From: Ricardo Cañuelo <ricardo.canuelo@xxxxxxxxxxxxx> Subject: selftests: add mincore() tests Add a test suite for the mincore() syscall. It tests most of its use cases as well as its interface. Tests implemented: - basic interface test - behavior on anonymous mappings - behavior on anonymous mappings with huge tlb pages - file-backed mapping with a regular file - file-backed mapping with a tmpfs file Link: http://lkml.kernel.org/r/20200728100450.4065-1-ricardo.canuelo@xxxxxxxxxxxxx Signed-off-by: Ricardo Cañuelo <ricardo.canuelo@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- tools/testing/selftests/Makefile | 1 tools/testing/selftests/mincore/.gitignore | 2 tools/testing/selftests/mincore/Makefile | 6 tools/testing/selftests/mincore/mincore_selftest.c | 361 +++++++++++ 4 files changed, 370 insertions(+) --- a/tools/testing/selftests/Makefile~selftests-add-mincore-tests +++ a/tools/testing/selftests/Makefile @@ -32,6 +32,7 @@ TARGETS += lkdtm TARGETS += membarrier TARGETS += memfd TARGETS += memory-hotplug +TARGETS += mincore TARGETS += mount TARGETS += mqueue TARGETS += net --- /dev/null +++ a/tools/testing/selftests/mincore/.gitignore @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0+ +mincore_selftest --- /dev/null +++ a/tools/testing/selftests/mincore/Makefile @@ -0,0 +1,6 @@ +# SPDX-License-Identifier: GPL-2.0+ + +CFLAGS += -Wall + +TEST_GEN_PROGS := mincore_selftest +include ../lib.mk --- /dev/null +++ a/tools/testing/selftests/mincore/mincore_selftest.c @@ -0,0 +1,361 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * kselftest suite for mincore(). + * + * Copyright (C) 2020 Collabora, Ltd. + */ + +#define _GNU_SOURCE + +#include <stdio.h> +#include <errno.h> +#include <unistd.h> +#include <stdlib.h> +#include <sys/mman.h> +#include <string.h> +#include <fcntl.h> +#include <string.h> + +#include "../kselftest.h" +#include "../kselftest_harness.h" + +/* Default test file size: 4MB */ +#define MB (1UL << 20) +#define FILE_SIZE (4 * MB) + + +/* + * Tests the user interface. This test triggers most of the documented + * error conditions in mincore(). + */ +TEST(basic_interface) +{ + int retval; + int page_size; + unsigned char vec[1]; + char *addr; + + page_size = sysconf(_SC_PAGESIZE); + + /* Query a 0 byte sized range */ + retval = mincore(0, 0, vec); + EXPECT_EQ(0, retval); + + /* Addresses in the specified range are invalid or unmapped */ + errno = 0; + retval = mincore(NULL, page_size, vec); + EXPECT_EQ(-1, retval); + EXPECT_EQ(ENOMEM, errno); + + errno = 0; + addr = mmap(NULL, page_size, PROT_READ | PROT_WRITE, + MAP_SHARED | MAP_ANONYMOUS, -1, 0); + ASSERT_NE(MAP_FAILED, addr) { + TH_LOG("mmap error: %s", strerror(errno)); + } + + /* <addr> argument is not page-aligned */ + errno = 0; + retval = mincore(addr + 1, page_size, vec); + EXPECT_EQ(-1, retval); + EXPECT_EQ(EINVAL, errno); + + /* <length> argument is too large */ + errno = 0; + retval = mincore(addr, -1, vec); + EXPECT_EQ(-1, retval); + EXPECT_EQ(ENOMEM, errno); + + /* <vec> argument points to an illegal address */ + errno = 0; + retval = mincore(addr, page_size, NULL); + EXPECT_EQ(-1, retval); + EXPECT_EQ(EFAULT, errno); + munmap(addr, page_size); +} + + +/* + * Test mincore() behavior on a private anonymous page mapping. + * Check that the page is not loaded into memory right after the mapping + * but after accessing it (on-demand allocation). + * Then free the page and check that it's not memory-resident. + */ +TEST(check_anonymous_locked_pages) +{ + unsigned char vec[1]; + char *addr; + int retval; + int page_size; + + page_size = sysconf(_SC_PAGESIZE); + + /* Map one page and check it's not memory-resident */ + errno = 0; + addr = mmap(NULL, page_size, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + ASSERT_NE(MAP_FAILED, addr) { + TH_LOG("mmap error: %s", strerror(errno)); + } + retval = mincore(addr, page_size, vec); + ASSERT_EQ(0, retval); + ASSERT_EQ(0, vec[0]) { + TH_LOG("Page found in memory before use"); + } + + /* Touch the page and check again. It should now be in memory */ + addr[0] = 1; + mlock(addr, page_size); + retval = mincore(addr, page_size, vec); + ASSERT_EQ(0, retval); + ASSERT_EQ(1, vec[0]) { + TH_LOG("Page not found in memory after use"); + } + + /* + * It shouldn't be memory-resident after unlocking it and + * marking it as unneeded. + */ + munlock(addr, page_size); + madvise(addr, page_size, MADV_DONTNEED); + retval = mincore(addr, page_size, vec); + ASSERT_EQ(0, retval); + ASSERT_EQ(0, vec[0]) { + TH_LOG("Page in memory after being zapped"); + } + munmap(addr, page_size); +} + + +/* + * Check mincore() behavior on huge pages. + * This test will be skipped if the mapping fails (ie. if there are no + * huge pages available). + * + * Make sure the system has at least one free huge page, check + * "HugePages_Free" in /proc/meminfo. + * Increment /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages if + * needed. + */ +TEST(check_huge_pages) +{ + unsigned char vec[1]; + char *addr; + int retval; + int page_size; + + page_size = sysconf(_SC_PAGESIZE); + + errno = 0; + addr = mmap(NULL, page_size, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, + -1, 0); + if (addr == MAP_FAILED) { + if (errno == ENOMEM) + SKIP(return, "No huge pages available."); + else + TH_LOG("mmap error: %s", strerror(errno)); + } + retval = mincore(addr, page_size, vec); + ASSERT_EQ(0, retval); + ASSERT_EQ(0, vec[0]) { + TH_LOG("Page found in memory before use"); + } + + addr[0] = 1; + mlock(addr, page_size); + retval = mincore(addr, page_size, vec); + ASSERT_EQ(0, retval); + ASSERT_EQ(1, vec[0]) { + TH_LOG("Page not found in memory after use"); + } + + munlock(addr, page_size); + munmap(addr, page_size); +} + + +/* + * Test mincore() behavior on a file-backed page. + * No pages should be loaded into memory right after the mapping. Then, + * accessing any address in the mapping range should load the page + * containing the address and a number of subsequent pages (readahead). + * + * The actual readahead settings depend on the test environment, so we + * can't make a lot of assumptions about that. This test covers the most + * general cases. + */ +TEST(check_file_mmap) +{ + unsigned char *vec; + int vec_size; + char *addr; + int retval; + int page_size; + int fd; + int i; + int ra_pages = 0; + + page_size = sysconf(_SC_PAGESIZE); + vec_size = FILE_SIZE / page_size; + if (FILE_SIZE % page_size) + vec_size++; + + vec = calloc(vec_size, sizeof(unsigned char)); + ASSERT_NE(NULL, vec) { + TH_LOG("Can't allocate array"); + } + + errno = 0; + fd = open(".", O_TMPFILE | O_RDWR, 0600); + ASSERT_NE(-1, fd) { + TH_LOG("Can't create temporary file: %s", + strerror(errno)); + } + errno = 0; + retval = fallocate(fd, 0, 0, FILE_SIZE); + ASSERT_EQ(0, retval) { + TH_LOG("Error allocating space for the temporary file: %s", + strerror(errno)); + } + + /* + * Map the whole file, the pages shouldn't be fetched yet. + */ + errno = 0; + addr = mmap(NULL, FILE_SIZE, PROT_READ | PROT_WRITE, + MAP_SHARED, fd, 0); + ASSERT_NE(MAP_FAILED, addr) { + TH_LOG("mmap error: %s", strerror(errno)); + } + retval = mincore(addr, FILE_SIZE, vec); + ASSERT_EQ(0, retval); + for (i = 0; i < vec_size; i++) { + ASSERT_EQ(0, vec[i]) { + TH_LOG("Unexpected page in memory"); + } + } + + /* + * Touch a page in the middle of the mapping. We expect the next + * few pages (the readahead window) to be populated too. + */ + addr[FILE_SIZE / 2] = 1; + retval = mincore(addr, FILE_SIZE, vec); + ASSERT_EQ(0, retval); + ASSERT_EQ(1, vec[FILE_SIZE / 2 / page_size]) { + TH_LOG("Page not found in memory after use"); + } + + i = FILE_SIZE / 2 / page_size + 1; + while (i < vec_size && vec[i]) { + ra_pages++; + i++; + } + EXPECT_GT(ra_pages, 0) { + TH_LOG("No read-ahead pages found in memory"); + } + + EXPECT_LT(i, vec_size) { + TH_LOG("Read-ahead pages reached the end of the file"); + } + /* + * End of the readahead window. The rest of the pages shouldn't + * be in memory. + */ + if (i < vec_size) { + while (i < vec_size && !vec[i]) + i++; + EXPECT_EQ(vec_size, i) { + TH_LOG("Unexpected page in memory beyond readahead window"); + } + } + + munmap(addr, FILE_SIZE); + close(fd); + free(vec); +} + + +/* + * Test mincore() behavior on a page backed by a tmpfs file. This test + * performs the same steps as the previous one. However, we don't expect + * any readahead in this case. + */ +TEST(check_tmpfs_mmap) +{ + unsigned char *vec; + int vec_size; + char *addr; + int retval; + int page_size; + int fd; + int i; + int ra_pages = 0; + + page_size = sysconf(_SC_PAGESIZE); + vec_size = FILE_SIZE / page_size; + if (FILE_SIZE % page_size) + vec_size++; + + vec = calloc(vec_size, sizeof(unsigned char)); + ASSERT_NE(NULL, vec) { + TH_LOG("Can't allocate array"); + } + + errno = 0; + fd = open("/dev/shm", O_TMPFILE | O_RDWR, 0600); + ASSERT_NE(-1, fd) { + TH_LOG("Can't create temporary file: %s", + strerror(errno)); + } + errno = 0; + retval = fallocate(fd, 0, 0, FILE_SIZE); + ASSERT_EQ(0, retval) { + TH_LOG("Error allocating space for the temporary file: %s", + strerror(errno)); + } + + /* + * Map the whole file, the pages shouldn't be fetched yet. + */ + errno = 0; + addr = mmap(NULL, FILE_SIZE, PROT_READ | PROT_WRITE, + MAP_SHARED, fd, 0); + ASSERT_NE(MAP_FAILED, addr) { + TH_LOG("mmap error: %s", strerror(errno)); + } + retval = mincore(addr, FILE_SIZE, vec); + ASSERT_EQ(0, retval); + for (i = 0; i < vec_size; i++) { + ASSERT_EQ(0, vec[i]) { + TH_LOG("Unexpected page in memory"); + } + } + + /* + * Touch a page in the middle of the mapping. We expect only + * that page to be fetched into memory. + */ + addr[FILE_SIZE / 2] = 1; + retval = mincore(addr, FILE_SIZE, vec); + ASSERT_EQ(0, retval); + ASSERT_EQ(1, vec[FILE_SIZE / 2 / page_size]) { + TH_LOG("Page not found in memory after use"); + } + + i = FILE_SIZE / 2 / page_size + 1; + while (i < vec_size && vec[i]) { + ra_pages++; + i++; + } + ASSERT_EQ(ra_pages, 0) { + TH_LOG("Read-ahead pages found in memory"); + } + + munmap(addr, FILE_SIZE); + close(fd); + free(vec); +} + +TEST_HARNESS_MAIN _
