Commit 39619982 authored by Zhansaya Bagdauletkyzy's avatar Zhansaya Bagdauletkyzy Committed by Linus Torvalds
Browse files

selftests: vm: add KSM zero page merging test 

Add check_ksm_zero_page_merge() function to test that empty pages are
being handled properly.  For this, several zero pages are allocated and
merged using madvise.  If use_zero_pages is enabled, the pages must be
shared with the special kernel zero pages; otherwise, they are merged as
usual duplicate pages.  The test is run as follows: ./ksm_tests -Z

Link: https://lkml.kernel.org/r/6d0caab00d4bdccf5e3791cb95cf6dfd5eb85e45.1626252248.git.zhansayabagdaulet@gmail.com


Signed-off-by: default avatarZhansaya Bagdauletkyzy <zhansayabagdaulet@gmail.com>
Reviewed-by: default avatarPavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: default avatarTyler Hicks <tyhicks@linux.microsoft.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a40c80e3

tools/testing/selftests/vm/ksm_tests.c

+67 −3
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#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



struct ksm_sysfs {

	unsigned long max_page_sharing;
@@ -25,7 +26,8 @@ struct ksm_sysfs { 


enum ksm_test_name {

	CHECK_KSM_MERGE,

	CHECK_KSM_UNMERGE

	CHECK_KSM_UNMERGE,

	CHECK_KSM_ZERO_PAGE_MERGE

};



static int ksm_write_sysfs(const char *file_path, unsigned long val)
@@ -80,10 +82,12 @@ static int str_to_prot(char *prot_str) 


static void print_help(void)

{

	printf("usage: ksm_tests [-h] <test type> [-a prot] [-p page_count] [-l timeout]\n");

	printf("usage: ksm_tests [-h] <test type> [-a prot] [-p page_count] [-l timeout]\n"

	       "[-z use_zero_pages]\n");



	printf("Supported <test type>:\n"

	       " -M (page merging)\n"

	       " -Z (zero pages merging)\n"

	       " -U (page unmerging)\n\n");



	printf(" -a: specify the access protections of pages.\n"
@@ -93,6 +97,8 @@ static void print_help(void) 
	       "     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);



	exit(0);

}
@@ -289,6 +295,50 @@ static int check_ksm_unmerge(int mapping, int prot, int timeout, size_t page_siz 
	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;

}



int main(int argc, char *argv[])

{

	int ret, opt;
@@ -298,8 +348,9 @@ int main(int argc, char *argv[]) 
	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;



	while ((opt = getopt(argc, argv, "ha:p:l:MU")) != -1) {

	while ((opt = getopt(argc, argv, "ha:p:l:z:MUZ")) != -1) {

		switch (opt) {

		case 'a':

			prot = str_to_prot(optarg);
@@ -321,11 +372,20 @@ int main(int argc, char *argv[]) 
		case 'h':

			print_help();

			break;

		case 'z':

			if (strcmp(optarg, "0") == 0)

				use_zero_pages = 0;

			else

				use_zero_pages = 1;

			break;

		case 'M':

			break;

		case 'U':

			test_name = CHECK_KSM_UNMERGE;

			break;

		case 'Z':

			test_name = CHECK_KSM_ZERO_PAGE_MERGE;

			break;

		default:

			return KSFT_FAIL;

		}
@@ -359,6 +419,10 @@ int main(int argc, char *argv[]) 
		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;

	}



	if (ksm_restore(&ksm_sysfs_old)) {

tools/testing/selftests/vm/run_vmtests.sh

+32 −0
Original line number Diff line number Diff line
@@ -409,6 +409,38 @@ else 
	exitcode=1

fi



echo "----------------------------------------------------------"

echo "running KSM test with 10 zero pages and use_zero_pages = 0"

echo "----------------------------------------------------------"

./ksm_tests -Z -p 10 -z 0

ret_val=$?



if [ $ret_val -eq 0 ]; then

	echo "[PASS]"

elif [ $ret_val -eq $ksft_skip ]; then

	 echo "[SKIP]"

	 exitcode=$ksft_skip

else

	echo "[FAIL]"

	exitcode=1

fi



echo "----------------------------------------------------------"

echo "running KSM test with 10 zero pages and use_zero_pages = 1"

echo "----------------------------------------------------------"

./ksm_tests -Z -p 10 -z 1

ret_val=$?



if [ $ret_val -eq 0 ]; then

	echo "[PASS]"

elif [ $ret_val -eq $ksft_skip ]; then

	 echo "[SKIP]"

	 exitcode=$ksft_skip

else

	echo "[FAIL]"

	exitcode=1

fi



exit $exitcode



exit $exitcode