From: Roman Gushchin <guro@xxxxxx> Subject: kselftests: cgroup: add kernel memory accounting tests Add some tests to cover the kernel memory accounting functionality. These are covering some issues (and changes) we had recently. 1) A test which allocates a lot of negative dentries, checks memcg slab statistics, creates memory pressure by setting memory.max to some low value and checks that some number of slabs was reclaimed. 2) A test which covers side effects of memcg destruction: it creates and destroys a large number of sub-cgroups, each containing a multi-threaded workload which allocates and releases some kernel memory. Then it checks that the charge ans memory.stats do add up on the parent level. 3) A test which reads /proc/kpagecgroup and implicitly checks that it doesn't crash the system. 4) A test which spawns a large number of threads and checks that the kernel stacks accounting works as expected. 5) A test which checks that living charged slab objects are not preventing the memory cgroup from being released after being deleted by a user. Link: http://lkml.kernel.org/r/20200623174037.3951353-19-guro@xxxxxx Signed-off-by: Roman Gushchin <guro@xxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Shakeel Butt <shakeelb@xxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- tools/testing/selftests/cgroup/.gitignore | 1 tools/testing/selftests/cgroup/Makefile | 2 tools/testing/selftests/cgroup/test_kmem.c | 382 +++++++++++++++++++ 3 files changed, 385 insertions(+) --- a/tools/testing/selftests/cgroup/.gitignore~kselftests-cgroup-add-kernel-memory-accounting-tests +++ a/tools/testing/selftests/cgroup/.gitignore @@ -2,3 +2,4 @@ test_memcontrol test_core test_freezer +test_kmem \ No newline at end of file --- a/tools/testing/selftests/cgroup/Makefile~kselftests-cgroup-add-kernel-memory-accounting-tests +++ a/tools/testing/selftests/cgroup/Makefile @@ -6,11 +6,13 @@ all: TEST_FILES := with_stress.sh TEST_PROGS := test_stress.sh TEST_GEN_PROGS = test_memcontrol +TEST_GEN_PROGS += test_kmem TEST_GEN_PROGS += test_core TEST_GEN_PROGS += test_freezer include ../lib.mk $(OUTPUT)/test_memcontrol: cgroup_util.c ../clone3/clone3_selftests.h +$(OUTPUT)/test_kmem: cgroup_util.c ../clone3/clone3_selftests.h $(OUTPUT)/test_core: cgroup_util.c ../clone3/clone3_selftests.h $(OUTPUT)/test_freezer: cgroup_util.c ../clone3/clone3_selftests.h --- /dev/null +++ a/tools/testing/selftests/cgroup/test_kmem.c @@ -0,0 +1,382 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE + +#include <linux/limits.h> +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <unistd.h> +#include <sys/wait.h> +#include <errno.h> +#include <sys/sysinfo.h> +#include <pthread.h> + +#include "../kselftest.h" +#include "cgroup_util.h" + + +static int alloc_dcache(const char *cgroup, void *arg) +{ + unsigned long i; + struct stat st; + char buf[128]; + + for (i = 0; i < (unsigned long)arg; i++) { + snprintf(buf, sizeof(buf), + "/something-non-existent-with-a-long-name-%64lu-%d", + i, getpid()); + stat(buf, &st); + } + + return 0; +} + +/* + * This test allocates 100000 of negative dentries with long names. + * Then it checks that "slab" in memory.stat is larger than 1M. + * Then it sets memory.high to 1M and checks that at least 1/2 + * of slab memory has been reclaimed. + */ +static int test_kmem_basic(const char *root) +{ + int ret = KSFT_FAIL; + char *cg = NULL; + long slab0, slab1, current; + + cg = cg_name(root, "kmem_basic_test"); + if (!cg) + goto cleanup; + + if (cg_create(cg)) + goto cleanup; + + if (cg_run(cg, alloc_dcache, (void *)100000)) + goto cleanup; + + slab0 = cg_read_key_long(cg, "memory.stat", "slab "); + if (slab0 < (1 << 20)) + goto cleanup; + + cg_write(cg, "memory.high", "1M"); + slab1 = cg_read_key_long(cg, "memory.stat", "slab "); + if (slab1 <= 0) + goto cleanup; + + current = cg_read_long(cg, "memory.current"); + if (current <= 0) + goto cleanup; + + if (slab1 < slab0 / 2 && current < slab0 / 2) + ret = KSFT_PASS; +cleanup: + cg_destroy(cg); + free(cg); + + return ret; +} + +static void *alloc_kmem_fn(void *arg) +{ + alloc_dcache(NULL, (void *)100); + return NULL; +} + +static int alloc_kmem_smp(const char *cgroup, void *arg) +{ + int nr_threads = 2 * get_nprocs(); + pthread_t *tinfo; + unsigned long i; + int ret = -1; + + tinfo = calloc(nr_threads, sizeof(pthread_t)); + if (tinfo == NULL) + return -1; + + for (i = 0; i < nr_threads; i++) { + if (pthread_create(&tinfo[i], NULL, &alloc_kmem_fn, + (void *)i)) { + free(tinfo); + return -1; + } + } + + for (i = 0; i < nr_threads; i++) { + ret = pthread_join(tinfo[i], NULL); + if (ret) + break; + } + + free(tinfo); + return ret; +} + +static int cg_run_in_subcgroups(const char *parent, + int (*fn)(const char *cgroup, void *arg), + void *arg, int times) +{ + char *child; + int i; + + for (i = 0; i < times; i++) { + child = cg_name_indexed(parent, "child", i); + if (!child) + return -1; + + if (cg_create(child)) { + cg_destroy(child); + free(child); + return -1; + } + + if (cg_run(child, fn, NULL)) { + cg_destroy(child); + free(child); + return -1; + } + + cg_destroy(child); + free(child); + } + + return 0; +} + +/* + * The test creates and destroys a large number of cgroups. In each cgroup it + * allocates some slab memory (mostly negative dentries) using 2 * NR_CPUS + * threads. Then it checks the sanity of numbers on the parent level: + * the total size of the cgroups should be roughly equal to + * anon + file + slab + kernel_stack. + */ +static int test_kmem_memcg_deletion(const char *root) +{ + long current, slab, anon, file, kernel_stack, sum; + int ret = KSFT_FAIL; + char *parent; + + parent = cg_name(root, "kmem_memcg_deletion_test"); + if (!parent) + goto cleanup; + + if (cg_create(parent)) + goto cleanup; + + if (cg_write(parent, "cgroup.subtree_control", "+memory")) + goto cleanup; + + if (cg_run_in_subcgroups(parent, alloc_kmem_smp, NULL, 100)) + goto cleanup; + + current = cg_read_long(parent, "memory.current"); + slab = cg_read_key_long(parent, "memory.stat", "slab "); + anon = cg_read_key_long(parent, "memory.stat", "anon "); + file = cg_read_key_long(parent, "memory.stat", "file "); + kernel_stack = cg_read_key_long(parent, "memory.stat", "kernel_stack "); + if (current < 0 || slab < 0 || anon < 0 || file < 0 || + kernel_stack < 0) + goto cleanup; + + sum = slab + anon + file + kernel_stack; + if (abs(sum - current) < 4096 * 32 * 2 * get_nprocs()) { + ret = KSFT_PASS; + } else { + printf("memory.current = %ld\n", current); + printf("slab + anon + file + kernel_stack = %ld\n", sum); + printf("slab = %ld\n", slab); + printf("anon = %ld\n", anon); + printf("file = %ld\n", file); + printf("kernel_stack = %ld\n", kernel_stack); + } + +cleanup: + cg_destroy(parent); + free(parent); + + return ret; +} + +/* + * The test reads the entire /proc/kpagecgroup. If the operation went + * successfully (and the kernel didn't panic), the test is treated as passed. + */ +static int test_kmem_proc_kpagecgroup(const char *root) +{ + unsigned long buf[128]; + int ret = KSFT_FAIL; + ssize_t len; + int fd; + + fd = open("/proc/kpagecgroup", O_RDONLY); + if (fd < 0) + return ret; + + do { + len = read(fd, buf, sizeof(buf)); + } while (len > 0); + + if (len == 0) + ret = KSFT_PASS; + + close(fd); + return ret; +} + +static void *pthread_wait_fn(void *arg) +{ + sleep(100); + return NULL; +} + +static int spawn_1000_threads(const char *cgroup, void *arg) +{ + int nr_threads = 1000; + pthread_t *tinfo; + unsigned long i; + long stack; + int ret = -1; + + tinfo = calloc(nr_threads, sizeof(pthread_t)); + if (tinfo == NULL) + return -1; + + for (i = 0; i < nr_threads; i++) { + if (pthread_create(&tinfo[i], NULL, &pthread_wait_fn, + (void *)i)) { + free(tinfo); + return(-1); + } + } + + stack = cg_read_key_long(cgroup, "memory.stat", "kernel_stack "); + if (stack >= 4096 * 1000) + ret = 0; + + free(tinfo); + return ret; +} + +/* + * The test spawns a process, which spawns 1000 threads. Then it checks + * that memory.stat's kernel_stack is at least 1000 pages large. + */ +static int test_kmem_kernel_stacks(const char *root) +{ + int ret = KSFT_FAIL; + char *cg = NULL; + + cg = cg_name(root, "kmem_kernel_stacks_test"); + if (!cg) + goto cleanup; + + if (cg_create(cg)) + goto cleanup; + + if (cg_run(cg, spawn_1000_threads, NULL)) + goto cleanup; + + ret = KSFT_PASS; +cleanup: + cg_destroy(cg); + free(cg); + + return ret; +} + +/* + * This test sequentionally creates 30 child cgroups, allocates some + * kernel memory in each of them, and deletes them. Then it checks + * that the number of dying cgroups on the parent level is 0. + */ +static int test_kmem_dead_cgroups(const char *root) +{ + int ret = KSFT_FAIL; + char *parent; + long dead; + int i; + + parent = cg_name(root, "kmem_dead_cgroups_test"); + if (!parent) + goto cleanup; + + if (cg_create(parent)) + goto cleanup; + + if (cg_write(parent, "cgroup.subtree_control", "+memory")) + goto cleanup; + + if (cg_run_in_subcgroups(parent, alloc_dcache, (void *)100, 30)) + goto cleanup; + + for (i = 0; i < 5; i++) { + dead = cg_read_key_long(parent, "cgroup.stat", + "nr_dying_descendants "); + if (dead == 0) { + ret = KSFT_PASS; + break; + } + /* + * Reclaiming cgroups might take some time, + * let's wait a bit and repeat. + */ + sleep(1); + } + +cleanup: + cg_destroy(parent); + free(parent); + + return ret; +} + +#define T(x) { x, #x } +struct kmem_test { + int (*fn)(const char *root); + const char *name; +} tests[] = { + T(test_kmem_basic), + T(test_kmem_memcg_deletion), + T(test_kmem_proc_kpagecgroup), + T(test_kmem_kernel_stacks), + T(test_kmem_dead_cgroups), +}; +#undef T + +int main(int argc, char **argv) +{ + char root[PATH_MAX]; + int i, ret = EXIT_SUCCESS; + + if (cg_find_unified_root(root, sizeof(root))) + ksft_exit_skip("cgroup v2 isn't mounted\n"); + + /* + * Check that memory controller is available: + * memory is listed in cgroup.controllers + */ + if (cg_read_strstr(root, "cgroup.controllers", "memory")) + ksft_exit_skip("memory controller isn't available\n"); + + if (cg_read_strstr(root, "cgroup.subtree_control", "memory")) + if (cg_write(root, "cgroup.subtree_control", "+memory")) + ksft_exit_skip("Failed to set memory controller\n"); + + for (i = 0; i < ARRAY_SIZE(tests); i++) { + switch (tests[i].fn(root)) { + case KSFT_PASS: + ksft_test_result_pass("%s\n", tests[i].name); + break; + case KSFT_SKIP: + ksft_test_result_skip("%s\n", tests[i].name); + break; + default: + ret = EXIT_FAILURE; + ksft_test_result_fail("%s\n", tests[i].name); + break; + } + } + + return ret; +} _
