[PATCH linux-kselftest-test 0/3] kunit: support module-based build

[PATCH linux-kselftest-test 0/3] kunit: support module-based build

[Alan Maguire]

For consumers wishing to run kunit on real hardware, it would be
ideal if the kunit framework and tests supported module-based builds.
This is an advantage as it reduces the test task to running
"modprobe mytests.ko", and CONFIG_KUNIT* options can be "always on"
(or rather "always m").  KUnit based tests will load the kunit module
as an implicit dependency.

Alan Maguire (3):
  kunit: allow kunit tests to be loaded as a module
  kunit: allow kunit to be loaded as a module
  kunit: update documentation to describe module-based build

 Documentation/dev-tools/kunit/faq.rst   |  3 ++-
 Documentation/dev-tools/kunit/index.rst |  3 +++
 Documentation/dev-tools/kunit/usage.rst | 16 +++++++++++++++
 include/kunit/test.h                    | 36 ++++++++++++++++++++++++---------
 kernel/sysctl-test.c                    |  6 +++++-
 kunit/Kconfig                           |  6 +++---
 kunit/Makefile                          |  9 +++++++++
 kunit/assert.c                          |  8 ++++++++
 kunit/example-test.c                    |  6 +++++-
 kunit/string-stream-test.c              |  9 +++++++--
 kunit/string-stream.c                   |  7 +++++++
 kunit/test-test.c                       |  8 ++++++--
 kunit/test.c                            | 12 +++++++++++
 kunit/try-catch.c                       |  8 ++++++--
 lib/Kconfig.debug                       |  4 ++--
 15 files changed, 117 insertions(+), 24 deletions(-)

-- 
1.8.3.1

[PATCH linux-kselftest-test 1/3] kunit: allow kunit tests to be loaded as a module

[Alan Maguire]

as tests are added to kunit, it will become less feasible to execute
all built tests together.  By supporting modular tests we provide
a simple way to do selective execution on a running system; specifying

CONFIG_KUNIT=y
CONFIG_KUNIT_EXAMPLE_TEST=m

...means we can simply "insmod example-test.ko" to run the tests.

To achieve this we need to

o export the required symbols in kunit
o support a new way of declaring test suites.  Because a module cannot
  do multiple late_initcall()s, we provide a kunit_test_suites() macro
  to declare multiple suites within the same module at once.

Signed-off-by: Knut Omang <knut.omang@oracle.com>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
---
 include/kunit/test.h       | 36 ++++++++++++++++++++++++++----------
 kernel/sysctl-test.c       |  6 +++++-
 kunit/Kconfig              |  4 ++--
 kunit/assert.c             |  8 ++++++++
 kunit/example-test.c       |  6 +++++-
 kunit/string-stream-test.c |  9 +++++++--
 kunit/string-stream.c      |  7 +++++++
 kunit/test-test.c          |  8 ++++++--
 kunit/test.c               |  8 ++++++++
 kunit/try-catch.c          |  8 ++++++--
 lib/Kconfig.debug          |  4 ++--
 11 files changed, 82 insertions(+), 22 deletions(-)

diff --git a/include/kunit/test.h b/include/kunit/test.h
index dba4830..37a21dd 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -12,6 +12,7 @@
 #include <kunit/assert.h>
 #include <kunit/try-catch.h>
 #include <linux/kernel.h>
+#include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/types.h>
 
@@ -197,31 +198,46 @@ struct kunit {
 int kunit_run_tests(struct kunit_suite *suite);
 
 /**
- * kunit_test_suite() - used to register a &struct kunit_suite with KUnit.
+ * kunit_test_suites() - used to register &struct kunit_suite suites with KUnit.
  *
- * @suite: a statically allocated &struct kunit_suite.
+ * @...: a list of statically allocated &struct kunit_suite.
  *
- * Registers @suite with the test framework. See &struct kunit_suite for
+ * Registers @... suites with the test framework. See &struct kunit_suite for
  * more information.
  *
- * NOTE: Currently KUnit tests are all run as late_initcalls; this means
+ * When builtin,  KUnit tests are all run as late_initcalls; this means
  * that they cannot test anything where tests must run at a different init
  * phase. One significant restriction resulting from this is that KUnit
  * cannot reliably test anything that is initialize in the late_init phase;
  * another is that KUnit is useless to test things that need to be run in
  * an earlier init phase.
  *
+ * An alternative is to build the tests as a module.  Because modules
+ * do not support multiple late_initcall()s, we need to initialize an
+ * array of suites for a module.
+ *
  * TODO(brendanhiggins@google.com): Don't run all KUnit tests as
  * late_initcalls.  I have some future work planned to dispatch all KUnit
  * tests from the same place, and at the very least to do so after
  * everything else is definitely initialized.
  */
-#define kunit_test_suite(suite)						       \
-	static int kunit_suite_init##suite(void)			       \
-	{								       \
-		return kunit_run_tests(&suite);				       \
-	}								       \
-	late_initcall(kunit_suite_init##suite)
+#define kunit_test_suites(...)						\
+	static struct kunit_suite *suites[] = { __VA_ARGS__, NULL};	\
+	static int kunit_test_suites_init(void)				\
+	{								\
+		unsigned int i;						\
+		for (i = 0; suites[i] != NULL; i++)			\
+			kunit_run_tests(suites[i]);			\
+		return 0;						\
+	}								\
+	late_initcall(kunit_test_suites_init);				\
+	static void __exit kunit_test_suites_exit(void)			\
+	{								\
+		return;							\
+	}								\
+	module_exit(kunit_test_suites_exit)
+
+#define	kunit_test_suite(suite)	kunit_test_suites(suite)
 
 /*
  * Like kunit_alloc_resource() below, but returns the struct kunit_resource
diff --git a/kernel/sysctl-test.c b/kernel/sysctl-test.c
index 2a63241..15161c5 100644
--- a/kernel/sysctl-test.c
+++ b/kernel/sysctl-test.c
@@ -389,4 +389,8 @@ static void sysctl_test_api_dointvec_write_single_greater_int_max(
 	.test_cases = sysctl_test_cases,
 };
 
-kunit_test_suite(sysctl_test_suite);
+kunit_test_suite(&sysctl_test_suite);
+
+#ifdef MODULE
+MODULE_LICENSE("GPL");
+#endif /* MODULE */
diff --git a/kunit/Kconfig b/kunit/Kconfig
index 8541ef9..f28bf086 100644
--- a/kunit/Kconfig
+++ b/kunit/Kconfig
@@ -15,7 +15,7 @@ config KUNIT
 	  Documentation/dev-tools/kunit/.
 
 config KUNIT_TEST
-	bool "KUnit test for KUnit"
+	tristate "KUnit test for KUnit"
 	depends on KUNIT
 	help
 	  Enables the unit tests for the KUnit test framework. These tests test
@@ -25,7 +25,7 @@ config KUNIT_TEST
 	  expected.
 
 config KUNIT_EXAMPLE_TEST
-	bool "Example test for KUnit"
+	tristate "Example test for KUnit"
 	depends on KUNIT
 	help
 	  Enables an example unit test that illustrates some of the basic
diff --git a/kunit/assert.c b/kunit/assert.c
index 86013d4..92eba2a 100644
--- a/kunit/assert.c
+++ b/kunit/assert.c
@@ -24,6 +24,7 @@ void kunit_base_assert_format(const struct kunit_assert *assert,
 	string_stream_add(stream, "%s FAILED at %s:%d\n",
 			 expect_or_assert, assert->file, assert->line);
 }
+EXPORT_SYMBOL_GPL(kunit_base_assert_format);
 
 void kunit_assert_print_msg(const struct kunit_assert *assert,
 			    struct string_stream *stream)
@@ -31,6 +32,7 @@ void kunit_assert_print_msg(const struct kunit_assert *assert,
 	if (assert->message.fmt)
 		string_stream_add(stream, "\n%pV", &assert->message);
 }
+EXPORT_SYMBOL_GPL(kunit_assert_print_msg);
 
 void kunit_fail_assert_format(const struct kunit_assert *assert,
 			      struct string_stream *stream)
@@ -38,6 +40,7 @@ void kunit_fail_assert_format(const struct kunit_assert *assert,
 	kunit_base_assert_format(assert, stream);
 	string_stream_add(stream, "%pV", &assert->message);
 }
+EXPORT_SYMBOL_GPL(kunit_fail_assert_format);
 
 void kunit_unary_assert_format(const struct kunit_assert *assert,
 			       struct string_stream *stream)
@@ -56,6 +59,7 @@ void kunit_unary_assert_format(const struct kunit_assert *assert,
 				 unary_assert->condition);
 	kunit_assert_print_msg(assert, stream);
 }
+EXPORT_SYMBOL_GPL(kunit_unary_assert_format);
 
 void kunit_ptr_not_err_assert_format(const struct kunit_assert *assert,
 				     struct string_stream *stream)
@@ -76,6 +80,7 @@ void kunit_ptr_not_err_assert_format(const struct kunit_assert *assert,
 	}
 	kunit_assert_print_msg(assert, stream);
 }
+EXPORT_SYMBOL_GPL(kunit_ptr_not_err_assert_format);
 
 void kunit_binary_assert_format(const struct kunit_assert *assert,
 				struct string_stream *stream)
@@ -97,6 +102,7 @@ void kunit_binary_assert_format(const struct kunit_assert *assert,
 			 binary_assert->right_value);
 	kunit_assert_print_msg(assert, stream);
 }
+EXPORT_SYMBOL_GPL(kunit_binary_assert_format);
 
 void kunit_binary_ptr_assert_format(const struct kunit_assert *assert,
 				    struct string_stream *stream)
@@ -118,6 +124,7 @@ void kunit_binary_ptr_assert_format(const struct kunit_assert *assert,
 			 binary_assert->right_value);
 	kunit_assert_print_msg(assert, stream);
 }
+EXPORT_SYMBOL_GPL(kunit_binary_ptr_assert_format);
 
 void kunit_binary_str_assert_format(const struct kunit_assert *assert,
 				    struct string_stream *stream)
@@ -139,3 +146,4 @@ void kunit_binary_str_assert_format(const struct kunit_assert *assert,
 			 binary_assert->right_value);
 	kunit_assert_print_msg(assert, stream);
 }
+EXPORT_SYMBOL_GPL(kunit_binary_str_assert_format);
diff --git a/kunit/example-test.c b/kunit/example-test.c
index f64a829..6c6a408 100644
--- a/kunit/example-test.c
+++ b/kunit/example-test.c
@@ -85,4 +85,8 @@ static int example_test_init(struct kunit *test)
  * This registers the above test suite telling KUnit that this is a suite of
  * tests that need to be run.
  */
-kunit_test_suite(example_test_suite);
+kunit_test_suite(&example_test_suite);
+
+#ifdef MODULE
+MODULE_LICENSE("GPL");
+#endif /* MODULE */
diff --git a/kunit/string-stream-test.c b/kunit/string-stream-test.c
index 76cc05e..7a3e7a0 100644
--- a/kunit/string-stream-test.c
+++ b/kunit/string-stream-test.c
@@ -45,8 +45,13 @@ static void string_stream_test_get_string(struct kunit *test)
 	{}
 };
 
-static struct kunit_suite string_stream_test_suite = {
+struct kunit_suite string_stream_test_suite = {
 	.name = "string-stream-test",
 	.test_cases = string_stream_test_cases
 };
-kunit_test_suite(string_stream_test_suite);
+
+kunit_test_suite(&string_stream_test_suite);
+
+#ifdef MODULE
+MODULE_LICENSE("GPL");
+#endif /* MODULE */
diff --git a/kunit/string-stream.c b/kunit/string-stream.c
index e6d17aa..e4f3a97 100644
--- a/kunit/string-stream.c
+++ b/kunit/string-stream.c
@@ -100,6 +100,7 @@ int string_stream_vadd(struct string_stream *stream,
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(string_stream_vadd);
 
 int string_stream_add(struct string_stream *stream, const char *fmt, ...)
 {
@@ -112,6 +113,7 @@ int string_stream_add(struct string_stream *stream, const char *fmt, ...)
 
 	return result;
 }
+EXPORT_SYMBOL_GPL(string_stream_add);
 
 static void string_stream_clear(struct string_stream *stream)
 {
@@ -145,6 +147,7 @@ char *string_stream_get_string(struct string_stream *stream)
 
 	return buf;
 }
+EXPORT_SYMBOL_GPL(string_stream_get_string);
 
 int string_stream_append(struct string_stream *stream,
 			 struct string_stream *other)
@@ -158,11 +161,13 @@ int string_stream_append(struct string_stream *stream,
 
 	return string_stream_add(stream, other_content);
 }
+EXPORT_SYMBOL_GPL(string_stream_append);
 
 bool string_stream_is_empty(struct string_stream *stream)
 {
 	return list_empty(&stream->fragments);
 }
+EXPORT_SYMBOL_GPL(string_stream_is_empty);
 
 struct string_stream_alloc_context {
 	struct kunit *test;
@@ -207,6 +212,7 @@ struct string_stream *alloc_string_stream(struct kunit *test, gfp_t gfp)
 				    gfp,
 				    &context);
 }
+EXPORT_SYMBOL_GPL(alloc_string_stream);
 
 int string_stream_destroy(struct string_stream *stream)
 {
@@ -215,3 +221,4 @@ int string_stream_destroy(struct string_stream *stream)
 				      string_stream_free,
 				      stream);
 }
+EXPORT_SYMBOL_GPL(string_stream_destroy);
diff --git a/kunit/test-test.c b/kunit/test-test.c
index 5ebe059..b5fdbe3 100644
--- a/kunit/test-test.c
+++ b/kunit/test-test.c
@@ -100,7 +100,6 @@ static int kunit_try_catch_test_init(struct kunit *test)
 	.init = kunit_try_catch_test_init,
 	.test_cases = kunit_try_catch_test_cases,
 };
-kunit_test_suite(kunit_try_catch_test_suite);
 
 /*
  * Context for testing test managed resources
@@ -328,4 +327,9 @@ static void kunit_resource_test_exit(struct kunit *test)
 	.exit = kunit_resource_test_exit,
 	.test_cases = kunit_resource_test_cases,
 };
-kunit_test_suite(kunit_resource_test_suite);
+kunit_test_suites(&kunit_resource_test_suite,
+		  &kunit_try_catch_test_suite);
+
+#ifdef MODULE
+MODULE_LICENSE("GPL");
+#endif /* MODULE */
diff --git a/kunit/test.c b/kunit/test.c
index c83c0fa..e7896f1 100644
--- a/kunit/test.c
+++ b/kunit/test.c
@@ -171,6 +171,7 @@ void kunit_do_assertion(struct kunit *test,
 	if (assert->type == KUNIT_ASSERTION)
 		kunit_abort(test);
 }
+EXPORT_SYMBOL_GPL(kunit_do_assertion);
 
 void kunit_init_test(struct kunit *test, const char *name)
 {
@@ -179,6 +180,7 @@ void kunit_init_test(struct kunit *test, const char *name)
 	test->name = name;
 	test->success = true;
 }
+EXPORT_SYMBOL_GPL(kunit_init_test);
 
 /*
  * Initializes and runs test case. Does not clean up or do post validations.
@@ -317,6 +319,7 @@ int kunit_run_tests(struct kunit_suite *suite)
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(kunit_run_tests);
 
 struct kunit_resource *kunit_alloc_and_get_resource(struct kunit *test,
 						    kunit_resource_init_t init,
@@ -342,6 +345,7 @@ struct kunit_resource *kunit_alloc_and_get_resource(struct kunit *test,
 
 	return res;
 }
+EXPORT_SYMBOL_GPL(kunit_alloc_and_get_resource);
 
 static void kunit_resource_free(struct kunit *test, struct kunit_resource *res)
 {
@@ -400,6 +404,7 @@ int kunit_resource_destroy(struct kunit *test,
 	kunit_resource_free(test, resource);
 	return 0;
 }
+EXPORT_SYMBOL_GPL(kunit_resource_destroy);
 
 struct kunit_kmalloc_params {
 	size_t size;
@@ -435,6 +440,7 @@ void *kunit_kmalloc(struct kunit *test, size_t size, gfp_t gfp)
 				    gfp,
 				    &params);
 }
+EXPORT_SYMBOL_GPL(kunit_kmalloc);
 
 void kunit_kfree(struct kunit *test, const void *ptr)
 {
@@ -447,6 +453,7 @@ void kunit_kfree(struct kunit *test, const void *ptr)
 
 	WARN_ON(rc);
 }
+EXPORT_SYMBOL_GPL(kunit_kfree);
 
 void kunit_cleanup(struct kunit *test)
 {
@@ -476,3 +483,4 @@ void kunit_cleanup(struct kunit *test)
 		kunit_resource_free(test, resource);
 	}
 }
+EXPORT_SYMBOL_GPL(kunit_cleanup);
diff --git a/kunit/try-catch.c b/kunit/try-catch.c
index 55686839..a288012 100644
--- a/kunit/try-catch.c
+++ b/kunit/try-catch.c
@@ -19,6 +19,7 @@ void __noreturn kunit_try_catch_throw(struct kunit_try_catch *try_catch)
 	try_catch->try_result = -EFAULT;
 	complete_and_exit(try_catch->try_completion, -EFAULT);
 }
+EXPORT_SYMBOL_GPL(kunit_try_catch_throw);
 
 static int kunit_generic_run_threadfn_adapter(void *data)
 {
@@ -50,6 +51,7 @@ static unsigned long kunit_test_timeout(void)
 	 * For more background on this topic, see:
 	 * https://mike-bland.com/2011/11/01/small-medium-large.html
 	 */
+#ifndef MODULE
 	if (sysctl_hung_task_timeout_secs) {
 		/*
 		 * If sysctl_hung_task is active, just set the timeout to some
@@ -60,9 +62,9 @@ static unsigned long kunit_test_timeout(void)
 		 */
 		timeout_msecs = (sysctl_hung_task_timeout_secs - 1) *
 				MSEC_PER_SEC;
-	} else {
+	} else
+#endif
 		timeout_msecs = 300 * MSEC_PER_SEC; /* 5 min */
-	}
 
 	return timeout_msecs;
 }
@@ -106,6 +108,7 @@ void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
 
 	try_catch->catch(try_catch->context);
 }
+EXPORT_SYMBOL_GPL(kunit_try_catch_run);
 
 void kunit_try_catch_init(struct kunit_try_catch *try_catch,
 			  struct kunit *test,
@@ -116,3 +119,4 @@ void kunit_try_catch_init(struct kunit_try_catch *try_catch,
 	try_catch->try = try;
 	try_catch->catch = catch;
 }
+EXPORT_SYMBOL_GPL(kunit_try_catch_init);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index a425741..1d1e38d 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1966,10 +1966,10 @@ config TEST_SYSCTL
 	  If unsure, say N.
 
 config SYSCTL_KUNIT_TEST
-	bool "KUnit test for sysctl"
+	tristate "KUnit test for sysctl"
 	depends on KUNIT
 	help
-	  This builds the proc sysctl unit test, which runs on boot.
+	  This builds the proc sysctl unit test, which runs on boot/module load.
 	  Tests the API contract and implementation correctness of sysctl.
 	  For more information on KUnit and unit tests in general please refer
 	  to the KUnit documentation in Documentation/dev-tools/kunit/.
-- 
1.8.3.1

[PATCH linux-kselftest-test 2/3] kunit: allow kunit to be loaded as a module

[Alan Maguire]

Making kunit itself buildable as a module allows for "always-on"
kunit configuration; specifying CONFIG_KUNIT=m means the module
is built but only used when loaded.  Kunit test modules will load
kunit.ko as an implicit dependency, so simply running
"modprobe my-kunit-tests" will load the tests along with the kunit
module and run them.

Signed-off-by: Knut Omang <knut.omang@oracle.com>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
---
 kunit/Kconfig  | 2 +-
 kunit/Makefile | 9 +++++++++
 kunit/test.c   | 4 ++++
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/kunit/Kconfig b/kunit/Kconfig
index f28bf086..d84f480 100644
--- a/kunit/Kconfig
+++ b/kunit/Kconfig
@@ -5,7 +5,7 @@
 menu "KUnit support"
 
 config KUNIT
-	bool "Enable support for unit tests (KUnit)"
+	tristate "Enable support for unit tests (KUnit)"
 	help
 	  Enables support for kernel unit tests (KUnit), a lightweight unit
 	  testing and mocking framework for the Linux kernel. These tests are
diff --git a/kunit/Makefile b/kunit/Makefile
index 769d940..932a3f2 100644
--- a/kunit/Makefile
+++ b/kunit/Makefile
@@ -1,7 +1,16 @@
+ifeq ($(CONFIG_KUNIT),m)
+obj-$(CONFIG_KUNIT) +=			kunit.o
+
+kunit-objs +=				test.o \
+					string-stream.o \
+					assert.o \
+					try-catch.o
+else
 obj-$(CONFIG_KUNIT) +=			test.o \
 					string-stream.o \
 					assert.o \
 					try-catch.o
+endif
 
 obj-$(CONFIG_KUNIT_TEST) +=		test-test.o \
 					string-stream-test.o
diff --git a/kunit/test.c b/kunit/test.c
index e7896f1..6024627 100644
--- a/kunit/test.c
+++ b/kunit/test.c
@@ -484,3 +484,7 @@ void kunit_cleanup(struct kunit *test)
 	}
 }
 EXPORT_SYMBOL_GPL(kunit_cleanup);
+
+#ifdef MODULE
+MODULE_LICENSE("GPL");
+#endif /* MODULE */
-- 
1.8.3.1

Re: [PATCH linux-kselftest-test 2/3] kunit: allow kunit to be loaded as a module

[Andy Shevchenko]

On Tue, Oct 08, 2019 at 03:43:51PM +0100, Alan Maguire wrote:
> Making kunit itself buildable as a module allows for "always-on"
> kunit configuration; specifying CONFIG_KUNIT=m means the module
> is built but only used when loaded.  Kunit test modules will load
> kunit.ko as an implicit dependency, so simply running
> "modprobe my-kunit-tests" will load the tests along with the kunit
> module and run them.

> +#ifdef MODULE

> +#endif /* MODULE */

This is strange. Why do you need ifdef?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH linux-kselftest-test 2/3] kunit: allow kunit to be loaded as a module

[Alan Maguire]

On Tue, 8 Oct 2019, Andy Shevchenko wrote:

> On Tue, Oct 08, 2019 at 03:43:51PM +0100, Alan Maguire wrote:
> > Making kunit itself buildable as a module allows for "always-on"
> > kunit configuration; specifying CONFIG_KUNIT=m means the module
> > is built but only used when loaded.  Kunit test modules will load
> > kunit.ko as an implicit dependency, so simply running
> > "modprobe my-kunit-tests" will load the tests along with the kunit
> > module and run them.
> 
> > +#ifdef MODULE
> 
> > +#endif /* MODULE */
> 
> This is strange. Why do you need ifdef?
>

Ah, this was an incorrect assumption on my part; I thought that
declaring a module license for built-in code might trigger a warning 
during build. I'll remove the #ifdef MODULE around licenses in v3 (v2 has 
already gone out as I mistakenly initially sent the wrong version of the 
patches). I've verified that removing it triggers no warnings.

Thanks to you and Randy for spotting this!

Alan

> -- 
> With Best Regards,
> Andy Shevchenko
> 
> 
> 

[PATCH linux-kselftest-test 3/3] kunit: update documentation to describe module-based build

[Alan Maguire]

Documentation should describe how to build kunit and tests as
modules.

Signed-off-by: Knut Omang <knut.omang@oracle.com>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
---
 Documentation/dev-tools/kunit/faq.rst   |  3 ++-
 Documentation/dev-tools/kunit/index.rst |  3 +++
 Documentation/dev-tools/kunit/usage.rst | 16 ++++++++++++++++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/Documentation/dev-tools/kunit/faq.rst b/Documentation/dev-tools/kunit/faq.rst
index bf20951..ea55b24 100644
--- a/Documentation/dev-tools/kunit/faq.rst
+++ b/Documentation/dev-tools/kunit/faq.rst
@@ -29,7 +29,8 @@ Yes, well, mostly.
 
 For the most part, the KUnit core framework (what you use to write the tests)
 can compile to any architecture; it compiles like just another part of the
-kernel and runs when the kernel boots. However, there is some infrastructure,
+kernel and runs when the kernel boots, or when built as a module, when the
+module is loaded.  However, there is some infrastructure,
 like the KUnit Wrapper (``tools/testing/kunit/kunit.py``) that does not support
 other architectures.
 
diff --git a/Documentation/dev-tools/kunit/index.rst b/Documentation/dev-tools/kunit/index.rst
index 26ffb46..7ddc385 100644
--- a/Documentation/dev-tools/kunit/index.rst
+++ b/Documentation/dev-tools/kunit/index.rst
@@ -48,6 +48,9 @@ to a standalone program that can be run like any other program directly inside
 of a host operating system; to be clear, it does not require any virtualization
 support; it is just a regular program.
 
+Alternatively, kunit and kunit tests can be built as modules and tests will
+run when the test module is loaded.
+
 KUnit is fast. Excluding build time, from invocation to completion KUnit can run
 several dozen tests in only 10 to 20 seconds; this might not sound like a big
 deal to some people, but having such fast and easy to run tests fundamentally
diff --git a/Documentation/dev-tools/kunit/usage.rst b/Documentation/dev-tools/kunit/usage.rst
index c6e6963..fa0f03f 100644
--- a/Documentation/dev-tools/kunit/usage.rst
+++ b/Documentation/dev-tools/kunit/usage.rst
@@ -539,6 +539,22 @@ Interspersed in the kernel logs you might see the following:
 
 Congratulations, you just ran a KUnit test on the x86 architecture!
 
+In a similar manner, kunit and kunit tests can also be built as modules,
+so if you wanted to run tests in this way you might add the following config
+options to your ``.config``:
+
+.. code-block:: none
+
+        CONFIG_KUNIT=m
+        CONFIG_KUNIT_EXAMPLE_TEST=m
+
+Once the kernel is built and installed, a simple
+
+.. code-block:: bash
+	modprobe example-test
+
+...will run the tests.
+
 Writing new tests for other architectures
 -----------------------------------------
 
-- 
1.8.3.1