From c0dddb7aa5f85e6150a1e3230e01d5ba286eded9 Mon Sep 17 00:00:00 2001 From: Nhat Pham Date: Fri, 6 Oct 2023 11:46:29 -0700 Subject: selftests: add a selftest to verify hugetlb usage in memcg This patch add a new kselftest to demonstrate and verify the new hugetlb memcg accounting behavior. Link: https://lkml.kernel.org/r/20231006184629.155543-5-nphamcs@gmail.com Signed-off-by: Nhat Pham Cc: Frank van der Linden Cc: Johannes Weiner Cc: Michal Hocko Cc: Mike Kravetz Cc: Muchun Song Cc: Rik van Riel Cc: Roman Gushchin Cc: Shakeel Butt Cc: Shuah Khan Cc: Tejun heo Cc: Yosry Ahmed Cc: Zefan Li Signed-off-by: Andrew Morton --- tools/testing/selftests/cgroup/.gitignore | 1 + tools/testing/selftests/cgroup/Makefile | 2 + .../testing/selftests/cgroup/test_hugetlb_memcg.c | 234 +++++++++++++++++++++ 3 files changed, 237 insertions(+) create mode 100644 tools/testing/selftests/cgroup/test_hugetlb_memcg.c (limited to 'tools/testing/selftests/cgroup') diff --git a/tools/testing/selftests/cgroup/.gitignore b/tools/testing/selftests/cgroup/.gitignore index af8c3f30b9c1..2732e0b29271 100644 --- a/tools/testing/selftests/cgroup/.gitignore +++ b/tools/testing/selftests/cgroup/.gitignore @@ -7,4 +7,5 @@ test_kill test_cpu test_cpuset test_zswap +test_hugetlb_memcg wait_inotify diff --git a/tools/testing/selftests/cgroup/Makefile b/tools/testing/selftests/cgroup/Makefile index c27f05f6ce9b..00b441928909 100644 --- a/tools/testing/selftests/cgroup/Makefile +++ b/tools/testing/selftests/cgroup/Makefile @@ -14,6 +14,7 @@ TEST_GEN_PROGS += test_kill TEST_GEN_PROGS += test_cpu TEST_GEN_PROGS += test_cpuset TEST_GEN_PROGS += test_zswap +TEST_GEN_PROGS += test_hugetlb_memcg LOCAL_HDRS += $(selfdir)/clone3/clone3_selftests.h $(selfdir)/pidfd/pidfd.h @@ -27,3 +28,4 @@ $(OUTPUT)/test_kill: cgroup_util.c $(OUTPUT)/test_cpu: cgroup_util.c $(OUTPUT)/test_cpuset: cgroup_util.c $(OUTPUT)/test_zswap: cgroup_util.c +$(OUTPUT)/test_hugetlb_memcg: cgroup_util.c diff --git a/tools/testing/selftests/cgroup/test_hugetlb_memcg.c b/tools/testing/selftests/cgroup/test_hugetlb_memcg.c new file mode 100644 index 000000000000..f0fefeb4cc24 --- /dev/null +++ b/tools/testing/selftests/cgroup/test_hugetlb_memcg.c @@ -0,0 +1,234 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE + +#include +#include +#include +#include +#include +#include +#include "../kselftest.h" +#include "cgroup_util.h" + +#define ADDR ((void *)(0x0UL)) +#define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB) +/* mapping 8 MBs == 4 hugepages */ +#define LENGTH (8UL*1024*1024) +#define PROTECTION (PROT_READ | PROT_WRITE) + +/* borrowed from mm/hmm-tests.c */ +static long get_hugepage_size(void) +{ + int fd; + char buf[2048]; + int len; + char *p, *q, *path = "/proc/meminfo", *tag = "Hugepagesize:"; + long val; + + fd = open(path, O_RDONLY); + if (fd < 0) { + /* Error opening the file */ + return -1; + } + + len = read(fd, buf, sizeof(buf)); + close(fd); + if (len < 0) { + /* Error in reading the file */ + return -1; + } + if (len == sizeof(buf)) { + /* Error file is too large */ + return -1; + } + buf[len] = '\0'; + + /* Search for a tag if provided */ + if (tag) { + p = strstr(buf, tag); + if (!p) + return -1; /* looks like the line we want isn't there */ + p += strlen(tag); + } else + p = buf; + + val = strtol(p, &q, 0); + if (*q != ' ') { + /* Error parsing the file */ + return -1; + } + + return val; +} + +static int set_file(const char *path, long value) +{ + FILE *file; + int ret; + + file = fopen(path, "w"); + if (!file) + return -1; + ret = fprintf(file, "%ld\n", value); + fclose(file); + return ret; +} + +static int set_nr_hugepages(long value) +{ + return set_file("/proc/sys/vm/nr_hugepages", value); +} + +static unsigned int check_first(char *addr) +{ + return *(unsigned int *)addr; +} + +static void write_data(char *addr) +{ + unsigned long i; + + for (i = 0; i < LENGTH; i++) + *(addr + i) = (char)i; +} + +static int hugetlb_test_program(const char *cgroup, void *arg) +{ + char *test_group = (char *)arg; + void *addr; + long old_current, expected_current, current; + int ret = EXIT_FAILURE; + + old_current = cg_read_long(test_group, "memory.current"); + set_nr_hugepages(20); + current = cg_read_long(test_group, "memory.current"); + if (current - old_current >= MB(2)) { + ksft_print_msg( + "setting nr_hugepages should not increase hugepage usage.\n"); + ksft_print_msg("before: %ld, after: %ld\n", old_current, current); + return EXIT_FAILURE; + } + + addr = mmap(ADDR, LENGTH, PROTECTION, FLAGS, 0, 0); + if (addr == MAP_FAILED) { + ksft_print_msg("fail to mmap.\n"); + return EXIT_FAILURE; + } + current = cg_read_long(test_group, "memory.current"); + if (current - old_current >= MB(2)) { + ksft_print_msg("mmap should not increase hugepage usage.\n"); + ksft_print_msg("before: %ld, after: %ld\n", old_current, current); + goto out_failed_munmap; + } + old_current = current; + + /* read the first page */ + check_first(addr); + expected_current = old_current + MB(2); + current = cg_read_long(test_group, "memory.current"); + if (!values_close(expected_current, current, 5)) { + ksft_print_msg("memory usage should increase by around 2MB.\n"); + ksft_print_msg( + "expected memory: %ld, actual memory: %ld\n", + expected_current, current); + goto out_failed_munmap; + } + + /* write to the whole range */ + write_data(addr); + current = cg_read_long(test_group, "memory.current"); + expected_current = old_current + MB(8); + if (!values_close(expected_current, current, 5)) { + ksft_print_msg("memory usage should increase by around 8MB.\n"); + ksft_print_msg( + "expected memory: %ld, actual memory: %ld\n", + expected_current, current); + goto out_failed_munmap; + } + + /* unmap the whole range */ + munmap(addr, LENGTH); + current = cg_read_long(test_group, "memory.current"); + expected_current = old_current; + if (!values_close(expected_current, current, 5)) { + ksft_print_msg("memory usage should go back down.\n"); + ksft_print_msg( + "expected memory: %ld, actual memory: %ld\n", + expected_current, current); + return ret; + } + + ret = EXIT_SUCCESS; + return ret; + +out_failed_munmap: + munmap(addr, LENGTH); + return ret; +} + +static int test_hugetlb_memcg(char *root) +{ + int ret = KSFT_FAIL; + char *test_group; + + test_group = cg_name(root, "hugetlb_memcg_test"); + if (!test_group || cg_create(test_group)) { + ksft_print_msg("fail to create cgroup.\n"); + goto out; + } + + if (cg_write(test_group, "memory.max", "100M")) { + ksft_print_msg("fail to set cgroup memory limit.\n"); + goto out; + } + + /* disable swap */ + if (cg_write(test_group, "memory.swap.max", "0")) { + ksft_print_msg("fail to disable swap.\n"); + goto out; + } + + if (!cg_run(test_group, hugetlb_test_program, (void *)test_group)) + ret = KSFT_PASS; +out: + cg_destroy(test_group); + free(test_group); + return ret; +} + +int main(int argc, char **argv) +{ + char root[PATH_MAX]; + int ret = EXIT_SUCCESS, has_memory_hugetlb_acc; + + has_memory_hugetlb_acc = proc_mount_contains("memory_hugetlb_accounting"); + if (has_memory_hugetlb_acc < 0) + ksft_exit_skip("Failed to query cgroup mount option\n"); + else if (!has_memory_hugetlb_acc) + ksft_exit_skip("memory hugetlb accounting is disabled\n"); + + /* Unit is kB! */ + if (get_hugepage_size() != 2048) { + ksft_print_msg("test_hugetlb_memcg requires 2MB hugepages\n"); + ksft_test_result_skip("test_hugetlb_memcg\n"); + return ret; + } + + if (cg_find_unified_root(root, sizeof(root))) + ksft_exit_skip("cgroup v2 isn't mounted\n"); + + switch (test_hugetlb_memcg(root)) { + case KSFT_PASS: + ksft_test_result_pass("test_hugetlb_memcg\n"); + break; + case KSFT_SKIP: + ksft_test_result_skip("test_hugetlb_memcg\n"); + break; + default: + ret = EXIT_FAILURE; + ksft_test_result_fail("test_hugetlb_memcg\n"); + break; + } + + return ret; +} -- cgit v1.2.3 From 6479b29203dedb724f4f4e08e1cc0dcf432c333b Mon Sep 17 00:00:00 2001 From: Nhat Pham Date: Fri, 20 Oct 2023 15:20:09 -0700 Subject: selftests: add a sanity check for zswap We recently encountered a bug that makes all zswap store attempt fail. Specifically, after: "141fdeececb3 mm/zswap: delay the initialization of zswap" if we build a kernel with zswap disabled by default, then enabled after the swapfile is set up, the zswap tree will not be initialized. As a result, all zswap store calls will be short-circuited. We have to perform another swapon to get zswap working properly again. Fortunately, this issue has since been fixed by the patch that kills frontswap: "42c06a0e8ebe mm: kill frontswap" which performs zswap_swapon() unconditionally, i.e always initializing the zswap tree. This test add a sanity check that ensure zswap storing works as intended. Link: https://lkml.kernel.org/r/20231020222009.2358953-1-nphamcs@gmail.com Signed-off-by: Nhat Pham Acked-by: Rik van Riel Cc: Domenico Cerasuolo Cc: Johannes Weiner Cc: Shuah Khan Cc: Tejun Heo Cc: Zefan Li Signed-off-by: Andrew Morton --- tools/testing/selftests/cgroup/test_zswap.c | 48 +++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) (limited to 'tools/testing/selftests/cgroup') diff --git a/tools/testing/selftests/cgroup/test_zswap.c b/tools/testing/selftests/cgroup/test_zswap.c index 49def87a909b..c99d2adaca3f 100644 --- a/tools/testing/selftests/cgroup/test_zswap.c +++ b/tools/testing/selftests/cgroup/test_zswap.c @@ -55,6 +55,11 @@ static int get_zswap_written_back_pages(size_t *value) return read_int("/sys/kernel/debug/zswap/written_back_pages", value); } +static long get_zswpout(const char *cgroup) +{ + return cg_read_key_long(cgroup, "memory.stat", "zswpout "); +} + static int allocate_bytes(const char *cgroup, void *arg) { size_t size = (size_t)arg; @@ -68,6 +73,48 @@ static int allocate_bytes(const char *cgroup, void *arg) return 0; } +/* + * Sanity test to check that pages are written into zswap. + */ +static int test_zswap_usage(const char *root) +{ + long zswpout_before, zswpout_after; + int ret = KSFT_FAIL; + char *test_group; + + /* Set up */ + test_group = cg_name(root, "no_shrink_test"); + if (!test_group) + goto out; + if (cg_create(test_group)) + goto out; + if (cg_write(test_group, "memory.max", "1M")) + goto out; + + zswpout_before = get_zswpout(test_group); + if (zswpout_before < 0) { + ksft_print_msg("Failed to get zswpout\n"); + goto out; + } + + /* Allocate more than memory.max to push memory into zswap */ + if (cg_run(test_group, allocate_bytes, (void *)MB(4))) + goto out; + + /* Verify that pages come into zswap */ + zswpout_after = get_zswpout(test_group); + if (zswpout_after <= zswpout_before) { + ksft_print_msg("zswpout does not increase after test program\n"); + goto out; + } + ret = KSFT_PASS; + +out: + cg_destroy(test_group); + free(test_group); + return ret; +} + /* * When trying to store a memcg page in zswap, if the memcg hits its memory * limit in zswap, writeback should not be triggered. @@ -235,6 +282,7 @@ struct zswap_test { int (*fn)(const char *root); const char *name; } tests[] = { + T(test_zswap_usage), T(test_no_kmem_bypass), T(test_no_invasive_cgroup_shrink), }; -- cgit v1.2.3