Check that a partial MREMAP_DONTUNMAP operation on mlocked memory preserves locked-memory accounting and that unmapping both mappings returns VmLck to its original value.
This tests for a locked_vm accounting leak after a partial remap. Signed-off-by: Muhammad Mahdi Amirpour <[email protected]> --- tools/testing/selftests/mm/mremap_dontunmap.c | 95 ++++++++++++++++++- 1 file changed, 94 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/mm/mremap_dontunmap.c b/tools/testing/selftests/mm/mremap_dontunmap.c index 96ba537facf..a0fd99ff825 100644 --- a/tools/testing/selftests/mm/mremap_dontunmap.c +++ b/tools/testing/selftests/mm/mremap_dontunmap.c @@ -335,6 +335,98 @@ static void mremap_dontunmap_partial_mapping_overwrite(void) ksft_test_result_pass("%s\n", __func__); } +static long get_vmlck_kb(void) +{ + FILE *f = fopen("/proc/self/status", "r"); + char *line = NULL; + size_t len = 0; + long kb = -1; + + if (!f) + ksft_exit_fail_msg("fopen /proc/self/status: %s\n", + strerror(errno)); + + while (getline(&line, &len, f) != -1) { + if (sscanf(line, "VmLck: %ld kB", &kb) == 1) + break; + } + + free(line); + fclose(f); + + if (kb < 0) + ksft_exit_fail_msg("VmLck not found in /proc/self/status\n"); + + return kb; +} + +static void mremap_dontunmap_partial_mlocked(void) +{ + unsigned long num_pages = 10; + size_t size = num_pages * page_size; + size_t half = (num_pages / 2) * page_size; + void *src, *dst; + long baseline, locked, remapped, after; + bool pass; + + baseline = get_vmlck_kb(); + + src = mmap(NULL, size, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (src == MAP_FAILED) + ksft_exit_fail_msg("mmap source: %s\n", strerror(errno)); + + dst = mmap(NULL, half, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (dst == MAP_FAILED) + ksft_exit_fail_msg("mmap destination: %s\n", strerror(errno)); + + memset(src, 'a', size); + + if (mlock(src, size)) { + if (errno == EPERM || errno == ENOMEM) { + ksft_print_msg("mlock unavailable: %s\n", + strerror(errno)); + + if (munmap(dst, half)) + ksft_exit_fail_msg("munmap destination: %s\n", + strerror(errno)); + if (munmap(src, size)) + ksft_exit_fail_msg("munmap source: %s\n", + strerror(errno)); + + ksft_test_result_skip("%s\n", __func__); + return; + } + ksft_exit_fail_msg("mlock: %s\n", strerror(errno)); + } + + locked = get_vmlck_kb(); + + if (mremap(src + half, half, half, + MREMAP_MAYMOVE | MREMAP_FIXED | MREMAP_DONTUNMAP, + dst) == MAP_FAILED) + ksft_exit_fail_msg("mremap: %s\n", strerror(errno)); + + remapped = get_vmlck_kb(); + + if (munmap(dst, half)) + ksft_exit_fail_msg("munmap destination: %s\n", + strerror(errno)); + if (munmap(src, size)) + ksft_exit_fail_msg("munmap source: %s\n", strerror(errno)); + + after = get_vmlck_kb(); + + pass = locked == baseline + (long)(size / 1024) && + remapped == locked && + after == baseline; + + ksft_test_result(pass, + "%s (baseline=%ld kB, locked=%ld kB, remapped=%ld kB, after=%ld kB)\n", + __func__, baseline, locked, remapped, after); +} + int main(void) { ksft_print_header(); @@ -348,7 +440,7 @@ int main(void) ksft_finished(); } - ksft_set_plan(5); + ksft_set_plan(6); // Keep a page sized buffer around for when we need it. page_buffer = @@ -361,6 +453,7 @@ int main(void) mremap_dontunmap_simple_fixed(); mremap_dontunmap_partial_mapping(); mremap_dontunmap_partial_mapping_overwrite(); + mremap_dontunmap_partial_mlocked(); BUG_ON(munmap(page_buffer, page_size) == -1, "unable to unmap page buffer"); -- 2.55.0
