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Subject[RFC PATCH 2/3] vmalloc: add test driver to analyse vmalloc allocator
Date
This adds a new kernel module for analysis of vmalloc allocator. It is
only enabled as a module. There are two main reasons this module should
be used for: performance evaluation and stressing of vmalloc subsystem.

It consists of several test cases. As of now there are 8. The module
has five parameters we can specify to change its the behaviour.

1) run_test_mask - set of tests to be run

id: 1, name: fix_size_alloc_test
id: 2, name: full_fit_alloc_test
id: 4, name: long_busy_list_alloc_test
id: 8, name: random_size_alloc_test
id: 16, name: fix_align_alloc_test
id: 32, name: random_size_align_alloc_test
id: 64, name: align_shift_alloc_test
id: 128, name: pcpu_alloc_test

By default all tests are in run test mask. If you want to select some
specific tests it is possible to pass the mask. For example for first,
second and fourth tests we go 11 value.

2) test_repeat_count - how many times each test should be repeated
By default it is one time per test. It is possible to pass any number.
As high the value is the test duration gets increased.

3) test_loop_count - internal test loop counter. By default it is set
to 1000000.

4) single_cpu_test - use one CPU to run the tests
By default this parameter is set to false. It means that all online
CPUs execute tests. By setting it to 1, the tests are executed by
first online CPU only.

5) sequential_test_order - run tests in sequential order
By default this parameter is set to false. It means that before running
tests the order is shuffled. It is possible to make it sequential, just
set it to 1.

Performance analysis:
In order to evaluate performance of vmalloc allocations, usually it
makes sense to use only one CPU that runs tests, use sequential order,
number of repeat tests can be different as well as set of test mask.

For example if we want to run all tests, to use one CPU and repeat each
test 3 times. Insert the module passing following parameters:

single_cpu_test=1 sequential_test_order=1 test_repeat_count=3

with following output:

<snip>
Summary: fix_size_alloc_test passed: 3 failed: 0 repeat: 3 loops: 1000000 avg: 901177 usec
Summary: full_fit_alloc_test passed: 3 failed: 0 repeat: 3 loops: 1000000 avg: 1039341 usec
Summary: long_busy_list_alloc_test passed: 3 failed: 0 repeat: 3 loops: 1000000 avg: 11775763 usec
Summary: random_size_alloc_test passed 3: failed: 0 repeat: 3 loops: 1000000 avg: 6081992 usec
Summary: fix_align_alloc_test passed: 3 failed: 0 repeat: 3, loops: 1000000 avg: 2003712 usec
Summary: random_size_align_alloc_test passed: 3 failed: 0 repeat: 3 loops: 1000000 avg: 2895689 usec
Summary: align_shift_alloc_test passed: 0 failed: 3 repeat: 3 loops: 1000000 avg: 573 usec
Summary: pcpu_alloc_test passed: 3 failed: 0 repeat: 3 loops: 1000000 avg: 95802 usec
All test took CPU0=192945605995 cycles
<snip>

The align_shift_alloc_test is expected to be failed.

Stressing:
In order to stress the vmalloc subsystem we run all available test cases
on all available CPUs simultaneously. In order to prevent constant behaviour
pattern, the test cases array is shuffled by default to randomize the order
of test execution.

For example if we want to run all tests(default), use all online CPUs(default)
with shuffled order(default) and to repeat each test 30 times. The command
would be like:

modprobe vmalloc_test test_repeat_count=30

Expected results are the system is alive, there are no any BUG_ONs or Kernel
Panics the tests are completed, no memory leaks.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
---
lib/Kconfig.debug | 12 ++
lib/Makefile | 1 +
lib/test_vmalloc.c | 548 +++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 561 insertions(+)
create mode 100644 lib/test_vmalloc.c

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 1af29b8224fd..c95c91bc426c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1861,6 +1861,18 @@ config TEST_LKM

If unsure, say N.

+config TEST_VMALLOC
+ tristate "Test module for stress/performance analysis of vmalloc allocator"
+ default n
+ depends on m
+ help
+ This builds the "test_vmalloc" module that should be used for
+ stress and performance analysis. So, any new change for vmalloc
+ subsystem can be evaluated from performance and stability point
+ of view.
+
+ If unsure, say N.
+
config TEST_USER_COPY
tristate "Test user/kernel boundary protections"
depends on m
diff --git a/lib/Makefile b/lib/Makefile
index db06d1237898..ebcfdcdde4fa 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -60,6 +60,7 @@ UBSAN_SANITIZE_test_ubsan.o := y
obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
obj-$(CONFIG_TEST_LIST_SORT) += test_list_sort.o
obj-$(CONFIG_TEST_LKM) += test_module.o
+obj-$(CONFIG_TEST_VMALLOC) += test_vmalloc.o
obj-$(CONFIG_TEST_OVERFLOW) += test_overflow.o
obj-$(CONFIG_TEST_RHASHTABLE) += test_rhashtable.o
obj-$(CONFIG_TEST_SORT) += test_sort.o
diff --git a/lib/test_vmalloc.c b/lib/test_vmalloc.c
new file mode 100644
index 000000000000..5e15a16bbc9c
--- /dev/null
+++ b/lib/test_vmalloc.c
@@ -0,0 +1,548 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Test module for stress and analyze performance of vmalloc allocator.
+ * (C) 2018 Uladzislau Rezki (Sony) <urezki@gmail.com>
+ */
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+#include <linux/random.h>
+#include <linux/kthread.h>
+#include <linux/moduleparam.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/rwsem.h>
+#include <linux/mm.h>
+
+#define __param(type, name, init, msg) \
+ static type name = init; \
+ module_param(name, type, 0444); \
+ MODULE_PARM_DESC(name, msg) \
+
+__param(bool, single_cpu_test, false,
+ "Use single first online CPU to run tests");
+
+__param(bool, sequential_test_order, false,
+ "Use sequential stress tests order");
+
+__param(int, test_repeat_count, 1,
+ "Set test repeat counter");
+
+__param(int, test_loop_count, 1000000,
+ "Set test loop counter");
+
+__param(int, run_test_mask, INT_MAX,
+ "Set tests specified in the mask.\n\n"
+ "\t\tid: 1, name: fix_size_alloc_test\n"
+ "\t\tid: 2, name: full_fit_alloc_test\n"
+ "\t\tid: 4, name: long_busy_list_alloc_test\n"
+ "\t\tid: 8, name: random_size_alloc_test\n"
+ "\t\tid: 16, name: fix_align_alloc_test\n"
+ "\t\tid: 32, name: random_size_align_alloc_test\n"
+ "\t\tid: 64, name: align_shift_alloc_test\n"
+ "\t\tid: 128, name: pcpu_alloc_test\n"
+ /* Add a new test case description here. */
+);
+
+/*
+ * Depends on single_cpu_test parameter. If it is true, then
+ * use first online CPU to trigger a test on, otherwise go with
+ * all online CPUs.
+ */
+static cpumask_t cpus_run_test_mask = CPU_MASK_NONE;
+
+/*
+ * Read write semaphore for synchronization of setup
+ * phase that is done in main thread and workers.
+ */
+static DECLARE_RWSEM(prepare_for_test_rwsem);
+
+/*
+ * Completion tracking for worker threads.
+ */
+static DECLARE_COMPLETION(test_all_done_comp);
+static atomic_t test_n_undone = ATOMIC_INIT(0);
+
+static inline void
+test_report_one_done(void)
+{
+ if (atomic_dec_and_test(&test_n_undone))
+ complete(&test_all_done_comp);
+}
+
+static int random_size_align_alloc_test(void)
+{
+ unsigned long size, align, rnd;
+ void *ptr;
+ int i;
+
+ for (i = 0; i < test_loop_count; i++) {
+ get_random_bytes(&rnd, sizeof(rnd));
+
+ /*
+ * Maximum 1024 pages, if PAGE_SIZE is 4096.
+ */
+ align = 1 << (rnd % 23);
+
+ /*
+ * Maximum 10 pages.
+ */
+ size = ((rnd % 10) + 1) * PAGE_SIZE;
+
+ ptr = __vmalloc_node_range(size, align,
+ VMALLOC_START, VMALLOC_END,
+ GFP_KERNEL | __GFP_ZERO,
+ PAGE_KERNEL,
+ 0, 0, __builtin_return_address(0));
+
+ if (!ptr)
+ return -1;
+
+ vfree(ptr);
+ }
+
+ return 0;
+}
+
+/*
+ * This test case is supposed to be failed.
+ */
+static int align_shift_alloc_test(void)
+{
+ unsigned long align;
+ void *ptr;
+ int i;
+
+ for (i = 0; i < BITS_PER_LONG; i++) {
+ align = ((unsigned long) 1) << i;
+
+ ptr = __vmalloc_node_range(PAGE_SIZE, align,
+ VMALLOC_START, VMALLOC_END,
+ GFP_KERNEL | __GFP_ZERO,
+ PAGE_KERNEL,
+ 0, 0, __builtin_return_address(0));
+
+ if (!ptr)
+ return -1;
+
+ vfree(ptr);
+ }
+
+ return 0;
+}
+
+static int fix_align_alloc_test(void)
+{
+ void *ptr;
+ int i;
+
+ for (i = 0; i < test_loop_count; i++) {
+ ptr = __vmalloc_node_range(5 * PAGE_SIZE,
+ THREAD_ALIGN << 1,
+ VMALLOC_START, VMALLOC_END,
+ GFP_KERNEL | __GFP_ZERO,
+ PAGE_KERNEL,
+ 0, 0, __builtin_return_address(0));
+
+ if (!ptr)
+ return -1;
+
+ vfree(ptr);
+ }
+
+ return 0;
+}
+
+static int random_size_alloc_test(void)
+{
+ unsigned int n;
+ void *p;
+ int i;
+
+ for (i = 0; i < test_loop_count; i++) {
+ get_random_bytes(&n, sizeof(i));
+ n = (n % 100) + 1;
+
+ p = vmalloc(n * PAGE_SIZE);
+
+ if (!p)
+ return -1;
+
+ *((__u8 *)p) = 1;
+ vfree(p);
+ }
+
+ return 0;
+}
+
+static int long_busy_list_alloc_test(void)
+{
+ void *ptr_1, *ptr_2;
+ void **ptr;
+ int rv = -1;
+ int i;
+
+ ptr = vmalloc(sizeof(void *) * 15000);
+ if (!ptr)
+ return rv;
+
+ for (i = 0; i < 15000; i++)
+ ptr[i] = vmalloc(1 * PAGE_SIZE);
+
+ for (i = 0; i < test_loop_count; i++) {
+ ptr_1 = vmalloc(100 * PAGE_SIZE);
+ if (!ptr_1)
+ goto leave;
+
+ ptr_2 = vmalloc(1 * PAGE_SIZE);
+ if (!ptr_2) {
+ vfree(ptr_1);
+ goto leave;
+ }
+
+ *((__u8 *)ptr_1) = 0;
+ *((__u8 *)ptr_2) = 1;
+
+ vfree(ptr_1);
+ vfree(ptr_2);
+ }
+
+ /* Success */
+ rv = 0;
+
+leave:
+ for (i = 0; i < 15000; i++)
+ vfree(ptr[i]);
+
+ vfree(ptr);
+ return rv;
+}
+
+static int full_fit_alloc_test(void)
+{
+ void **ptr, **junk_ptr, *tmp;
+ int junk_length;
+ int rv = -1;
+ int i;
+
+ junk_length = fls(num_online_cpus());
+ junk_length *= (32 * 1024 * 1024 / PAGE_SIZE);
+
+ ptr = vmalloc(sizeof(void *) * junk_length);
+ if (!ptr)
+ return rv;
+
+ junk_ptr = vmalloc(sizeof(void *) * junk_length);
+ if (!junk_ptr) {
+ vfree(ptr);
+ return rv;
+ }
+
+ for (i = 0; i < junk_length; i++) {
+ ptr[i] = vmalloc(1 * PAGE_SIZE);
+ junk_ptr[i] = vmalloc(1 * PAGE_SIZE);
+ }
+
+ for (i = 0; i < junk_length; i++)
+ vfree(junk_ptr[i]);
+
+ for (i = 0; i < test_loop_count; i++) {
+ tmp = vmalloc(1 * PAGE_SIZE);
+
+ if (!tmp)
+ goto error;
+
+ *((__u8 *)tmp) = 1;
+ vfree(tmp);
+ }
+
+ /* Success */
+ rv = 0;
+
+error:
+ for (i = 0; i < junk_length; i++)
+ vfree(ptr[i]);
+
+ vfree(ptr);
+ vfree(junk_ptr);
+
+ return rv;
+}
+
+static int fix_size_alloc_test(void)
+{
+ void *ptr;
+ int i;
+
+ for (i = 0; i < test_loop_count; i++) {
+ ptr = vmalloc(3 * PAGE_SIZE);
+
+ if (!ptr)
+ return -1;
+
+ *((__u8 *)ptr) = 0;
+
+ vfree(ptr);
+ }
+
+ return 0;
+}
+
+static int
+pcpu_alloc_test(void)
+{
+ int rv = 0;
+#ifndef CONFIG_NEED_PER_CPU_KM
+ void __percpu **pcpu;
+ size_t size, align;
+ int i;
+
+ pcpu = vmalloc(sizeof(void __percpu *) * 35000);
+ if (!pcpu)
+ return -1;
+
+ for (i = 0; i < 35000; i++) {
+ unsigned int r;
+
+ get_random_bytes(&r, sizeof(i));
+ size = (r % (PAGE_SIZE / 4)) + 1;
+
+ /*
+ * Maximum PAGE_SIZE
+ */
+ get_random_bytes(&r, sizeof(i));
+ align = 1 << ((i % 11) + 1);
+
+ pcpu[i] = __alloc_percpu(size, align);
+ if (!pcpu[i])
+ rv = -1;
+ }
+
+ for (i = 0; i < 35000; i++)
+ free_percpu(pcpu[i]);
+
+ vfree(pcpu);
+#endif
+ return rv;
+}
+
+struct test_case_desc {
+ const char *test_name;
+ int (*test_func)(void);
+};
+
+static struct test_case_desc test_case_array[] = {
+ { "fix_size_alloc_test", fix_size_alloc_test },
+ { "full_fit_alloc_test", full_fit_alloc_test },
+ { "long_busy_list_alloc_test", long_busy_list_alloc_test },
+ { "random_size_alloc_test", random_size_alloc_test },
+ { "fix_align_alloc_test", fix_align_alloc_test },
+ { "random_size_align_alloc_test", random_size_align_alloc_test },
+ { "align_shift_alloc_test", align_shift_alloc_test },
+ { "pcpu_alloc_test", pcpu_alloc_test },
+ /* Add a new test case here. */
+};
+
+struct test_case_data {
+ int test_failed;
+ int test_passed;
+ s64 time;
+};
+
+/* Split it to get rid of: WARNING: line over 80 characters */
+static struct test_case_data
+ per_cpu_test_data[NR_CPUS][ARRAY_SIZE(test_case_array)];
+
+static struct test_driver {
+ struct task_struct *task;
+ unsigned long start;
+ unsigned long stop;
+ int cpu;
+} per_cpu_test_driver[NR_CPUS];
+
+static void shuffle_array(int *arr, int n)
+{
+ unsigned int rnd;
+ int i, j, x;
+
+ for (i = n - 1; i > 0; i--) {
+ get_random_bytes(&rnd, sizeof(rnd));
+
+ /* Cut the range. */
+ j = rnd % i;
+
+ /* Swap indexes. */
+ x = arr[i];
+ arr[i] = arr[j];
+ arr[j] = x;
+ }
+}
+
+static int test_func(void *private)
+{
+ struct test_driver *t = private;
+ cpumask_t newmask = CPU_MASK_NONE;
+ int random_array[ARRAY_SIZE(test_case_array)];
+ int index, i, j, ret;
+ ktime_t kt;
+
+ cpumask_set_cpu(t->cpu, &newmask);
+ set_cpus_allowed_ptr(current, &newmask);
+
+ for (i = 0; i < ARRAY_SIZE(test_case_array); i++)
+ random_array[i] = i;
+
+ if (!sequential_test_order)
+ shuffle_array(random_array, ARRAY_SIZE(test_case_array));
+
+ /*
+ * Block until initialization is done.
+ */
+ down_read(&prepare_for_test_rwsem);
+
+ t->start = get_cycles();
+ for (i = 0; i < ARRAY_SIZE(test_case_array); i++) {
+ index = random_array[i];
+
+ /*
+ * Skip tests if run_test_mask has been specified.
+ */
+ if (!((run_test_mask & (1 << index)) >> index))
+ continue;
+
+ kt = ktime_get();
+ for (j = 0; j < test_repeat_count; j++) {
+ ret = test_case_array[index].test_func();
+ if (!ret)
+ per_cpu_test_data[t->cpu][index].test_passed++;
+ else
+ per_cpu_test_data[t->cpu][index].test_failed++;
+ }
+
+ /*
+ * Take an average time that test took.
+ */
+ per_cpu_test_data[t->cpu][index].time =
+ ktime_us_delta(ktime_get(), kt) / test_repeat_count;
+ }
+ t->stop = get_cycles();
+
+ up_read(&prepare_for_test_rwsem);
+ test_report_one_done();
+
+ /*
+ * Wait for the kthread_stop() call.
+ */
+ while (!kthread_should_stop())
+ msleep(10);
+
+ return 0;
+}
+
+static void
+init_test_configurtion(void)
+{
+ /*
+ * Reset all data of all CPUs.
+ */
+ memset(per_cpu_test_data, 0, sizeof(per_cpu_test_data));
+
+ if (single_cpu_test)
+ cpumask_set_cpu(cpumask_first(cpu_online_mask),
+ &cpus_run_test_mask);
+ else
+ cpumask_and(&cpus_run_test_mask, cpu_online_mask,
+ cpu_online_mask);
+
+ if (test_repeat_count <= 0)
+ test_repeat_count = 1;
+
+ if (test_loop_count <= 0)
+ test_loop_count = 1;
+}
+
+static void do_concurrent_test(void)
+{
+ int cpu, ret;
+
+ /*
+ * Set some basic configurations plus sanity check.
+ */
+ init_test_configurtion();
+
+ /*
+ * Put on hold all workers.
+ */
+ down_write(&prepare_for_test_rwsem);
+
+ for_each_cpu(cpu, &cpus_run_test_mask) {
+ struct test_driver *t = &per_cpu_test_driver[cpu];
+
+ t->cpu = cpu;
+ t->task = kthread_run(test_func, t, "vmalloc_test/%d", cpu);
+
+ if (!IS_ERR(t->task))
+ /* Success. */
+ atomic_inc(&test_n_undone);
+ else
+ pr_err("Failed to start kthread for %d CPU\n", cpu);
+ }
+
+ /*
+ * Now let the workers do their job.
+ */
+ up_write(&prepare_for_test_rwsem);
+
+ /*
+ * Sleep quiet until all workers are done with 1 second
+ * interval. Since the test can take a lot of time we
+ * can run into a stack trace of the hung task. That is
+ * why we go with completion_timeout and HZ value.
+ */
+ do {
+ ret = wait_for_completion_timeout(&test_all_done_comp, HZ);
+ } while (!ret);
+
+ for_each_cpu(cpu, &cpus_run_test_mask) {
+ struct test_driver *t = &per_cpu_test_driver[cpu];
+ int i;
+
+ if (!IS_ERR(t->task))
+ kthread_stop(t->task);
+
+ for (i = 0; i < ARRAY_SIZE(test_case_array); i++) {
+ if (!((run_test_mask & (1 << i)) >> i))
+ continue;
+
+ pr_info(
+ "Summary: %s passed: %d failed: %d repeat: %d loops: %d avg: %llu usec\n",
+ test_case_array[i].test_name,
+ per_cpu_test_data[cpu][i].test_passed,
+ per_cpu_test_data[cpu][i].test_failed,
+ test_repeat_count, test_loop_count,
+ per_cpu_test_data[cpu][i].time);
+ }
+
+ pr_info("All test took CPU%d=%lu cycles\n",
+ cpu, t->stop - t->start);
+ }
+}
+
+static int vmalloc_test_init(void)
+{
+ do_concurrent_test();
+ return -EAGAIN; /* Fail will directly unload the module */
+}
+
+static void vmalloc_test_exit(void)
+{
+}
+
+module_init(vmalloc_test_init)
+module_exit(vmalloc_test_exit)
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Uladzislau Rezki");
+MODULE_DESCRIPTION("vmalloc test module");
--
2.11.0
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