On Fri, 28 Jan 2022 at 02:41, Peng Liu <liupeng256@huawei.com> wrote:

The parameter kfence_sample_interval can be set via boot parameter
and late shell command, which is convenient for automatical tests

s/automatical/automated/

and KFENCE parameter optimation. However, KFENCE test case just use

s/optimation/optimization/

compile time CONFIG_KFENCE_SAMPLE_INTERVAL, this will make KFENCE
test case not run as user desired. This patch will make KFENCE test
case compatible with run-time-set sample interval.

I'm not too particular about it, but "This patch" is usually bad style:
https://www.kernel.org/doc/html/latest/process/submitting-patches.html#describe-your-changes

I'm sorry for the "bad style", and I will carefully revise later.

v1->v2:
- Use EXPORT_SYMBOL_GPL replace EXPORT_SYMBOL

Changelog is usually placed after '---', because it's mostly redundant
once committed. Often maintainers include a "Link" to the original
patch which then has history and discussion.

Signed-off-by: Peng Liu <liupeng256@huawei.com>

Reviewed-by: Marco Elver <elver@google.com>

---
 include/linux/kfence.h  | 2 ++
 mm/kfence/core.c        | 3 ++-
 mm/kfence/kfence_test.c | 8 ++++----
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/include/linux/kfence.h b/include/linux/kfence.h
index 4b5e3679a72c..f49e64222628 100644
--- a/include/linux/kfence.h
+++ b/include/linux/kfence.h
@@ -17,6 +17,8 @@
 #include <linux/atomic.h>
 #include <linux/static_key.h>

+extern unsigned long kfence_sample_interval;
+
 /*
  * We allocate an even number of pages, as it simplifies calculations to map
  * address to metadata indices; effectively, the very first page serves as an
diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index 5ad40e3add45..13128fa13062 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -47,7 +47,8 @@

 static bool kfence_enabled __read_mostly;

-static unsigned long kfence_sample_interval __read_mostly = CONFIG_KFENCE_SAMPLE_INTERVAL;
+unsigned long kfence_sample_interval __read_mostly = CONFIG_KFENCE_SAMPLE_INTERVAL;
+EXPORT_SYMBOL_GPL(kfence_sample_interval); /* Export for test modules. */

 #ifdef MODULE_PARAM_PREFIX
 #undef MODULE_PARAM_PREFIX
diff --git a/mm/kfence/kfence_test.c b/mm/kfence/kfence_test.c
index a22b1af85577..50dbb815a2a8 100644
--- a/mm/kfence/kfence_test.c
+++ b/mm/kfence/kfence_test.c
@@ -268,13 +268,13 @@ static void *test_alloc(struct kunit *test, size_t size, gfp_t gfp, enum allocat
         * 100x the sample interval should be more than enough to ensure we get
         * a KFENCE allocation eventually.
         */
-       timeout = jiffies + msecs_to_jiffies(100 * CONFIG_KFENCE_SAMPLE_INTERVAL);
+       timeout = jiffies + msecs_to_jiffies(100 * kfence_sample_interval);
        /*
         * Especially for non-preemption kernels, ensure the allocation-gate
         * timer can catch up: after @resched_after, every failed allocation
         * attempt yields, to ensure the allocation-gate timer is scheduled.
         */
-       resched_after = jiffies + msecs_to_jiffies(CONFIG_KFENCE_SAMPLE_INTERVAL);
+       resched_after = jiffies + msecs_to_jiffies(kfence_sample_interval);
        do {
                if (test_cache)
                        alloc = kmem_cache_alloc(test_cache, gfp);
@@ -608,7 +608,7 @@ static void test_gfpzero(struct kunit *test)
        int i;

        /* Skip if we think it'd take too long. */
-       KFENCE_TEST_REQUIRES(test, CONFIG_KFENCE_SAMPLE_INTERVAL <= 100);
+       KFENCE_TEST_REQUIRES(test, kfence_sample_interval <= 100);

        setup_test_cache(test, size, 0, NULL);
        buf1 = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
@@ -739,7 +739,7 @@ static void test_memcache_alloc_bulk(struct kunit *test)
         * 100x the sample interval should be more than enough to ensure we get
         * a KFENCE allocation eventually.
         */
-       timeout = jiffies + msecs_to_jiffies(100 * CONFIG_KFENCE_SAMPLE_INTERVAL);
+       timeout = jiffies + msecs_to_jiffies(100 * kfence_sample_interval);
        do {
                void *objects[100];
                int i, num = kmem_cache_alloc_bulk(test_cache, GFP_ATOMIC, ARRAY_SIZE(objects),
--
2.18.0.huawei.25

.

I'm sorry for the latency due to the spring festival. Thank you for your advice,
and I will send a revised patch later.

Thanks,
-- Peng Liu