On Mon, Jan 02, 2023 at 04:34:14PM +0100, David Hildenbrand wrote:
On 02.01.23 15:44, Lorenzo Stoakes wrote:
Add a test to assert that we can mremap() and expand a mapping starting from an offset within an existing mapping. We unmap the last page in a 3 page mapping to ensure that the remap should always succeed, before remapping from the 2nd page.
This is additionally a regression test for the issue solved in "mm, mremap: fix mremap() expanding vma with addr inside vma" and confirmed to fail prior to the change and pass after it.
Finally, this patch updates the existing mremap expand merge test to check error conditions and reduce code duplication between the two tests.
Signed-off-by: Lorenzo Stoakes lstoakes@gmail.com
tools/testing/selftests/vm/mremap_test.c | 115 ++++++++++++++++++----- 1 file changed, 93 insertions(+), 22 deletions(-)
diff --git a/tools/testing/selftests/vm/mremap_test.c b/tools/testing/selftests/vm/mremap_test.c
...
- start = mmap(NULL, 3 * page_size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);- if (start == MAP_FAILED) {
ksft_print_msg("mmap failed: %s\n", strerror(errno));I'd
ksft_test_result_fail(...) return;
goto out;- }
- munmap(start + page_size, page_size);
- remap = mremap(start, page_size, 2 * page_size, 0);
- if (remap == MAP_FAILED) {
ksft_print_msg("mremap failed: %s\n", strerror(errno));munmap(start, page_size);munmap(start + 2 * page_size, page_size);goto out;dito
ksft_test_result_fail(...) ... return;
- }
- success = is_range_mapped(maps_fp, start, start + 3 * page_size);
- munmap(start, 3 * page_size);
+out:
then you can drop the out label.
I have to disagree on this, to be consistent with the other tests the failure messages should include the test name, and putting the ksft_test_result_fail("test name") in each branch as well as the error message would just be wilful duplication.
I do think it's a pity C lacks mechanisms such that gotos are sometimes necessary, but I can only right so many wrongs in this patch :)
- if (success)
ksft_test_result_pass("%s\n", test_name);- else
ksft_test_result_fail("%s\n", test_name);+}
+/*
- Similar to mremap_expand_merge() except instead of removing the middle page,
- we remove the last then attempt to remap offset from the second page. This
- should result in the mapping being restored to its former state.
- */
+static void mremap_expand_merge_offset(FILE *maps_fp, unsigned long page_size) +{
- char *test_name = "mremap expand merge offset";
- bool success = false;
- char *remap, *start;
- start = mmap(NULL, 3 * page_size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);- if (start == MAP_FAILED) {
ksft_print_msg("mmap failed: %s\n", strerror(errno));goto out;- }
- /* Unmap final page to ensure we have space to expand. */
- munmap(start + 2 * page_size, page_size);
- remap = mremap(start + page_size, page_size, 2 * page_size, 0);
- if (remap == MAP_FAILED) {
ksft_print_msg("mremap failed: %s\n", strerror(errno));munmap(start, 2 * page_size);goto out;- }
- success = is_range_mapped(maps_fp, start, start + 3 * page_size);
- munmap(start, 3 * page_size);
+out:
dito.
if (success) ksft_test_result_pass("%s\n", test_name); else ksft_test_result_fail("%s\n", test_name);
- fclose(fp); } /*
@@ -385,6 +447,7 @@ int main(int argc, char **argv) struct test perf_test_cases[MAX_PERF_TEST]; int page_size; time_t t;
- FILE *maps_fp;
I'd simply use a global variable, same applies for page_size. But passing it around is also ok.
I am trying to keep things consistent with what's gone before in this code, and given page_size is being passed around I think the 'when in Rome' principle applies equally to passing the fp around I think.
pattern_seed = (unsigned int) time(&t); @@ -458,7 +521,15 @@ int main(int argc, char **argv) run_mremap_test_case(test_cases[i], &failures, threshold_mb, pattern_seed);
- mremap_expand_merge(page_size);
- maps_fp = fopen("/proc/self/maps", "r");
- if (maps_fp == NULL) {
ksft_print_msg("Failed to read /proc/self/maps: %s\n", strerror(errno));Maybe simply fail the test completely and return -errno ?
Ack on this one, will spin a v3 with this as otherwise we might miss test failures here.
- } else {
mremap_expand_merge(maps_fp, page_size);mremap_expand_merge_offset(maps_fp, page_size);fclose(maps_fp);No need to fclose, just keep it open ...
I'd rather we did fclose() to keep things clean, as who knows what additional tests may be added later and to be pedantic about matching an fopen() with an fclose().
- } if (run_perf_tests) { ksft_print_msg("\n%s\n",
Acked-by: David Hildenbrand david@redhat.com
Thanks!
-- Thanks,
David / dhildenb