[PATCH] drm/buddy: Fix alloc_range() error handling code

[Arunpravin Paneer Selvam]

Hi Christian,

On 2/8/2024 12:27 PM, Christian König wrote:
> Am 07.02.24 um 18:44 schrieb Arunpravin Paneer Selvam:
>> Few users have observed display corruption when they boot
>> the machine to KDE Plasma or playing games. We have root
>> caused the problem that whenever alloc_range() couldn't
>> find the required memory blocks the function was returning
>> SUCCESS in some of the corner cases.
>>
>> The right approach would be if the total allocated size
>> is less than the required size, the function should
>> return -ENOSPC.
>>
>> Gitlab ticket link - 
>> https://gitlab.freedesktop.org/drm/amd/-/issues/3097
>> Fixes: 0a1844bf0b53 ("drm/buddy: Improve contiguous memory allocation")
>> Signed-off-by: Arunpravin Paneer Selvam 
>> <Arunpravin.PaneerSelvam at amd.com>
>> Tested-by: Mario Limonciello <mario.limonciello at amd.com>
>
> Acked-by: Christian König <christian.koenig at amd.com>
>
> CC: stable.. ?
I will check and add the stable kernel version.

Thanks,
Arun.
>
>> ---
>>   drivers/gpu/drm/drm_buddy.c | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
>> index f57e6d74fb0e..c1a99bf4dffd 100644
>> --- a/drivers/gpu/drm/drm_buddy.c
>> +++ b/drivers/gpu/drm/drm_buddy.c
>> @@ -539,6 +539,12 @@ static int __alloc_range(struct drm_buddy *mm,
>>       } while (1);
>>         list_splice_tail(&allocated, blocks);
>> +
>> +    if (total_allocated < size) {
>> +        err = -ENOSPC;
>> +        goto err_free;
>> +    }
>> +
>>       return 0;
>>     err_undo:
>