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Subject[RFC v2 4/5] workqueue, cgroup: add test module
Date
Test the basic functionality of cgroup aware workqueues.  Inspired by
Matthew Wilcox's test_xarray.c

Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
---
kernel/workqueue.c | 1 +
lib/Kconfig.debug | 12 +
lib/Makefile | 1 +
lib/test_cgroup_workqueue.c | 325 ++++++++++++++++++
.../selftests/cgroup_workqueue/Makefile | 9 +
.../testing/selftests/cgroup_workqueue/config | 1 +
.../cgroup_workqueue/test_cgroup_workqueue.sh | 104 ++++++
7 files changed, 453 insertions(+)
create mode 100644 lib/test_cgroup_workqueue.c
create mode 100644 tools/testing/selftests/cgroup_workqueue/Makefile
create mode 100644 tools/testing/selftests/cgroup_workqueue/config
create mode 100755 tools/testing/selftests/cgroup_workqueue/test_cgroup_workqueue.sh

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index c8cc69e296c0..15459b5bb0bf 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1825,6 +1825,7 @@ bool queue_cgroup_work_node(int node, struct workqueue_struct *wq,
local_irq_restore(flags);
return ret;
}
+EXPORT_SYMBOL_GPL(queue_cgroup_work_node);

static inline bool worker_in_child_cgroup(struct worker *worker)
{
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index d5a4a4036d2f..9909a306c142 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2010,6 +2010,18 @@ config TEST_STACKINIT

If unsure, say N.

+config TEST_CGROUP_WQ
+ tristate "Test cgroup-aware workqueues at runtime"
+ depends on CGROUPS
+ help
+ Test cgroup-aware workqueues, in which workers attach to the
+ cgroup specified by the queueing task. Basic test coverage
+ for whether workers attach to the expected cgroup, both for
+ cgroup-aware and unaware works, and whether workers are
+ throttled by the memory controller.
+
+ If unsure, say N.
+
endif # RUNTIME_TESTING_MENU

config MEMTEST
diff --git a/lib/Makefile b/lib/Makefile
index 18c2be516ab4..d08b4a50bfd1 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -92,6 +92,7 @@ obj-$(CONFIG_TEST_OBJAGG) += test_objagg.o
obj-$(CONFIG_TEST_STACKINIT) += test_stackinit.o

obj-$(CONFIG_TEST_LIVEPATCH) += livepatch/
+obj-$(CONFIG_TEST_CGROUP_WQ) += test_cgroup_workqueue.o

ifeq ($(CONFIG_DEBUG_KOBJECT),y)
CFLAGS_kobject.o += -DDEBUG
diff --git a/lib/test_cgroup_workqueue.c b/lib/test_cgroup_workqueue.c
new file mode 100644
index 000000000000..466ec4e6e55b
--- /dev/null
+++ b/lib/test_cgroup_workqueue.c
@@ -0,0 +1,325 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * test_cgroup_workqueue.c: Test cgroup-aware workqueues
+ * Copyright (c) 2019 Oracle and/or its affiliates. All rights reserved.
+ * Author: Daniel Jordan <daniel.m.jordan@oracle.com>
+ *
+ * Inspired by Matthew Wilcox's test_xarray.c.
+ */
+
+#include <linux/cgroup.h>
+#include <linux/kconfig.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/rcupdate.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/vmalloc.h>
+#include <linux/workqueue.h>
+
+static atomic_long_t cwq_tests_run = ATOMIC_LONG_INIT(0);
+static atomic_long_t cwq_tests_passed = ATOMIC_LONG_INIT(0);
+
+static struct workqueue_struct *cwq_cgroup_aware_wq;
+static struct workqueue_struct *cwq_cgroup_unaware_wq;
+
+/* cgroup v2 hierarchy mountpoint */
+static char *cwq_cgrp_root_path = "/test_cgroup_workqueue";
+module_param(cwq_cgrp_root_path, charp, 0444);
+static struct cgroup *cwq_cgrp_root;
+
+static char *cwq_cgrp_1_path = "/cwq_1";
+module_param(cwq_cgrp_1_path, charp, 0444);
+static struct cgroup *cwq_cgrp_1;
+
+static char *cwq_cgrp_2_path = "/cwq_2";
+module_param(cwq_cgrp_2_path, charp, 0444);
+static struct cgroup *cwq_cgrp_2;
+
+static char *cwq_cgrp_3_path = "/cwq_3";
+module_param(cwq_cgrp_3_path, charp, 0444);
+static struct cgroup *cwq_cgrp_3;
+
+static size_t cwq_memcg_max = 1ul << 20;
+module_param(cwq_memcg_max, ulong, 0444);
+
+#define CWQ_BUG(x, test_name) ({ \
+ int __ret_cwq_bug = !!(x); \
+ atomic_long_inc(&cwq_tests_run); \
+ if (__ret_cwq_bug) { \
+ pr_warn("BUG at %s:%d\n", __func__, __LINE__); \
+ pr_warn("%s\n", (test_name)); \
+ dump_stack(); \
+ } else { \
+ atomic_long_inc(&cwq_tests_passed); \
+ } \
+ __ret_cwq_bug; \
+})
+
+#define CWQ_BUG_ON(x) CWQ_BUG((x), "<no test name>")
+
+struct cwq_data {
+ struct cgroup_work cwork;
+ struct cgroup *expected_cgroup;
+ const char *test_name;
+};
+
+#define CWQ_INIT_DATA(data, func, expected_cgrp) do { \
+ INIT_WORK_ONSTACK(&(data)->work, (func)); \
+ (data)->expected_cgroup = (expected_cgrp); \
+} while (0)
+
+static void cwq_verify_worker_cgroup(struct work_struct *work)
+{
+ struct cgroup_work *cwork = container_of(work, struct cgroup_work,
+ work);
+ struct cwq_data *data = container_of(cwork, struct cwq_data, cwork);
+ struct cgroup *worker_cgroup;
+
+ CWQ_BUG(!(current->flags & PF_WQ_WORKER), data->test_name);
+
+ rcu_read_lock();
+ worker_cgroup = task_dfl_cgroup(current);
+ rcu_read_unlock();
+
+ CWQ_BUG(worker_cgroup != data->expected_cgroup, data->test_name);
+}
+
+static noinline void cwq_test_reg_work_on_cgrp_unaware_wq(void)
+{
+ struct cwq_data data;
+
+ data.expected_cgroup = cwq_cgrp_root;
+ data.test_name = __func__;
+ INIT_WORK_ONSTACK(&data.cwork.work, cwq_verify_worker_cgroup);
+
+ CWQ_BUG_ON(!queue_work(cwq_cgroup_unaware_wq, &data.cwork.work));
+ flush_work(&data.cwork.work);
+}
+
+static noinline void cwq_test_cgrp_work_on_cgrp_aware_wq(void)
+{
+ struct cwq_data data;
+
+ data.expected_cgroup = cwq_cgrp_1;
+ data.test_name = __func__;
+ INIT_CGROUP_WORK_ONSTACK(&data.cwork, cwq_verify_worker_cgroup);
+
+ CWQ_BUG_ON(!queue_cgroup_work(cwq_cgroup_aware_wq, &data.cwork,
+ cwq_cgrp_1));
+ flush_work(&data.cwork.work);
+}
+
+static struct cgroup *cwq_get_random_cgroup(void)
+{
+ switch (prandom_u32_max(4)) {
+ case 1: return cwq_cgrp_1;
+ case 2: return cwq_cgrp_2;
+ case 3: return cwq_cgrp_3;
+ default: return cwq_cgrp_root;
+ }
+}
+
+#define CWQ_NWORK 256
+static noinline void cwq_test_many_cgrp_works_on_cgrp_aware_wq(void)
+{
+ int i;
+ struct cwq_data *data_array = kmalloc_array(CWQ_NWORK,
+ sizeof(struct cwq_data),
+ GFP_KERNEL);
+ if (CWQ_BUG_ON(!data_array))
+ return;
+
+ for (i = 0; i < CWQ_NWORK; ++i) {
+ struct cgroup *cgrp = cwq_get_random_cgroup();
+
+ data_array[i].expected_cgroup = cgrp;
+ data_array[i].test_name = __func__;
+ INIT_CGROUP_WORK(&data_array[i].cwork,
+ cwq_verify_worker_cgroup);
+ CWQ_BUG_ON(!queue_cgroup_work(cwq_cgroup_aware_wq,
+ &data_array[i].cwork,
+ cgrp));
+ }
+
+ for (i = 0; i < CWQ_NWORK; ++i)
+ flush_work(&data_array[i].cwork.work);
+
+ kfree(data_array);
+}
+
+static void cwq_verify_worker_obeys_memcg(struct work_struct *work)
+{
+ struct cgroup_work *cwork = container_of(work, struct cgroup_work,
+ work);
+ struct cwq_data *data = container_of(cwork, struct cwq_data, cwork);
+ struct cgroup *worker_cgroup;
+ void *mem;
+
+ CWQ_BUG(!(current->flags & PF_WQ_WORKER), data->test_name);
+
+ rcu_read_lock();
+ worker_cgroup = task_dfl_cgroup(current);
+ rcu_read_unlock();
+
+ CWQ_BUG(worker_cgroup != data->expected_cgroup, data->test_name);
+
+ mem = __vmalloc(cwq_memcg_max * 2, __GFP_ACCOUNT | __GFP_NOWARN,
+ PAGE_KERNEL);
+ if (data->expected_cgroup == cwq_cgrp_2) {
+ /*
+ * cwq_cgrp_2 has its memory.max set to cwq_memcg_max, so the
+ * allocation should fail.
+ */
+ CWQ_BUG(mem, data->test_name);
+ } else {
+ /*
+ * Other cgroups don't have a memory.max limit, so the
+ * allocation should succeed.
+ */
+ CWQ_BUG(!mem, data->test_name);
+ }
+ vfree(mem);
+}
+
+static noinline void cwq_test_reg_work_is_not_throttled_by_memcg(void)
+{
+ struct cwq_data data;
+
+ if (!IS_ENABLED(CONFIG_MEMCG_KMEM) || !cwq_memcg_max)
+ return;
+
+ data.expected_cgroup = cwq_cgrp_root;
+ data.test_name = __func__;
+ INIT_WORK_ONSTACK(&data.cwork.work, cwq_verify_worker_obeys_memcg);
+ CWQ_BUG_ON(!queue_work(cwq_cgroup_unaware_wq, &data.cwork.work));
+ flush_work(&data.cwork.work);
+}
+
+static noinline void cwq_test_cgrp_work_is_throttled_by_memcg(void)
+{
+ struct cwq_data data;
+
+ if (!IS_ENABLED(CONFIG_MEMCG_KMEM) || !cwq_memcg_max)
+ return;
+
+ /*
+ * The kselftest shell script enables the memory controller in
+ * cwq_cgrp_2 and sets memory.max to cwq_memcg_max.
+ */
+ data.expected_cgroup = cwq_cgrp_2;
+ data.test_name = __func__;
+ INIT_CGROUP_WORK_ONSTACK(&data.cwork, cwq_verify_worker_obeys_memcg);
+
+ CWQ_BUG_ON(!queue_cgroup_work(cwq_cgroup_aware_wq, &data.cwork,
+ cwq_cgrp_2));
+ flush_work(&data.cwork.work);
+}
+
+static noinline void cwq_test_cgrp_work_is_not_throttled_by_memcg(void)
+{
+ struct cwq_data data;
+
+ if (!IS_ENABLED(CONFIG_MEMCG_KMEM) || !cwq_memcg_max)
+ return;
+
+ /*
+ * The kselftest shell script doesn't set a memory limit for cwq_cgrp_1
+ * or _3, so a cgroup work should still be able to allocate memory
+ * above that limit.
+ */
+ data.expected_cgroup = cwq_cgrp_1;
+ data.test_name = __func__;
+ INIT_CGROUP_WORK_ONSTACK(&data.cwork, cwq_verify_worker_obeys_memcg);
+
+ CWQ_BUG_ON(!queue_cgroup_work(cwq_cgroup_aware_wq, &data.cwork,
+ cwq_cgrp_1));
+ flush_work(&data.cwork.work);
+
+ /*
+ * And cgroup workqueues shouldn't choke on a cgroup that's disabled
+ * the memory controller, such as cwq_cgrp_3.
+ */
+ data.expected_cgroup = cwq_cgrp_3;
+ data.test_name = __func__;
+ INIT_CGROUP_WORK_ONSTACK(&data.cwork, cwq_verify_worker_obeys_memcg);
+
+ CWQ_BUG_ON(!queue_cgroup_work(cwq_cgroup_aware_wq, &data.cwork,
+ cwq_cgrp_3));
+ flush_work(&data.cwork.work);
+}
+
+static int cwq_init(void)
+{
+ s64 passed, run;
+
+ pr_warn("cgroup workqueue test module\n");
+
+ cwq_cgroup_aware_wq = alloc_workqueue("cwq_cgroup_aware_wq",
+ WQ_UNBOUND | WQ_CGROUP, 0);
+ if (!cwq_cgroup_aware_wq) {
+ pr_warn("cwq_cgroup_aware_wq allocation failed\n");
+ return -EAGAIN;
+ }
+
+ cwq_cgroup_unaware_wq = alloc_workqueue("cwq_cgroup_unaware_wq",
+ WQ_UNBOUND, 0);
+ if (!cwq_cgroup_unaware_wq) {
+ pr_warn("cwq_cgroup_unaware_wq allocation failed\n");
+ goto alloc_wq_fail;
+ }
+
+ cwq_cgrp_root = cgroup_get_from_path("/");
+ if (IS_ERR(cwq_cgrp_root)) {
+ pr_warn("can't get root cgroup\n");
+ goto cgroup_get_fail;
+ }
+
+ cwq_cgrp_1 = cgroup_get_from_path(cwq_cgrp_1_path);
+ if (IS_ERR(cwq_cgrp_1)) {
+ pr_warn("can't get child cgroup 1\n");
+ goto cgroup_get_fail;
+ }
+
+ cwq_cgrp_2 = cgroup_get_from_path(cwq_cgrp_2_path);
+ if (IS_ERR(cwq_cgrp_2)) {
+ pr_warn("can't get child cgroup 2\n");
+ goto cgroup_get_fail;
+ }
+
+ cwq_cgrp_3 = cgroup_get_from_path(cwq_cgrp_3_path);
+ if (IS_ERR(cwq_cgrp_3)) {
+ pr_warn("can't get child cgroup 3\n");
+ goto cgroup_get_fail;
+ }
+
+ cwq_test_reg_work_on_cgrp_unaware_wq();
+ cwq_test_cgrp_work_on_cgrp_aware_wq();
+ cwq_test_many_cgrp_works_on_cgrp_aware_wq();
+ cwq_test_reg_work_is_not_throttled_by_memcg();
+ cwq_test_cgrp_work_is_throttled_by_memcg();
+ cwq_test_cgrp_work_is_not_throttled_by_memcg();
+
+ passed = atomic_long_read(&cwq_tests_passed);
+ run = atomic_long_read(&cwq_tests_run);
+ pr_warn("cgroup workqueues: %lld of %lld tests passed\n", passed, run);
+ return (run == passed) ? 0 : -EINVAL;
+
+cgroup_get_fail:
+ destroy_workqueue(cwq_cgroup_unaware_wq);
+alloc_wq_fail:
+ destroy_workqueue(cwq_cgroup_aware_wq);
+ return -EAGAIN; /* better ideas? */
+}
+
+static void cwq_exit(void)
+{
+ destroy_workqueue(cwq_cgroup_aware_wq);
+ destroy_workqueue(cwq_cgroup_unaware_wq);
+}
+
+module_init(cwq_init);
+module_exit(cwq_exit);
+MODULE_AUTHOR("Daniel Jordan <daniel.m.jordan@oracle.com>");
+MODULE_LICENSE("GPL");
diff --git a/tools/testing/selftests/cgroup_workqueue/Makefile b/tools/testing/selftests/cgroup_workqueue/Makefile
new file mode 100644
index 000000000000..2ba1cd922670
--- /dev/null
+++ b/tools/testing/selftests/cgroup_workqueue/Makefile
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-2.0
+
+all:
+
+TEST_PROGS := test_cgroup_workqueue.sh
+
+include ../lib.mk
+
+clean:
diff --git a/tools/testing/selftests/cgroup_workqueue/config b/tools/testing/selftests/cgroup_workqueue/config
new file mode 100644
index 000000000000..ae38b8f3c3db
--- /dev/null
+++ b/tools/testing/selftests/cgroup_workqueue/config
@@ -0,0 +1 @@
+CONFIG_TEST_CGROUP_WQ=m
diff --git a/tools/testing/selftests/cgroup_workqueue/test_cgroup_workqueue.sh b/tools/testing/selftests/cgroup_workqueue/test_cgroup_workqueue.sh
new file mode 100755
index 000000000000..33251276d2cf
--- /dev/null
+++ b/tools/testing/selftests/cgroup_workqueue/test_cgroup_workqueue.sh
@@ -0,0 +1,104 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# Runs cgroup workqueue kernel module tests
+
+# hierarchy: root
+# / \
+# 1 2
+# /
+# 3
+CG_ROOT='/test_cgroup_workqueue'
+CG_1='/cwq_1'
+CG_2='/cwq_2'
+CG_3='/cwq_3'
+MEMCG_MAX="$((2**16))" # small but arbitrary amount
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+cg_mnt=''
+cg_mnt_mounted=''
+cg_1_created=''
+cg_2_created=''
+cg_3_created=''
+
+cleanup()
+{
+ [ -n "$cg_3_created" ] && rmdir "$CG_ROOT/$CG_1/$CG_3" || exit 1
+ [ -n "$cg_2_created" ] && rmdir "$CG_ROOT/$CG_2" || exit 1
+ [ -n "$cg_1_created" ] && rmdir "$CG_ROOT/$CG_1" || exit 1
+ [ -n "$cg_mnt_mounted" ] && umount "$CG_ROOT" || exit 1
+ [ -n "$cg_mnt_created" ] && rmdir "$CG_ROOT" || exit 1
+ exit "$1"
+}
+
+if ! /sbin/modprobe -q -n test_cgroup_workqueue; then
+ echo "cgroup_workqueue: module test_cgroup_workqueue not found [SKIP]"
+ exit $ksft_skip
+fi
+
+# Setup cgroup v2 hierarchy
+if mkdir "$CG_ROOT"; then
+ cg_mnt_created=1
+else
+ echo "cgroup_workqueue: can't create cgroup mountpoint at $CG_ROOT"
+ cleanup 1
+fi
+
+if mount -t cgroup2 none "$CG_ROOT"; then
+ cg_mnt_mounted=1
+else
+ echo "cgroup_workqueue: couldn't mount cgroup hierarchy at $CG_ROOT"
+ cleanup 1
+fi
+
+if grep -q memory "$CG_ROOT/cgroup.controllers"; then
+ /bin/echo +memory > "$CG_ROOT/cgroup.subtree_control"
+ cwq_memcg_max="$MEMCG_MAX"
+else
+ # Tell test module not to run memory.max tests.
+ cwq_memcg_max=0
+fi
+
+if mkdir "$CG_ROOT/$CG_1"; then
+ cg_1_created=1
+else
+ echo "cgroup_workqueue: can't mkdir $CG_ROOT/$CG_1"
+ cleanup 1
+fi
+
+if mkdir "$CG_ROOT/$CG_2"; then
+ cg_2_created=1
+else
+ echo "cgroup_workqueue: can't mkdir $CG_ROOT/$CG_2"
+ cleanup 1
+fi
+
+if mkdir "$CG_ROOT/$CG_1/$CG_3"; then
+ cg_3_created=1
+ # Ensure the memory controller is disabled as expected in $CG_3's
+ # parent, $CG_1, for testing.
+ if grep -q memory "$CG_ROOT/$CG_1/cgroup.subtree_control"; then
+ /bin/echo -memory > "$CG_ROOT/$CG_1/cgroup.subtree_control"
+ fi
+else
+ echo "cgroup_workqueue: can't mkdir $CG_ROOT/$CG_1/$CG_3"
+ cleanup 1
+fi
+
+if (( cwq_memcg_max != 0 )); then
+ /bin/echo "$MEMCG_MAX" > "$CG_ROOT/$CG_2/memory.max"
+fi
+
+if /sbin/modprobe -q test_cgroup_workqueue cwq_cgrp_root_path="$CG_ROOT" \
+ cwq_cgrp_1_path="$CG_1" \
+ cwq_cgrp_2_path="$CG_2" \
+ cwq_cgrp_3_path="$CG_1/$CG_3" \
+ cwq_memcg_max="$cwq_memcg_max"; then
+ echo "cgroup_workqueue: ok"
+ /sbin/modprobe -q -r test_cgroup_workqueue
+ cleanup 0
+else
+ echo "cgroup_workqueue: [FAIL]"
+ cleanup 1
+fi
--
2.21.0
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