FYI
On 09.10.25 09:01, Christian König wrote:
> On 02.10.25 17:05, David Rosca wrote:
>> drm_sched_entity_flush should only kill the entity if the current
>> process is the last user of the entity. The last_user is only set
>> when adding new job, so entities that had no jobs submitted to them
>> have NULL last_user and would always be killed.
>> Another issue is setting last_user to NULL from drm_sched_entity_flush,
>> which causes subsequent calls to kill the entity.
>>
>> Signed-off-by: David Rosca <[email protected]>
>> Fixes: 51564e9f06f0 ("drm/amdgpu: Avoid extra evict-restore process.")
>
> Good catch, but in general please CC the relevant maintainers and mailing
> lists for scheduler patches.
>
>> ---
>> drivers/gpu/drm/scheduler/sched_entity.c | 5 ++---
>> 1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/scheduler/sched_entity.c
>> b/drivers/gpu/drm/scheduler/sched_entity.c
>> index 8867b95ab089..a325e4a59990 100644
>> --- a/drivers/gpu/drm/scheduler/sched_entity.c
>> +++ b/drivers/gpu/drm/scheduler/sched_entity.c
>> @@ -70,6 +70,7 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
>> entity->guilty = guilty;
>> entity->num_sched_list = num_sched_list;
>> entity->priority = priority;
>> + entity->last_user = current->group_leader;
>> /*
>> * It's perfectly valid to initialize an entity without having a valid
>> * scheduler attached. It's just not valid to use the scheduler before
>> it
>> @@ -278,7 +279,6 @@ static void drm_sched_entity_kill(struct
>> drm_sched_entity *entity)
>> long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout)
>> {
>> struct drm_gpu_scheduler *sched;
>> - struct task_struct *last_user;
>> long ret = timeout;
>>
>> if (!entity->rq)
>> @@ -301,8 +301,7 @@ long drm_sched_entity_flush(struct drm_sched_entity
>> *entity, long timeout)
>> }
>>
>> /* For killed process disable any more IBs enqueue right now */
>> - last_user = cmpxchg(&entity->last_user, current->group_leader, NULL);
>> - if ((!last_user || last_user == current->group_leader) &&
>> + if (entity->last_user == current->group_leader &&
>
> You still need the cmpxchg() here or otherwise drm_sched_entity_kill() would
> run multiple times.
>
> Regards,
> Christian.
>
>> (current->flags & PF_EXITING) && (current->exit_code == SIGKILL))
>> drm_sched_entity_kill(entity);
>>
>
