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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: David Hildenbrand <david@redhat.com>
Acked-by: Stefan 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: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2023-04-22 22:54:19 +02:00 committed by Andrew Morton
parent 24139c07f4
commit 1150ea9338
1 changed files with 40 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

46
tools/testing/selftests/mm/ksm_functional_tests.c
View File

@ -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)