On Wed, Oct 16, 2024 at 7:26 PM <jeffxu@xxxxxxxxxxxx> wrote:
>
> From: Jeff Xu <jeffxu@xxxxxxxxxx>
>
> It appears there is a regression on the latest mm,
> when munmap seals memory, it can cause an unexpected VMA split.
> E.g. repro use this test.
It appears that this test has some dependency tests that haven't been
merged, so can't be run as is.
This is the repro step:
- Allocate 12 pages (0-11).
- Seal middle 4 pages (4567)
- munmap (2345) - this will fail
Seeing VMA for page (0123) is split as 2 VMAs (01)-(23), those 2 VMA
have the same attribute, and should be merged as one.
> ---
> tools/testing/selftests/mm/mseal_test.c | 76 +++++++++++++++++++++++++
> 1 file changed, 76 insertions(+)
>
> diff --git a/tools/testing/selftests/mm/mseal_test.c b/tools/testing/selftests/mm/mseal_test.c
> index fa74dbe4a684..0af33e13b606 100644
> --- a/tools/testing/selftests/mm/mseal_test.c
> +++ b/tools/testing/selftests/mm/mseal_test.c
> @@ -1969,6 +1969,79 @@ static void test_madvise_filebacked_was_writable(bool seal)
> REPORT_TEST_PASS();
> }
>
> +static void test_munmap_free_multiple_ranges_with_split(bool seal)
> +{
> + void *ptr;
> + unsigned long page_size = getpagesize();
> + unsigned long size = 12 * page_size;
> + int ret;
> + int prot;
> +
> + setup_single_address(size, &ptr);
> + FAIL_TEST_IF_FALSE(ptr != (void *)-1);
> +
> + /* seal the middle 4 page */
> + if (seal) {
> + ret = sys_mseal(ptr + 4 * page_size, 4 * page_size);
> + FAIL_TEST_IF_FALSE(!ret);
> +
> + size = get_vma_size(ptr, &prot);
> + FAIL_TEST_IF_FALSE(size == 4 * page_size);
> + FAIL_TEST_IF_FALSE(prot == 4);
> +
> + size = get_vma_size(ptr + 4 * page_size, &prot);
> + FAIL_TEST_IF_FALSE(size == 4 * page_size);
> + FAIL_TEST_IF_FALSE(prot == 4);
> +
> + size = get_vma_size(ptr + 8 * page_size, &prot);
> + FAIL_TEST_IF_FALSE(size == 4 * page_size);
> + FAIL_TEST_IF_FALSE(prot == 4);
> + }
> +
> + /* munmap 4 pages from the third page */
> + ret = sys_munmap(ptr + 2 * page_size, 4 * page_size);
> + if (seal) {
> + FAIL_TEST_IF_FALSE(ret);
> + FAIL_TEST_IF_FALSE(errno == EPERM);
> +
> + size = get_vma_size(ptr, &prot);
> + FAIL_TEST_IF_FALSE(size == 4 * page_size);
> + FAIL_TEST_IF_FALSE(prot == 4);
> +
> + size = get_vma_size(ptr + 4 * page_size, &prot);
> + FAIL_TEST_IF_FALSE(size == 4 * page_size);
> + FAIL_TEST_IF_FALSE(prot == 4);
> +
> + size = get_vma_size(ptr + 8 * page_size, &prot);
> + FAIL_TEST_IF_FALSE(size == 4 * page_size);
> + FAIL_TEST_IF_FALSE(prot == 4);
> + } else
> + FAIL_TEST_IF_FALSE(!ret);
> +
> + /* munmap 4 pages from the sealed page */
> + ret = sys_munmap(ptr + 6 * page_size, 4 * page_size);
> + if (seal) {
> + FAIL_TEST_IF_FALSE(ret);
> + FAIL_TEST_IF_FALSE(errno == EPERM);
> +
> + size = get_vma_size(ptr + 4 * page_size, &prot);
> + FAIL_TEST_IF_FALSE(size == 4 * page_size);
> + FAIL_TEST_IF_FALSE(prot == 4);
> +
> + size = get_vma_size(ptr + 4 * page_size, &prot);
> + FAIL_TEST_IF_FALSE(size == 4 * page_size);
> + FAIL_TEST_IF_FALSE(prot == 4);
> +
> + size = get_vma_size(ptr + 8 * page_size, &prot);
> + FAIL_TEST_IF_FALSE(size == 4 * page_size);
> + FAIL_TEST_IF_FALSE(prot == 4);
> + } else
> + FAIL_TEST_IF_FALSE(!ret);
> +
> + REPORT_TEST_PASS();
> +}
> +
> +
> int main(int argc, char **argv)
> {
> bool test_seal = seal_support();
> @@ -2099,5 +2172,8 @@ int main(int argc, char **argv)
> test_madvise_filebacked_was_writable(false);
> test_madvise_filebacked_was_writable(true);
>
> + test_munmap_free_multiple_ranges_with_split(false);
> + test_munmap_free_multiple_ranges_with_split(true);
> +
> ksft_finished();
> }
> --
> 2.47.0.rc1.288.g06298d1525-goog
>
