This is a note to let you know that I've just added the patch titled
drm/sched: Check scheduler work queue before calling timeout handling
to the 6.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-sched-check-scheduler-work-queue-before-calling-.patch
and it can be found in the queue-6.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 71dd79df1cac03bdd90c094a3fc3deeb35fd74e6
Author: Vitaly Prosyak <vitaly.prosyak@xxxxxxx>
Date: Wed May 10 09:51:11 2023 -0400
drm/sched: Check scheduler work queue before calling timeout handling
[ Upstream commit 2da5bffe9eaa5819a868e8eaaa11b3fd0f16a691 ]
During an IGT GPU reset test we see again oops despite of
commit 0c8c901aaaebc9 (drm/sched: Check scheduler ready before calling
timeout handling).
It uses ready condition whether to call drm_sched_fault which unwind
the TDR leads to GPU reset.
However it looks the ready condition is overloaded with other meanings,
for example, for the following stack is related GPU reset :
0 gfx_v9_0_cp_gfx_start
1 gfx_v9_0_cp_gfx_resume
2 gfx_v9_0_cp_resume
3 gfx_v9_0_hw_init
4 gfx_v9_0_resume
5 amdgpu_device_ip_resume_phase2
does the following:
/* start the ring */
gfx_v9_0_cp_gfx_start(adev);
ring->sched.ready = true;
The same approach is for other ASICs as well :
gfx_v8_0_cp_gfx_resume
gfx_v10_0_kiq_resume, etc...
As a result, our GPU reset test causes GPU fault which calls unconditionally gfx_v9_0_fault
and then drm_sched_fault. However now it depends on whether the interrupt service routine
drm_sched_fault is executed after gfx_v9_0_cp_gfx_start is completed which sets the ready
field of the scheduler to true even for uninitialized schedulers and causes oops vs
no fault or when ISR drm_sched_fault is completed prior gfx_v9_0_cp_gfx_start and
NULL pointer dereference does not occur.
Use the field timeout_wq to prevent oops for uninitialized schedulers.
The field could be initialized by the work queue of resetting the domain.
v1: Corrections to commit message (Luben)
Fixes: 11b3b9f461c5c4 ("drm/sched: Check scheduler ready before calling timeout handling")
Signed-off-by: Vitaly Prosyak <vitaly.prosyak@xxxxxxx>
Link: https://lore.kernel.org/r/20230510135111.58631-1-vitaly.prosyak@xxxxxxx
Reviewed-by: Luben Tuikov <luben.tuikov@xxxxxxx>
Signed-off-by: Luben Tuikov <luben.tuikov@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index 1e08cc5a17029..78c959eaef0c5 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -308,7 +308,7 @@ static void drm_sched_start_timeout(struct drm_gpu_scheduler *sched)
*/
void drm_sched_fault(struct drm_gpu_scheduler *sched)
{
- if (sched->ready)
+ if (sched->timeout_wq)
mod_delayed_work(sched->timeout_wq, &sched->work_tdr, 0);
}
EXPORT_SYMBOL(drm_sched_fault);
