diff options
Diffstat (limited to 'tools/testing/selftests/mm/ksm_functional_tests.c')
| -rw-r--r-- | tools/testing/selftests/mm/ksm_functional_tests.c | 650 |
1 files changed, 650 insertions, 0 deletions
diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c new file mode 100644 index 000000000000..d615767e396b --- /dev/null +++ b/tools/testing/selftests/mm/ksm_functional_tests.c @@ -0,0 +1,650 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * KSM functional tests + * + * Copyright 2022, Red Hat, Inc. + * + * Author(s): David Hildenbrand <david@redhat.com> + */ +#define _GNU_SOURCE +#include <stdlib.h> +#include <string.h> +#include <stdbool.h> +#include <stdint.h> +#include <unistd.h> +#include <errno.h> +#include <fcntl.h> +#include <sys/mman.h> +#include <sys/prctl.h> +#include <sys/syscall.h> +#include <sys/ioctl.h> +#include <sys/wait.h> +#include <linux/userfaultfd.h> + +#include "../kselftest.h" +#include "vm_util.h" + +#define KiB 1024u +#define MiB (1024 * KiB) +#define FORK_EXEC_CHILD_PRG_NAME "ksm_fork_exec_child" + +static int mem_fd; +static int ksm_fd; +static int ksm_full_scans_fd; +static int proc_self_ksm_stat_fd; +static int proc_self_ksm_merging_pages_fd; +static int ksm_use_zero_pages_fd; +static int pagemap_fd; +static size_t pagesize; + +static bool range_maps_duplicates(char *addr, unsigned long size) +{ + unsigned long offs_a, offs_b, pfn_a, pfn_b; + + /* + * There is no easy way to check if there are KSM pages mapped into + * this range. We only check that the range does not map the same PFN + * twice by comparing each pair of mapped pages. + */ + for (offs_a = 0; offs_a < size; offs_a += pagesize) { + pfn_a = pagemap_get_pfn(pagemap_fd, addr + offs_a); + /* Page not present or PFN not exposed by the kernel. */ + if (pfn_a == -1ul || !pfn_a) + continue; + + for (offs_b = offs_a + pagesize; offs_b < size; + offs_b += pagesize) { + pfn_b = pagemap_get_pfn(pagemap_fd, addr + offs_b); + if (pfn_b == -1ul || !pfn_b) + continue; + if (pfn_a == pfn_b) + return true; + } + } + return false; +} + +static long get_my_ksm_zero_pages(void) +{ + char buf[200]; + char *substr_ksm_zero; + size_t value_pos; + ssize_t read_size; + unsigned long my_ksm_zero_pages; + + if (!proc_self_ksm_stat_fd) + return 0; + + read_size = pread(proc_self_ksm_stat_fd, buf, sizeof(buf) - 1, 0); + if (read_size < 0) + return -errno; + + buf[read_size] = 0; + + substr_ksm_zero = strstr(buf, "ksm_zero_pages"); + if (!substr_ksm_zero) + return 0; + + value_pos = strcspn(substr_ksm_zero, "0123456789"); + my_ksm_zero_pages = strtol(substr_ksm_zero + value_pos, NULL, 10); + + return my_ksm_zero_pages; +} + +static long get_my_merging_pages(void) +{ + char buf[10]; + ssize_t ret; + + if (proc_self_ksm_merging_pages_fd < 0) + return proc_self_ksm_merging_pages_fd; + + ret = pread(proc_self_ksm_merging_pages_fd, buf, sizeof(buf) - 1, 0); + if (ret <= 0) + return -errno; + buf[ret] = 0; + + return strtol(buf, NULL, 10); +} + +static long ksm_get_full_scans(void) +{ + char buf[10]; + ssize_t ret; + + ret = pread(ksm_full_scans_fd, buf, sizeof(buf) - 1, 0); + if (ret <= 0) + return -errno; + buf[ret] = 0; + + return strtol(buf, NULL, 10); +} + +static int ksm_merge(void) +{ + long start_scans, end_scans; + + /* Wait for two full scans such that any possible merging happened. */ + start_scans = ksm_get_full_scans(); + if (start_scans < 0) + return start_scans; + if (write(ksm_fd, "1", 1) != 1) + return -errno; + do { + end_scans = ksm_get_full_scans(); + if (end_scans < 0) + return end_scans; + } while (end_scans < start_scans + 2); + + return 0; +} + +static int ksm_unmerge(void) +{ + if (write(ksm_fd, "2", 1) != 1) + return -errno; + return 0; +} + +static char *mmap_and_merge_range(char val, unsigned long size, int prot, + bool use_prctl) +{ + char *map; + int ret; + + /* Stabilize accounting by disabling KSM completely. */ + if (ksm_unmerge()) { + ksft_test_result_fail("Disabling (unmerging) KSM failed\n"); + return MAP_FAILED; + } + + if (get_my_merging_pages() > 0) { + ksft_test_result_fail("Still pages merged\n"); + return MAP_FAILED; + } + + map = mmap(NULL, size, PROT_READ|PROT_WRITE, + MAP_PRIVATE|MAP_ANON, -1, 0); + if (map == MAP_FAILED) { + ksft_test_result_fail("mmap() failed\n"); + return MAP_FAILED; + } + + /* Don't use THP. Ignore if THP are not around on a kernel. */ + if (madvise(map, size, MADV_NOHUGEPAGE) && errno != EINVAL) { + ksft_test_result_fail("MADV_NOHUGEPAGE failed\n"); + goto unmap; + } + + /* Make sure each page contains the same values to merge them. */ + memset(map, val, size); + + if (mprotect(map, size, prot)) { + ksft_test_result_skip("mprotect() failed\n"); + goto unmap; + } + + if (use_prctl) { + ret = prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0); + if (ret < 0 && errno == EINVAL) { + ksft_test_result_skip("PR_SET_MEMORY_MERGE not supported\n"); + goto unmap; + } else if (ret) { + ksft_test_result_fail("PR_SET_MEMORY_MERGE=1 failed\n"); + goto unmap; + } + } else if (madvise(map, size, MADV_MERGEABLE)) { + ksft_test_result_fail("MADV_MERGEABLE failed\n"); + goto unmap; + } + + /* Run KSM to trigger merging and wait. */ + if (ksm_merge()) { + ksft_test_result_fail("Running KSM failed\n"); + goto unmap; + } + + /* + * Check if anything was merged at all. Ignore the zero page that is + * accounted differently (depending on kernel support). + */ + if (val && !get_my_merging_pages()) { + ksft_test_result_fail("No pages got merged\n"); + goto unmap; + } + + return map; +unmap: + munmap(map, size); + return MAP_FAILED; +} + +static void test_unmerge(void) +{ + const unsigned int size = 2 * MiB; + char *map; + + ksft_print_msg("[RUN] %s\n", __func__); + + map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, false); + if (map == MAP_FAILED) + return; + + if (madvise(map, size, MADV_UNMERGEABLE)) { + ksft_test_result_fail("MADV_UNMERGEABLE failed\n"); + goto unmap; + } + + ksft_test_result(!range_maps_duplicates(map, size), + "Pages were unmerged\n"); +unmap: + munmap(map, size); +} + +static void test_unmerge_zero_pages(void) +{ + const unsigned int size = 2 * MiB; + char *map; + unsigned int offs; + unsigned long pages_expected; + + ksft_print_msg("[RUN] %s\n", __func__); + + if (proc_self_ksm_stat_fd < 0) { + ksft_test_result_skip("open(\"/proc/self/ksm_stat\") failed\n"); + return; + } + if (ksm_use_zero_pages_fd < 0) { + ksft_test_result_skip("open \"/sys/kernel/mm/ksm/use_zero_pages\" failed\n"); + return; + } + if (write(ksm_use_zero_pages_fd, "1", 1) != 1) { + ksft_test_result_skip("write \"/sys/kernel/mm/ksm/use_zero_pages\" failed\n"); + return; + } + + /* Let KSM deduplicate zero pages. */ + map = mmap_and_merge_range(0x00, size, PROT_READ | PROT_WRITE, false); + if (map == MAP_FAILED) + return; + + /* Check if ksm_zero_pages is updated correctly after KSM merging */ + pages_expected = size / pagesize; + if (pages_expected != get_my_ksm_zero_pages()) { + ksft_test_result_fail("'ksm_zero_pages' updated after merging\n"); + goto unmap; + } + + /* Try to unmerge half of the region */ + if (madvise(map, size / 2, MADV_UNMERGEABLE)) { + ksft_test_result_fail("MADV_UNMERGEABLE failed\n"); + goto unmap; + } + + /* Check if ksm_zero_pages is updated correctly after unmerging */ + pages_expected /= 2; + if (pages_expected != get_my_ksm_zero_pages()) { + ksft_test_result_fail("'ksm_zero_pages' updated after unmerging\n"); + goto unmap; + } + + /* Trigger unmerging of the other half by writing to the pages. */ + for (offs = size / 2; offs < size; offs += pagesize) + *((unsigned int *)&map[offs]) = offs; + + /* Now we should have no zeropages remaining. */ + if (get_my_ksm_zero_pages()) { + ksft_test_result_fail("'ksm_zero_pages' updated after write fault\n"); + goto unmap; + } + + /* Check if ksm zero pages are really unmerged */ + ksft_test_result(!range_maps_duplicates(map, size), + "KSM zero pages were unmerged\n"); +unmap: + munmap(map, size); +} + +static void test_unmerge_discarded(void) +{ + const unsigned int size = 2 * MiB; + char *map; + + ksft_print_msg("[RUN] %s\n", __func__); + + map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, false); + if (map == MAP_FAILED) + return; + + /* Discard half of all mapped pages so we have pte_none() entries. */ + if (madvise(map, size / 2, MADV_DONTNEED)) { + ksft_test_result_fail("MADV_DONTNEED failed\n"); + goto unmap; + } + + if (madvise(map, size, MADV_UNMERGEABLE)) { + ksft_test_result_fail("MADV_UNMERGEABLE failed\n"); + goto unmap; + } + + ksft_test_result(!range_maps_duplicates(map, size), + "Pages were unmerged\n"); +unmap: + munmap(map, size); +} + +#ifdef __NR_userfaultfd +static void test_unmerge_uffd_wp(void) +{ + struct uffdio_writeprotect uffd_writeprotect; + const unsigned int size = 2 * MiB; + struct uffdio_api uffdio_api; + char *map; + int uffd; + + ksft_print_msg("[RUN] %s\n", __func__); + + map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, false); + if (map == MAP_FAILED) + return; + + /* See if UFFD is around. */ + uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK); + if (uffd < 0) { + ksft_test_result_skip("__NR_userfaultfd failed\n"); + goto unmap; + } + + /* See if UFFD-WP is around. */ + uffdio_api.api = UFFD_API; + uffdio_api.features = UFFD_FEATURE_PAGEFAULT_FLAG_WP; + if (ioctl(uffd, UFFDIO_API, &uffdio_api) < 0) { + ksft_test_result_fail("UFFDIO_API failed\n"); + goto close_uffd; + } + if (!(uffdio_api.features & UFFD_FEATURE_PAGEFAULT_FLAG_WP)) { + ksft_test_result_skip("UFFD_FEATURE_PAGEFAULT_FLAG_WP not available\n"); + goto close_uffd; + } + + /* Register UFFD-WP, no need for an actual handler. */ + if (uffd_register(uffd, map, size, false, true, false)) { + ksft_test_result_fail("UFFDIO_REGISTER_MODE_WP failed\n"); + goto close_uffd; + } + + /* Write-protect the range using UFFD-WP. */ + uffd_writeprotect.range.start = (unsigned long) map; + uffd_writeprotect.range.len = size; + uffd_writeprotect.mode = UFFDIO_WRITEPROTECT_MODE_WP; + if (ioctl(uffd, UFFDIO_WRITEPROTECT, &uffd_writeprotect)) { + ksft_test_result_fail("UFFDIO_WRITEPROTECT failed\n"); + goto close_uffd; + } + + if (madvise(map, size, MADV_UNMERGEABLE)) { + ksft_test_result_fail("MADV_UNMERGEABLE failed\n"); + goto close_uffd; + } + + ksft_test_result(!range_maps_duplicates(map, size), + "Pages were unmerged\n"); +close_uffd: + close(uffd); +unmap: + munmap(map, size); +} +#endif + +/* Verify that KSM can be enabled / queried with prctl. */ +static void test_prctl(void) +{ + int ret; + + ksft_print_msg("[RUN] %s\n", __func__); + + ret = prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0); + if (ret < 0 && errno == EINVAL) { + ksft_test_result_skip("PR_SET_MEMORY_MERGE not supported\n"); + return; + } else if (ret) { + ksft_test_result_fail("PR_SET_MEMORY_MERGE=1 failed\n"); + return; + } + + ret = prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0); + if (ret < 0) { + ksft_test_result_fail("PR_GET_MEMORY_MERGE failed\n"); + return; + } else if (ret != 1) { + ksft_test_result_fail("PR_SET_MEMORY_MERGE=1 not effective\n"); + return; + } + + ret = prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0); + if (ret) { + ksft_test_result_fail("PR_SET_MEMORY_MERGE=0 failed\n"); + return; + } + + ret = prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0); + if (ret < 0) { + ksft_test_result_fail("PR_GET_MEMORY_MERGE failed\n"); + return; + } else if (ret != 0) { + ksft_test_result_fail("PR_SET_MEMORY_MERGE=0 not effective\n"); + return; + } + + ksft_test_result_pass("Setting/clearing PR_SET_MEMORY_MERGE works\n"); +} + +/* Verify that prctl ksm flag is inherited. */ +static void test_prctl_fork(void) +{ + int ret, status; + pid_t child_pid; + + ksft_print_msg("[RUN] %s\n", __func__); + + ret = prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0); + if (ret < 0 && errno == EINVAL) { + ksft_test_result_skip("PR_SET_MEMORY_MERGE not supported\n"); + return; + } else if (ret) { + ksft_test_result_fail("PR_SET_MEMORY_MERGE=1 failed\n"); + return; + } + + child_pid = fork(); + if (!child_pid) { + exit(prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0)); + } else if (child_pid < 0) { + ksft_test_result_fail("fork() failed\n"); + return; + } + + if (waitpid(child_pid, &status, 0) < 0) { + ksft_test_result_fail("waitpid() failed\n"); + return; + } else if (WEXITSTATUS(status) != 1) { + ksft_test_result_fail("unexpected PR_GET_MEMORY_MERGE result in child\n"); + return; + } + + if (prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0)) { + ksft_test_result_fail("PR_SET_MEMORY_MERGE=0 failed\n"); + return; + } + + ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n"); +} + +static int ksm_fork_exec_child(void) +{ + /* Test if KSM is enabled for the process. */ + return prctl(PR_GET_MEMORY_MERGE, 0, 0, 0, 0) == 1; +} + +static void test_prctl_fork_exec(void) +{ + int ret, status; + pid_t child_pid; + + ksft_print_msg("[RUN] %s\n", __func__); + + ret = prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0); + if (ret < 0 && errno == EINVAL) { + ksft_test_result_skip("PR_SET_MEMORY_MERGE not supported\n"); + return; + } else if (ret) { + ksft_test_result_fail("PR_SET_MEMORY_MERGE=1 failed\n"); + return; + } + + child_pid = fork(); + if (child_pid == -1) { + ksft_test_result_skip("fork() failed\n"); + return; + } else if (child_pid == 0) { + char *prg_name = "./ksm_functional_tests"; + char *argv_for_program[] = { prg_name, FORK_EXEC_CHILD_PRG_NAME }; + + execv(prg_name, argv_for_program); + return; + } + + if (waitpid(child_pid, &status, 0) > 0) { + if (WIFEXITED(status)) { + status = WEXITSTATUS(status); + if (status) { + ksft_test_result_fail("KSM not enabled\n"); + return; + } + } else { + ksft_test_result_fail("program didn't terminate normally\n"); + return; + } + } else { + ksft_test_result_fail("waitpid() failed\n"); + return; + } + + if (prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0)) { + ksft_test_result_fail("PR_SET_MEMORY_MERGE=0 failed\n"); + return; + } + + ksft_test_result_pass("PR_SET_MEMORY_MERGE value is inherited\n"); +} + +static void test_prctl_unmerge(void) +{ + const unsigned int size = 2 * MiB; + char *map; + + ksft_print_msg("[RUN] %s\n", __func__); + + map = mmap_and_merge_range(0xcf, size, PROT_READ | PROT_WRITE, true); + if (map == MAP_FAILED) + return; + + if (prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0)) { + ksft_test_result_fail("PR_SET_MEMORY_MERGE=0 failed\n"); + goto unmap; + } + + ksft_test_result(!range_maps_duplicates(map, size), + "Pages were unmerged\n"); +unmap: + munmap(map, size); +} + +static void test_prot_none(void) +{ + const unsigned int size = 2 * MiB; + char *map; + int i; + + ksft_print_msg("[RUN] %s\n", __func__); + + map = mmap_and_merge_range(0x11, size, PROT_NONE, false); + if (map == MAP_FAILED) + goto unmap; + + /* Store a unique value in each page on one half using ptrace */ + for (i = 0; i < size / 2; i += pagesize) { + lseek(mem_fd, (uintptr_t) map + i, SEEK_SET); + if (write(mem_fd, &i, sizeof(i)) != sizeof(i)) { + ksft_test_result_fail("ptrace write failed\n"); + goto unmap; + } + } + + /* Trigger unsharing on the other half. */ + if (madvise(map + size / 2, size / 2, MADV_UNMERGEABLE)) { + ksft_test_result_fail("MADV_UNMERGEABLE failed\n"); + goto unmap; + } + + ksft_test_result(!range_maps_duplicates(map, size), + "Pages were unmerged\n"); +unmap: + munmap(map, size); +} + +int main(int argc, char **argv) +{ + unsigned int tests = 8; + int err; + + if (argc > 1 && !strcmp(argv[1], FORK_EXEC_CHILD_PRG_NAME)) { + exit(ksm_fork_exec_child() == 1 ? 0 : 1); + } + +#ifdef __NR_userfaultfd + tests++; +#endif + + ksft_print_header(); + ksft_set_plan(tests); + + pagesize = getpagesize(); + + mem_fd = open("/proc/self/mem", O_RDWR); + if (mem_fd < 0) + ksft_exit_fail_msg("opening /proc/self/mem failed\n"); + ksm_fd = open("/sys/kernel/mm/ksm/run", O_RDWR); + if (ksm_fd < 0) + ksft_exit_skip("open(\"/sys/kernel/mm/ksm/run\") failed\n"); + ksm_full_scans_fd = open("/sys/kernel/mm/ksm/full_scans", O_RDONLY); + if (ksm_full_scans_fd < 0) + ksft_exit_skip("open(\"/sys/kernel/mm/ksm/full_scans\") failed\n"); + pagemap_fd = open("/proc/self/pagemap", O_RDONLY); + if (pagemap_fd < 0) + ksft_exit_skip("open(\"/proc/self/pagemap\") failed\n"); + proc_self_ksm_stat_fd = open("/proc/self/ksm_stat", O_RDONLY); + proc_self_ksm_merging_pages_fd = open("/proc/self/ksm_merging_pages", + O_RDONLY); + ksm_use_zero_pages_fd = open("/sys/kernel/mm/ksm/use_zero_pages", O_RDWR); + + test_unmerge(); + test_unmerge_zero_pages(); + test_unmerge_discarded(); +#ifdef __NR_userfaultfd + test_unmerge_uffd_wp(); +#endif + + test_prot_none(); + + test_prctl(); + test_prctl_fork(); + test_prctl_fork_exec(); + test_prctl_unmerge(); + + err = ksft_get_fail_cnt(); + if (err) + ksft_exit_fail_msg("%d out of %d tests failed\n", + err, ksft_test_num()); + return ksft_exit_pass(); +} |