Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx> writes:
> new file mode 100644
> index 0000000000000..3153ebac6909b
> --- /dev/null
> +++ b/tools/testing/selftests/vm/soft-dirty.c
> @@ -0,0 +1,146 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <stdio.h>
> +#include <string.h>
> +#include <stdbool.h>
> +#include <fcntl.h>
> +#include <stdint.h>
> +#include <malloc.h>
> +#include <sys/mman.h>
> +#include "../kselftest.h"
> +#include "vm_util.h"
> +
> +#define PAGEMAP_FILE_PATH "/proc/self/pagemap"
> +#define TEST_ITERATIONS 10000
> +
> +static void test_simple(int pagemap_fd, int pagesize)
> +{
> + int i;
> + char *map;
> +
> + map = aligned_alloc(pagesize, pagesize);
> + if (!map)
> + ksft_exit_fail_msg("mmap failed\n");
> +
> + clear_softdirty();
> +
> + for (i = 0 ; i < TEST_ITERATIONS; i++) {
> + if (pagemap_is_softdirty(pagemap_fd, map) == 1) {
> + ksft_print_msg("dirty bit was 1, but should be 0 (i=%d)\n", i);
> + break;
> + }
> +
> + clear_softdirty();
> + // Write something to the page to get the dirty bit enabled on the page
> + map[0] = i % 255;
you don't need this mod at all but at least it should be 256 :). I think
Either 'map[0] = !map[0]' or keeping the original 'map[0]++' is fine.
> +
> + if (pagemap_is_softdirty(pagemap_fd, map) == 0) {
> + ksft_print_msg("dirty bit was 0, but should be 1 (i=%d)\n", i);
> + break;
> + }
> +
> + clear_softdirty();
> + }
> + free(map);
> +
> + ksft_test_result(i == TEST_ITERATIONS, "Test %s\n", __func__);
> +}
> +
> +static void test_vma_reuse(int pagemap_fd, int pagesize)
> +{
> + char *map, *map2;
> +
> + map = mmap(NULL, pagesize, (PROT_READ | PROT_WRITE), (MAP_PRIVATE | MAP_ANON), -1, 0);
> + if (map == MAP_FAILED)
> + ksft_exit_fail_msg("mmap failed");
> +
> + clear_softdirty();
> +
> + /* Write to the page before unmapping and map the same size region again to check
> + * if same memory region is gotten next time and if dirty bit is preserved across
> + * this type of allocations.
> + */
This reads weird. It should *not* be preserved across different
mappings. Also, we are not testing if the same region is reused, we are
depending on it to test the sd bit.
/* Ensures the soft-dirty bit is reset accross different mappings on the
same address. */
> + map[0]++;
This is inconsistent with the other two tests.
> +
> + munmap(map, pagesize);
> +
> + map2 = mmap(NULL, pagesize, (PROT_READ | PROT_WRITE), (MAP_PRIVATE | MAP_ANON), -1, 0);
> + if (map2 == MAP_FAILED)
> + ksft_exit_fail_msg("mmap failed");
> +
> + ksft_test_result(map == map2, "Test %s reused memory location\n", __func__);
if map != map2, the test itself is broken, meaning we should skip it, not
fail, i guess.
--
Gabriel Krisman Bertazi
