On 12/11/2025 09:18, Philipp Stanner wrote:
drm_sched_job_arm() just panics the kernel with BUG_ON() in case of an
entity being NULL. If the entity is NULL, subsequent accesses will crash
the particular CPU anyways with a NULL pointer exception backtrace.
Remove the BUG_ON().
Signed-off-by: Philipp Stanner <[email protected]>
---
Changes in v2:
- Drop BUG_ON() instead of replacing it. (Tvrtko)
The option of removing the BUG_ON was conditional on brainstorming a bit
whether we think the null pointer dereference is the worst that can
happen or not.
Other option was "WARN_ON_ONCE() return" in arm and push.
Problem being, if we allow it to continue, are we opening up the
possibly to mess up the kernel in a worse way.
For example push job writes to the entity. Okay offsets are low so is
the zero page always safe to write? I don't know but sounds scary. From
that point of view BUG_ON or WARN_ON_ONCE with exit are safer options.
Regards,
Tvrtko
---
drivers/gpu/drm/scheduler/sched_main.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/drivers/gpu/drm/scheduler/sched_main.c
b/drivers/gpu/drm/scheduler/sched_main.c
index 1d4f1b822e7b..05eb50d4cf08 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -857,7 +857,6 @@ void drm_sched_job_arm(struct drm_sched_job *job)
struct drm_gpu_scheduler *sched;
struct drm_sched_entity *entity = job->entity;
- BUG_ON(!entity);
drm_sched_entity_select_rq(entity);
sched = entity->rq->sched;
