Currently, dmem charging is driver-driven through direct calls to dmem_cgroup_try_charge() (for example TTM). That does not give cgroup selftests a generic way to trigger alloc/free paths from userspace in a chosen cgroup, so coverage of nested dmem.max still needs a synthetic region.
Add tools/testing/selftests/cgroup/test_modules/dmem_selftest.c as an OOT helper, built like other test_modules (no extra Kconfig needed). Tests can insmod the .ko module to register a "dmem_selftest" region. Module parameters drive a single outstanding allocation against the calling task's cgroup: /sys/module/dmem_selftest/parameters/alloc /sys/module/dmem_selftest/parameters/free Writing a size to alloc triggers dmem_cgroup_try_charge() for the calling task's cgroup. Writing to free with no argument releases the outstanding charge via dmem_cgroup_uncharge(). Only a single outstanding charge is supported. This provides a deterministic, driver-independent mechanism for exercising dmem accounting paths in selftests. Signed-off-by: Albert Esteve <[email protected]> --- tools/testing/selftests/cgroup/Makefile | 1 + tools/testing/selftests/cgroup/config | 1 + .../testing/selftests/cgroup/test_modules/Makefile | 17 +++ .../selftests/cgroup/test_modules/dmem_selftest.c | 146 +++++++++++++++++++++ 4 files changed, 165 insertions(+) diff --git a/tools/testing/selftests/cgroup/Makefile b/tools/testing/selftests/cgroup/Makefile index e01584c2189a..a08661320a07 100644 --- a/tools/testing/selftests/cgroup/Makefile +++ b/tools/testing/selftests/cgroup/Makefile @@ -6,6 +6,7 @@ all: ${HELPER_PROGS} TEST_FILES := with_stress.sh TEST_PROGS := test_stress.sh test_cpuset_prs.sh test_cpuset_v1_hp.sh TEST_GEN_FILES := wait_inotify +TEST_GEN_MODS_DIR := test_modules # Keep the lists lexicographically sorted TEST_GEN_PROGS = test_core TEST_GEN_PROGS += test_cpu diff --git a/tools/testing/selftests/cgroup/config b/tools/testing/selftests/cgroup/config index 39f979690dd3..2ee0488c3d65 100644 --- a/tools/testing/selftests/cgroup/config +++ b/tools/testing/selftests/cgroup/config @@ -1,5 +1,6 @@ CONFIG_CGROUPS=y CONFIG_CGROUP_CPUACCT=y +CONFIG_CGROUP_DMEM=y CONFIG_CGROUP_FREEZER=y CONFIG_CGROUP_SCHED=y CONFIG_MEMCG=y diff --git a/tools/testing/selftests/cgroup/test_modules/Makefile b/tools/testing/selftests/cgroup/test_modules/Makefile new file mode 100644 index 000000000000..dd8a17313cec --- /dev/null +++ b/tools/testing/selftests/cgroup/test_modules/Makefile @@ -0,0 +1,17 @@ +# SPDX-License-Identifier: GPL-2.0 +TESTMODS_DIR := $(realpath $(dir $(abspath $(lastword $(MAKEFILE_LIST))))) +KDIR ?= /lib/modules/$(shell uname -r)/build + +obj-m += dmem_selftest.o + +# Ensure that KDIR exists, otherwise skip the compilation +modules: +ifneq ("$(wildcard $(KDIR))", "") + $(Q)$(MAKE) -C $(KDIR) modules KBUILD_EXTMOD=$(TESTMODS_DIR) +endif + +# Ensure that KDIR exists, otherwise skip the clean target +clean: +ifneq ("$(wildcard $(KDIR))", "") + $(Q)$(MAKE) -C $(KDIR) clean KBUILD_EXTMOD=$(TESTMODS_DIR) +endif diff --git a/tools/testing/selftests/cgroup/test_modules/dmem_selftest.c b/tools/testing/selftests/cgroup/test_modules/dmem_selftest.c new file mode 100644 index 000000000000..a763a156f13f --- /dev/null +++ b/tools/testing/selftests/cgroup/test_modules/dmem_selftest.c @@ -0,0 +1,146 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Kselftest helper for the dmem cgroup controller. + * + * Registers a synthetic dmem region so tests can trigger allocations + * from the calling task's cgroup via module parameters: + * /sys/module/dmem_selftest/parameters/alloc + * /sys/module/dmem_selftest/parameters/free + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/cgroup_dmem.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/mutex.h> +#include <linux/panic.h> +#include <linux/sysfs.h> + +#define DM_SELFTEST_REGION_NAME "dmem_selftest" +#define DM_SELFTEST_REGION_SIZE (256ULL * 1024 * 1024) + +static struct dmem_cgroup_region *selftest_region; +static struct dmem_cgroup_pool_state *alloc_pool; +static u64 alloc_size; +static DEFINE_MUTEX(alloc_lock); + +static int param_set_alloc(const char *val, const struct kernel_param *kp) +{ + struct dmem_cgroup_pool_state *pool = NULL, *limit = NULL; + u64 size; + int ret; + + if (!selftest_region) + return -ENODEV; + + ret = kstrtou64(val, 0, &size); + if (ret) + return ret; + if (!size || size > DM_SELFTEST_REGION_SIZE) + return -EINVAL; + + mutex_lock(&alloc_lock); + if (alloc_pool) { + mutex_unlock(&alloc_lock); + return -EBUSY; + } + + ret = dmem_cgroup_try_charge(selftest_region, size, &pool, &limit); + if (ret == -EAGAIN && limit) + dmem_cgroup_pool_state_put(limit); + if (ret) { + mutex_unlock(&alloc_lock); + return ret; + } + + alloc_pool = pool; + alloc_size = size; + mutex_unlock(&alloc_lock); + return 0; +} + +static int param_get_alloc(char *buffer, const struct kernel_param *kp) +{ + u64 size; + + mutex_lock(&alloc_lock); + size = alloc_size; + mutex_unlock(&alloc_lock); + return sysfs_emit(buffer, "%llu\n", size); +} + +static const struct kernel_param_ops alloc_ops = { + .set = param_set_alloc, + .get = param_get_alloc, +}; + +module_param_cb(alloc, &alloc_ops, NULL, 0644); +MODULE_PARM_DESC(alloc, "Allocate (charge) SIZE bytes against the calling task's dmem cgroup"); + +static int param_set_free(const char *val, const struct kernel_param *kp) +{ + mutex_lock(&alloc_lock); + if (!alloc_pool) { + mutex_unlock(&alloc_lock); + return -EINVAL; + } + + dmem_cgroup_uncharge(alloc_pool, alloc_size); + alloc_pool = NULL; + alloc_size = 0; + mutex_unlock(&alloc_lock); + return 0; +} + +static const struct kernel_param_ops free_ops = { + .flags = KERNEL_PARAM_OPS_FL_NOARG, + .set = param_set_free, +}; + +module_param_cb(free, &free_ops, NULL, 0200); +MODULE_PARM_DESC(free, "Free the outstanding dmem selftest allocation"); + +static int __init dmem_selftest_init(void) +{ + static const struct dmem_cgroup_init init = { + .size = DM_SELFTEST_REGION_SIZE, + }; + + selftest_region = dmem_cgroup_register_region(&init, DM_SELFTEST_REGION_NAME); + if (IS_ERR(selftest_region)) + return PTR_ERR(selftest_region); + if (!selftest_region) + return -EINVAL; + + add_taint(TAINT_TEST, LOCKDEP_STILL_OK); + pr_info("region '%s' registered; parameters alloc/free\n", + DM_SELFTEST_REGION_NAME); + return 0; +} + +static void __exit dmem_selftest_exit(void) +{ + mutex_lock(&alloc_lock); + if (alloc_pool) { + dmem_cgroup_uncharge(alloc_pool, alloc_size); + alloc_pool = NULL; + alloc_size = 0; + } + mutex_unlock(&alloc_lock); + + if (selftest_region) { + dmem_cgroup_unregister_region(selftest_region); + selftest_region = NULL; + } + pr_info("unloaded.\n"); +} + +module_init(dmem_selftest_init); +module_exit(dmem_selftest_exit); + +MODULE_AUTHOR("Albert Esteve <[email protected]>"); +MODULE_DESCRIPTION("Kselftest helper for cgroup dmem controller"); +MODULE_LICENSE("GPL"); +MODULE_INFO(test, "Y"); -- 2.55.0
