Merge tag 'mm-stable-2023-02-20-13-37' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - Daniel Verkamp has contributed a memfd series ("mm/memfd: add
   F_SEAL_EXEC") which permits the setting of the memfd execute bit at
   memfd creation time, with the option of sealing the state of the X
   bit.

 - Peter Xu adds a patch series ("mm/hugetlb: Make huge_pte_offset()
   thread-safe for pmd unshare") which addresses a rare race condition
   related to PMD unsharing.

 - Several folioification patch serieses from Matthew Wilcox, Vishal
   Moola, Sidhartha Kumar and Lorenzo Stoakes

 - Johannes Weiner has a series ("mm: push down lock_page_memcg()")
   which does perform some memcg maintenance and cleanup work.

 - SeongJae Park has added DAMOS filtering to DAMON, with the series
   "mm/damon/core: implement damos filter".

   These filters provide users with finer-grained control over DAMOS's
   actions. SeongJae has also done some DAMON cleanup work.

 - Kairui Song adds a series ("Clean up and fixes for swap").

 - Vernon Yang contributed the series "Clean up and refinement for maple
   tree".

 - Yu Zhao has contributed the "mm: multi-gen LRU: memcg LRU" series. It
   adds to MGLRU an LRU of memcgs, to improve the scalability of global
   reclaim.

 - David Hildenbrand has added some userfaultfd cleanup work in the
   series "mm: uffd-wp + change_protection() cleanups".

 - Christoph Hellwig has removed the generic_writepages() library
   function in the series "remove generic_writepages".

 - Baolin Wang has performed some maintenance on the compaction code in
   his series "Some small improvements for compaction".

 - Sidhartha Kumar is doing some maintenance work on struct page in his
   series "Get rid of tail page fields".

 - David Hildenbrand contributed some cleanup, bugfixing and
   generalization of pte management and of pte debugging in his series
   "mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on all architectures with
   swap PTEs".

 - Mel Gorman and Neil Brown have removed the __GFP_ATOMIC allocation
   flag in the series "Discard __GFP_ATOMIC".

 - Sergey Senozhatsky has improved zsmalloc's memory utilization with
   his series "zsmalloc: make zspage chain size configurable".

 - Joey Gouly has added prctl() support for prohibiting the creation of
   writeable+executable mappings.

   The previous BPF-based approach had shortcomings. See "mm: In-kernel
   support for memory-deny-write-execute (MDWE)".

 - Waiman Long did some kmemleak cleanup and bugfixing in the series
   "mm/kmemleak: Simplify kmemleak_cond_resched() & fix UAF".

 - T.J. Alumbaugh has contributed some MGLRU cleanup work in his series
   "mm: multi-gen LRU: improve".

 - Jiaqi Yan has provided some enhancements to our memory error
   statistics reporting, mainly by presenting the statistics on a
   per-node basis. See the series "Introduce per NUMA node memory error
   statistics".

 - Mel Gorman has a second and hopefully final shot at fixing a CPU-hog
   regression in compaction via his series "Fix excessive CPU usage
   during compaction".

 - Christoph Hellwig does some vmalloc maintenance work in the series
   "cleanup vfree and vunmap".

 - Christoph Hellwig has removed block_device_operations.rw_page() in
   ths series "remove ->rw_page".

 - We get some maple_tree improvements and cleanups in Liam Howlett's
   series "VMA tree type safety and remove __vma_adjust()".

 - Suren Baghdasaryan has done some work on the maintainability of our
   vm_flags handling in the series "introduce vm_flags modifier
   functions".

 - Some pagemap cleanup and generalization work in Mike Rapoport's
   series "mm, arch: add generic implementation of pfn_valid() for
   FLATMEM" and "fixups for generic implementation of pfn_valid()"

 - Baoquan He has done some work to make /proc/vmallocinfo and
   /proc/kcore better represent the real state of things in his series
   "mm/vmalloc.c: allow vread() to read out vm_map_ram areas".

 - Jason Gunthorpe rationalized the GUP system's interface to the rest
   of the kernel in the series "Simplify the external interface for
   GUP".

 - SeongJae Park wishes to migrate people from DAMON's debugfs interface
   over to its sysfs interface. To support this, we'll temporarily be
   printing warnings when people use the debugfs interface. See the
   series "mm/damon: deprecate DAMON debugfs interface".

 - Andrey Konovalov provided the accurately named "lib/stackdepot: fixes
   and clean-ups" series.

 - Huang Ying has provided a dramatic reduction in migration's TLB flush
   IPI rates with the series "migrate_pages(): batch TLB flushing".

 - Arnd Bergmann has some objtool fixups in "objtool warning fixes".

* tag 'mm-stable-2023-02-20-13-37' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (505 commits)
  include/linux/migrate.h: remove unneeded externs
  mm/memory_hotplug: cleanup return value handing in do_migrate_range()
  mm/uffd: fix comment in handling pte markers
  mm: change to return bool for isolate_movable_page()
  mm: hugetlb: change to return bool for isolate_hugetlb()
  mm: change to return bool for isolate_lru_page()
  mm: change to return bool for folio_isolate_lru()
  objtool: add UACCESS exceptions for __tsan_volatile_read/write
  kmsan: disable ftrace in kmsan core code
  kasan: mark addr_has_metadata __always_inline
  mm: memcontrol: rename memcg_kmem_enabled()
  sh: initialize max_mapnr
  m68k/nommu: add missing definition of ARCH_PFN_OFFSET
  mm: percpu: fix incorrect size in pcpu_obj_full_size()
  maple_tree: reduce stack usage with gcc-9 and earlier
  mm: page_alloc: call panic() when memoryless node allocation fails
  mm: multi-gen LRU: avoid futile retries
  migrate_pages: move THP/hugetlb migration support check to simplify code
  migrate_pages: batch flushing TLB
  migrate_pages: share more code between _unmap and _move
  ...

1 files changed, 849 insertions, 0 deletions

diff --git a/tools/testing/selftests/mm/ksm_tests.c b/tools/testing/selftests/mm/ksm_tests.c
new file mode 100644
index 000000000000..f9eb4d67e0dd
--- /dev/null
+++ b/tools/testing/selftests/mm/ksm_tests.c
@@ -0,0 +1,849 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <sys/mman.h>
+#include <stdbool.h>
+#include <time.h>
+#include <string.h>
+#include <numa.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <err.h>
+
+#include "../kselftest.h"
+#include <include/vdso/time64.h>
+#include "util.h"
+
+#define KSM_SYSFS_PATH "/sys/kernel/mm/ksm/"
+#define KSM_FP(s) (KSM_SYSFS_PATH s)
+#define KSM_SCAN_LIMIT_SEC_DEFAULT 120
+#define KSM_PAGE_COUNT_DEFAULT 10l
+#define KSM_PROT_STR_DEFAULT "rw"
+#define KSM_USE_ZERO_PAGES_DEFAULT false
+#define KSM_MERGE_ACROSS_NODES_DEFAULT true
+#define MB (1ul << 20)
+
+struct ksm_sysfs {
+	unsigned long max_page_sharing;
+	unsigned long merge_across_nodes;
+	unsigned long pages_to_scan;
+	unsigned long run;
+	unsigned long sleep_millisecs;
+	unsigned long stable_node_chains_prune_millisecs;
+	unsigned long use_zero_pages;
+};
+
+enum ksm_test_name {
+	CHECK_KSM_MERGE,
+	CHECK_KSM_UNMERGE,
+	CHECK_KSM_ZERO_PAGE_MERGE,
+	CHECK_KSM_NUMA_MERGE,
+	KSM_MERGE_TIME,
+	KSM_MERGE_TIME_HUGE_PAGES,
+	KSM_UNMERGE_TIME,
+	KSM_COW_TIME
+};
+
+static int ksm_write_sysfs(const char *file_path, unsigned long val)
+{
+	FILE *f = fopen(file_path, "w");
+
+	if (!f) {
+		fprintf(stderr, "f %s\n", file_path);
+		perror("fopen");
+		return 1;
+	}
+	if (fprintf(f, "%lu", val) < 0) {
+		perror("fprintf");
+		fclose(f);
+		return 1;
+	}
+	fclose(f);
+
+	return 0;
+}
+
+static int ksm_read_sysfs(const char *file_path, unsigned long *val)
+{
+	FILE *f = fopen(file_path, "r");
+
+	if (!f) {
+		fprintf(stderr, "f %s\n", file_path);
+		perror("fopen");
+		return 1;
+	}
+	if (fscanf(f, "%lu", val) != 1) {
+		perror("fscanf");
+		fclose(f);
+		return 1;
+	}
+	fclose(f);
+
+	return 0;
+}
+
+static int str_to_prot(char *prot_str)
+{
+	int prot = 0;
+
+	if ((strchr(prot_str, 'r')) != NULL)
+		prot |= PROT_READ;
+	if ((strchr(prot_str, 'w')) != NULL)
+		prot |= PROT_WRITE;
+	if ((strchr(prot_str, 'x')) != NULL)
+		prot |= PROT_EXEC;
+
+	return prot;
+}
+
+static void print_help(void)
+{
+	printf("usage: ksm_tests [-h] <test type> [-a prot] [-p page_count] [-l timeout]\n"
+	       "[-z use_zero_pages] [-m merge_across_nodes] [-s size]\n");
+
+	printf("Supported <test type>:\n"
+	       " -M (page merging)\n"
+	       " -Z (zero pages merging)\n"
+	       " -N (merging of pages in different NUMA nodes)\n"
+	       " -U (page unmerging)\n"
+	       " -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"
+	       "    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");
+
+	printf(" -a: specify the access protections of pages.\n"
+	       "     <prot> must be of the form [rwx].\n"
+	       "     Default: %s\n", KSM_PROT_STR_DEFAULT);
+	printf(" -p: specify the number of pages to test.\n"
+	       "     Default: %ld\n", KSM_PAGE_COUNT_DEFAULT);
+	printf(" -l: limit the maximum running time (in seconds) for a test.\n"
+	       "     Default: %d seconds\n", KSM_SCAN_LIMIT_SEC_DEFAULT);
+	printf(" -z: change use_zero_pages tunable\n"
+	       "     Default: %d\n", KSM_USE_ZERO_PAGES_DEFAULT);
+	printf(" -m: change merge_across_nodes tunable\n"
+	       "     Default: %d\n", KSM_MERGE_ACROSS_NODES_DEFAULT);
+	printf(" -s: the size of duplicated memory area (in MiB)\n");
+
+	exit(0);
+}
+
+static void  *allocate_memory(void *ptr, int prot, int mapping, char data, size_t map_size)
+{
+	void *map_ptr = mmap(ptr, map_size, PROT_WRITE, mapping, -1, 0);
+
+	if (!map_ptr) {
+		perror("mmap");
+		return NULL;
+	}
+	memset(map_ptr, data, map_size);
+	if (mprotect(map_ptr, map_size, prot)) {
+		perror("mprotect");
+		munmap(map_ptr, map_size);
+		return NULL;
+	}
+
+	return map_ptr;
+}
+
+static int ksm_do_scan(int scan_count, struct timespec start_time, int timeout)
+{
+	struct timespec cur_time;
+	unsigned long cur_scan, init_scan;
+
+	if (ksm_read_sysfs(KSM_FP("full_scans"), &init_scan))
+		return 1;
+	cur_scan = init_scan;
+
+	while (cur_scan < init_scan + scan_count) {
+		if (ksm_read_sysfs(KSM_FP("full_scans"), &cur_scan))
+			return 1;
+		if (clock_gettime(CLOCK_MONOTONIC_RAW, &cur_time)) {
+			perror("clock_gettime");
+			return 1;
+		}
+		if ((cur_time.tv_sec - start_time.tv_sec) > timeout) {
+			printf("Scan time limit exceeded\n");
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+static int ksm_merge_pages(void *addr, size_t size, struct timespec start_time, int timeout)
+{
+	if (madvise(addr, size, MADV_MERGEABLE)) {
+		perror("madvise");
+		return 1;
+	}
+	if (ksm_write_sysfs(KSM_FP("run"), 1))
+		return 1;
+
+	/* Since merging occurs only after 2 scans, make sure to get at least 2 full scans */
+	if (ksm_do_scan(2, start_time, timeout))
+		return 1;
+
+	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;
+
+	if (ksm_read_sysfs(KSM_FP("pages_shared"), &pages_shared) ||
+	    ksm_read_sysfs(KSM_FP("pages_sharing"), &pages_sharing) ||
+	    ksm_read_sysfs(KSM_FP("max_page_sharing"), &max_page_sharing))
+		return false;
+
+	/*
+	 * Since there must be at least 2 pages for merging and 1 page can be
+	 * shared with the limited number of pages (max_page_sharing), sometimes
+	 * there are 'leftover' pages that cannot be merged. For example, if there
+	 * are 11 pages and max_page_sharing = 10, then only 10 pages will be
+	 * merged and the 11th page won't be affected. As a result, when the number
+	 * of duplicate pages is divided by max_page_sharing and the remainder is 1,
+	 * pages_shared and pages_sharing values will be equal between dupl_page_count
+	 * and dupl_page_count - 1.
+	 */
+	if (dupl_page_count % max_page_sharing == 1 || dupl_page_count % max_page_sharing == 0) {
+		if (pages_shared == dupl_page_count / max_page_sharing &&
+		    pages_sharing == pages_shared * (max_page_sharing - 1))
+			return true;
+	} else {
+		if (pages_shared == (dupl_page_count / max_page_sharing + 1) &&
+		    pages_sharing == dupl_page_count - pages_shared)
+			return true;
+	}
+
+	return false;
+}
+
+static int ksm_save_def(struct ksm_sysfs *ksm_sysfs)
+{
+	if (ksm_read_sysfs(KSM_FP("max_page_sharing"), &ksm_sysfs->max_page_sharing) ||
+	    numa_available() ? 0 :
+		ksm_read_sysfs(KSM_FP("merge_across_nodes"), &ksm_sysfs->merge_across_nodes) ||
+	    ksm_read_sysfs(KSM_FP("sleep_millisecs"), &ksm_sysfs->sleep_millisecs) ||
+	    ksm_read_sysfs(KSM_FP("pages_to_scan"), &ksm_sysfs->pages_to_scan) ||
+	    ksm_read_sysfs(KSM_FP("run"), &ksm_sysfs->run) ||
+	    ksm_read_sysfs(KSM_FP("stable_node_chains_prune_millisecs"),
+			   &ksm_sysfs->stable_node_chains_prune_millisecs) ||
+	    ksm_read_sysfs(KSM_FP("use_zero_pages"), &ksm_sysfs->use_zero_pages))
+		return 1;
+
+	return 0;
+}
+
+static int ksm_restore(struct ksm_sysfs *ksm_sysfs)
+{
+	if (ksm_write_sysfs(KSM_FP("max_page_sharing"), ksm_sysfs->max_page_sharing) ||
+	    numa_available() ? 0 :
+		ksm_write_sysfs(KSM_FP("merge_across_nodes"), ksm_sysfs->merge_across_nodes) ||
+	    ksm_write_sysfs(KSM_FP("pages_to_scan"), ksm_sysfs->pages_to_scan) ||
+	    ksm_write_sysfs(KSM_FP("run"), ksm_sysfs->run) ||
+	    ksm_write_sysfs(KSM_FP("sleep_millisecs"), ksm_sysfs->sleep_millisecs) ||
+	    ksm_write_sysfs(KSM_FP("stable_node_chains_prune_millisecs"),
+			    ksm_sysfs->stable_node_chains_prune_millisecs) ||
+	    ksm_write_sysfs(KSM_FP("use_zero_pages"), ksm_sysfs->use_zero_pages))
+		return 1;
+
+	return 0;
+}
+
+static int check_ksm_merge(int mapping, int prot, long page_count, int timeout, size_t page_size)
+{
+	void *map_ptr;
+	struct timespec start_time;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		return KSFT_FAIL;
+	}
+
+	/* fill pages with the same data and merge them */
+	map_ptr = allocate_memory(NULL, prot, mapping, '*', page_size * page_count);
+	if (!map_ptr)
+		return KSFT_FAIL;
+
+	if (ksm_merge_pages(map_ptr, page_size * page_count, start_time, timeout))
+		goto err_out;
+
+	/* verify that the right number of pages are merged */
+	if (assert_ksm_pages_count(page_count)) {
+		printf("OK\n");
+		munmap(map_ptr, page_size * page_count);
+		return KSFT_PASS;
+	}
+
+err_out:
+	printf("Not OK\n");
+	munmap(map_ptr, page_size * page_count);
+	return KSFT_FAIL;
+}
+
+static int check_ksm_unmerge(int mapping, int prot, int timeout, size_t page_size)
+{
+	void *map_ptr;
+	struct timespec start_time;
+	int page_count = 2;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		return KSFT_FAIL;
+	}
+
+	/* fill pages with the same data and merge them */
+	map_ptr = allocate_memory(NULL, prot, mapping, '*', page_size * page_count);
+	if (!map_ptr)
+		return KSFT_FAIL;
+
+	if (ksm_merge_pages(map_ptr, page_size * page_count, start_time, timeout))
+		goto err_out;
+
+	/* change 1 byte in each of the 2 pages -- KSM must automatically unmerge them */
+	memset(map_ptr, '-', 1);
+	memset(map_ptr + page_size, '+', 1);
+
+	/* get at least 1 scan, so KSM can detect that the pages were modified */
+	if (ksm_do_scan(1, start_time, timeout))
+		goto err_out;
+
+	/* check that unmerging was successful and 0 pages are currently merged */
+	if (assert_ksm_pages_count(0)) {
+		printf("OK\n");
+		munmap(map_ptr, page_size * page_count);
+		return KSFT_PASS;
+	}
+
+err_out:
+	printf("Not OK\n");
+	munmap(map_ptr, page_size * page_count);
+	return KSFT_FAIL;
+}
+
+static int check_ksm_zero_page_merge(int mapping, int prot, long page_count, int timeout,
+				     bool use_zero_pages, size_t page_size)
+{
+	void *map_ptr;
+	struct timespec start_time;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		return KSFT_FAIL;
+	}
+
+	if (ksm_write_sysfs(KSM_FP("use_zero_pages"), use_zero_pages))
+		return KSFT_FAIL;
+
+	/* fill pages with zero and try to merge them */
+	map_ptr = allocate_memory(NULL, prot, mapping, 0, page_size * page_count);
+	if (!map_ptr)
+		return KSFT_FAIL;
+
+	if (ksm_merge_pages(map_ptr, page_size * page_count, start_time, timeout))
+		goto err_out;
+
+       /*
+	* verify that the right number of pages are merged:
+	* 1) if use_zero_pages is set to 1, empty pages are merged
+	*    with the kernel zero page instead of with each other;
+	* 2) if use_zero_pages is set to 0, empty pages are not treated specially
+	*    and merged as usual.
+	*/
+	if (use_zero_pages && !assert_ksm_pages_count(0))
+		goto err_out;
+	else if (!use_zero_pages && !assert_ksm_pages_count(page_count))
+		goto err_out;
+
+	printf("OK\n");
+	munmap(map_ptr, page_size * page_count);
+	return KSFT_PASS;
+
+err_out:
+	printf("Not OK\n");
+	munmap(map_ptr, page_size * page_count);
+	return KSFT_FAIL;
+}
+
+static int get_next_mem_node(int node)
+{
+
+	long node_size;
+	int mem_node = 0;
+	int i, max_node = numa_max_node();
+
+	for (i = node + 1; i <= max_node + node; i++) {
+		mem_node = i % (max_node + 1);
+		node_size = numa_node_size(mem_node, NULL);
+		if (node_size > 0)
+			break;
+	}
+	return mem_node;
+}
+
+static int get_first_mem_node(void)
+{
+	return get_next_mem_node(numa_max_node());
+}
+
+static int check_ksm_numa_merge(int mapping, int prot, int timeout, bool merge_across_nodes,
+				size_t page_size)
+{
+	void *numa1_map_ptr, *numa2_map_ptr;
+	struct timespec start_time;
+	int page_count = 2;
+	int first_node;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		return KSFT_FAIL;
+	}
+
+	if (numa_available() < 0) {
+		perror("NUMA support not enabled");
+		return KSFT_SKIP;
+	}
+	if (numa_num_configured_nodes() <= 1) {
+		printf("At least 2 NUMA nodes must be available\n");
+		return KSFT_SKIP;
+	}
+	if (ksm_write_sysfs(KSM_FP("merge_across_nodes"), merge_across_nodes))
+		return KSFT_FAIL;
+
+	/* allocate 2 pages in 2 different NUMA nodes and fill them with the same data */
+	first_node = get_first_mem_node();
+	numa1_map_ptr = numa_alloc_onnode(page_size, first_node);
+	numa2_map_ptr = numa_alloc_onnode(page_size, get_next_mem_node(first_node));
+	if (!numa1_map_ptr || !numa2_map_ptr) {
+		perror("numa_alloc_onnode");
+		return KSFT_FAIL;
+	}
+
+	memset(numa1_map_ptr, '*', page_size);
+	memset(numa2_map_ptr, '*', page_size);
+
+	/* try to merge the pages */
+	if (ksm_merge_pages(numa1_map_ptr, page_size, start_time, timeout) ||
+	    ksm_merge_pages(numa2_map_ptr, page_size, start_time, timeout))
+		goto err_out;
+
+       /*
+	* verify that the right number of pages are merged:
+	* 1) if merge_across_nodes was enabled, 2 duplicate pages will be merged;
+	* 2) if merge_across_nodes = 0, there must be 0 merged pages, since there is
+	*    only 1 unique page in each node and they can't be shared.
+	*/
+	if (merge_across_nodes && !assert_ksm_pages_count(page_count))
+		goto err_out;
+	else if (!merge_across_nodes && !assert_ksm_pages_count(0))
+		goto err_out;
+
+	numa_free(numa1_map_ptr, page_size);
+	numa_free(numa2_map_ptr, page_size);
+	printf("OK\n");
+	return KSFT_PASS;
+
+err_out:
+	numa_free(numa1_map_ptr, page_size);
+	numa_free(numa2_map_ptr, page_size);
+	printf("Not OK\n");
+	return KSFT_FAIL;
+}
+
+static int ksm_merge_hugepages_time(int mapping, int prot, int timeout, size_t map_size)
+{
+	void *map_ptr, *map_ptr_orig;
+	struct timespec start_time, end_time;
+	unsigned long scan_time_ns;
+	int pagemap_fd, n_normal_pages, n_huge_pages;
+
+	map_size *= MB;
+	size_t len = map_size;
+
+	len -= len % HPAGE_SIZE;
+	map_ptr_orig = mmap(NULL, len + HPAGE_SIZE, PROT_READ | PROT_WRITE,
+			MAP_ANONYMOUS | MAP_NORESERVE | MAP_PRIVATE, -1, 0);
+	map_ptr = map_ptr_orig + HPAGE_SIZE - (uintptr_t)map_ptr_orig % HPAGE_SIZE;
+
+	if (map_ptr_orig == MAP_FAILED)
+		err(2, "initial mmap");
+
+	if (madvise(map_ptr, len + HPAGE_SIZE, MADV_HUGEPAGE))
+		err(2, "MADV_HUGEPAGE");
+
+	pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
+	if (pagemap_fd < 0)
+		err(2, "open pagemap");
+
+	n_normal_pages = 0;
+	n_huge_pages = 0;
+	for (void *p = map_ptr; p < map_ptr + len; p += HPAGE_SIZE) {
+		if (allocate_transhuge(p, pagemap_fd) < 0)
+			n_normal_pages++;
+		else
+			n_huge_pages++;
+	}
+	printf("Number of normal pages:    %d\n", n_normal_pages);
+	printf("Number of huge pages:    %d\n", n_huge_pages);
+
+	memset(map_ptr, '*', len);
+
+	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, &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_orig, len + HPAGE_SIZE);
+	return KSFT_PASS;
+
+err_out:
+	printf("Not OK\n");
+	munmap(map_ptr_orig, len + HPAGE_SIZE);
+	return KSFT_FAIL;
+}
+
+static int ksm_merge_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, &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_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;
+	struct timespec start_time, end_time;
+	unsigned long cow_time_ns;
+
+	/* page_count must be less than 2*page_size */
+	size_t page_count = 4000;
+
+	map_ptr = allocate_memory(NULL, prot, mapping, '*', page_size * page_count);
+	if (!map_ptr)
+		return KSFT_FAIL;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		return KSFT_FAIL;
+	}
+	for (size_t i = 0; i < page_count - 1; i = i + 2)
+		memset(map_ptr + page_size * i, '-', 1);
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &end_time)) {
+		perror("clock_gettime");
+		return KSFT_FAIL;
+	}
+
+	cow_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\n", (page_size * page_count) / MB);
+	printf("Not merged pages:\n");
+	printf("Total time:     %ld.%09ld s\n", cow_time_ns / NSEC_PER_SEC,
+	       cow_time_ns % NSEC_PER_SEC);
+	printf("Average speed:  %.3f MiB/s\n\n", ((page_size * (page_count / 2)) / MB) /
+					       ((double)cow_time_ns / NSEC_PER_SEC));
+
+	/* Create 2000 pairs of duplicate pages */
+	for (size_t i = 0; i < page_count - 1; i = i + 2) {
+		memset(map_ptr + page_size * i, '+', i / 2 + 1);
+		memset(map_ptr + page_size * (i + 1), '+', i / 2 + 1);
+	}
+	if (ksm_merge_pages(map_ptr, page_size * page_count, start_time, timeout))
+		goto err_out;
+
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
+		perror("clock_gettime");
+		goto err_out;
+	}
+	for (size_t i = 0; i < page_count - 1; i = i + 2)
+		memset(map_ptr + page_size * i, '-', 1);
+	if (clock_gettime(CLOCK_MONOTONIC_RAW, &end_time)) {
+		perror("clock_gettime");
+		goto err_out;
+	}
+
+	cow_time_ns = (end_time.tv_sec - start_time.tv_sec) * NSEC_PER_SEC +
+		       (end_time.tv_nsec - start_time.tv_nsec);
+
+	printf("Merged pages:\n");
+	printf("Total time:     %ld.%09ld s\n", cow_time_ns / NSEC_PER_SEC,
+	       cow_time_ns % NSEC_PER_SEC);
+	printf("Average speed:  %.3f MiB/s\n", ((page_size * (page_count / 2)) / MB) /
+					       ((double)cow_time_ns / NSEC_PER_SEC));
+
+	munmap(map_ptr, page_size * page_count);
+	return KSFT_PASS;
+
+err_out:
+	printf("Not OK\n");
+	munmap(map_ptr, page_size * page_count);
+	return KSFT_FAIL;
+}
+
+int main(int argc, char *argv[])
+{
+	int ret, opt;
+	int prot = 0;
+	int ksm_scan_limit_sec = KSM_SCAN_LIMIT_SEC_DEFAULT;
+	long page_count = KSM_PAGE_COUNT_DEFAULT;
+	size_t page_size = sysconf(_SC_PAGESIZE);
+	struct ksm_sysfs ksm_sysfs_old;
+	int test_name = CHECK_KSM_MERGE;
+	bool use_zero_pages = KSM_USE_ZERO_PAGES_DEFAULT;
+	bool merge_across_nodes = KSM_MERGE_ACROSS_NODES_DEFAULT;
+	long size_MB = 0;
+
+	while ((opt = getopt(argc, argv, "ha:p:l:z:m:s:MUZNPCHD")) != -1) {
+		switch (opt) {
+		case 'a':
+			prot = str_to_prot(optarg);
+			break;
+		case 'p':
+			page_count = atol(optarg);
+			if (page_count <= 0) {
+				printf("The number of pages must be greater than 0\n");
+				return KSFT_FAIL;
+			}
+			break;
+		case 'l':
+			ksm_scan_limit_sec = atoi(optarg);
+			if (ksm_scan_limit_sec <= 0) {
+				printf("Timeout value must be greater than 0\n");
+				return KSFT_FAIL;
+			}
+			break;
+		case 'h':
+			print_help();
+			break;
+		case 'z':
+			if (strcmp(optarg, "0") == 0)
+				use_zero_pages = 0;
+			else
+				use_zero_pages = 1;
+			break;
+		case 'm':
+			if (strcmp(optarg, "0") == 0)
+				merge_across_nodes = 0;
+			else
+				merge_across_nodes = 1;
+			break;
+		case 's':
+			size_MB = atoi(optarg);
+			if (size_MB <= 0) {
+				printf("Size must be greater than 0\n");
+				return KSFT_FAIL;
+			}
+		case 'M':
+			break;
+		case 'U':
+			test_name = CHECK_KSM_UNMERGE;
+			break;
+		case 'Z':
+			test_name = CHECK_KSM_ZERO_PAGE_MERGE;
+			break;
+		case 'N':
+			test_name = CHECK_KSM_NUMA_MERGE;
+			break;
+		case 'P':
+			test_name = KSM_MERGE_TIME;
+			break;
+		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;
+		default:
+			return KSFT_FAIL;
+		}
+	}
+
+	if (prot == 0)
+		prot = str_to_prot(KSM_PROT_STR_DEFAULT);
+
+	if (access(KSM_SYSFS_PATH, F_OK)) {
+		printf("Config KSM not enabled\n");
+		return KSFT_SKIP;
+	}
+
+	if (ksm_save_def(&ksm_sysfs_old)) {
+		printf("Cannot save default tunables\n");
+		return KSFT_FAIL;
+	}
+
+	if (ksm_write_sysfs(KSM_FP("run"), 2) ||
+	    ksm_write_sysfs(KSM_FP("sleep_millisecs"), 0) ||
+	    numa_available() ? 0 :
+		ksm_write_sysfs(KSM_FP("merge_across_nodes"), 1) ||
+	    ksm_write_sysfs(KSM_FP("pages_to_scan"), page_count))
+		return KSFT_FAIL;
+
+	switch (test_name) {
+	case CHECK_KSM_MERGE:
+		ret = check_ksm_merge(MAP_PRIVATE | MAP_ANONYMOUS, prot, page_count,
+				      ksm_scan_limit_sec, page_size);
+		break;
+	case CHECK_KSM_UNMERGE:
+		ret = check_ksm_unmerge(MAP_PRIVATE | MAP_ANONYMOUS, prot, ksm_scan_limit_sec,
+					page_size);
+		break;
+	case CHECK_KSM_ZERO_PAGE_MERGE:
+		ret = check_ksm_zero_page_merge(MAP_PRIVATE | MAP_ANONYMOUS, prot, page_count,
+						ksm_scan_limit_sec, use_zero_pages, page_size);
+		break;
+	case CHECK_KSM_NUMA_MERGE:
+		ret = check_ksm_numa_merge(MAP_PRIVATE | MAP_ANONYMOUS, prot, ksm_scan_limit_sec,
+					   merge_across_nodes, page_size);
+		break;
+	case KSM_MERGE_TIME:
+		if (size_MB == 0) {
+			printf("Option '-s' is required.\n");
+			return KSFT_FAIL;
+		}
+		ret = ksm_merge_time(MAP_PRIVATE | MAP_ANONYMOUS, prot, ksm_scan_limit_sec,
+				     size_MB);
+		break;
+	case KSM_MERGE_TIME_HUGE_PAGES:
+		if (size_MB == 0) {
+			printf("Option '-s' is required.\n");
+			return KSFT_FAIL;
+		}
+		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);
+		break;
+	}
+
+	if (ksm_restore(&ksm_sysfs_old)) {
+		printf("Cannot restore default tunables\n");
+		return KSFT_FAIL;
+	}
+
+	return ret;
+}