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.
Acked-by: Stefan Roesch shr@devkernel.io Signed-off-by: David Hildenbrand david@redhat.com --- .../selftests/mm/ksm_functional_tests.c | 46 ++++++++++++++++--- 1 file changed, 40 insertions(+), 6 deletions(-)
diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c index 7bc9fc17c9f0..26853badae70 100644 --- a/tools/testing/selftests/mm/ksm_functional_tests.c +++ b/tools/testing/selftests/mm/ksm_functional_tests.c @@ -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)