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);
>
