On Thu, Dec 19, 2024 at 09:30:30AM +0000, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx>
>
> After commit
> 746ae46c1113 ("drm/sched: Mark scheduler work queues with WQ_MEM_RECLAIM")
> amdgpu started seeing the following warning:
>
> [ ] workqueue: WQ_MEM_RECLAIM sdma0:drm_sched_run_job_work [gpu_sched] is flushing !WQ_MEM_RECLAIM events:amdgpu_device_delay_enable_gfx_off [amdgpu]
> ...
> [ ] Workqueue: sdma0 drm_sched_run_job_work [gpu_sched]
> ...
> [ ] Call Trace:
> [ ] <TASK>
> ...
> [ ] ? check_flush_dependency+0xf5/0x110
> ...
> [ ] cancel_delayed_work_sync+0x6e/0x80
> [ ] amdgpu_gfx_off_ctrl+0xab/0x140 [amdgpu]
> [ ] amdgpu_ring_alloc+0x40/0x50 [amdgpu]
> [ ] amdgpu_ib_schedule+0xf4/0x810 [amdgpu]
> [ ] ? drm_sched_run_job_work+0x22c/0x430 [gpu_sched]
> [ ] amdgpu_job_run+0xaa/0x1f0 [amdgpu]
> [ ] drm_sched_run_job_work+0x257/0x430 [gpu_sched]
> [ ] process_one_work+0x217/0x720
> ...
> [ ] </TASK>
>
> The intent of the verifcation done in check_flush_depedency is to ensure
> forward progress during memory reclaim, by flagging cases when either a
> memory reclaim process, or a memory reclaim work item is flushed from a
> context not marked as memory reclaim safe.
>
> This is correct when flushing, but when called from the
> cancel(_delayed)_work_sync() paths it is a false positive because work is
> either already running, or will not be running at all. Therefore
> cancelling it is safe and we can relax the warning criteria by letting the
> helper know of the calling context.
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx>
> Fixes: fca839c00a12 ("workqueue: warn if memory reclaim tries to flush !WQ_MEM_RECLAIM workqueue")
> References: 746ae46c1113 ("drm/sched: Mark scheduler work queues with WQ_MEM_RECLAIM")
> Cc: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
> Cc: Alex Deucher <alexander.deucher@xxxxxxx>
> Cc: Christian König <christian.koenig@xxxxxxx
> Cc: Matthew Brost <matthew.brost@xxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # v4.5+
Applied to wq/for-6.13-fixes.
Thanks.
--
tejun
