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Vitaly Prosyak
2da5bffe9e
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: 11b3b9f461 ("drm/sched: Check scheduler ready before calling timeout handling")
Signed-off-by: Vitaly Prosyak <vitaly.prosyak@amd.com>
Link: https://lore.kernel.org/r/20230510135111.58631-1-vitaly.prosyak@amd.com
Reviewed-by: Luben Tuikov <luben.tuikov@amd.com>
Signed-off-by: Luben Tuikov <luben.tuikov@amd.com>
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