Currently, tools/testing/selftests/cgroup/ does not include a dmem-specific test binary. This leaves dmem charge and limit behavior largely unvalidated in kselftest coverage.
Add test_dmem and wire it into the cgroup selftests Makefile. The new test exercises dmem controller behavior through the dmem_selftest debugfs interface for the dmem_selftest region. The test adds three complementary checks: - test_dmem_max creates a nested hierarchy with per-leaf dmem.max values and verifies that over-limit charges fail while in-limit charges succeed with bounded rounding in dmem.current. - test_dmem_min and test_dmem_low verify that charging from a cgroup with the corresponding protection knob set updates dmem.current as expected. - test_dmem_charge_byte_granularity validates accounting bounds for non-page-aligned charge sizes and uncharge-to-zero behavior. This provides deterministic userspace coverage for dmem accounting and hard-limit enforcement using a test helper module, without requiring subsystem-specific production drivers. Signed-off-by: Albert Esteve <[email protected]> --- tools/testing/selftests/cgroup/.gitignore | 1 + tools/testing/selftests/cgroup/Makefile | 2 + tools/testing/selftests/cgroup/test_dmem.c | 487 +++++++++++++++++++++++++++++ 3 files changed, 490 insertions(+) diff --git a/tools/testing/selftests/cgroup/.gitignore b/tools/testing/selftests/cgroup/.gitignore index 952e4448bf070..ea2322598217d 100644 --- a/tools/testing/selftests/cgroup/.gitignore +++ b/tools/testing/selftests/cgroup/.gitignore @@ -2,6 +2,7 @@ test_core test_cpu test_cpuset +test_dmem test_freezer test_hugetlb_memcg test_kill diff --git a/tools/testing/selftests/cgroup/Makefile b/tools/testing/selftests/cgroup/Makefile index e01584c2189ac..e1a5e9316620e 100644 --- a/tools/testing/selftests/cgroup/Makefile +++ b/tools/testing/selftests/cgroup/Makefile @@ -10,6 +10,7 @@ TEST_GEN_FILES := wait_inotify TEST_GEN_PROGS = test_core TEST_GEN_PROGS += test_cpu TEST_GEN_PROGS += test_cpuset +TEST_GEN_PROGS += test_dmem TEST_GEN_PROGS += test_freezer TEST_GEN_PROGS += test_hugetlb_memcg TEST_GEN_PROGS += test_kill @@ -26,6 +27,7 @@ include lib/libcgroup.mk $(OUTPUT)/test_core: $(LIBCGROUP_O) $(OUTPUT)/test_cpu: $(LIBCGROUP_O) $(OUTPUT)/test_cpuset: $(LIBCGROUP_O) +$(OUTPUT)/test_dmem: $(LIBCGROUP_O) $(OUTPUT)/test_freezer: $(LIBCGROUP_O) $(OUTPUT)/test_hugetlb_memcg: $(LIBCGROUP_O) $(OUTPUT)/test_kill: $(LIBCGROUP_O) diff --git a/tools/testing/selftests/cgroup/test_dmem.c b/tools/testing/selftests/cgroup/test_dmem.c new file mode 100644 index 0000000000000..cdd5cb7206f16 --- /dev/null +++ b/tools/testing/selftests/cgroup/test_dmem.c @@ -0,0 +1,487 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Test the dmem (device memory) cgroup controller. + * + * Depends on dmem_selftest kernel module. + */ + +#define _GNU_SOURCE + +#include <linux/limits.h> +#include <errno.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 "kselftest.h" +#include "cgroup_util.h" + +/* kernel/cgroup/dmem_selftest.c */ +#define DM_SELFTEST_REGION "dmem_selftest" +#define DM_SELFTEST_CHARGE "/sys/kernel/debug/dmem_selftest/charge" +#define DM_SELFTEST_UNCHARGE "/sys/kernel/debug/dmem_selftest/uncharge" + +/* + * Parse the first line of dmem.capacity (root): + * "<name> <size_in_bytes>" + * Returns 1 if a region was found, 0 if capacity is empty, -1 on read error. + */ +static int parse_first_region(const char *root, char *name, size_t name_len, + unsigned long long *size_out) +{ + char buf[4096]; + char nm[256]; + unsigned long long sz; + + if (cg_read(root, "dmem.capacity", buf, sizeof(buf)) < 0) + return -1; + + if (sscanf(buf, "%255s %llu", nm, &sz) < 2) + return 0; + + if (name_len <= strlen(nm)) + return -1; + + strcpy(name, nm); + *size_out = sz; + return 1; +} + +/* + * Read the numeric limit for @region_name from a multiline + * dmem.{min,low,max} file. Returns bytes, + * or -1 if the line is "<name> max", or -2 if missing/err. + */ +static long long dmem_read_limit_for_region(const char *cgroup, const char *ctrl, + const char *region_name) +{ + char buf[4096]; + char *line, *saveptr = NULL; + char fname[256]; + char fval[64]; + + if (cg_read(cgroup, ctrl, buf, sizeof(buf)) < 0) + return -2; + + for (line = strtok_r(buf, "\n", &saveptr); line; + line = strtok_r(NULL, "\n", &saveptr)) { + if (!line[0]) + continue; + if (sscanf(line, "%255s %63s", fname, fval) != 2) + continue; + if (strcmp(fname, region_name)) + continue; + if (!strcmp(fval, "max")) + return -1; + return strtoll(fval, NULL, 0); + } + return -2; +} + +static long long dmem_read_limit(const char *cgroup, const char *ctrl) +{ + return dmem_read_limit_for_region(cgroup, ctrl, DM_SELFTEST_REGION); +} + +static int dmem_write_limit(const char *cgroup, const char *ctrl, + const char *val) +{ + char wr[512]; + + snprintf(wr, sizeof(wr), "%s %s", DM_SELFTEST_REGION, val); + return cg_write(cgroup, ctrl, wr); +} + +static int dmem_selftest_charge_bytes(unsigned long long bytes) +{ + char wr[32]; + + snprintf(wr, sizeof(wr), "%llu", bytes); + return write_text(DM_SELFTEST_CHARGE, wr, strlen(wr)); +} + +static int dmem_selftest_uncharge(void) +{ + return write_text(DM_SELFTEST_UNCHARGE, "\n", 1); +} + +/* + * First, this test creates the following hierarchy: + * A + * A/B dmem.max=1M + * A/B/C dmem.max=75K + * A/B/D dmem.max=25K + * A/B/E dmem.max=8K + * A/B/F dmem.max=0 + * + * Then for each leaf cgroup it tries to charge above dmem.max + * and expects the charge request to fail and dmem.current to + * remain unchanged. + * + * For leaves with non-zero dmem.max, it additionally charges a + * smaller amount and verifies accounting grows within one PAGE_SIZE + * rounding bound, then uncharges and verifies dmem.current returns + * to the previous value. + * + */ +static int test_dmem_max(const char *root) +{ + static const char * const leaf_max[] = { "75K", "25K", "8K", "0" }; + static const unsigned long long fail_sz[] = { + (75ULL * 1024ULL) + 1ULL, + (25ULL * 1024ULL) + 1ULL, + (8ULL * 1024ULL) + 1ULL, + 1ULL + }; + static const unsigned long long pass_sz[] = { + 4096ULL, 4096ULL, 4096ULL, 0ULL + }; + char *parent[2] = {NULL}; + char *children[4] = {NULL}; + unsigned long long cap; + char region[256]; + long long page_size; + long long cur_before, cur_after; + int ret = KSFT_FAIL; + int charged = 0; + int in_child = 0; + long long v; + int i; + + if (access(DM_SELFTEST_CHARGE, W_OK) != 0) + return KSFT_SKIP; + + if (parse_first_region(root, region, sizeof(region), &cap) != 1) + return KSFT_SKIP; + if (strcmp(region, DM_SELFTEST_REGION) != 0) + return KSFT_SKIP; + + page_size = sysconf(_SC_PAGESIZE); + if (page_size <= 0) + goto cleanup; + + parent[0] = cg_name(root, "dmem_prot_0"); + parent[1] = cg_name(parent[0], "dmem_prot_1"); + if (!parent[0] || !parent[1]) + goto cleanup; + + if (cg_create(parent[0])) + goto cleanup; + + if (cg_write(parent[0], "cgroup.subtree_control", "+dmem")) + goto cleanup; + + if (cg_create(parent[1])) + goto cleanup; + + if (cg_write(parent[1], "cgroup.subtree_control", "+dmem")) + goto cleanup; + + for (i = 0; i < 4; i++) { + children[i] = cg_name_indexed(parent[1], "dmem_child", i); + if (!children[i]) + goto cleanup; + if (cg_create(children[i])) + goto cleanup; + } + + if (dmem_write_limit(parent[1], "dmem.max", "1M")) + goto cleanup; + for (i = 0; i < 4; i++) + if (dmem_write_limit(children[i], "dmem.max", leaf_max[i])) + goto cleanup; + + v = dmem_read_limit(parent[1], "dmem.max"); + if (!values_close(v, 1024LL * 1024LL, 3)) + goto cleanup; + v = dmem_read_limit(children[0], "dmem.max"); + if (!values_close(v, 75LL * 1024LL, 3)) + goto cleanup; + v = dmem_read_limit(children[1], "dmem.max"); + if (!values_close(v, 25LL * 1024LL, 3)) + goto cleanup; + v = dmem_read_limit(children[2], "dmem.max"); + if (!values_close(v, 8LL * 1024LL, 3)) + goto cleanup; + v = dmem_read_limit(children[3], "dmem.max"); + if (v != 0) + goto cleanup; + + for (i = 0; i < 4; i++) { + if (cg_enter_current(children[i])) + goto cleanup; + in_child = 1; + + cur_before = dmem_read_limit(children[i], "dmem.current"); + if (cur_before < 0) + goto cleanup; + + if (dmem_selftest_charge_bytes(fail_sz[i]) == 0) + goto cleanup; + + cur_after = dmem_read_limit(children[i], "dmem.current"); + if (cur_after != cur_before) + goto cleanup; + + if (pass_sz[i] > 0) { + if (dmem_selftest_charge_bytes(pass_sz[i]) < 0) + goto cleanup; + charged = 1; + + cur_after = dmem_read_limit(children[i], "dmem.current"); + if (cur_after < cur_before + (long long)pass_sz[i]) + goto cleanup; + if (cur_after > cur_before + (long long)pass_sz[i] + page_size) + goto cleanup; + + if (dmem_selftest_uncharge() < 0) + goto cleanup; + charged = 0; + + cur_after = dmem_read_limit(children[i], "dmem.current"); + if (cur_after != cur_before) + goto cleanup; + } + + if (cg_enter_current(root)) + goto cleanup; + in_child = 0; + } + + ret = KSFT_PASS; + +cleanup: + if (charged) + dmem_selftest_uncharge(); + if (in_child) + cg_enter_current(root); + for (i = 3; i >= 0; i--) { + if (!children[i]) + continue; + cg_destroy(children[i]); + free(children[i]); + } + for (i = 1; i >= 0; i--) { + if (!parent[i]) + continue; + cg_destroy(parent[i]); + free(parent[i]); + } + return ret; +} + +/* + * This test sets dmem.min and dmem.low on a child cgroup, then charge + * from that context and verify dmem.current tracks the charged bytes + * (within one page rounding). + */ +static int test_dmem_charge_with_attr(const char *root, bool min) +{ + char region[256]; + unsigned long long cap; + const unsigned long long charge_sz = 12345ULL; + const char *attribute = min ? "dmem.min" : "dmem.low"; + int ret = KSFT_FAIL; + char *cg = NULL; + long long cur; + long long page_size; + int charged = 0; + int in_child = 0; + + if (access(DM_SELFTEST_CHARGE, W_OK) != 0) + return KSFT_SKIP; + + if (parse_first_region(root, region, sizeof(region), &cap) != 1) + return KSFT_SKIP; + if (strcmp(region, DM_SELFTEST_REGION) != 0) + return KSFT_SKIP; + + page_size = sysconf(_SC_PAGESIZE); + if (page_size <= 0) + goto cleanup; + + cg = cg_name(root, "test_dmem_attr"); + if (!cg) + goto cleanup; + + if (cg_create(cg)) + goto cleanup; + + if (cg_enter_current(cg)) + goto cleanup; + in_child = 1; + + if (dmem_write_limit(cg, attribute, "16K")) + goto cleanup; + + if (dmem_selftest_charge_bytes(charge_sz) < 0) + goto cleanup; + charged = 1; + + cur = dmem_read_limit(cg, "dmem.current"); + if (cur < (long long)charge_sz) + goto cleanup; + if (cur > (long long)charge_sz + page_size) + goto cleanup; + + if (dmem_selftest_uncharge() < 0) + goto cleanup; + charged = 0; + + cur = dmem_read_limit(cg, "dmem.current"); + if (cur != 0) + goto cleanup; + + ret = KSFT_PASS; + +cleanup: + if (charged) + dmem_selftest_uncharge(); + if (in_child) + cg_enter_current(root); + cg_destroy(cg); + free(cg); + return ret; +} + +static int test_dmem_min(const char *root) +{ + return test_dmem_charge_with_attr(root, "dmem.min"); +} + +static int test_dmem_low(const char *root) +{ + return test_dmem_charge_with_attr(root, "dmem.low"); +} + +/* + * This test charges non-page-aligned byte sizes and verify dmem.current + * stays consistent: it must account at least the requested bytes and + * never exceed one kernel page of rounding overhead. Then uncharge must + * return usage to 0. + */ +static int test_dmem_charge_byte_granularity(const char *root) +{ + static const unsigned long long sizes[] = { 1ULL, 4095ULL, 4097ULL, 12345ULL }; + char *cg = NULL; + unsigned long long cap; + char region[256]; + long long cur; + long long page_size; + int ret = KSFT_FAIL; + int charged = 0; + int in_child = 0; + size_t i; + + if (access(DM_SELFTEST_CHARGE, W_OK) != 0) + return KSFT_SKIP; + + if (parse_first_region(root, region, sizeof(region), &cap) != 1) + return KSFT_SKIP; + if (strcmp(region, DM_SELFTEST_REGION) != 0) + return KSFT_SKIP; + + page_size = sysconf(_SC_PAGESIZE); + if (page_size <= 0) + goto cleanup; + + cg = cg_name(root, "dmem_dbg_byte_gran"); + if (!cg) + goto cleanup; + + if (cg_create(cg)) + goto cleanup; + + if (dmem_write_limit(cg, "dmem.max", "8M")) + goto cleanup; + + if (cg_enter_current(cg)) + goto cleanup; + in_child = 1; + + for (i = 0; i < ARRAY_SIZE(sizes); i++) { + if (dmem_selftest_charge_bytes(sizes[i]) < 0) + goto cleanup; + charged = 1; + + cur = dmem_read_limit(cg, "dmem.current"); + if (cur < (long long)sizes[i]) + goto cleanup; + if (cur > (long long)sizes[i] + page_size) + goto cleanup; + + if (dmem_selftest_uncharge() < 0) + goto cleanup; + charged = 0; + + cur = dmem_read_limit(cg, "dmem.current"); + if (cur != 0) + goto cleanup; + } + + ret = KSFT_PASS; + +cleanup: + if (charged) + dmem_selftest_uncharge(); + if (in_child) + cg_enter_current(root); + if (cg) { + cg_destroy(cg); + free(cg); + } + return ret; +} + +#define T(x) { x, #x } +struct dmem_test { + int (*fn)(const char *root); + const char *name; +} tests[] = { + T(test_dmem_max), + T(test_dmem_min), + T(test_dmem_low), + T(test_dmem_charge_byte_granularity), +}; +#undef T + +int main(int argc, char **argv) +{ + char root[PATH_MAX]; + int i; + + ksft_print_header(); + ksft_set_plan(ARRAY_SIZE(tests)); + + if (cg_find_unified_root(root, sizeof(root), NULL)) + ksft_exit_skip("cgroup v2 isn't mounted\n"); + + if (cg_read_strstr(root, "cgroup.controllers", "dmem")) + ksft_exit_skip("dmem controller isn't available (CONFIG_CGROUP_DMEM?)\n"); + + if (cg_read_strstr(root, "cgroup.subtree_control", "dmem")) + if (cg_write(root, "cgroup.subtree_control", "+dmem")) + ksft_exit_skip("Failed to enable dmem 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 (need CONFIG_DMEM_SELFTEST, modprobe dmem_selftest)\n", + tests[i].name); + break; + default: + ksft_test_result_fail("%s\n", tests[i].name); + break; + } + } + + ksft_finished(); +} -- 2.52.0
