tmpname}.c
+tmpfile_o=${tmpname}.o
+
+# liburing
+echo "#include <sys/types.h>"        > $tmpfile_c
+echo "#include <liburing.h>"        >> $tmpfile_c
+echo "int func(void) { return 0; }" >> $tmpfile_c
+
+CC=${1:?"Usage: $0 <compiler> # example compiler: gcc"}
+$CC -c $tmpfile_c -o $tmpfile_o >/dev/null 2>&1
+
+if [ -f $tmpfile_o ]; then
+    echo "#define LOCAL_CONFIG_HAVE_LIBURING 1"  > $OUTPUT_H_FILE
+    echo "COW_EXTRA_LIBS = -luring"              > $OUTPUT_MKFILE
+else
+    echo "// No liburing support found"          > $OUTPUT_H_FILE
+    echo "# No liburing support found, so:"      > $OUTPUT_MKFILE
+    echo "COW_EXTRA_LIBS = "                    >> $OUTPUT_MKFILE
+fi
+
+rm ${tmpname}.*
diff --git a/tools/testing/selftests/vm/cow.c b/tools/testing/selftests/vm/cow.c
new file mode 100644
index 000000000000..26f6ea3079e2
--- /dev/null
+++ b/tools/testing/selftests/vm/cow.c
@@ -0,0 +1,1536 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * COW (Copy On Write) tests.
+ *
+ * Copyright 2022, Red Hat, Inc.
+ *
+ * Author(s): David Hildenbrand <david@redhat.com>
+ */
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <dirent.h>
+#include <assert.h>
+#include <sys/mman.h>
+#include <sys/ioctl.h>
+#include <sys/wait.h>
+#include <linux/memfd.h>
+
+#include "local_config.h"
+#ifdef LOCAL_CONFIG_HAVE_LIBURING
+#include <liburing.h>
+#endif /* LOCAL_CONFIG_HAVE_LIBURING */
+
+#include "../../../../mm/gup_test.h"
+#include "../kselftest.h"
+#include "vm_util.h"
+
+static size_t pagesize;
+static int pagemap_fd;
+static size_t thpsize;
+static int nr_hugetlbsizes;
+static size_t hugetlbsizes[10];
+static int gup_fd;
+static bool has_huge_zeropage;
+
+static void detect_thpsize(void)
+{
+	int fd = open("/sys/kernel/mm/transparent_hugepage/hpage_pmd_size",
+		      O_RDONLY);
+	size_t size = 0;
+	char buf[15];
+	int ret;
+
+	if (fd < 0)
+		return;
+
+	ret = pread(fd, buf, sizeof(buf), 0);
+	if (ret > 0 && ret < sizeof(buf)) {
+		buf[ret] = 0;
+
+		size = strtoul(buf, NULL, 10);
+		if (size < pagesize)
+			size = 0;
+		if (size > 0) {
+			thpsize = size;
+			ksft_print_msg("[INFO] detected THP size: %zu KiB\n",
+				       thpsize / 1024);
+		}
+	}
+
+	close(fd);
+}
+
+static void detect_huge_zeropage(void)
+{
+	int fd = open("/sys/kernel/mm/transparent_hugepage/use_zero_page",
+		      O_RDONLY);
+	size_t enabled = 0;
+	char buf[15];
+	int ret;
+
+	if (fd < 0)
+		return;
+
+	ret = pread(fd, buf, sizeof(buf), 0);
+	if (ret > 0 && ret < sizeof(buf)) {
+		buf[ret] = 0;
+
+		enabled = strtoul(buf, NULL, 10);
+		if (enabled == 1) {
+			has_huge_zeropage = true;
+			ksft_print_msg("[INFO] huge zeropage is enabled\n");
+		}
+	}
+
+	close(fd);
+}
+
+static void detect_hugetlbsizes(void)
+{
+	DIR *dir = opendir("/sys/kernel/mm/hugepages/");
+
+	if (!dir)
+		return;
+
+	while (nr_hugetlbsizes < ARRAY_SIZE(hugetlbsizes)) {
+		struct dirent *entry = readdir(dir);
+		size_t kb;
+
+		if (!entry)
+			break;
+		if (entry->d_type != DT_DIR)
+			continue;
+		if (sscanf(entry->d_name, "hugepages-%zukB", &kb) != 1)
+			continue;
+		hugetlbsizes[nr_hugetlbsizes] = kb * 1024;
+		nr_hugetlbsizes++;
+		ksft_print_msg("[INFO] detected hugetlb size: %zu KiB\n",
+			       kb);
+	}
+	closedir(dir);
+}
+
+static bool range_is_swapped(void *addr, size_t size)
+{
+	for (; size; addr += pagesize, size -= pagesize)
+		if (!pagemap_is_swapped(pagemap_fd, addr))
+			return false;
+	return true;
+}
+
+struct comm_pipes {
+	int child_ready[2];
+	int parent_ready[2];
+};
+
+static int setup_comm_pipes(struct comm_pipes *comm_pipes)
+{
+	if (pipe(comm_pipes->child_ready) < 0)
+		return -errno;
+	if (pipe(comm_pipes->parent_ready) < 0) {
+		close(comm_pipes->child_ready[0]);
+		close(comm_pipes->child_ready[1]);
+		return -errno;
+	}
+
+	return 0;
+}
+
+static void close_comm_pipes(struct comm_pipes *comm_pipes)
+{
+	close(comm_pipes->child_ready[0]);
+	close(comm_pipes->child_ready[1]);
+	close(comm_pipes->parent_ready[0]);
+	close(comm_pipes->parent_ready[1]);
+}
+
+static int child_memcmp_fn(char *mem, size_t size,
+			   struct comm_pipes *comm_pipes)
+{
+	char *old = malloc(size);
+	char buf;
+
+	/* Backup the original content. */
+	memcpy(old, mem, size);
+
+	/* Wait until the parent modified the page. */
+	write(comm_pipes->child_ready[1], "0", 1);
+	while (read(comm_pipes->parent_ready[0], &buf, 1) != 1)
+		;
+
+	/* See if we still read the old values. */
+	return memcmp(old, mem, size);
+}
+
+static int child_vmsplice_memcmp_fn(char *mem, size_t size,
+				    struct comm_pipes *comm_pipes)
+{
+	struct iovec iov = {
+		.iov_base = mem,
+		.iov_len = size,
+	};
+	ssize_t cur, total, transferred;
+	char *old, *new;
+	int fds[2];
+	char buf;
+
+	old = malloc(size);
+	new = malloc(size);
+
+	/* Backup the original content. */
+	memcpy(old, mem, size);
+
+	if (pipe(fds) < 0)
+		return -errno;
+
+	/* Trigger a read-only pin. */
+	transferred = vmsplice(fds[1], &iov, 1, 0);
+	if (transferred < 0)
+		return -errno;
+	if (transferred == 0)
+		return -EINVAL;
+
+	/* Unmap it from our page tables. */
+	if (munmap(mem, size) < 0)
+		return -errno;
+
+	/* Wait until the parent modified it. */
+	write(comm_pipes->child_ready[1], "0", 1);
+	while (read(comm_pipes->parent_ready[0], &buf, 1) != 1)
+		;
+
+	/* See if we still read the old values via the pipe. */
+	for (total = 0; total < transferred; total += cur) {
+		cur = read(fds[0], new + total, transferred - total);
+		if (cur < 0)
+			return -errno;
+	}
+
+	return memcmp(old, new, transferred);
+}
+
+typedef int (*child_fn)(char *mem, size_t size, struct comm_pipes *comm_pipes);
+
+static void do_test_cow_in_parent(char *mem, size_t size, bool do_mprotect,
+				  child_fn fn)
+{
+	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;
+	}
+
+	ret = fork();
+	if (ret < 0) {
+		ksft_test_result_fail("fork() failed\n");
+		goto close_comm_pipes;
+	} else if (!ret) {
+		exit(fn(mem, size, &comm_pipes));
+	}
+
+	while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
+		;
+
+	if (do_mprotect) {
+		/*
+		 * mprotect() optimizations might try avoiding
+		 * write-faults by directly mapping pages writable.
+		 */
+		ret = mprotect(mem, size, PROT_READ);
+		ret |= mprotect(mem, size, PROT_READ|PROT_WRITE);
+		if (ret) {
+			ksft_test_result_fail("mprotect() failed\n");
+			write(comm_pipes.parent_ready[1], "0", 1);
+			wait(&ret);
+			goto close_comm_pipes;
+		}
+	}
+
+	/* 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_cow_in_parent(char *mem, size_t size)
+{
+	do_test_cow_in_parent(mem, size, false, child_memcmp_fn);
+}
+
+static void test_cow_in_parent_mprotect(char *mem, size_t size)
+{
+	do_test_cow_in_parent(mem, size, true, child_memcmp_fn);
+}
+
+static void test_vmsplice_in_child(char *mem, size_t size)
+{
+	do_test_cow_in_parent(mem, size, false, child_vmsplice_memcmp_fn);
+}
+
+static void test_vmsplice_in_child_mprotect(char *mem, size_t size)
+{
+	do_test_cow_in_parent(mem, size, true, child_vmsplice_memcmp_fn);
+}
+
+static void do_test_vmsplice_in_parent(char *mem, size_t size,
+				       bool before_fork)
+{
+	struct iovec iov = {
+		.iov_base = mem,
+		.iov_len = size,
+	};
+	ssize_t cur, total, transferred;
+	struct comm_pipes comm_pipes;
+	char *old, *new;
+	int ret, fds[2];
+	char buf;
+
+	old = malloc(size);
+	new = malloc(size);
+
+	memcpy(old, mem, size);
+
+	ret = setup_comm_pipes(&comm_pipes);
+	if (ret) {
+		ksft_test_result_fail("pipe() failed\n");
+		goto free;
+	}
+
+	if (pipe(fds) < 0) {
+		ksft_test_result_fail("pipe() failed\n");
+		goto close_comm_pipes;
+	}
+
+	if (before_fork) {
+		transferred = vmsplice(fds[1], &iov, 1, 0);
+		if (transferred <= 0) {
+			ksft_test_result_fail("vmsplice() failed\n");
+			goto close_pipe;
+		}
+	}
+
+	ret = fork();
+	if (ret < 0) {
+		ksft_test_result_fail("fork() failed\n");
+		goto close_pipe;
+	} else if (!ret) {
+		write(comm_pipes.child_ready[1], "0", 1);
+		while (read(comm_pipes.parent_ready[0], &buf, 1) != 1)
+			;
+		/* Modify page content in the child. */
+		memset(mem, 0xff, size);
+		exit(0);
+	}
+
+	if (!before_fork) {
+		transferred = vmsplice(fds[1], &iov, 1, 0);
+		if (transferred <= 0) {
+			ksft_test_result_fail("vmsplice() failed\n");
+			wait(&ret);
+			goto close_pipe;
+		}
+	}
+
+	while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
+		;
+	if (munmap(mem, size) < 0) {
+		ksft_test_result_fail("munmap() failed\n");
+		goto close_pipe;
+	}
+	write(comm_pipes.parent_ready[1], "0", 1);
+
+	/* Wait until the child is done writing. */
+	wait(&ret);
+	if (!WIFEXITED(ret)) {
+		ksft_test_result_fail("wait() failed\n");
+		goto close_pipe;
+	}
+
+	/* See if we still read the old values. */
+	for (total = 0; total < transferred; total += cur) {
+		cur = read(fds[0], new + total, transferred - total);
+		if (cur < 0) {
+			ksft_test_result_fail("read() failed\n");
+			goto close_pipe;
+		}
+	}
+
+	ksft_test_result(!memcmp(old, new, transferred),
+			 "No leak from child into parent\n");
+close_pipe:
+	close(fds[0]);
+	close(fds[1]);
+close_comm_pipes:
+	close_comm_pipes(&comm_pipes);
+free:
+	free(old);
+	free(new);
+}
+
+static void test_vmsplice_before_fork(char *mem, size_t size)
+{
+	do_test_vmsplice_in_parent(mem, size, true);
+}
+
+static void test_vmsplice_after_fork(char *mem, size_t size)
+{
+	do_test_vmsplice_in_parent(mem, size, false);
+}
+
+#ifdef LOCAL_CONFIG_HAVE_LIBURING
+static void do_test_iouring(char *mem, size_t size, bool use_fork)
+{
+	struct comm_pipes comm_pipes;
+	struct io_uring_cqe *cqe;
+	struct io_uring_sqe *sqe;
+	struct io_uring ring;
+	ssize_t cur, total;
+	struct iovec iov;
+	char *buf, *tmp;
+	int ret, fd;
+	FILE *file;
+
+	ret = setup_comm_pipes(&comm_pipes);
+	if (ret) {
+		ksft_test_result_fail("pipe() failed\n");
+		return;
+	}
+
+	file = tmpfile();
+	if (!file) {
+		ksft_test_result_fail("tmpfile() failed\n");
+		goto close_comm_pipes;
+	}
+	fd = fileno(file);
+	assert(fd);
+
+	tmp = malloc(size);
+	if (!tmp) {
+		ksft_test_result_fail("malloc() failed\n");
+		goto close_file;
+	}
+
+	/* Skip on errors, as we might just lack kernel support. */
+	ret = io_uring_queue_init(1, &ring, 0);
+	if (ret < 0) {
+		ksft_test_result_skip("io_uring_queue_init() failed\n");
+		goto free_tmp;
+	}
+
+	/*
+	 * Register the range as a fixed buffer. This will FOLL_WRITE | FOLL_PIN
+	 * | FOLL_LONGTERM the range.
+	 *
+	 * Skip on errors, as we might just lack kernel support or might not
+	 * have sufficient MEMLOCK permissions.
+	 */
+	iov.iov_base = mem;
+	iov.iov_len = size;
+	ret = io_uring_register_buffers(&ring, &iov, 1);
+	if (ret) {
+		ksft_test_result_skip("io_uring_register_buffers() failed\n");
+		goto queue_exit;
+	}
+
+	if (use_fork) {
+		/*
+		 * fork() and keep the child alive until we're done. Note that
+		 * we expect the pinned page to not get shared with the child.
+		 */
+		ret = fork();
+		if (ret < 0) {
+			ksft_test_result_fail("fork() failed\n");
+			goto unregister_buffers;
+		} else if (!ret) {
+			write(comm_pipes.child_ready[1], "0", 1);
+			while (read(comm_pipes.parent_ready[0], &buf, 1) != 1)
+				;
+			exit(0);
+		}
+
+		while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
+			;
+	} else {
+		/*
+		 * Map the page R/O into the page table. Enable softdirty
+		 * tracking to stop the page from getting mapped R/W immediately
+		 * again by mprotect() optimizations. Note that we don't have an
+		 * easy way to test if that worked (the pagemap does not export
+		 * if the page is mapped R/O vs. R/W).
+		 */
+		ret = mprotect(mem, size, PROT_READ);
+		clear_softdirty();
+		ret |= mprotect(mem, size, PROT_READ | PROT_WRITE);
+		if (ret) {
+			ksft_test_result_fail("mprotect() failed\n");
+			goto unregister_buffers;
+		}
+	}
+
+	/*
+	 * Modify the page and write page content as observed by the fixed
+	 * buffer pin to the file so we can verify it.
+	 */
+	memset(mem, 0xff, size);
+	sqe = io_uring_get_sqe(&ring);
+	if (!sqe) {
+		ksft_test_result_fail("io_uring_get_sqe() failed\n");
+		goto quit_child;
+	}
+	io_uring_prep_write_fixed(sqe, fd, mem, size, 0, 0);
+
+	ret = io_uring_submit(&ring);
+	if (ret < 0) {
+		ksft_test_result_fail("io_uring_submit() failed\n");
+		goto quit_child;
+	}
+
+	ret = io_uring_wait_cqe(&ring, &cqe);
+	if (ret < 0) {
+		ksft_test_result_fail("io_uring_wait_cqe() failed\n");
+		goto quit_child;
+	}
+
+	if (cqe->res != size) {
+		ksft_test_result_fail("write_fixed failed\n");
+		goto quit_child;
+	}
+	io_uring_cqe_seen(&ring, cqe);
+
+	/* Read back the file content to the temporary buffer. */
+	total = 0;
+	while (total < size) {
+		cur = pread(fd, tmp + total, size - total, total);
+		if (cur < 0) {
+			ksft_test_result_fail("pread() failed\n");
+			goto quit_child;
+		}
+		total += cur;
+	}
+
+	/* Finally, check if we read what we expected. */
+	ksft_test_result(!memcmp(mem, tmp, size),
+			 "Longterm R/W pin is reliable\n");
+
+quit_child:
+	if (use_fork) {
+		write(comm_pipes.parent_ready[1], "0", 1);
+		wait(&ret);
+	}
+unregister_buffers:
+	io_uring_unregister_buffers(&ring);
+queue_exit:
+	io_uring_queue_exit(&ring);
+free_tmp:
+	free(tmp);
+close_file:
+	fclose(file);
+close_comm_pipes:
+	close_comm_pipes(&comm_pipes);
+}
+
+static void test_iouring_ro(char *mem, size_t size)
+{
+	do_test_iouring(mem, size, false);
+}
+
+static void test_iouring_fork(char *mem, size_t size)
+{
+	do_test_iouring(mem, size, true);
+}
+
+#endif /* LOCAL_CONFIG_HAVE_LIBURING */
+
+enum ro_pin_test {
+	RO_PIN_TEST,
+	RO_PIN_TEST_SHARED,
+	RO_PIN_TEST_PREVIOUSLY_SHARED,
+	RO_PIN_TEST_RO_EXCLUSIVE,
+};
+
+static void do_test_ro_pin(char *mem, size_t size, enum ro_pin_test test,
+			   bool fast)
+{
+	struct pin_longterm_test args;
+	struct comm_pipes comm_pipes;
+	char *tmp, buf;
+	__u64 tmp_val;
+	int ret;
+
+	if (gup_fd < 0) {
+		ksft_test_result_skip("gup_test not available\n");
+		return;
+	}
+
+	tmp = malloc(size);
+	if (!tmp) {
+		ksft_test_result_fail("malloc() failed\n");
+		return;
+	}
+
+	ret = setup_comm_pipes(&comm_pipes);
+	if (ret) {
+		ksft_test_result_fail("pipe() failed\n");
+		goto free_tmp;
+	}
+
+	switch (test) {
+	case RO_PIN_TEST:
+		break;
+	case RO_PIN_TEST_SHARED:
+	case RO_PIN_TEST_PREVIOUSLY_SHARED:
+		/*
+		 * Share the pages with our child. As the pages are not pinned,
+		 * this should just work.
+		 */
+		ret = fork();
+		if (ret < 0) {
+			ksft_test_result_fail("fork() failed\n");
+			goto close_comm_pipes;
+		} else if (!ret) {
+			write(comm_pipes.child_ready[1], "0", 1);
+			while (read(comm_pipes.parent_ready[0], &buf, 1) != 1)
+				;
+			exit(0);
+		}
+
+		/* Wait until our child is ready. */
+		while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
+			;
+
+		if (test == RO_PIN_TEST_PREVIOUSLY_SHARED) {
+			/*
+			 * Tell the child to quit now and wait until it quit.
+			 * The pages should now be mapped R/O into our page
+			 * tables, but they are no longer shared.
+			 */
+			write(comm_pipes.parent_ready[1], "0", 1);
+			wait(&ret);
+			if (!WIFEXITED(ret))
+				ksft_print_msg("[INFO] wait() failed\n");
+		}
+		break;
+	case RO_PIN_TEST_RO_EXCLUSIVE:
+		/*
+		 * Map the page R/O into the page table. Enable softdirty
+		 * tracking to stop the page from getting mapped R/W immediately
+		 * again by mprotect() optimizations. Note that we don't have an
+		 * easy way to test if that worked (the pagemap does not export
+		 * if the page is mapped R/O vs. R/W).
+		 */
+		ret = mprotect(mem, size, PROT_READ);
+		clear_softdirty();
+		ret |= mprotect(mem, size, PROT_READ | PROT_WRITE);
+		if (ret) {
+			ksft_test_result_fail("mprotect() failed\n");
+			goto close_comm_pipes;
+		}
+		break;
+	default:
+		assert(false);
+	}
+
+	/* Take a R/O pin. This should trigger unsharing. */
+	args.addr = (__u64)(uintptr_t)mem;
+	args.size = size;
+	args.flags = fast ? PIN_LONGTERM_TEST_FLAG_USE_FAST : 0;
+	ret = ioctl(gup_fd, PIN_LONGTERM_TEST_START, &args);
+	if (ret) {
+		if (errno == EINVAL)
+			ksft_test_result_skip("PIN_LONGTERM_TEST_START failed\n");
+		else
+			ksft_test_result_fail("PIN_LONGTERM_TEST_START failed\n");
+		goto wait;
+	}
+
+	/* Modify the page. */
+	memset(mem, 0xff, size);
+
+	/*
+	 * Read back the content via the pin to the temporary buffer and
+	 * test if we observed the modification.
+	 */
+	tmp_val = (__u64)(uintptr_t)tmp;
+	ret = ioctl(gup_fd, PIN_LONGTERM_TEST_READ, &tmp_val);
+	if (ret)
+		ksft_test_result_fail("PIN_LONGTERM_TEST_READ failed\n");
+	else
+		ksft_test_result(!memcmp(mem, tmp, size),
+				 "Longterm R/O pin is reliable\n");
+
+	ret = ioctl(gup_fd, PIN_LONGTERM_TEST_STOP);
+	if (ret)
+		ksft_print_msg("[INFO] PIN_LONGTERM_TEST_STOP failed\n");
+wait:
+	switch (test) {
+	case RO_PIN_TEST_SHARED:
+		write(comm_pipes.parent_ready[1], "0", 1);
+		wait(&ret);
+		if (!WIFEXITED(ret))
+			ksft_print_msg("[INFO] wait() failed\n");
+		break;
+	default:
+		break;
+	}
+close_comm_pipes:
+	close_comm_pipes(&comm_pipes);
+free_tmp:
+	free(tmp);
+}
+
+static void test_ro_pin_on_shared(char *mem, size_t size)
+{
+	do_test_ro_pin(mem, size, RO_PIN_TEST_SHARED, false);
+}
+
+static void test_ro_fast_pin_on_shared(char *mem, size_t size)
+{
+	do_test_ro_pin(mem, size, RO_PIN_TEST_SHARED, true);
+}
+
+static void test_ro_pin_on_ro_previously_shared(char *mem, size_t size)
+{
+	do_test_ro_pin(mem, size, RO_PIN_TEST_PREVIOUSLY_SHARED, false);
+}
+
+static void test_ro_fast_pin_on_ro_previously_shared(char *mem, size_t size)
+{
+	do_test_ro_pin(mem, size, RO_PIN_TEST_PREVIOUSLY_SHARED, true);
+}
+
+static void test_ro_pin_on_ro_exclusive(char *mem, size_t size)
+{
+	do_test_ro_pin(mem, size, RO_PIN_TEST_RO_EXCLUSIVE, false);
+}
+
+static void test_ro_fast_pin_on_ro_exclusive(char *mem, size_t size)
+{
+	do_test_ro_pin(mem, size, RO_PIN_TEST_RO_EXCLUSIVE, true);
+}
+
+typedef void (*test_fn)(char *mem, size_t size);
+
+static void do_run_with_base_page(test_fn fn, bool swapout)
+{
+	char *mem;
+	int ret;
+
+	mem = mmap(NULL, pagesize, PROT_READ | PROT_WRITE,
+		   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		return;
+	}
+
+	ret = madvise(mem, pagesize, MADV_NOHUGEPAGE);
+	/* Ignore if not around on a kernel. */
+	if (ret && errno != EINVAL) {
+		ksft_test_result_fail("MADV_NOHUGEPAGE failed\n");
+		goto munmap;
+	}
+
+	/* Populate a base page. */
+	memset(mem, 0, pagesize);
+
+	if (swapout) {
+		madvise(mem, pagesize, MADV_PAGEOUT);
+		if (!pagemap_is_swapped(pagemap_fd, mem)) {
+			ksft_test_result_skip("MADV_PAGEOUT did not work, is swap enabled?\n");
+			goto munmap;
+		}
+	}
+
+	fn(mem, pagesize);
+munmap:
+	munmap(mem, pagesize);
+}
+
+static void run_with_base_page(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with base page\n", desc);
+	do_run_with_base_page(fn, false);
+}
+
+static void run_with_base_page_swap(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with swapped out base page\n", desc);
+	do_run_with_base_page(fn, true);
+}
+
+enum thp_run {
+	THP_RUN_PMD,
+	THP_RUN_PMD_SWAPOUT,
+	THP_RUN_PTE,
+	THP_RUN_PTE_SWAPOUT,
+	THP_RUN_SINGLE_PTE,
+	THP_RUN_SINGLE_PTE_SWAPOUT,
+	THP_RUN_PARTIAL_MREMAP,
+	THP_RUN_PARTIAL_SHARED,
+};
+
+static void do_run_with_thp(test_fn fn, enum thp_run thp_run)
+{
+	char *mem, *mmap_mem, *tmp, *mremap_mem = MAP_FAILED;
+	size_t size, mmap_size, mremap_size;
+	int ret;
+
+	/* For alignment purposes, we need twice the thp size. */
+	mmap_size = 2 * thpsize;
+	mmap_mem = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (mmap_mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		return;
+	}
+
+	/* We need a THP-aligned memory area. */
+	mem = (char *)(((uintptr_t)mmap_mem + thpsize) & ~(thpsize - 1));
+
+	ret = madvise(mem, thpsize, MADV_HUGEPAGE);
+	if (ret) {
+		ksft_test_result_fail("MADV_HUGEPAGE failed\n");
+		goto munmap;
+	}
+
+	/*
+	 * Try to populate a THP. Touch the first sub-page and test if we get
+	 * another sub-page populated automatically.
+	 */
+	mem[0] = 0;
+	if (!pagemap_is_populated(pagemap_fd, mem + pagesize)) {
+		ksft_test_result_skip("Did not get a THP populated\n");
+		goto munmap;
+	}
+	memset(mem, 0, thpsize);
+
+	size = thpsize;
+	switch (thp_run) {
+	case THP_RUN_PMD:
+	case THP_RUN_PMD_SWAPOUT:
+		break;
+	case THP_RUN_PTE:
+	case THP_RUN_PTE_SWAPOUT:
+		/*
+		 * Trigger PTE-mapping the THP by temporarily mapping a single
+		 * subpage R/O.
+		 */
+		ret = mprotect(mem + pagesize, pagesize, PROT_READ);
+		if (ret) {
+			ksft_test_result_fail("mprotect() failed\n");
+			goto munmap;
+		}
+		ret = mprotect(mem + pagesize, pagesize, PROT_READ | PROT_WRITE);
+		if (ret) {
+			ksft_test_result_fail("mprotect() failed\n");
+			goto munmap;
+		}
+		break;
+	case THP_RUN_SINGLE_PTE:
+	case THP_RUN_SINGLE_PTE_SWAPOUT:
+		/*
+		 * Discard all but a single subpage of that PTE-mapped THP. What
+		 * remains is a single PTE mapping a single subpage.
+		 */
+		ret = madvise(mem + pagesize, thpsize - pagesize, MADV_DONTNEED);
+		if (ret) {
+			ksft_test_result_fail("MADV_DONTNEED failed\n");
+			goto munmap;
+		}
+		size = pagesize;
+		break;
+	case THP_RUN_PARTIAL_MREMAP:
+		/*
+		 * Remap half of the THP. We need some new memory location
+		 * for that.
+		 */
+		mremap_size = thpsize / 2;
+		mremap_mem = mmap(NULL, mremap_size, PROT_NONE,
+				  MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+		if (mem == MAP_FAILED) {
+			ksft_test_result_fail("mmap() failed\n");
+			goto munmap;
+		}
+		tmp = mremap(mem + mremap_size, mremap_size, mremap_size,
+			     MREMAP_MAYMOVE | MREMAP_FIXED, mremap_mem);
+		if (tmp != mremap_mem) {
+			ksft_test_result_fail("mremap() failed\n");
+			goto munmap;
+		}
+		size = mremap_size;
+		break;
+	case THP_RUN_PARTIAL_SHARED:
+		/*
+		 * Share the first page of the THP with a child and quit the
+		 * child. This will result in some parts of the THP never
+		 * have been shared.
+		 */
+		ret = madvise(mem + pagesize, thpsize - pagesize, MADV_DONTFORK);
+		if (ret) {
+			ksft_test_result_fail("MADV_DONTFORK failed\n");
+			goto munmap;
+		}
+		ret = fork();
+		if (ret < 0) {
+			ksft_test_result_fail("fork() failed\n");
+			goto munmap;
+		} else if (!ret) {
+			exit(0);
+		}
+		wait(&ret);
+		/* Allow for sharing all pages again. */
+		ret = madvise(mem + pagesize, thpsize - pagesize, MADV_DOFORK);
+		if (ret) {
+			ksft_test_result_fail("MADV_DOFORK failed\n");
+			goto munmap;
+		}
+		break;
+	default:
+		assert(false);
+	}
+
+	switch (thp_run) {
+	case THP_RUN_PMD_SWAPOUT:
+	case THP_RUN_PTE_SWAPOUT:
+	case THP_RUN_SINGLE_PTE_SWAPOUT:
+		madvise(mem, size, MADV_PAGEOUT);
+		if (!range_is_swapped(mem, size)) {
+			ksft_test_result_skip("MADV_PAGEOUT did not work, is swap enabled?\n");
+			goto munmap;
+		}
+		break;
+	default:
+		break;
+	}
+
+	fn(mem, size);
+munmap:
+	munmap(mmap_mem, mmap_size);
+	if (mremap_mem != MAP_FAILED)
+		munmap(mremap_mem, mremap_size);
+}
+
+static void run_with_thp(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with THP\n", desc);
+	do_run_with_thp(fn, THP_RUN_PMD);
+}
+
+static void run_with_thp_swap(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with swapped-out THP\n", desc);
+	do_run_with_thp(fn, THP_RUN_PMD_SWAPOUT);
+}
+
+static void run_with_pte_mapped_thp(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with PTE-mapped THP\n", desc);
+	do_run_with_thp(fn, THP_RUN_PTE);
+}
+
+static void run_with_pte_mapped_thp_swap(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with swapped-out, PTE-mapped THP\n", desc);
+	do_run_with_thp(fn, THP_RUN_PTE_SWAPOUT);
+}
+
+static void run_with_single_pte_of_thp(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with single PTE of THP\n", desc);
+	do_run_with_thp(fn, THP_RUN_SINGLE_PTE);
+}
+
+static void run_with_single_pte_of_thp_swap(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with single PTE of swapped-out THP\n", desc);
+	do_run_with_thp(fn, THP_RUN_SINGLE_PTE_SWAPOUT);
+}
+
+static void run_with_partial_mremap_thp(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with partially mremap()'ed THP\n", desc);
+	do_run_with_thp(fn, THP_RUN_PARTIAL_MREMAP);
+}
+
+static void run_with_partial_shared_thp(test_fn fn, const char *desc)
+{
+	ksft_print_msg("[RUN] %s ... with partially shared THP\n", desc);
+	do_run_with_thp(fn, THP_RUN_PARTIAL_SHARED);
+}
+
+static void run_with_hugetlb(test_fn fn, const char *desc, size_t hugetlbsize)
+{
+	int flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB;
+	char *mem, *dummy;
+
+	ksft_print_msg("[RUN] %s ... with hugetlb (%zu kB)\n", desc,
+		       hugetlbsize / 1024);
+
+	flags |= __builtin_ctzll(hugetlbsize) << MAP_HUGE_SHIFT;
+
+	mem = mmap(NULL, hugetlbsize, PROT_READ | PROT_WRITE, flags, -1, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_skip("need more free huge pages\n");
+		return;
+	}
+
+	/* Populate an huge page. */
+	memset(mem, 0, hugetlbsize);
+
+	/*
+	 * We need a total of two hugetlb pages to handle COW/unsharing
+	 * properly, otherwise we might get zapped by a SIGBUS.
+	 */
+	dummy = mmap(NULL, hugetlbsize, PROT_READ | PROT_WRITE, flags, -1, 0);
+	if (dummy == MAP_FAILED) {
+		ksft_test_result_skip("need more free huge pages\n");
+		goto munmap;
+	}
+	munmap(dummy, hugetlbsize);
+
+	fn(mem, hugetlbsize);
+munmap:
+	munmap(mem, hugetlbsize);
+}
+
+struct test_case {
+	const char *desc;
+	test_fn fn;
+};
+
+/*
+ * Test cases that are specific to anonymous pages: pages in private mappings
+ * that may get shared via COW during fork().
+ */
+static const struct test_case anon_test_cases[] = {
+	/*
+	 * Basic COW tests for fork() without any GUP. If we miss to break COW,
+	 * either the child can observe modifications by the parent or the
+	 * other way around.
+	 */
+	{
+		"Basic COW after fork()",
+		test_cow_in_parent,
+	},
+	/*
+	 * Basic test, but do an additional mprotect(PROT_READ)+
+	 * mprotect(PROT_READ|PROT_WRITE) in the parent before write access.
+	 */
+	{
+		"Basic COW after fork() with mprotect() optimization",
+		test_cow_in_parent_mprotect,
+	},
+	/*
+	 * vmsplice() [R/O GUP] + unmap in the child; modify in the parent. If
+	 * we miss to break COW, the child observes modifications by the parent.
+	 * This is CVE-2020-29374 reported by Jann Horn.
+	 */
+	{
+		"vmsplice() + unmap in child",
+		test_vmsplice_in_child
+	},
+	/*
+	 * vmsplice() test, but do an additional mprotect(PROT_READ)+
+	 * mprotect(PROT_READ|PROT_WRITE) in the parent before write access.
+	 */
+	{
+		"vmsplice() + unmap in child with mprotect() optimization",
+		test_vmsplice_in_child_mprotect
+	},
+	/*
+	 * vmsplice() [R/O GUP] in parent before fork(), unmap in parent after
+	 * fork(); modify in the child. If we miss to break COW, the parent
+	 * observes modifications by the child.
+	 */
+	{
+		"vmsplice() before fork(), unmap in parent after fork()",
+		test_vmsplice_before_fork,
+	},
+	/*
+	 * vmsplice() [R/O GUP] + unmap in parent after fork(); modify in the
+	 * child. If we miss to break COW, the parent observes modifications by
+	 * the child.
+	 */
+	{
+		"vmsplice() + unmap in parent after fork()",
+		test_vmsplice_after_fork,
+	},
+#ifdef LOCAL_CONFIG_HAVE_LIBURING
+	/*
+	 * Take a R/W longterm pin and then map the page R/O into the page
+	 * table to trigger a write fault on next access. When modifying the
+	 * page, the page content must be visible via the pin.
+	 */
+	{
+		"R/O-mapping a page registered as iouring fixed buffer",
+		test_iouring_ro,
+	},
+	/*
+	 * Take a R/W longterm pin and then fork() a child. When modifying the
+	 * page, the page content must be visible via the pin. We expect the
+	 * pinned page to not get shared with the child.
+	 */
+	{
+		"fork() with an iouring fixed buffer",
+		test_iouring_fork,
+	},
+
+#endif /* LOCAL_CONFIG_HAVE_LIBURING */
+	/*
+	 * Take a R/O longterm pin on a R/O-mapped shared anonymous page.
+	 * When modifying the page via the page table, the page content change
+	 * must be visible via the pin.
+	 */
+	{
+		"R/O GUP pin on R/O-mapped shared page",
+		test_ro_pin_on_shared,
+	},
+	/* Same as above, but using GUP-fast. */
+	{
+		"R/O GUP-fast pin on R/O-mapped shared page",
+		test_ro_fast_pin_on_shared,
+	},
+	/*
+	 * Take a R/O longterm pin on a R/O-mapped exclusive anonymous page that
+	 * was previously shared. When modifying the page via the page table,
+	 * the page content change must be visible via the pin.
+	 */
+	{
+		"R/O GUP pin on R/O-mapped previously-shared page",
+		test_ro_pin_on_ro_previously_shared,
+	},
+	/* Same as above, but using GUP-fast. */
+	{
+		"R/O GUP-fast pin on R/O-mapped previously-shared page",
+		test_ro_fast_pin_on_ro_previously_shared,
+	},
+	/*
+	 * Take a R/O longterm pin on a R/O-mapped exclusive anonymous page.
+	 * When modifying the page via the page table, the page content change
+	 * must be visible via the pin.
+	 */
+	{
+		"R/O GUP pin on R/O-mapped exclusive page",
+		test_ro_pin_on_ro_exclusive,
+	},
+	/* Same as above, but using GUP-fast. */
+	{
+		"R/O GUP-fast pin on R/O-mapped exclusive page",
+		test_ro_fast_pin_on_ro_exclusive,
+	},
+};
+
+static void run_anon_test_case(struct test_case const *test_case)
+{
+	int i;
+
+	run_with_base_page(test_case->fn, test_case->desc);
+	run_with_base_page_swap(test_case->fn, test_case->desc);
+	if (thpsize) {
+		run_with_thp(test_case->fn, test_case->desc);
+		run_with_thp_swap(test_case->fn, test_case->desc);
+		run_with_pte_mapped_thp(test_case->fn, test_case->desc);
+		run_with_pte_mapped_thp_swap(test_case->fn, test_case->desc);
+		run_with_single_pte_of_thp(test_case->fn, test_case->desc);
+		run_with_single_pte_of_thp_swap(test_case->fn, test_case->desc);
+		run_with_partial_mremap_thp(test_case->fn, test_case->desc);
+		run_with_partial_shared_thp(test_case->fn, test_case->desc);
+	}
+	for (i = 0; i < nr_hugetlbsizes; i++)
+		run_with_hugetlb(test_case->fn, test_case->desc,
+				 hugetlbsizes[i]);
+}
+
+static void run_anon_test_cases(void)
+{
+	int i;
+
+	ksft_print_msg("[INFO] Anonymous memory tests in private mappings\n");
+
+	for (i = 0; i < ARRAY_SIZE(anon_test_cases); i++)
+		run_anon_test_case(&anon_test_cases[i]);
+}
+
+static int tests_per_anon_test_case(void)
+{
+	int tests = 2 + nr_hugetlbsizes;
+
+	if (thpsize)
+		tests += 8;
+	return tests;
+}
+
+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)
+{
+	char *old = malloc(size);
+
+	/* Backup the original content. */
+	memcpy(old, smem, size);
+
+	/* Modify the page. */
+	memset(mem, 0xff, size);
+
+	/* See if we still read the old values via the other mapping. */
+	ksft_test_result(!memcmp(smem, old, size),
+			 "Other mapping not modified\n");
+	free(old);
+}
+
+static void test_ro_pin(char *mem, const char *smem, size_t size)
+{
+	do_test_ro_pin(mem, size, RO_PIN_TEST, false);
+}
+
+static void test_ro_fast_pin(char *mem, const char *smem, size_t size)
+{
+	do_test_ro_pin(mem, size, RO_PIN_TEST, true);
+}
+
+static void run_with_zeropage(non_anon_test_fn fn, const char *desc)
+{
+	char *mem, *smem, tmp;
+
+	ksft_print_msg("[RUN] %s ... with shared zeropage\n", desc);
+
+	mem = mmap(NULL, pagesize, PROT_READ | PROT_WRITE,
+		   MAP_PRIVATE | MAP_ANON, -1, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		return;
+	}
+
+	smem = mmap(NULL, pagesize, PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		goto munmap;
+	}
+
+	/* Read from the page to populate the shared zeropage. */
+	tmp = *mem + *smem;
+	asm volatile("" : "+r" (tmp));
+
+	fn(mem, smem, pagesize);
+munmap:
+	munmap(mem, pagesize);
+	if (smem != MAP_FAILED)
+		munmap(smem, pagesize);
+}
+
+static void run_with_huge_zeropage(non_anon_test_fn fn, const char *desc)
+{
+	char *mem, *smem, *mmap_mem, *mmap_smem, tmp;
+	size_t mmap_size;
+	int ret;
+
+	ksft_print_msg("[RUN] %s ... with huge zeropage\n", desc);
+
+	if (!has_huge_zeropage) {
+		ksft_test_result_skip("Huge zeropage not enabled\n");
+		return;
+	}
+
+	/* For alignment purposes, we need twice the thp size. */
+	mmap_size = 2 * thpsize;
+	mmap_mem = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (mmap_mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		return;
+	}
+	mmap_smem = mmap(NULL, mmap_size, PROT_READ,
+			 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (mmap_smem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		goto munmap;
+	}
+
+	/* We need a THP-aligned memory area. */
+	mem = (char *)(((uintptr_t)mmap_mem + thpsize) & ~(thpsize - 1));
+	smem = (char *)(((uintptr_t)mmap_smem + thpsize) & ~(thpsize - 1));
+
+	ret = madvise(mem, thpsize, MADV_HUGEPAGE);
+	ret |= madvise(smem, thpsize, MADV_HUGEPAGE);
+	if (ret) {
+		ksft_test_result_fail("MADV_HUGEPAGE failed\n");
+		goto munmap;
+	}
+
+	/*
+	 * Read from the memory to populate the huge shared zeropage. Read from
+	 * the first sub-page and test if we get another sub-page populated
+	 * automatically.
+	 */
+	tmp = *mem + *smem;
+	asm volatile("" : "+r" (tmp));
+	if (!pagemap_is_populated(pagemap_fd, mem + pagesize) ||
+	    !pagemap_is_populated(pagemap_fd, smem + pagesize)) {
+		ksft_test_result_skip("Did not get THPs populated\n");
+		goto munmap;
+	}
+
+	fn(mem, smem, thpsize);
+munmap:
+	munmap(mmap_mem, mmap_size);
+	if (mmap_smem != MAP_FAILED)
+		munmap(mmap_smem, mmap_size);
+}
+
+static void run_with_memfd(non_anon_test_fn fn, const char *desc)
+{
+	char *mem, *smem, tmp;
+	int fd;
+
+	ksft_print_msg("[RUN] %s ... with memfd\n", desc);
+
+	fd = memfd_create("test", 0);
+	if (fd < 0) {
+		ksft_test_result_fail("memfd_create() failed\n");
+		return;
+	}
+
+	/* File consists of a single page filled with zeroes. */
+	if (fallocate(fd, 0, 0, pagesize)) {
+		ksft_test_result_fail("fallocate() failed\n");
+		goto close;
+	}
+
+	/* Create a private mapping of the memfd. */
+	mem = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		goto close;
+	}
+	smem = mmap(NULL, pagesize, PROT_READ, MAP_SHARED, fd, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		goto munmap;
+	}
+
+	/* Fault the page in. */
+	tmp = *mem + *smem;
+	asm volatile("" : "+r" (tmp));
+
+	fn(mem, smem, pagesize);
+munmap:
+	munmap(mem, pagesize);
+	if (smem != MAP_FAILED)
+		munmap(smem, pagesize);
+close:
+	close(fd);
+}
+
+static void run_with_tmpfile(non_anon_test_fn fn, const char *desc)
+{
+	char *mem, *smem, tmp;
+	FILE *file;
+	int fd;
+
+	ksft_print_msg("[RUN] %s ... with tmpfile\n", desc);
+
+	file = tmpfile();
+	if (!file) {
+		ksft_test_result_fail("tmpfile() failed\n");
+		return;
+	}
+
+	fd = fileno(file);
+	if (fd < 0) {
+		ksft_test_result_skip("fileno() failed\n");
+		return;
+	}
+
+	/* File consists of a single page filled with zeroes. */
+	if (fallocate(fd, 0, 0, pagesize)) {
+		ksft_test_result_fail("fallocate() failed\n");
+		goto close;
+	}
+
+	/* Create a private mapping of the memfd. */
+	mem = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		goto close;
+	}
+	smem = mmap(NULL, pagesize, PROT_READ, MAP_SHARED, fd, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		goto munmap;
+	}
+
+	/* Fault the page in. */
+	tmp = *mem + *smem;
+	asm volatile("" : "+r" (tmp));
+
+	fn(mem, smem, pagesize);
+munmap:
+	munmap(mem, pagesize);
+	if (smem != MAP_FAILED)
+		munmap(smem, pagesize);
+close:
+	fclose(file);
+}
+
+static void run_with_memfd_hugetlb(non_anon_test_fn fn, const char *desc,
+				   size_t hugetlbsize)
+{
+	int flags = MFD_HUGETLB;
+	char *mem, *smem, tmp;
+	int fd;
+
+	ksft_print_msg("[RUN] %s ... with memfd hugetlb (%zu kB)\n", desc,
+		       hugetlbsize / 1024);
+
+	flags |= __builtin_ctzll(hugetlbsize) << MFD_HUGE_SHIFT;
+
+	fd = memfd_create("test", flags);
+	if (fd < 0) {
+		ksft_test_result_skip("memfd_create() failed\n");
+		return;
+	}
+
+	/* File consists of a single page filled with zeroes. */
+	if (fallocate(fd, 0, 0, hugetlbsize)) {
+		ksft_test_result_skip("need more free huge pages\n");
+		goto close;
+	}
+
+	/* Create a private mapping of the memfd. */
+	mem = mmap(NULL, hugetlbsize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd,
+		   0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_skip("need more free huge pages\n");
+		goto close;
+	}
+	smem = mmap(NULL, hugetlbsize, PROT_READ, MAP_SHARED, fd, 0);
+	if (mem == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		goto munmap;
+	}
+
+	/* Fault the page in. */
+	tmp = *mem + *smem;
+	asm volatile("" : "+r" (tmp));
+
+	fn(mem, smem, hugetlbsize);
+munmap:
+	munmap(mem, hugetlbsize);
+	if (mem != MAP_FAILED)
+		munmap(smem, hugetlbsize);
+close:
+	close(fd);
+}
+
+struct non_anon_test_case {
+	const char *desc;
+	non_anon_test_fn fn;
+};
+
+/*
+ * Test cases that target any pages in private mappings that are not anonymous:
+ * pages that may get shared via COW ndependent of fork(). This includes
+ * the shared zeropage(s), pagecache pages, ...
+ */
+static const struct non_anon_test_case non_anon_test_cases[] = {
+	/*
+	 * Basic COW test without any GUP. If we miss to break COW, changes are
+	 * visible via other private/shared mappings.
+	 */
+	{
+		"Basic COW",
+		test_cow,
+	},
+	/*
+	 * Take a R/O longterm pin. When modifying the page via the page table,
+	 * the page content change must be visible via the pin.
+	 */
+	{
+		"R/O longterm GUP pin",
+		test_ro_pin,
+	},
+	/* Same as above, but using GUP-fast. */
+	{
+		"R/O longterm GUP-fast pin",
+		test_ro_fast_pin,
+	},
+};
+
+static void run_non_anon_test_case(struct non_anon_test_case const *test_case)
+{
+	int i;
+
+	run_with_zeropage(test_case->fn, test_case->desc);
+	run_with_memfd(test_case->fn, test_case->desc);
+	run_with_tmpfile(test_case->fn, test_case->desc);
+	if (thpsize)
+		run_with_huge_zeropage(test_case->fn, test_case->desc);
+	for (i = 0; i < nr_hugetlbsizes; i++)
+		run_with_memfd_hugetlb(test_case->fn, test_case->desc,
+				       hugetlbsizes[i]);
+}
+
+static void run_non_anon_test_cases(void)
+{
+	int i;
+
+	ksft_print_msg("[RUN] Non-anonymous memory tests in private mappings\n");
+
+	for (i = 0; i < ARRAY_SIZE(non_anon_test_cases); i++)
+		run_non_anon_test_case(&non_anon_test_cases[i]);
+}
+
+static int tests_per_non_anon_test_case(void)
+{
+	int tests = 3 + nr_hugetlbsizes;
+
+	if (thpsize)
+		tests += 1;
+	return tests;
+}
+
+int main(int argc, char **argv)
+{
+	int err;
+
+	pagesize = getpagesize();
+	detect_thpsize();
+	detect_hugetlbsizes();
+	detect_huge_zeropage();
+
+	ksft_print_header();
+	ksft_set_plan(ARRAY_SIZE(anon_test_cases) * tests_per_anon_test_case() +
+		      ARRAY_SIZE(non_anon_test_cases) * tests_per_non_anon_test_case());
+
+	gup_fd = open("/sys/kernel/debug/gup_test", O_RDWR);
+	pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
+	if (pagemap_fd < 0)
+		ksft_exit_fail_msg("opening pagemap failed\n");
+
+	run_anon_test_cases();
+	run_non_anon_test_cases();
+
+	err = ksft_get_fail_cnt();
+	if (err)
+		ksft_exit_fail_msg("%d out of %d tests failed\n",
+				   err, ksft_test_num());
+	return ksft_exit_pass();
+}
diff --git a/tools/testing/selftests/vm/hugepage-mmap.c b/tools/testing/selftests/vm/hugepage-mmap.c
index 93f9e7b81331..955ef87f382c 100644
--- a/tools/testing/selftests/vm/hugepage-mmap.c
+++ b/tools/testing/selftests/vm/hugepage-mmap.c
@@ -16,14 +16,13 @@
  * range.
  * Other architectures, such as ppc64, i386 or x86_64 are not so constrained.
  */
-
+#define _GNU_SOURCE
 #include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>
 #include <sys/mman.h>
 #include <fcntl.h>
 
-#define FILE_NAME "huge/hugepagefile"
 #define LENGTH (256UL*1024*1024)
 #define PROTECTION (PROT_READ | PROT_WRITE)
 
@@ -67,16 +66,16 @@ int main(void)
 	void *addr;
 	int fd, ret;
 
-	fd = open(FILE_NAME, O_CREAT | O_RDWR, 0755);
+	fd = memfd_create("hugepage-mmap", MFD_HUGETLB);
 	if (fd < 0) {
-		perror("Open failed");
+		perror("memfd_create() failed");
 		exit(1);
 	}
 
 	addr = mmap(ADDR, LENGTH, PROTECTION, FLAGS, fd, 0);
 	if (addr == MAP_FAILED) {
 		perror("mmap");
-		unlink(FILE_NAME);
+		close(fd);
 		exit(1);
 	}
 
@@ -87,7 +86,6 @@ int main(void)
 
 	munmap(addr, LENGTH);
 	close(fd);
-	unlink(FILE_NAME);
 
 	return ret;
 }
diff --git a/tools/testing/selftests/vm/hugepage-mremap.c b/tools/testing/selftests/vm/hugepage-mremap.c
index e63a0214f639..e53b5eaa8fce 100644
--- a/tools/testing/selftests/vm/hugepage-mremap.c
+++ b/tools/testing/selftests/vm/hugepage-mremap.c
@@ -22,6 +22,7 @@
 #include <sys/syscall.h> /* Definition of SYS_* constants */
 #include <linux/userfaultfd.h>
 #include <sys/ioctl.h>
+#include <string.h>
 
 #define DEFAULT_LENGTH_MB 10UL
 #define MB_TO_BYTES(x) (x * 1024 * 1024)
@@ -108,26 +109,23 @@ static void register_region_with_uffd(char *addr, size_t len)
 int main(int argc, char *argv[])
 {
 	size_t length = 0;
+	int ret = 0, fd;
 
-	if (argc != 2 && argc != 3) {
-		printf("Usage: %s [length_in_MB] <hugetlb_file>\n", argv[0]);
+	if (argc >= 2 && !strcmp(argv[1], "-h")) {
+		printf("Usage: %s [length_in_MB]\n", argv[0]);
 		exit(1);
 	}
 
 	/* Read memory length as the first arg if valid, otherwise fallback to
 	 * the default length.
 	 */
-	if (argc == 3)
-		length = argc > 2 ? (size_t)atoi(argv[1]) : 0UL;
+	if (argc >= 2)
+		length = (size_t)atoi(argv[1]);
+	else
+		length = DEFAULT_LENGTH_MB;
 
-	length = length > 0 ? length : DEFAULT_LENGTH_MB;
 	length = MB_TO_BYTES(length);
-
-	int ret = 0;
-
-	/* last arg is the hugetlb file name */
-	int fd = open(argv[argc-1], O_CREAT | O_RDWR, 0755);
-
+	fd = memfd_create(argv[0], MFD_HUGETLB);
 	if (fd < 0) {
 		perror("Open failed");
 		exit(1);
@@ -185,7 +183,6 @@ int main(int argc, char *argv[])
 	}
 
 	close(fd);
-	unlink(argv[argc-1]);
 
 	return ret;
 }
diff --git a/tools/testing/selftests/vm/hugetlb-madvise.c b/tools/testing/selftests/vm/hugetlb-madvise.c
index 3c9943131881..a634f47d1e56 100644
--- a/tools/testing/selftests/vm/hugetlb-madvise.c
+++ b/tools/testing/selftests/vm/hugetlb-madvise.c
@@ -12,6 +12,7 @@
  * directory.
  */
 
+#define _GNU_SOURCE
 #include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>
@@ -19,7 +20,6 @@
 #define __USE_GNU
 #include <fcntl.h>
 
-#define USAGE	"USAGE: %s <hugepagefile_name>\n"
 #define MIN_FREE_PAGES	20
 #define NR_HUGE_PAGES	10	/* common number of pages to map/allocate */
 
@@ -103,11 +103,6 @@ int main(int argc, char **argv)
 	int fd;
 	int ret;
 
-	if (argc != 2) {
-		printf(USAGE, argv[0]);
-		exit(1);
-	}
-
 	huge_page_size = default_huge_page_size();
 	if (!huge_page_size) {
 		printf("Unable to determine huge page size, exiting!\n");
@@ -125,9 +120,9 @@ int main(int argc, char **argv)
 		exit(1);
 	}
 
-	fd = open(argv[1], O_CREAT | O_RDWR, 0755);
+	fd = memfd_create(argv[0], MFD_HUGETLB);
 	if (fd < 0) {
-		perror("Open failed");
+		perror("memfd_create() failed");
 		exit(1);
 	}
 
@@ -200,7 +195,7 @@ int main(int argc, char **argv)
 			exit(1);
 	}
 
-	/* addr + length should be aligned up to huge page size */
+	/* addr + length should be aligned down to huge page size */
 	if (madvise(addr,
 			((NR_HUGE_PAGES - 1) * huge_page_size) + base_page_size,
 			MADV_DONTNEED)) {
@@ -208,10 +203,11 @@ int main(int argc, char **argv)
 		exit(1);
 	}
 
-	/* should free all pages in mapping */
-	validate_free_pages(free_hugepages);
+	/* should free all but last page in mapping */
+	validate_free_pages(free_hugepages - 1);
 
 	(void)munmap(addr, NR_HUGE_PAGES * huge_page_size);
+	validate_free_pages(free_hugepages);
 
 	/*
 	 * Test MADV_DONTNEED on anonymous private mapping
@@ -406,6 +402,5 @@ int main(int argc, char **argv)
 	(void)munmap(addr2, NR_HUGE_PAGES * huge_page_size);
 
 	close(fd);
-	unlink(argv[1]);
 	return 0;
 }
diff --git a/tools/testing/selftests/vm/ksm_functional_tests.c b/tools/testing/selftests/vm/ksm_functional_tests.c
new file mode 100644
index 000000000000..b11b7e5115dc
--- /dev/null
+++ b/tools/testing/selftests/vm/ksm_functional_tests.c
@@ -0,0 +1,279 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * KSM functional tests
+ *
+ * Copyright 2022, Red Hat, Inc.
+ *
+ * Author(s): David Hildenbrand <david@redhat.com>
+ */
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <sys/ioctl.h>
+#include <linux/userfaultfd.h>
+
+#include "../kselftest.h"
+#include "vm_util.h"
+
+#define KiB 1024u
+#define MiB (1024 * KiB)
+
+static int ksm_fd;
+static int ksm_full_scans_fd;
+static int pagemap_fd;
+static size_t pagesize;
+
+static bool range_maps_duplicates(char *addr, unsigned long size)
+{
+	unsigned long offs_a, offs_b, pfn_a, pfn_b;
+
+	/*
+	 * 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.
+	 */
+	for (offs_a = 0; offs_a < size; offs_a += pagesize) {
+		pfn_a = pagemap_get_pfn(pagemap_fd, addr + offs_a);
+		/* Page not present or PFN not exposed by the kernel. */
+		if (pfn_a == -1ul || !pfn_a)
+			continue;
+
+		for (offs_b = offs_a + pagesize; offs_b < size;
+		     offs_b += pagesize) {
+			pfn_b = pagemap_get_pfn(pagemap_fd, addr + offs_b);
+			if (pfn_b == -1ul || !pfn_b)
+				continue;
+			if (pfn_a == pfn_b)
+				return true;
+		}
+	}
+	return false;
+}
+
+static long ksm_get_full_scans(void)
+{
+	char buf[10];
+	ssize_t ret;
+
+	ret = pread(ksm_full_scans_fd, buf, sizeof(buf) - 1, 0);
+	if (ret <= 0)
+		return -errno;
+	buf[ret] = 0;
+
+	return strtol(buf, NULL, 10);
+}
+
+static int ksm_merge(void)
+{
+	long start_scans, end_scans;
+
+	/* Wait for two full scans such that any possible merging happened. */
+	start_scans = ksm_get_full_scans();
+	if (start_scans < 0)
+		return start_scans;
+	if (write(ksm_fd, "1", 1) != 1)
+		return -errno;
+	do {
+		end_scans = ksm_get_full_scans();
+		if (end_scans < 0)
+			return end_scans;
+	} while (end_scans < start_scans + 2);
+
+	return 0;
+}
+
+static char *mmap_and_merge_range(char val, unsigned long size)
+{
+	char *map;
+
+	map = mmap(NULL, size, PROT_READ|PROT_WRITE,
+		   MAP_PRIVATE|MAP_ANON, -1, 0);
+	if (map == MAP_FAILED) {
+		ksft_test_result_fail("mmap() failed\n");
+		return MAP_FAILED;
+	}
+
+	/* Don't use THP. Ignore if THP are not around on a kernel. */
+	if (madvise(map, size, MADV_NOHUGEPAGE) && errno != EINVAL) {
+		ksft_test_result_fail("MADV_NOHUGEPAGE failed\n");
+		goto unmap;
+	}
+
+	/* Make sure each page contains the same values to merge them. */
+	memset(map, val, size);
+	if (madvise(map, size, MADV_MERGEABLE)) {
+		ksft_test_result_fail("MADV_MERGEABLE failed\n");
+		goto unmap;
+	}
+
+	/* Run KSM to trigger merging and wait. */
+	if (ksm_merge()) {
+		ksft_test_result_fail("Running KSM failed\n");
+		goto unmap;
+	}
+	return map;
+unmap:
+	munmap(map, size);
+	return MAP_FAILED;
+}
+
+static void test_unmerge(void)
+{
+	const unsigned int size = 2 * MiB;
+	char *map;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	map = mmap_and_merge_range(0xcf, size);
+	if (map == MAP_FAILED)
+		return;
+
+	if (madvise(map, size, MADV_UNMERGEABLE)) {
+		ksft_test_result_fail("MADV_UNMERGEABLE failed\n");
+		goto unmap;
+	}
+
+	ksft_test_result(!range_maps_duplicates(map, size),
+			 "Pages were unmerged\n");
+unmap:
+	munmap(map, size);
+}
+
+static void test_unmerge_discarded(void)
+{
+	const unsigned int size = 2 * MiB;
+	char *map;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	map = mmap_and_merge_range(0xcf, size);
+	if (map == MAP_FAILED)
+		return;
+
+	/* Discard half of all mapped pages so we have pte_none() entries. */
+	if (madvise(map, size / 2, MADV_DONTNEED)) {
+		ksft_test_result_fail("MADV_DONTNEED failed\n");
+		goto unmap;
+	}
+
+	if (madvise(map, size, MADV_UNMERGEABLE)) {
+		ksft_test_result_fail("MADV_UNMERGEABLE failed\n");
+		goto unmap;
+	}
+
+	ksft_test_result(!range_maps_duplicates(map, size),
+			 "Pages were unmerged\n");
+unmap:
+	munmap(map, size);
+}
+
+#ifdef __NR_userfaultfd
+static void test_unmerge_uffd_wp(void)
+{
+	struct uffdio_writeprotect uffd_writeprotect;
+	struct uffdio_register uffdio_register;
+	const unsigned int size = 2 * MiB;
+	struct uffdio_api uffdio_api;
+	char *map;
+	int uffd;
+
+	ksft_print_msg("[RUN] %s\n", __func__);
+
+	map = mmap_and_merge_range(0xcf, size);
+	if (map == MAP_FAILED)
+		return;
+
+	/* See if UFFD is around. */
+	uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
+	if (uffd < 0) {
+		ksft_test_result_skip("__NR_userfaultfd failed\n");
+		goto unmap;
+	}
+
+	/* See if UFFD-WP is around. */
+	uffdio_api.api = UFFD_API;
+	uffdio_api.features = UFFD_FEATURE_PAGEFAULT_FLAG_WP;
+	if (ioctl(uffd, UFFDIO_API, &uffdio_api) < 0) {
+		ksft_test_result_fail("UFFDIO_API failed\n");
+		goto close_uffd;
+	}
+	if (!(uffdio_api.features & UFFD_FEATURE_PAGEFAULT_FLAG_WP)) {
+		ksft_test_result_skip("UFFD_FEATURE_PAGEFAULT_FLAG_WP not available\n");
+		goto close_uffd;
+	}
+
+	/* Register UFFD-WP, no need for an actual handler. */
+	uffdio_register.range.start = (unsigned long) map;
+	uffdio_register.range.len = size;
+	uffdio_register.mode = UFFDIO_REGISTER_MODE_WP;
+	if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) < 0) {
+		ksft_test_result_fail("UFFDIO_REGISTER_MODE_WP failed\n");
+		goto close_uffd;
+	}
+
+	/* Write-protect the range using UFFD-WP. */
+	uffd_writeprotect.range.start = (unsigned long) map;
+	uffd_writeprotect.range.len = size;
+	uffd_writeprotect.mode = UFFDIO_WRITEPROTECT_MODE_WP;
+	if (ioctl(uffd, UFFDIO_WRITEPROTECT, &uffd_writeprotect)) {
+		ksft_test_result_fail("UFFDIO_WRITEPROTECT failed\n");
+		goto close_uffd;
+	}
+
+	if (madvise(map, size, MADV_UNMERGEABLE)) {
+		ksft_test_result_fail("MADV_UNMERGEABLE failed\n");
+		goto close_uffd;
+	}
+
+	ksft_test_result(!range_maps_duplicates(map, size),
+			 "Pages were unmerged\n");
+close_uffd:
+	close(uffd);
+unmap:
+	munmap(map, size);
+}
+#endif
+
+int main(int argc, char **argv)
+{
+	unsigned int tests = 2;
+	int err;
+
+#ifdef __NR_userfaultfd
+	tests++;
+#endif
+
+	ksft_print_header();
+	ksft_set_plan(tests);
+
+	pagesize = getpagesize();
+
+	ksm_fd = open("/sys/kernel/mm/ksm/run", O_RDWR);
+	if (ksm_fd < 0)
+		ksft_exit_skip("open(\"/sys/kernel/mm/ksm/run\") failed\n");
+	ksm_full_scans_fd = open("/sys/kernel/mm/ksm/full_scans", O_RDONLY);
+	if (ksm_full_scans_fd < 0)
+		ksft_exit_skip("open(\"/sys/kernel/mm/ksm/full_scans\") failed\n");
+	pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
+	if (pagemap_fd < 0)
+		ksft_exit_skip("open(\"/proc/self/pagemap\") failed\n");
+
+	test_unmerge();
+	test_unmerge_discarded();
+#ifdef __NR_userfaultfd
+	test_unmerge_uffd_wp();
+#endif
+
+	err = ksft_get_fail_cnt();
+	if (err)
+		ksft_exit_fail_msg("%d out of %d tests failed\n",
+				   err, ksft_test_num());
+	return ksft_exit_pass();
+}
diff --git a/tools/testing/selftests/vm/ksm_tests.c b/tools/testing/selftests/vm/ksm_tests.c
index 0d85be2350fa..f9eb4d67e0dd 100644
--- a/tools/testing/selftests/vm/ksm_tests.c
+++ b/tools/testing/selftests/vm/ksm_tests.c
@@ -40,6 +40,7 @@ enum ksm_test_name {
 	CHECK_KSM_NUMA_MERGE,
 	KSM_MERGE_TIME,
 	KSM_MERGE_TIME_HUGE_PAGES,
+	KSM_UNMERGE_TIME,
 	KSM_COW_TIME
 };
 
@@ -108,7 +109,10 @@ static void print_help(void)
 	       " -P evaluate merging time and speed.\n"
 	       "    For this test, the size of duplicated memory area (in MiB)\n"
 	       "    must be provided using -s option\n"
-				 " -H evaluate merging time and speed of area allocated mostly with huge pages\n"
+	       " -H evaluate merging time and speed of area allocated mostly with huge pages\n"
+	       "    For this test, the size of duplicated memory area (in MiB)\n"
+	       "    must be provided using -s option\n"
+	       " -D evaluate unmerging time and speed when disabling KSM.\n"
 	       "    For this test, the size of duplicated memory area (in MiB)\n"
 	       "    must be provided using -s option\n"
 	       " -C evaluate the time required to break COW of merged pages.\n\n");
@@ -188,6 +192,16 @@ static int ksm_merge_pages(void *addr, size_t size, struct timespec start_time,
 	return 0;
 }
 
+static int ksm_unmerge_pages(void *addr, size_t size,
+			     struct timespec start_time, int timeout)
+{
+	if (madvise(addr, size, MADV_UNMERGEABLE)) {
+		perror("madvise");
+		return 1;
+	}
+	return 0;
+}
+
 static bool assert_ksm_pages_count(long dupl_page_count)
 {
 	unsigned long max_page_sharing, pages_sharing, pages_shared;
@@ -560,6 +574,53 @@ err_out:
 	return KSFT_FAIL;
 }
 
+static int ksm_unmerge_time(int mapping, int prot, int timeout, size_t map_size)
+{
+	void *map_ptr;
+	struct timespec start_time, end_time;
+	unsigned long scan_time_ns;
+
+	map_size *= MB;
+
+	map_ptr = allocate_memory(NULL, prot, mapping, '*', map_size);
+	if (!map_ptr)
+		return KSFT_FAIL;
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		goto err_out;
+	}
+	if (ksm_merge_pages(map_ptr, map_size, start_time, timeout))
+		goto err_out;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		goto err_out;
+	}
+	if (ksm_unmerge_pages(map_ptr, map_size, start_time, timeout))
+		goto err_out;
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &end_time)) {
+		perror("clock_gettime");
+		goto err_out;
+	}
+
+	scan_time_ns = (end_time.tv_sec - start_time.tv_sec) * NSEC_PER_SEC +
+		       (end_time.tv_nsec - start_time.tv_nsec);
+
+	printf("Total size:    %lu MiB\n", map_size / MB);
+	printf("Total time:    %ld.%09ld s\n", scan_time_ns / NSEC_PER_SEC,
+	       scan_time_ns % NSEC_PER_SEC);
+	printf("Average speed:  %.3f MiB/s\n", (map_size / MB) /
+					       ((double)scan_time_ns / NSEC_PER_SEC));
+
+	munmap(map_ptr, map_size);
+	return KSFT_PASS;
+
+err_out:
+	printf("Not OK\n");
+	munmap(map_ptr, map_size);
+	return KSFT_FAIL;
+}
+
 static int ksm_cow_time(int mapping, int prot, int timeout, size_t page_size)
 {
 	void *map_ptr;
@@ -644,7 +705,7 @@ int main(int argc, char *argv[])
 	bool merge_across_nodes = KSM_MERGE_ACROSS_NODES_DEFAULT;
 	long size_MB = 0;
 
-	while ((opt = getopt(argc, argv, "ha:p:l:z:m:s:MUZNPCH")) != -1) {
+	while ((opt = getopt(argc, argv, "ha:p:l:z:m:s:MUZNPCHD")) != -1) {
 		switch (opt) {
 		case 'a':
 			prot = str_to_prot(optarg);
@@ -701,6 +762,9 @@ int main(int argc, char *argv[])
 		case 'H':
 			test_name = KSM_MERGE_TIME_HUGE_PAGES;
 			break;
+		case 'D':
+			test_name = KSM_UNMERGE_TIME;
+			break;
 		case 'C':
 			test_name = KSM_COW_TIME;
 			break;
@@ -762,6 +826,14 @@ int main(int argc, char *argv[])
 		ret = ksm_merge_hugepages_time(MAP_PRIVATE | MAP_ANONYMOUS, prot,
 				ksm_scan_limit_sec, size_MB);
 		break;
+	case KSM_UNMERGE_TIME:
+		if (size_MB == 0) {
+			printf("Option '-s' is required.\n");
+			return KSFT_FAIL;
+		}
+		ret = ksm_unmerge_time(MAP_PRIVATE | MAP_ANONYMOUS, prot,
+				       ksm_scan_limit_sec, size_MB);
+		break;
 	case KSM_COW_TIME:
 		ret = ksm_cow_time(MAP_PRIVATE | MAP_ANONYMOUS, prot, ksm_scan_limit_sec,
 				   page_size);
diff --git a/tools/testing/selftests/vm/madv_populate.c b/tools/testing/selftests/vm/madv_populate.c
index 715a42e8e2cd..262eae6b58f2 100644
--- a/tools/testing/selftests/vm/madv_populate.c
+++ b/tools/testing/selftests/vm/madv_populate.c
@@ -20,6 +20,13 @@
 #include "../kselftest.h"
 #include "vm_util.h"
 
+#ifndef MADV_POPULATE_READ
+#define MADV_POPULATE_READ	22
+#endif /* MADV_POPULATE_READ */
+#ifndef MADV_POPULATE_WRITE
+#define MADV_POPULATE_WRITE	23
+#endif /* MADV_POPULATE_WRITE */
+
 /*
  * For now, we're using 2 MiB of private anonymous memory for all tests.
  */
@@ -27,14 +34,6 @@
 
 static size_t pagesize;
 
-static bool pagemap_is_populated(int fd, char *start)
-{
-	uint64_t entry = pagemap_get_entry(fd, start);
-
-	/* Present or swapped. */
-	return entry & 0xc000000000000000ull;
-}
-
 static void sense_support(void)
 {
 	char *addr;
diff --git a/tools/testing/selftests/vm/run_vmtests.sh b/tools/testing/selftests/vm/run_vmtests.sh
index e780e76c26b8..8984e0bb58c7 100755
--- a/tools/testing/selftests/vm/run_vmtests.sh
+++ b/tools/testing/selftests/vm/run_vmtests.sh
@@ -1,14 +1,88 @@
 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
-#please run as root
+# Please run as root
 
 # Kselftest framework requirement - SKIP code is 4.
 ksft_skip=4
 
-mnt=./huge
 exitcode=0
 
-#get huge pagesize and freepages from /proc/meminfo
+usage() {
+	cat <<EOF
+usage: ${BASH_SOURCE[0]:-$0} [ -h | -t "<categories>"]
+  -t: specify specific categories to tests to run
+  -h: display this message
+
+The default behavior is to run all tests.
+
+Alternatively, specific groups tests can be run by passing a string
+to the -t argument containing one or more of the following categories
+separated by spaces:
+- mmap
+	tests for mmap(2)
+- gup_test
+	tests for gup using gup_test interface
+- userfaultfd
+	tests for  userfaultfd(2)
+- compaction
+	a test for the patch "Allow compaction of unevictable pages"
+- mlock
+	tests for mlock(2)
+- mremap
+	tests for mremap(2)
+- hugevm
+	tests for very large virtual address space
+- vmalloc
+	vmalloc smoke tests
+- hmm
+	hmm smoke tests
+- madv_populate
+	test memadvise(2) MADV_POPULATE_{READ,WRITE} options
+- memfd_secret
+	test memfd_secret(2)
+- process_mrelease
+	test process_mrelease(2)
+- ksm
+	ksm tests that do not require >=2 NUMA nodes
+- ksm_numa
+	ksm tests that require >=2 NUMA nodes
+- pkey
+	memory protection key tests
+- soft_dirty
+	test soft dirty page bit semantics
+- cow
+	test copy-on-write semantics
+example: ./run_vmtests.sh -t "hmm mmap ksm"
+EOF
+	exit 0
+}
+
+
+while getopts "ht:" OPT; do
+	case ${OPT} in
+		"h") usage ;;
+		"t") VM_SELFTEST_ITEMS=${OPTARG} ;;
+	esac
+done
+shift $((OPTIND -1))
+
+# default behavior: run all tests
+VM_SELFTEST_ITEMS=${VM_SELFTEST_ITEMS:-default}
+
+test_selected() {
+	if [ "$VM_SELFTEST_ITEMS" == "default" ]; then
+		# If no VM_SELFTEST_ITEMS are specified, run all tests
+		return 0
+	fi
+	# If test selected argument is one of the test items
+	if [[ " ${VM_SELFTEST_ITEMS[*]} " =~ " ${1} " ]]; then
+	        return 0
+	else
+	        return 1
+	fi
+}
+
+# get huge pagesize and freepages from /proc/meminfo
 while read -r name size unit; do
 	if [ "$name" = "HugePages_Free:" ]; then
 		freepgs="$size"
@@ -28,7 +102,7 @@ hpgsize_MB=$((hpgsize_KB / 1024))
 half_ufd_size_MB=$((((nr_cpus * hpgsize_MB + 127) / 128) * 128))
 needmem_KB=$((half_ufd_size_MB * 2 * 1024))
 
-#set proper nr_hugepages
+# set proper nr_hugepages
 if [ -n "$freepgs" ] && [ -n "$hpgsize_KB" ]; then
 	nr_hugepgs=$(cat /proc/sys/vm/nr_hugepages)
 	needpgs=$((needmem_KB / hpgsize_KB))
@@ -57,144 +131,144 @@ else
 	exit 1
 fi
 
-#filter 64bit architectures
+# filter 64bit architectures
 ARCH64STR="arm64 ia64 mips64 parisc64 ppc64 ppc64le riscv64 s390x sh64 sparc64 x86_64"
 if [ -z "$ARCH" ]; then
 	ARCH=$(uname -m 2>/dev/null | sed -e 's/aarch64.*/arm64/')
 fi
 VADDR64=0
-echo "$ARCH64STR" | grep "$ARCH" && VADDR64=1
+echo "$ARCH64STR" | grep "$ARCH" &>/dev/null && VADDR64=1
 
 # Usage: run_test [test binary] [arbitrary test arguments...]
 run_test() {
-	local title="running $*"
-	local sep=$(echo -n "$title" | tr "[:graph:][:space:]" -)
-	printf "%s\n%s\n%s\n" "$sep" "$title" "$sep"
-
-	"$@"
-	local ret=$?
-	if [ $ret -eq 0 ]; then
-		echo "[PASS]"
-	elif [ $ret -eq $ksft_skip ]; then
-		echo "[SKIP]"
-		exitcode=$ksft_skip
-	else
-		echo "[FAIL]"
-		exitcode=1
-	fi
+	if test_selected ${CATEGORY}; then
+		local title="running $*"
+		local sep=$(echo -n "$title" | tr "[:graph:][:space:]" -)
+		printf "%s\n%s\n%s\n" "$sep" "$title" "$sep"
+
+		"$@"
+		local ret=$?
+		if [ $ret -eq 0 ]; then
+			echo "[PASS]"
+		elif [ $ret -eq $ksft_skip ]; then
+			echo "[SKIP]"
+			exitcode=$ksft_skip
+		else
+			echo "[FAIL]"
+			exitcode=1
+		fi
+	fi # test_selected
 }
 
-mkdir "$mnt"
-mount -t hugetlbfs none "$mnt"
-
-run_test ./hugepage-mmap
+CATEGORY="hugetlb" run_test ./hugepage-mmap
 
 shmmax=$(cat /proc/sys/kernel/shmmax)
 shmall=$(cat /proc/sys/kernel/shmall)
 echo 268435456 > /proc/sys/kernel/shmmax
 echo 4194304 > /proc/sys/kernel/shmall
-run_test ./hugepage-shm
+CATEGORY="hugetlb" run_test ./hugepage-shm
 echo "$shmmax" > /proc/sys/kernel/shmmax
 echo "$shmall" > /proc/sys/kernel/shmall
 
-run_test ./map_hugetlb
-
-run_test ./hugepage-mremap "$mnt"/huge_mremap
-rm -f "$mnt"/huge_mremap
-
-run_test ./hugepage-vmemmap
+CATEGORY="hugetlb" run_test ./map_hugetlb
+CATEGORY="hugetlb" run_test ./hugepage-mremap
+CATEGORY="hugetlb" run_test ./hugepage-vmemmap
+CATEGORY="hugetlb" run_test ./hugetlb-madvise
 
-run_test ./hugetlb-madvise "$mnt"/madvise-test
-rm -f "$mnt"/madvise-test
-
-echo "NOTE: The above hugetlb tests provide minimal coverage.  Use"
-echo "      https://github.com/libhugetlbfs/libhugetlbfs.git for"
-echo "      hugetlb regression testing."
+if test_selected "hugetlb"; then
+	echo "NOTE: These hugetlb tests provide minimal coverage.  Use"
+	echo "      https://github.com/libhugetlbfs/libhugetlbfs.git for"
+	echo "      hugetlb regression testing."
+fi
 
-run_test ./map_fixed_noreplace
+CATEGORY="mmap" run_test ./map_fixed_noreplace
 
 # get_user_pages_fast() benchmark
-run_test ./gup_test -u
+CATEGORY="gup_test" run_test ./gup_test -u
 # pin_user_pages_fast() benchmark
-run_test ./gup_test -a
+CATEGORY="gup_test" run_test ./gup_test -a
 # Dump pages 0, 19, and 4096, using pin_user_pages:
-run_test ./gup_test -ct -F 0x1 0 19 0x1000
+CATEGORY="gup_test" run_test ./gup_test -ct -F 0x1 0 19 0x1000
 
 uffd_mods=("" ":dev")
 for mod in "${uffd_mods[@]}"; do
-	run_test ./userfaultfd anon${mod} 20 16
+	CATEGORY="userfaultfd" run_test ./userfaultfd anon${mod} 20 16
 	# Hugetlb tests require source and destination huge pages. Pass in half
 	# the size ($half_ufd_size_MB), which is used for *each*.
-	run_test ./userfaultfd hugetlb${mod} "$half_ufd_size_MB" 32
-	run_test ./userfaultfd hugetlb_shared${mod} "$half_ufd_size_MB" 32 "$mnt"/uffd-test
-	rm -f "$mnt"/uffd-test
-	run_test ./userfaultfd shmem${mod} 20 16
+	CATEGORY="userfaultfd" run_test ./userfaultfd hugetlb${mod} "$half_ufd_size_MB" 32
+	CATEGORY="userfaultfd" run_test ./userfaultfd hugetlb_shared${mod} "$half_ufd_size_MB" 32
+	CATEGORY="userfaultfd" run_test ./userfaultfd shmem${mod} 20 16
 done
 
 #cleanup
-umount "$mnt"
-rm -rf "$mnt"
 echo "$nr_hugepgs" > /proc/sys/vm/nr_hugepages
 
-run_test ./compaction_test
+CATEGORY="compaction" run_test ./compaction_test
 
-run_test sudo -u nobody ./on-fault-limit
+CATEGORY="mlock" run_test sudo -u nobody ./on-fault-limit
 
-run_test ./map_populate
+CATEGORY="mmap" run_test ./map_populate
 
-run_test ./mlock-random-test
+CATEGORY="mlock" run_test ./mlock-random-test
 
-run_test ./mlock2-tests
+CATEGORY="mlock" run_test ./mlock2-tests
 
-run_test ./mrelease_test
+CATEGORY="process_mrelease" run_test ./mrelease_test
 
-run_test ./mremap_test
+CATEGORY="mremap" run_test ./mremap_test
 
-run_test ./thuge-gen
+CATEGORY="hugetlb" run_test ./thuge-gen
 
 if [ $VADDR64 -ne 0 ]; then
-	run_test ./virtual_address_range
+	CATEGORY="hugevm" run_test ./virtual_address_range
 
 	# virtual address 128TB switch test
-	run_test ./va_128TBswitch.sh
+	CATEGORY="hugevm" run_test ./va_128TBswitch.sh
 fi # VADDR64
 
 # vmalloc stability smoke test
-run_test ./test_vmalloc.sh smoke
+CATEGORY="vmalloc" run_test ./test_vmalloc.sh smoke
 
-run_test ./mremap_dontunmap
+CATEGORY="mremap" run_test ./mremap_dontunmap
 
-run_test ./test_hmm.sh smoke
+CATEGORY="hmm" run_test ./test_hmm.sh smoke
 
 # MADV_POPULATE_READ and MADV_POPULATE_WRITE tests
-run_test ./madv_populate
+CATEGORY="madv_populate" run_test ./madv_populate
 
-run_test ./memfd_secret
+CATEGORY="memfd_secret" run_test ./memfd_secret
 
 # KSM MADV_MERGEABLE test with 10 identical pages
-run_test ./ksm_tests -M -p 10
+CATEGORY="ksm" run_test ./ksm_tests -M -p 10
 # KSM unmerge test
-run_test ./ksm_tests -U
+CATEGORY="ksm" run_test ./ksm_tests -U
 # KSM test with 10 zero pages and use_zero_pages = 0
-run_test ./ksm_tests -Z -p 10 -z 0
+CATEGORY="ksm" run_test ./ksm_tests -Z -p 10 -z 0
 # KSM test with 10 zero pages and use_zero_pages = 1
-run_test ./ksm_tests -Z -p 10 -z 1
+CATEGORY="ksm" run_test ./ksm_tests -Z -p 10 -z 1
 # KSM test with 2 NUMA nodes and merge_across_nodes = 1
-run_test ./ksm_tests -N -m 1
+CATEGORY="ksm_numa" run_test ./ksm_tests -N -m 1
 # KSM test with 2 NUMA nodes and merge_across_nodes = 0
-run_test ./ksm_tests -N -m 0
+CATEGORY="ksm_numa" run_test ./ksm_tests -N -m 0
+
+CATEGORY="ksm" run_test ./ksm_functional_tests
+
+run_test ./ksm_functional_tests
 
 # protection_keys tests
 if [ -x ./protection_keys_32 ]
 then
-	run_test ./protection_keys_32
+	CATEGORY="pkey" run_test ./protection_keys_32
 fi
 
 if [ -x ./protection_keys_64 ]
 then
-	run_test ./protection_keys_64
+	CATEGORY="pkey" run_test ./protection_keys_64
 fi
 
-run_test ./soft-dirty
+CATEGORY="soft_dirty" run_test ./soft-dirty
+
+# COW tests
+CATEGORY="cow" run_test ./cow
 
 exit $exitcode
diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
index 297f250c1d95..7f22844ed704 100644
--- a/tools/testing/selftests/vm/userfaultfd.c
+++ b/tools/testing/selftests/vm/userfaultfd.c
@@ -93,10 +93,8 @@ static volatile bool test_uffdio_zeropage_eexist = true;
 static bool test_uffdio_wp = true;
 /* Whether to test uffd minor faults */
 static bool test_uffdio_minor = false;
-
 static bool map_shared;
-static int shm_fd;
-static int huge_fd;
+static int mem_fd;
 static unsigned long long *count_verify;
 static int uffd = -1;
 static int uffd_flags, finished, *pipefd;
@@ -143,7 +141,7 @@ const char *examples =
     "# Run hugetlb memory test on 256MiB region with 50 bounces:\n"
     "./userfaultfd hugetlb 256 50\n\n"
     "# Run the same hugetlb test but using shared file:\n"
-    "./userfaultfd hugetlb_shared 256 50 /dev/hugepages/hugefile\n\n"
+    "./userfaultfd hugetlb_shared 256 50\n\n"
     "# 10MiB-~6GiB 999 bounces anonymous test, "
     "continue forever unless an error triggers\n"
     "while ./userfaultfd anon $[RANDOM % 6000 + 10] 999; do true; done\n\n";
@@ -260,35 +258,21 @@ static void hugetlb_release_pages(char *rel_area)
 
 static void hugetlb_allocate_area(void **alloc_area, bool is_src)
 {
+	off_t size = nr_pages * page_size;
+	off_t offset = is_src ? 0 : size;
 	void *area_alias = NULL;
 	char **alloc_area_alias;
 
-	if (!map_shared)
-		*alloc_area = mmap(NULL,
-			nr_pages * page_size,
-			PROT_READ | PROT_WRITE,
-			MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB |
-				(is_src ? 0 : MAP_NORESERVE),
-			-1,
-			0);
-	else
-		*alloc_area = mmap(NULL,
-			nr_pages * page_size,
-			PROT_READ | PROT_WRITE,
-			MAP_SHARED |
-				(is_src ? 0 : MAP_NORESERVE),
-			huge_fd,
-			is_src ? 0 : nr_pages * page_size);
+	*alloc_area = mmap(NULL, size, PROT_READ | PROT_WRITE,
+			   (map_shared ? MAP_SHARED : MAP_PRIVATE) |
+			   (is_src ? 0 : MAP_NORESERVE),
+			   mem_fd, offset);
 	if (*alloc_area == MAP_FAILED)
 		err("mmap of hugetlbfs file failed");
 
 	if (map_shared) {
-		area_alias = mmap(NULL,
-			nr_pages * page_size,
-			PROT_READ | PROT_WRITE,
-			MAP_SHARED,
-			huge_fd,
-			is_src ? 0 : nr_pages * page_size);
+		area_alias = mmap(NULL, size, PROT_READ | PROT_WRITE,
+				  MAP_SHARED, mem_fd, offset);
 		if (area_alias == MAP_FAILED)
 			err("mmap of hugetlb file alias failed");
 	}
@@ -334,14 +318,14 @@ static void shmem_allocate_area(void **alloc_area, bool is_src)
 	}
 
 	*alloc_area = mmap(p, bytes, PROT_READ | PROT_WRITE, MAP_SHARED,
-			   shm_fd, offset);
+			   mem_fd, offset);
 	if (*alloc_area == MAP_FAILED)
 		err("mmap of memfd failed");
 	if (test_collapse && *alloc_area != p)
 		err("mmap of memfd failed at %p", p);
 
 	area_alias = mmap(p_alias, bytes, PROT_READ | PROT_WRITE, MAP_SHARED,
-			  shm_fd, offset);
+			  mem_fd, offset);
 	if (area_alias == MAP_FAILED)
 		err("mmap of memfd alias failed");
 	if (test_collapse && area_alias != p_alias)
@@ -1841,21 +1825,17 @@ int main(int argc, char **argv)
 	}
 	nr_pages = nr_pages_per_cpu * nr_cpus;
 
-	if (test_type == TEST_HUGETLB && map_shared) {
-		if (argc < 5)
-			usage();
-		huge_fd = open(argv[4], O_CREAT | O_RDWR, 0755);
-		if (huge_fd < 0)
-			err("Open of %s failed", argv[4]);
-		if (ftruncate(huge_fd, 0))
-			err("ftruncate %s to size 0 failed", argv[4]);
-	} else if (test_type == TEST_SHMEM) {
-		shm_fd = memfd_create(argv[0], 0);
-		if (shm_fd < 0)
+	if (test_type == TEST_SHMEM || test_type == TEST_HUGETLB) {
+		unsigned int memfd_flags = 0;
+
+		if (test_type == TEST_HUGETLB)
+			memfd_flags = MFD_HUGETLB;
+		mem_fd = memfd_create(argv[0], memfd_flags);
+		if (mem_fd < 0)
 			err("memfd_create");
-		if (ftruncate(shm_fd, nr_pages * page_size * 2))
+		if (ftruncate(mem_fd, nr_pages * page_size * 2))
 			err("ftruncate");
-		if (fallocate(shm_fd,
+		if (fallocate(mem_fd,
 			      FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, 0,
 			      nr_pages * page_size * 2))
 			err("fallocate");
diff --git a/tools/testing/selftests/vm/vm_util.c b/tools/testing/selftests/vm/vm_util.c
index f11f8adda521..40e795624ff3 100644
--- a/tools/testing/selftests/vm/vm_util.c
+++ b/tools/testing/selftests/vm/vm_util.c
@@ -28,6 +28,31 @@ bool pagemap_is_softdirty(int fd, char *start)
 	return entry & 0x0080000000000000ull;
 }
 
+bool pagemap_is_swapped(int fd, char *start)
+{
+	uint64_t entry = pagemap_get_entry(fd, start);
+
+	return entry & 0x4000000000000000ull;
+}
+
+bool pagemap_is_populated(int fd, char *start)
+{
+	uint64_t entry = pagemap_get_entry(fd, start);
+
+	/* Present or swapped. */
+	return entry & 0xc000000000000000ull;
+}
+
+unsigned long pagemap_get_pfn(int fd, char *start)
+{
+	uint64_t entry = pagemap_get_entry(fd, start);
+
+	/* If present (63th bit), PFN is at bit 0 -- 54. */
+	if (entry & 0x8000000000000000ull)
+		return entry & 0x007fffffffffffffull;
+	return -1ul;
+}
+
 void clear_softdirty(void)
 {
 	int ret;
diff --git a/tools/testing/selftests/vm/vm_util.h b/tools/testing/selftests/vm/vm_util.h
index 5c35de454e08..1995ee911ef2 100644
--- a/tools/testing/selftests/vm/vm_util.h
+++ b/tools/testing/selftests/vm/vm_util.h
@@ -4,6 +4,9 @@
 
 uint64_t pagemap_get_entry(int fd, char *start);
 bool pagemap_is_softdirty(int fd, char *start);
+bool pagemap_is_swapped(int fd, char *start);
+bool pagemap_is_populated(int fd, char *start);
+unsigned long pagemap_get_pfn(int fd, char *start);
 void clear_softdirty(void);
 bool check_for_pattern(FILE *fp, const char *pattern, char *buf, size_t len);
 uint64_t read_pmd_pagesize(void);