Commit 1150ea93 authored by David Hildenbrand's avatar David Hildenbrand Committed by Andrew Morton
Browse files

selftests/ksm: ksm_functional_tests: add prctl unmerge test 

Let's test whether setting PR_SET_MEMORY_MERGE to 0 after setting it to 1
will unmerge pages, similar to how setting MADV_UNMERGEABLE after setting
MADV_MERGEABLE would.

Link: https://lkml.kernel.org/r/20230422205420.30372-3-david@redhat.com


Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Acked-by: default avatarStefan Roesch <shr@devkernel.io>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 24139c07

tools/testing/selftests/mm/ksm_functional_tests.c

+40 −6
Original line number Diff line number Diff line
@@ -91,9 +91,10 @@ static int ksm_merge(void) 
	return 0;

}



static char *mmap_and_merge_range(char val, unsigned long size)

static char *mmap_and_merge_range(char val, unsigned long size, bool use_prctl)

{

	char *map;

	int ret;



	map = mmap(NULL, size, PROT_READ|PROT_WRITE,

		   MAP_PRIVATE|MAP_ANON, -1, 0);
@@ -110,7 +111,17 @@ static char *mmap_and_merge_range(char val, unsigned long size) 


	/* Make sure each page contains the same values to merge them. */

	memset(map, val, size);

	if (madvise(map, size, MADV_MERGEABLE)) {



	if (use_prctl) {

		ret = prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0);

		if (ret < 0 && errno == EINVAL) {

			ksft_test_result_skip("PR_SET_MEMORY_MERGE not supported\n");

			goto unmap;

		} else if (ret) {

			ksft_test_result_fail("PR_SET_MEMORY_MERGE=1 failed\n");

			goto unmap;

		}

	} else if (madvise(map, size, MADV_MERGEABLE)) {

		ksft_test_result_fail("MADV_MERGEABLE failed\n");

		goto unmap;

	}
@@ -133,7 +144,7 @@ static void test_unmerge(void) 


	ksft_print_msg("[RUN] %s\n", __func__);



	map = mmap_and_merge_range(0xcf, size);

	map = mmap_and_merge_range(0xcf, size, false);

	if (map == MAP_FAILED)

		return;
@@ -155,7 +166,7 @@ static void test_unmerge_discarded(void) 


	ksft_print_msg("[RUN] %s\n", __func__);



	map = mmap_and_merge_range(0xcf, size);

	map = mmap_and_merge_range(0xcf, size, false);

	if (map == MAP_FAILED)

		return;
@@ -187,7 +198,7 @@ static void test_unmerge_uffd_wp(void) 


	ksft_print_msg("[RUN] %s\n", __func__);



	map = mmap_and_merge_range(0xcf, size);

	map = mmap_and_merge_range(0xcf, size, false);

	if (map == MAP_FAILED)

		return;
@@ -323,9 +334,31 @@ static void test_prctl_fork(void) 
	ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n");

}



static void test_prctl_unmerge(void)

{

	const unsigned int size = 2 * MiB;

	char *map;



	ksft_print_msg("[RUN] %s\n", __func__);



	map = mmap_and_merge_range(0xcf, size, true);

	if (map == MAP_FAILED)

		return;



	if (prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0)) {

		ksft_test_result_fail("PR_SET_MEMORY_MERGE=0 failed\n");

		goto unmap;

	}



	ksft_test_result(!range_maps_duplicates(map, size),

			 "Pages were unmerged\n");

unmap:

	munmap(map, size);

}



int main(int argc, char **argv)

{

	unsigned int tests = 4;

	unsigned int tests = 5;

	int err;



#ifdef __NR_userfaultfd
@@ -355,6 +388,7 @@ int main(int argc, char **argv) 


	test_prctl();

	test_prctl_fork();

	test_prctl_unmerge();



	err = ksft_get_fail_cnt();

	if (err)