Re: [PATCH v2] kfence: Make test case compatible with run time set sample interval

["liupeng (DM)" <liupeng256@huawei.com>]

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On 2022/1/28 17:49, Marco Elver wrote:
> 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

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