| /* |
| * Copyright (c) 2016 Red Hat, Inc. |
| * |
| * This program is free software: you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation, either version 3 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| /* |
| * DESCRIPTION |
| * |
| * Page fault occurs in spite that madvise(WILLNEED) system call is called |
| * to prefetch the page. This issue is reproduced by running a program |
| * which sequentially accesses to a shared memory and calls madvise(WILLNEED) |
| * to the next page on a page fault. |
| * |
| * This bug is present in all RHEL7 versions. It looks like this was fixed in |
| * mainline kernel > v3.15 by the following patch: |
| * |
| * commit 55231e5c898c5c03c14194001e349f40f59bd300 |
| * Author: Johannes Weiner <hannes@cmpxchg.org> |
| * Date: Thu May 22 11:54:17 2014 -0700 |
| * |
| * mm: madvise: fix MADV_WILLNEED on shmem swapouts |
| */ |
| |
| #include <errno.h> |
| #include <stdio.h> |
| #include <sys/mount.h> |
| #include <sys/sysinfo.h> |
| #include "tst_test.h" |
| |
| #define CHUNK_SZ (400*1024*1024L) |
| #define CHUNK_PAGES (CHUNK_SZ / pg_sz) |
| #define PASS_THRESHOLD (CHUNK_SZ / 4) |
| |
| #define MNT_NAME "memory" |
| #define GROUP_NAME "madvise06" |
| |
| static const char drop_caches_fname[] = "/proc/sys/vm/drop_caches"; |
| static int pg_sz; |
| |
| static void check_path(const char *path) |
| { |
| if (access(path, R_OK | W_OK)) |
| tst_brk(TCONF, "file needed: %s\n", path); |
| } |
| |
| static void setup(void) |
| { |
| struct sysinfo sys_buf_start; |
| |
| pg_sz = getpagesize(); |
| |
| check_path(drop_caches_fname); |
| tst_res(TINFO, "dropping caches"); |
| sync(); |
| SAFE_FILE_PRINTF(drop_caches_fname, "3"); |
| |
| sysinfo(&sys_buf_start); |
| if (sys_buf_start.freeram < 2 * CHUNK_SZ) |
| tst_brk(TCONF, "System RAM is too small, skip test"); |
| if (sys_buf_start.freeswap < 2 * CHUNK_SZ) |
| tst_brk(TCONF, "System swap is too small"); |
| |
| SAFE_MKDIR(MNT_NAME, 0700); |
| if (mount("memory", MNT_NAME, "cgroup", 0, "memory") == -1) { |
| if (errno == ENODEV || errno == ENOENT) |
| tst_brk(TCONF, "memory cgroup needed"); |
| } |
| SAFE_MKDIR(MNT_NAME"/"GROUP_NAME, 0700); |
| |
| check_path("/proc/self/oom_score_adj"); |
| check_path(MNT_NAME"/"GROUP_NAME"/memory.limit_in_bytes"); |
| check_path(MNT_NAME"/"GROUP_NAME"/memory.swappiness"); |
| check_path(MNT_NAME"/"GROUP_NAME"/tasks"); |
| |
| SAFE_FILE_PRINTF("/proc/self/oom_score_adj", "%d", -1000); |
| SAFE_FILE_PRINTF(MNT_NAME"/"GROUP_NAME"/memory.limit_in_bytes", "%ld\n", |
| PASS_THRESHOLD); |
| SAFE_FILE_PRINTF(MNT_NAME"/"GROUP_NAME"/memory.swappiness", "60"); |
| SAFE_FILE_PRINTF(MNT_NAME"/"GROUP_NAME"/tasks", "%d\n", getpid()); |
| } |
| |
| static void cleanup(void) |
| { |
| SAFE_FILE_PRINTF(MNT_NAME"/tasks", "%d\n", getpid()); |
| SAFE_RMDIR(MNT_NAME"/"GROUP_NAME); |
| SAFE_UMOUNT(MNT_NAME); |
| } |
| |
| static void dirty_pages(char *ptr, long size) |
| { |
| long i; |
| long pages = size / pg_sz; |
| |
| for (i = 0; i < pages; i++) |
| ptr[i * pg_sz] = 'x'; |
| } |
| |
| static int get_page_fault_num(void) |
| { |
| int pg; |
| |
| SAFE_FILE_SCANF("/proc/self/stat", |
| "%*s %*s %*s %*s %*s %*s %*s %*s %*s %*s %*s %d", |
| &pg); |
| return pg; |
| } |
| |
| static void test_advice_willneed(void) |
| { |
| int loops = 50; |
| char *target; |
| long swapcached_start, swapcached; |
| int page_fault_num_1, page_fault_num_2; |
| |
| target = SAFE_MMAP(NULL, CHUNK_SZ, PROT_READ | PROT_WRITE, |
| MAP_SHARED | MAP_ANONYMOUS, |
| -1, 0); |
| dirty_pages(target, CHUNK_SZ); |
| |
| SAFE_FILE_LINES_SCANF("/proc/meminfo", "SwapCached: %ld", |
| &swapcached_start); |
| tst_res(TINFO, "SwapCached (before madvise): %ld", swapcached_start); |
| |
| TEST(madvise(target, CHUNK_SZ, MADV_WILLNEED)); |
| if (TEST_RETURN == -1) |
| tst_brk(TBROK | TERRNO, "madvise failed"); |
| |
| do { |
| loops--; |
| usleep(100000); |
| SAFE_FILE_LINES_SCANF("/proc/meminfo", "SwapCached: %ld", |
| &swapcached); |
| } while (swapcached < swapcached_start + PASS_THRESHOLD / 1024 |
| && loops > 0); |
| |
| tst_res(TINFO, "SwapCached (after madvise): %ld", swapcached); |
| if (swapcached > swapcached_start + PASS_THRESHOLD / 1024) { |
| tst_res(TPASS, "Regression test pass"); |
| SAFE_MUNMAP(target, CHUNK_SZ); |
| return; |
| } |
| |
| /* |
| * We may have hit a bug or we just have slow I/O, |
| * try accessing first page. |
| */ |
| page_fault_num_1 = get_page_fault_num(); |
| tst_res(TINFO, "PageFault(madvice / no mem access): %d", |
| page_fault_num_1); |
| target[0] = 'a'; |
| page_fault_num_2 = get_page_fault_num(); |
| tst_res(TINFO, "PageFault(madvice / mem access): %d", |
| page_fault_num_2); |
| |
| if (page_fault_num_1 != page_fault_num_2) |
| tst_res(TFAIL, "Bug has been reproduced"); |
| else |
| tst_res(TPASS, "Regression test pass"); |
| |
| SAFE_MUNMAP(target, CHUNK_SZ); |
| } |
| |
| static struct tst_test test = { |
| .tid = "madvise06", |
| .test_all = test_advice_willneed, |
| .setup = setup, |
| .cleanup = cleanup, |
| .min_kver = "3.10.0", |
| .needs_tmpdir = 1, |
| .needs_root = 1, |
| }; |