This patch implements six tests for the freezer controller for cgroup v2: 1) a simple test, which aims to freeze and unfreeze a cgroup with 100 processes 2) a more complicated tree test, which creates a hierarchy of cgroups, puts some processes in some cgroups, and tries to freeze and unfreeze different parts of the subtree 3) a forkbomb test: the test aims to freeze a forkbomb running in a cgroup, kill all tasks in the cgroup and remove the cgroup without the unfreezing. 4) rmdir test: the test creates two nested cgroups, freezes the parent one, checks that the child can be successfully removed, and a new child can be created 5) migration tests: the test checks migration of a task between frozen cgroups: from a frozen to a running, from a running to a frozen, and from a frozen to a frozen. 6) ptrace test: the test checks that it's possible to attach to a process in a frozen cgroup, get some information and detach, and the cgroup will remain frozen.

Expected output:

$ ./test_freezer ok 1 test_cgfreezer_simple ok 2 test_cgfreezer_tree ok 3 test_cgfreezer_forkbomb ok 4 test_cgrreezer_rmdir ok 5 test_cgfreezer_migrate ok 6 test_cgfreezer_ptrace

Signed-off-by: Roman Gushchin guro@fb.com Cc: Shuah Khan shuah@kernel.org Cc: Tejun Heo tj@kernel.org Cc: kernel-team@fb.com Cc: linux-kselftest@vger.kernel.org --- tools/testing/selftests/cgroup/.gitignore | 1 + tools/testing/selftests/cgroup/Makefile | 2 + tools/testing/selftests/cgroup/cgroup_util.c | 81 ++- tools/testing/selftests/cgroup/cgroup_util.h | 7 + tools/testing/selftests/cgroup/test_freezer.c | 685 ++++++++++++++++++ 5 files changed, 775 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/cgroup/test_freezer.c

diff --git a/tools/testing/selftests/cgroup/.gitignore b/tools/testing/selftests/cgroup/.gitignore index adacda50a4b2..7f9835624793 100644 --- a/tools/testing/selftests/cgroup/.gitignore +++ b/tools/testing/selftests/cgroup/.gitignore @@ -1,2 +1,3 @@ test_memcontrol test_core +test_freezer diff --git a/tools/testing/selftests/cgroup/Makefile b/tools/testing/selftests/cgroup/Makefile index 23fbaa4a9630..8d369b6a2069 100644 --- a/tools/testing/selftests/cgroup/Makefile +++ b/tools/testing/selftests/cgroup/Makefile @@ -5,8 +5,10 @@ all:

TEST_GEN_PROGS = test_memcontrol TEST_GEN_PROGS += test_core +TEST_GEN_PROGS += test_freezer

include ../lib.mk

$(OUTPUT)/test_memcontrol: cgroup_util.c $(OUTPUT)/test_core: cgroup_util.c +$(OUTPUT)/test_freezer: cgroup_util.c diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c index eba06f94433b..e9cdad673901 100644 --- a/tools/testing/selftests/cgroup/cgroup_util.c +++ b/tools/testing/selftests/cgroup/cgroup_util.c @@ -74,6 +74,16 @@ char *cg_name_indexed(const char *root, const char *name, int index) return ret; }

+char *cg_control(const char *cgroup, const char *control) +{ + size_t len = strlen(cgroup) + strlen(control) + 2; + char *ret = malloc(len); + + snprintf(ret, len, "%s/%s", cgroup, control); + + return ret; +} + int cg_read(const char *cgroup, const char *control, char *buf, size_t len) { char path[PATH_MAX]; @@ -196,7 +206,59 @@ int cg_create(const char *cgroup) return mkdir(cgroup, 0644); }

-static int cg_killall(const char *cgroup) +int cg_for_all_procs(const char *cgroup, int (*fn)(int pid, void *arg), + void *arg) +{ + char buf[PAGE_SIZE]; + char *ptr = buf; + int ret; + + if (cg_read(cgroup, "cgroup.procs", buf, sizeof(buf))) + return -1; + + while (ptr < buf + sizeof(buf)) { + int pid = strtol(ptr, &ptr, 10); + + if (pid == 0) + break; + if (*ptr) + ptr++; + else + break; + ret = fn(pid, arg); + if (ret) + return ret; + } + + return 0; +} + +int cg_wait_for_proc_count(const char *cgroup, int count) +{ + char buf[10 * PAGE_SIZE] = {0}; + int attempts; + char *ptr; + + for (attempts = 10; attempts >= 0; attempts--) { + int nr = 0; + + if (cg_read(cgroup, "cgroup.procs", buf, sizeof(buf))) + break; + + for (ptr = buf; *ptr; ptr++) + if (*ptr == '\n') + nr++; + + if (nr >= count) + return 0; + + usleep(100000); + } + + return -1; +} + +int cg_killall(const char *cgroup) { char buf[PAGE_SIZE]; char *ptr = buf; @@ -238,6 +300,14 @@ int cg_destroy(const char *cgroup) return ret; }

+int cg_enter(const char *cgroup, int pid) +{ + char pidbuf[64]; + + snprintf(pidbuf, sizeof(pidbuf), "%d", pid); + return cg_write(cgroup, "cgroup.procs", pidbuf); +} + int cg_enter_current(const char *cgroup) { char pidbuf[64]; @@ -367,3 +437,12 @@ int set_oom_adj_score(int pid, int score) close(fd); return 0; } + +char proc_read_text(int pid, const char *item, char *buf, size_t size) +{ + char path[PATH_MAX]; + + snprintf(path, sizeof(path), "/proc/%d/%s", pid, item); + + return read_text(path, buf, size); +} diff --git a/tools/testing/selftests/cgroup/cgroup_util.h b/tools/testing/selftests/cgroup/cgroup_util.h index 9ac8b7958f83..8ee63c00a668 100644 --- a/tools/testing/selftests/cgroup/cgroup_util.h +++ b/tools/testing/selftests/cgroup/cgroup_util.h @@ -18,6 +18,7 @@ static inline int values_close(long a, long b, int err) extern int cg_find_unified_root(char *root, size_t len); extern char *cg_name(const char *root, const char *name); extern char *cg_name_indexed(const char *root, const char *name, int index); +extern char *cg_control(const char *cgroup, const char *control); extern int cg_create(const char *cgroup); extern int cg_destroy(const char *cgroup); extern int cg_read(const char *cgroup, const char *control, @@ -32,6 +33,7 @@ extern int cg_write(const char *cgroup, const char *control, char *buf); extern int cg_run(const char *cgroup, int (*fn)(const char *cgroup, void *arg), void *arg); +extern int cg_enter(const char *cgroup, int pid); extern int cg_enter_current(const char *cgroup); extern int cg_run_nowait(const char *cgroup, int (*fn)(const char *cgroup, void *arg), @@ -41,3 +43,8 @@ extern int alloc_pagecache(int fd, size_t size); extern int alloc_anon(const char *cgroup, void *arg); extern int is_swap_enabled(void); extern int set_oom_adj_score(int pid, int score); +extern int cg_for_all_procs(const char *cgroup, int (*fn)(int pid, void *arg), + void *arg); +extern int cg_wait_for_proc_count(const char *cgroup, int count); +extern int cg_killall(const char *cgroup); +extern char proc_read_text(int pid, const char *item, char *buf, size_t size); diff --git a/tools/testing/selftests/cgroup/test_freezer.c b/tools/testing/selftests/cgroup/test_freezer.c new file mode 100644 index 000000000000..0c4106658360 --- /dev/null +++ b/tools/testing/selftests/cgroup/test_freezer.c @@ -0,0 +1,685 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include <stdbool.h> +#include <linux/limits.h> +#include <sys/ptrace.h> +#include <sys/types.h> +#include <sys/mman.h> +#include <unistd.h> +#include <stdio.h> +#include <errno.h> +#include <poll.h> +#include <stdlib.h> +#include <sys/inotify.h> +#include <string.h> +#include <sys/types.h> +#include <sys/wait.h> + +#include "../kselftest.h" +#include "cgroup_util.h" + +#define DEBUG +#ifdef DEBUG +#define debug(args...) fprintf(stderr, args) +#else +#define debug(args...) +#endif + +/* + * Freeze the given cgroup and wait for the inotify signal. + * If there is no signal in 10 seconds, treat this as an error. + */ +static int cg_freeze_wait(const char *cgroup, bool freeze) +{ + int fd, wd; + struct pollfd fds; + int ret = -1; + + fd = inotify_init1(IN_NONBLOCK); + if (fd == -1) + return fd; + + wd = inotify_add_watch(fd, cg_control(cgroup, "cgroup.events"), + IN_MODIFY); + if (wd == -1) { + close(fd); + return wd; + } + fds.fd = fd; + fds.events = POLLIN; + + ret = cg_write(cgroup, "cgroup.freeze", freeze ? "1" : "0"); + if (ret) { + close(fd); + return ret; + } + + while (true) { + wd = poll(&fds, 1, 10000); + + if (wd == -1 && errno == EINTR) + continue; + + if (wd == 1 && fds.revents & POLLIN) + ret = 0; + + break; + } + + close(fd); + + return ret; +} + +/* + * Check if the process is frozen and parked in a proper place. + */ +static int proc_check_frozen(int pid, void *arg) +{ + char buf[PAGE_SIZE]; + int len; + + len = proc_read_text(pid, "stat", buf, sizeof(buf)); + if (len == -1) { + debug("Can't get %d stat\n", pid); + return -1; + } + + if (strstr(buf, "(test_freezer) S ") == NULL) { + debug("Process %d in the unexpected state: %s\n", pid, buf); + return -1; + } + + len = proc_read_text(pid, "stack", buf, sizeof(buf)); + if (len == -1) { + debug("Can't get stack of the process %d\n", pid); + return -1; + } + + if (strstr(buf, "[<0>] cgroup_enter_frozen") != buf) { + debug("Process %d has unexpected stacktrace: %s\n", pid, buf); + return -1; + } + + return 0; +} + +/* + * Check if the cgroup is frozen and all belonging processes are + * parked in a proper place. + */ +static int cg_check_frozen(const char *cgroup, bool frozen) +{ + if (frozen) { + /* + * Check the cgroup.events::frozen value. + */ + if (cg_read_strstr(cgroup, "cgroup.events", "frozen 1") != 0) { + debug("Cgroup %s isn't unexpectedly frozen\n", cgroup); + return -1; + } + + /* + * Check that all processes are parked in the proper place. + */ + if (cg_for_all_procs(cgroup, proc_check_frozen, NULL)) { + debug("Some processes of cgroup %s are not frozen\n", + cgroup); + return -1; + } + } else { + /* + * Check the cgroup.events::frozen value. + */ + if (cg_read_strstr(cgroup, "cgroup.events", "frozen 0") != 0) { + debug("Cgroup %s is unexpectedly frozen\n", cgroup); + return -1; + } + } + + return 0; +} + +/* + * A simple process running in a sleep loop until being + * re-parented. + */ +static int child_fn(const char *cgroup, void *arg) +{ + int ppid = getppid(); + + while (getppid() == ppid) + usleep(1000); + + return getppid() == ppid; +} + +/* + * A simple test for the cgroup freezer: populated the cgroup with 100 + * running processes and freeze it. Then unfreeze it. Then it kills all + * processes and destroys the cgroup. + */ +static int test_cgfreezer_simple(const char *root) +{ + int ret = KSFT_FAIL; + char *cgroup = NULL; + int i; + + cgroup = cg_name(root, "cg_test"); + if (!cgroup) + goto cleanup; + + if (cg_create(cgroup)) + goto cleanup; + + for (i = 0; i < 100; i++) + cg_run_nowait(cgroup, child_fn, NULL); + + if (cg_wait_for_proc_count(cgroup, 100)) + goto cleanup; + + if (cg_check_frozen(cgroup, false)) + goto cleanup; + + if (cg_freeze_wait(cgroup, true)) + goto cleanup; + + if (cg_check_frozen(cgroup, true)) + goto cleanup; + + if (cg_freeze_wait(cgroup, false)) + goto cleanup; + + if (cg_check_frozen(cgroup, false)) + goto cleanup; + + ret = KSFT_PASS; + +cleanup: + if (cgroup) + cg_destroy(cgroup); + free(cgroup); + return ret; +} + +/* + * The test creates the following hierarchy: + * A + * / / \ \ + * B E I K + * /\ | + * C D F + * | + * G + * | + * H + * + * with a process in C, H and 3 processes in K. + * Then it tries to freeze and unfreeze the whole tree. + */ +static int test_cgfreezer_tree(const char *root) +{ + char *cgroup[10] = {0}; + int ret = KSFT_FAIL; + int i; + + cgroup[0] = cg_name(root, "cg_test_A"); + if (!cgroup[0]) + goto cleanup; + + cgroup[1] = cg_name(cgroup[0], "cg_test_B"); + if (!cgroup[1]) + goto cleanup; + + cgroup[2] = cg_name(cgroup[1], "cg_test_C"); + if (!cgroup[2]) + goto cleanup; + + cgroup[3] = cg_name(cgroup[1], "cg_test_D"); + if (!cgroup[3]) + goto cleanup; + + cgroup[4] = cg_name(cgroup[0], "cg_test_E"); + if (!cgroup[4]) + goto cleanup; + + cgroup[5] = cg_name(cgroup[4], "cg_test_F"); + if (!cgroup[5]) + goto cleanup; + + cgroup[6] = cg_name(cgroup[5], "cg_test_G"); + if (!cgroup[6]) + goto cleanup; + + cgroup[7] = cg_name(cgroup[6], "cg_test_H"); + if (!cgroup[7]) + goto cleanup; + + cgroup[8] = cg_name(cgroup[0], "cg_test_I"); + if (!cgroup[8]) + goto cleanup; + + cgroup[9] = cg_name(cgroup[0], "cg_test_K"); + if (!cgroup[9]) + goto cleanup; + + for (i = 0; i < 10; i++) + if (cg_create(cgroup[i])) + goto cleanup; + + cg_run_nowait(cgroup[2], child_fn, NULL); + cg_run_nowait(cgroup[7], child_fn, NULL); + cg_run_nowait(cgroup[9], child_fn, NULL); + cg_run_nowait(cgroup[9], child_fn, NULL); + cg_run_nowait(cgroup[9], child_fn, NULL); + + /* + * Wait until all child processes will enter + * corresponding cgroups. + */ + + if (cg_wait_for_proc_count(cgroup[2], 1) || + cg_wait_for_proc_count(cgroup[7], 1) || + cg_wait_for_proc_count(cgroup[9], 3)) + goto cleanup; + + /* + * Freeze B. + */ + if (cg_freeze_wait(cgroup[1], true)) + goto cleanup; + + if (cg_check_frozen(cgroup[1], true)) + goto cleanup; + + /* + * Freeze F. + */ + if (cg_freeze_wait(cgroup[5], true)) + goto cleanup; + + if (cg_check_frozen(cgroup[5], true)) + goto cleanup; + + /* + * Freeze G. + */ + if (cg_freeze_wait(cgroup[6], true)) + goto cleanup; + + if (cg_check_frozen(cgroup[6], true)) + goto cleanup; + + /* + * Check that A and E are not frozen. + */ + if (cg_check_frozen(cgroup[0], false)) + goto cleanup; + + if (cg_check_frozen(cgroup[4], false)) + goto cleanup; + + /* + * Freeze A. Check that A, B and E are frozen. + */ + if (cg_freeze_wait(cgroup[0], true)) + goto cleanup; + + if (cg_check_frozen(cgroup[0], true)) + goto cleanup; + + if (cg_check_frozen(cgroup[1], true)) + goto cleanup; + + if (cg_check_frozen(cgroup[4], true)) + goto cleanup; + + /* + * Unfreeze B, F and G + */ + if (cg_freeze_wait(cgroup[1], false)) + goto cleanup; + + if (cg_freeze_wait(cgroup[5], false)) + goto cleanup; + + if (cg_freeze_wait(cgroup[6], false)) + goto cleanup; + + /* + * Check that C and H are still frozen. + */ + if (cg_check_frozen(cgroup[2], true)) + goto cleanup; + + if (cg_check_frozen(cgroup[7], true)) + goto cleanup; + + /* + * Unfreezing A failed. Check that A, C and K are not frozen. + */ + if (cg_freeze_wait(cgroup[0], false)) + goto cleanup; + + if (cg_check_frozen(cgroup[0], false)) + goto cleanup; + + if (cg_check_frozen(cgroup[2], false)) + goto cleanup; + + if (cg_check_frozen(cgroup[9], false)) + goto cleanup; + + ret = KSFT_PASS; + +cleanup: + for (i = 9; i >= 0 && cgroup[i]; i--) { + cg_destroy(cgroup[i]); + free(cgroup[i]); + } + + return ret; +} + +/* + * A fork bomb emulator. + */ +static int forkbomb_fn(const char *cgroup, void *arg) +{ + int ppid; + + fork(); + fork(); + + ppid = getppid(); + + while (getppid() == ppid) + usleep(1000); + + return getppid() == ppid; +} + +/* + * The test runs a fork bomb in a cgroup and tries to freeze it. + * Then it kills all processes and checks that cgroup isn't populated + * anymore. + */ +static int test_cgfreezer_forkbomb(const char *root) +{ + int ret = KSFT_FAIL; + char *cgroup = NULL; + + cgroup = cg_name(root, "cg_forkbomb_test"); + if (!cgroup) + goto cleanup; + + if (cg_create(cgroup)) + goto cleanup; + + cg_run_nowait(cgroup, forkbomb_fn, NULL); + + usleep(100000); + + if (cg_freeze_wait(cgroup, true)) + goto cleanup; + + if (cg_check_frozen(cgroup, true)) + goto cleanup; + + if (cg_killall(cgroup)) + goto cleanup; + + if (cg_wait_for_proc_count(cgroup, 0)) + goto cleanup; + + ret = KSFT_PASS; + +cleanup: + if (cgroup) + cg_destroy(cgroup); + free(cgroup); + return ret; +} + +/* + * The test creates two nested cgroups, freezes the parent + * and removes the child. Then it checks that the parent cgroup + * remains frozen and it's possible to create a new child + * without unfreezing. The new child is frozen too. + */ +static int test_cgfreezer_rmdir(const char *root) +{ + int ret = KSFT_FAIL; + char *parent, *child = NULL; + + parent = cg_name(root, "cg_test_A"); + if (!parent) + goto cleanup; + + child = cg_name(parent, "cg_test_B"); + if (!child) + goto cleanup; + + if (cg_create(parent)) + goto cleanup; + + if (cg_create(child)) + goto cleanup; + + if (cg_freeze_wait(parent, true)) + goto cleanup; + + if (cg_check_frozen(parent, true)) + goto cleanup; + + if (cg_destroy(child)) + goto cleanup; + + if (cg_check_frozen(parent, true)) + goto cleanup; + + if (cg_create(child)) + goto cleanup; + + if (cg_check_frozen(child, true)) + goto cleanup; + + ret = KSFT_PASS; + +cleanup: + if (child) + cg_destroy(child); + free(child); + if (parent) + cg_destroy(parent); + free(parent); + return ret; +} + +/* + * The test creates two cgroups: A and B. The it runs a process in A, + * and performs several migrations: + * 1) A (running) -> B (frozen) + * 2) B (frozen) -> A (running) + * 3) A (frozen) -> B (frozen) + * + * One each step it checks that the actual state of cgroups matches + * the expected state. + */ +static int test_cgfreezer_migrate(const char *root) +{ + int ret = KSFT_FAIL; + char *cgroup[2] = {0}; + int pid; + + cgroup[0] = cg_name(root, "cg_test_A"); + if (!cgroup[0]) + goto cleanup; + + cgroup[1] = cg_name(root, "cg_test_B"); + if (!cgroup[1]) + goto cleanup; + + if (cg_create(cgroup[0])) + goto cleanup; + + if (cg_create(cgroup[1])) + goto cleanup; + + pid = cg_run_nowait(cgroup[0], child_fn, NULL); + if (pid < 0) + goto cleanup; + + if (cg_wait_for_proc_count(cgroup[0], 1)) + goto cleanup; + + /* + * Migrate from A (running) to B (frozen) + */ + if (cg_freeze_wait(cgroup[1], true)) + goto cleanup; + + if (cg_check_frozen(cgroup[1], true)) + goto cleanup; + + if (cg_enter(cgroup[1], pid)) + goto cleanup; + + if (cg_check_frozen(cgroup[0], false)) + goto cleanup; + + if (cg_check_frozen(cgroup[1], true)) + goto cleanup; + + /* + * Migrate from B (frozen) to A (running) + */ + if (cg_enter(cgroup[0], pid)) + goto cleanup; + + if (cg_check_frozen(cgroup[0], false)) + goto cleanup; + + if (cg_check_frozen(cgroup[1], true)) + goto cleanup; + + /* + * Migrate from A (frozen) to B (frozen) + */ + if (cg_freeze_wait(cgroup[0], true)) + goto cleanup; + + if (cg_check_frozen(cgroup[0], true)) + goto cleanup; + + if (cg_enter(cgroup[1], pid)) + goto cleanup; + + if (cg_check_frozen(cgroup[0], true)) + goto cleanup; + + if (cg_check_frozen(cgroup[1], true)) + goto cleanup; + + ret = KSFT_PASS; + +cleanup: + if (cgroup[0]) + cg_destroy(cgroup[0]); + free(cgroup[0]); + if (cgroup[1]) + cg_destroy(cgroup[1]); + free(cgroup[1]); + return ret; +} + +/* + * The test checks that ptrace works with a tracing process in a frozen cgroup. + */ +static int test_cgfreezer_ptrace(const char *root) +{ + int ret = KSFT_FAIL; + char *cgroup = NULL; + siginfo_t siginfo; + int pid; + + cgroup = cg_name(root, "cg_test"); + if (!cgroup) + goto cleanup; + + if (cg_create(cgroup)) + goto cleanup; + + pid = cg_run_nowait(cgroup, child_fn, NULL); + if (pid < 0) + goto cleanup; + + if (cg_wait_for_proc_count(cgroup, 1)) + goto cleanup; + + if (cg_freeze_wait(cgroup, true)) + goto cleanup; + + if (cg_check_frozen(cgroup, true)) + goto cleanup; + + if (ptrace(PTRACE_SEIZE, pid, NULL, NULL)) + goto cleanup; + + if (ptrace(PTRACE_INTERRUPT, pid, NULL, NULL)) + goto cleanup; + + waitpid(pid, NULL, 0); + + if (ptrace(PTRACE_GETSIGINFO, pid, NULL, &siginfo)) + goto cleanup; + + if (ptrace(PTRACE_DETACH, pid, NULL, NULL)) + goto cleanup; + + ret = KSFT_PASS; + +cleanup: + if (cgroup) + cg_destroy(cgroup); + free(cgroup); + return ret; +} + +#define T(x) { x, #x } +struct cgfreezer_test { + int (*fn)(const char *root); + const char *name; +} tests[] = { + T(test_cgfreezer_simple), + T(test_cgfreezer_tree), + T(test_cgfreezer_forkbomb), + T(test_cgfreezer_rmdir), + T(test_cgfreezer_migrate), + T(test_cgfreezer_ptrace), +}; +#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"); + 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; +}