[PATCH] drm/tests/drm_buddy: add alloc_contiguous test

[Matthew Auld]

On 12/02/2024 08:23, Arunpravin Paneer Selvam wrote:
> Hi Matthew,
> 
> Can I push this test case along with the bug fix patch.

Sure. Please go ahead.

> 
> Thanks,
> Arun.
> 
> On 2/8/2024 8:06 PM, Matthew Auld wrote:
>> Sanity check DRM_BUDDY_CONTIGUOUS_ALLOCATION.
>>
>> References: https://gitlab.freedesktop.org/drm/amd/-/issues/3097
>> Signed-off-by: Matthew Auld <matthew.auld at intel.com>
>> Cc: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam at amd.com>
>> Cc: Limonciello <mario.limonciello at amd.com>
>> Cc: Christian König <christian.koenig at amd.com>
>> ---
>>   drivers/gpu/drm/tests/drm_buddy_test.c | 89 ++++++++++++++++++++++++++
>>   1 file changed, 89 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/tests/drm_buddy_test.c 
>> b/drivers/gpu/drm/tests/drm_buddy_test.c
>> index ea2af6bd9abe..4215d8b5fcf0 100644
>> --- a/drivers/gpu/drm/tests/drm_buddy_test.c
>> +++ b/drivers/gpu/drm/tests/drm_buddy_test.c
>> @@ -8,6 +8,7 @@
>>   #include <linux/prime_numbers.h>
>>   #include <linux/sched/signal.h>
>> +#include <linux/sizes.h>
>>   #include <drm/drm_buddy.h>
>> @@ -18,6 +19,93 @@ static inline u64 get_size(int order, u64 chunk_size)
>>       return (1 << order) * chunk_size;
>>   }
>> +static void drm_test_buddy_alloc_contiguous(struct kunit *test)
>> +{
>> +    u64 mm_size, ps = SZ_4K, i, n_pages, total;
>> +    struct drm_buddy_block *block;
>> +    struct drm_buddy mm;
>> +    LIST_HEAD(left);
>> +    LIST_HEAD(middle);
>> +    LIST_HEAD(right);
>> +    LIST_HEAD(allocated);
>> +
>> +    mm_size = 16 * 3 * SZ_4K;
>> +
>> +    KUNIT_EXPECT_FALSE(test, drm_buddy_init(&mm, mm_size, ps));
>> +
>> +    /*
>> +     * Idea is to fragment the address space by alternating block
>> +     * allocations between three different lists; one for left, 
>> middle and
>> +     * right. We can then free a list to simulate fragmentation. In
>> +     * particular we want to exercise the 
>> DRM_BUDDY_CONTIGUOUS_ALLOCATION,
>> +     * including the try_harder path.
>> +     */
>> +
>> +    i = 0;
>> +    n_pages = mm_size / ps;
>> +    do {
>> +        struct list_head *list;
>> +        int slot = i % 3;
>> +
>> +        if (slot == 0)
>> +            list = &left;
>> +        else if (slot == 1)
>> +            list = &middle;
>> +        else
>> +            list = &right;
>> +        KUNIT_ASSERT_FALSE_MSG(test,
>> +                       drm_buddy_alloc_blocks(&mm, 0, mm_size,
>> +                                  ps, ps, list, 0),
>> +                       "buddy_alloc hit an error size=%d\n",
>> +                       ps);
>> +    } while (++i < n_pages);
>> +
>> +    KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
>> +                               3 * ps, ps, &allocated,
>> +                               DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>> +                   "buddy_alloc didn't error size=%d\n", 3 * ps);
>> +
>> +    drm_buddy_free_list(&mm, &middle);
>> +    KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
>> +                               3 * ps, ps, &allocated,
>> +                               DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>> +                   "buddy_alloc didn't error size=%llu\n", 3 * ps);
>> +    KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
>> +                               2 * ps, ps, &allocated,
>> +                               DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>> +                   "buddy_alloc didn't error size=%llu\n", 2 * ps);
>> +
>> +    drm_buddy_free_list(&mm, &right);
>> +    KUNIT_ASSERT_TRUE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
>> +                               3 * ps, ps, &allocated,
>> +                               DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>> +                   "buddy_alloc didn't error size=%llu\n", 3 * ps);
>> +    /*
>> +     * At this point we should have enough contiguous space for 2 
>> blocks,
>> +     * however they are never buddies (since we freed middle and 
>> right) so
>> +     * will require the try_harder logic to find them.
>> +     */
>> +    KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
>> +                               2 * ps, ps, &allocated,
>> +                               DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>> +                   "buddy_alloc hit an error size=%d\n", 2 * ps);
>> +
>> +    drm_buddy_free_list(&mm, &left);
>> +    KUNIT_ASSERT_FALSE_MSG(test, drm_buddy_alloc_blocks(&mm, 0, mm_size,
>> +                               3 * ps, ps, &allocated,
>> +                               DRM_BUDDY_CONTIGUOUS_ALLOCATION),
>> +                   "buddy_alloc hit an error size=%d\n", 3 * ps);
>> +
>> +    total = 0;
>> +    list_for_each_entry(block, &allocated, link)
>> +        total += drm_buddy_block_size(&mm, block);
>> +
>> +    KUNIT_ASSERT_EQ(test, total, ps * 2 + ps * 3);
>> +
>> +    drm_buddy_free_list(&mm, &allocated);
>> +    drm_buddy_fini(&mm);
>> +}
>> +
>>   static void drm_test_buddy_alloc_pathological(struct kunit *test)
>>   {
>>       u64 mm_size, size, start = 0;
>> @@ -280,6 +368,7 @@ static struct kunit_case drm_buddy_tests[] = {
>>       KUNIT_CASE(drm_test_buddy_alloc_optimistic),
>>       KUNIT_CASE(drm_test_buddy_alloc_pessimistic),
>>       KUNIT_CASE(drm_test_buddy_alloc_pathological),
>> +    KUNIT_CASE(drm_test_buddy_alloc_contiguous),
>>       {}
>>   };
>