On Mon, Jun 16, 2025 at 01:04:40PM -0400, Liam R. Howlett wrote: > * Aboorva Devarajan <[email protected]> [250616 12:07]: > > From: Donet Tom <[email protected]> > > > > This patch fixed 2 issues. > > > > 1)After fork() in test_prctl_fork, the child process uses the file > > descriptors from the parent process to read ksm_stat and > > ksm_merging_pages. This results in incorrect values being read (parent > > process ksm_stat and ksm_merge_pages will be read in child), causing > > the test to fail. > > > > This patch calls init_global_file_handles() in the child process to > > ensure that the current process's file descriptors are used to read > > ksm_stat and ksm_merging_pages. > > > > 2) All tests currently call ksm_merge to trigger page merging. > > To ensure the system remains in a consistent state for subsequent > > tests, it is better to call ksm_unmerge during the test cleanup phase > > > > In the test_prctl_fork test, after a fork(), reading ksm_merging_pages > > in the child process returns a non-zero value because a previous test > > performed a merge, and the child's memory state is inherited from the > > parent. > > > > Although the child process calls ksm_unmerge, the ksm_merging_pages > > counter in the parent is reset to zero, while the child's counter > > remains unchanged. This discrepancy causes the test to fail. > > > > To avoid this issue, each test should call ksm_unmerge during cleanup > > to ensure the counter is reset and the system is in a clean state for > > subsequent tests. > > > > Fixes: ?
Sorry I missed it. We will add and send a new version. > > > Signed-off-by: Donet Tom <[email protected]> > > Signed-off-by: Aboorva Devarajan <[email protected]> > > --- > > tools/testing/selftests/mm/ksm_functional_tests.c | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c > > b/tools/testing/selftests/mm/ksm_functional_tests.c > > index b61803e36d1c..d7d3c22c077a 100644 > > --- a/tools/testing/selftests/mm/ksm_functional_tests.c > > +++ b/tools/testing/selftests/mm/ksm_functional_tests.c > > @@ -46,6 +46,8 @@ static int ksm_use_zero_pages_fd; > > static int pagemap_fd; > > static size_t pagesize; > > > > +static void init_global_file_handles(void); > > + > > static bool range_maps_duplicates(char *addr, unsigned long size) > > { > > unsigned long offs_a, offs_b, pfn_a, pfn_b; > > @@ -274,6 +276,7 @@ static void test_unmerge(void) > > ksft_test_result(!range_maps_duplicates(map, size), > > "Pages were unmerged\n"); > > unmap: > > + ksm_unmerge(); > > munmap(map, size); > > } > > > > @@ -338,6 +341,7 @@ static void test_unmerge_zero_pages(void) > > ksft_test_result(!range_maps_duplicates(map, size), > > "KSM zero pages were unmerged\n"); > > unmap: > > + ksm_unmerge(); > > munmap(map, size); > > } > > > > @@ -366,6 +370,7 @@ static void test_unmerge_discarded(void) > > ksft_test_result(!range_maps_duplicates(map, size), > > "Pages were unmerged\n"); > > unmap: > > + ksm_unmerge(); > > munmap(map, size); > > } > > > > @@ -428,6 +433,7 @@ static void test_unmerge_uffd_wp(void) > > close_uffd: > > close(uffd); > > unmap: > > + ksm_unmerge(); > > munmap(map, size); > > } > > #endif > > @@ -491,6 +497,7 @@ static int test_child_ksm(void) > > else if (map == MAP_MERGE_SKIP) > > return -3; > > > > + ksm_unmerge(); > > munmap(map, size); > > return 0; > > } > > @@ -524,6 +531,7 @@ static void test_prctl_fork(void) > > > > child_pid = fork(); > > if (!child_pid) { > > + init_global_file_handles(); > > exit(test_child_ksm()); > > } else if (child_pid < 0) { > > ksft_test_result_fail("fork() failed\n"); > > @@ -620,6 +628,7 @@ static void test_prctl_unmerge(void) > > ksft_test_result(!range_maps_duplicates(map, size), > > "Pages were unmerged\n"); > > unmap: > > + ksm_unmerge(); > > munmap(map, size); > > } > > > > @@ -653,6 +662,7 @@ static void test_prot_none(void) > > ksft_test_result(!range_maps_duplicates(map, size), > > "Pages were unmerged\n"); > > unmap: > > + ksm_unmerge(); > > munmap(map, size); > > } > > > > -- > > 2.43.5 > > > >
