Re: [PATCH] drm/msm/a6xx: Fix recovery vs runpm race
On Fri, Dec 22, 2023 at 11:58 AM Akhil P Oommen
wrote:
>
> On Mon, Dec 18, 2023 at 07:59:24AM -0800, Rob Clark wrote:
> >
> > From: Rob Clark
> >
> > a6xx_recover() is relying on the gpu lock to serialize against incoming
> > submits doing a runpm get, as it tries to temporarily balance out the
> > runpm gets with puts in order to power off the GPU. Unfortunately this
> > gets worse when we (in a later patch) will move the runpm get out of the
> > scheduler thread/work to move it out of the fence signaling path.
> >
> > Instead we can just simplify the whole thing by using force_suspend() /
> > force_resume() instead of trying to be clever.
>
> At some places, we take a pm_runtime vote and access the gpu
> registers assuming it will be powered until we drop the vote.
> a6xx_get_timestamp()
> is an example. If we do a force suspend, it may cause bus errors from
> those threads. Now you have to serialize every place we do runtime_get/put
> with a
> mutex. Or is there a better way to handle the 'later patch' you
> mentioned?
So I was running into issues, when I started adding an igt test to
stress test recovery vs multi-threaded submit, with cxpd not always
suspending and getting "cx gdsc did not collapse", which may be
related.
I was considering using force_suspend() on the gmu and cxpd if
gpu->hang==true, I'm not sure. I ran out of time to play with this
when I was in the office.
The issue the 'later patch' is trying to deal with is getting memory
allocations out of the "fence signaling path", ie. out from the
drm/sched kthread/worker. One way to do that, without dragging all of
runpm/device-link/etc into it is to do the runpm get in the submit
ioctl before enqueuing the job to the scheduler. But then we can hold
a lock to protect against racing with recovery.
BR,
-R
> -Akhil.
>
> >
> > Reported-by: David Heidelberg
> > Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/10272
> > Fixes: abe2023b4cea ("drm/msm/gpu: Push gpu lock down past runpm")
> > Signed-off-by: Rob Clark
> > ---
> > drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 12 ++--
> > 1 file changed, 2 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > index 268737e59131..a5660d63535b 100644
> > --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > @@ -1244,12 +1244,7 @@ static void a6xx_recover(struct msm_gpu *gpu)
> > dev_pm_genpd_add_notifier(gmu->cxpd, >pd_nb);
> > dev_pm_genpd_synced_poweroff(gmu->cxpd);
> >
> > - /* Drop the rpm refcount from active submits */
> > - if (active_submits)
> > - pm_runtime_put(>pdev->dev);
> > -
> > - /* And the final one from recover worker */
> > - pm_runtime_put_sync(>pdev->dev);
> > + pm_runtime_force_suspend(>pdev->dev);
> >
> > if (!wait_for_completion_timeout(>pd_gate,
> > msecs_to_jiffies(1000)))
> > DRM_DEV_ERROR(>pdev->dev, "cx gdsc didn't collapse\n");
> > @@ -1258,10 +1253,7 @@ static void a6xx_recover(struct msm_gpu *gpu)
> >
> > pm_runtime_use_autosuspend(>pdev->dev);
> >
> > - if (active_submits)
> > - pm_runtime_get(>pdev->dev);
> > -
> > - pm_runtime_get_sync(>pdev->dev);
> > + pm_runtime_force_resume(>pdev->dev);
> >
> > gpu->active_submits = active_submits;
> > mutex_unlock(>active_lock);
> > --
> > 2.43.0
> >
Re: [PATCH] drm/msm/a6xx: Fix recovery vs runpm race
On Mon, Dec 18, 2023 at 07:59:24AM -0800, Rob Clark wrote:
>
> From: Rob Clark
>
> a6xx_recover() is relying on the gpu lock to serialize against incoming
> submits doing a runpm get, as it tries to temporarily balance out the
> runpm gets with puts in order to power off the GPU. Unfortunately this
> gets worse when we (in a later patch) will move the runpm get out of the
> scheduler thread/work to move it out of the fence signaling path.
>
> Instead we can just simplify the whole thing by using force_suspend() /
> force_resume() instead of trying to be clever.
At some places, we take a pm_runtime vote and access the gpu
registers assuming it will be powered until we drop the vote.
a6xx_get_timestamp()
is an example. If we do a force suspend, it may cause bus errors from
those threads. Now you have to serialize every place we do runtime_get/put with
a
mutex. Or is there a better way to handle the 'later patch' you
mentioned?
-Akhil.
>
> Reported-by: David Heidelberg
> Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/10272
> Fixes: abe2023b4cea ("drm/msm/gpu: Push gpu lock down past runpm")
> Signed-off-by: Rob Clark
> ---
> drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 12 ++--
> 1 file changed, 2 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index 268737e59131..a5660d63535b 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -1244,12 +1244,7 @@ static void a6xx_recover(struct msm_gpu *gpu)
> dev_pm_genpd_add_notifier(gmu->cxpd, >pd_nb);
> dev_pm_genpd_synced_poweroff(gmu->cxpd);
>
> - /* Drop the rpm refcount from active submits */
> - if (active_submits)
> - pm_runtime_put(>pdev->dev);
> -
> - /* And the final one from recover worker */
> - pm_runtime_put_sync(>pdev->dev);
> + pm_runtime_force_suspend(>pdev->dev);
>
> if (!wait_for_completion_timeout(>pd_gate, msecs_to_jiffies(1000)))
> DRM_DEV_ERROR(>pdev->dev, "cx gdsc didn't collapse\n");
> @@ -1258,10 +1253,7 @@ static void a6xx_recover(struct msm_gpu *gpu)
>
> pm_runtime_use_autosuspend(>pdev->dev);
>
> - if (active_submits)
> - pm_runtime_get(>pdev->dev);
> -
> - pm_runtime_get_sync(>pdev->dev);
> + pm_runtime_force_resume(>pdev->dev);
>
> gpu->active_submits = active_submits;
> mutex_unlock(>active_lock);
> --
> 2.43.0
>
[PATCH] drm/msm/a6xx: Fix recovery vs runpm race
From: Rob Clark
a6xx_recover() is relying on the gpu lock to serialize against incoming
submits doing a runpm get, as it tries to temporarily balance out the
runpm gets with puts in order to power off the GPU. Unfortunately this
gets worse when we (in a later patch) will move the runpm get out of the
scheduler thread/work to move it out of the fence signaling path.
Instead we can just simplify the whole thing by using force_suspend() /
force_resume() instead of trying to be clever.
Reported-by: David Heidelberg
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/10272
Fixes: abe2023b4cea ("drm/msm/gpu: Push gpu lock down past runpm")
Signed-off-by: Rob Clark
---
drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 12 ++--
1 file changed, 2 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 268737e59131..a5660d63535b 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -1244,12 +1244,7 @@ static void a6xx_recover(struct msm_gpu *gpu)
dev_pm_genpd_add_notifier(gmu->cxpd, >pd_nb);
dev_pm_genpd_synced_poweroff(gmu->cxpd);
- /* Drop the rpm refcount from active submits */
- if (active_submits)
- pm_runtime_put(>pdev->dev);
-
- /* And the final one from recover worker */
- pm_runtime_put_sync(>pdev->dev);
+ pm_runtime_force_suspend(>pdev->dev);
if (!wait_for_completion_timeout(>pd_gate, msecs_to_jiffies(1000)))
DRM_DEV_ERROR(>pdev->dev, "cx gdsc didn't collapse\n");
@@ -1258,10 +1253,7 @@ static void a6xx_recover(struct msm_gpu *gpu)
pm_runtime_use_autosuspend(>pdev->dev);
- if (active_submits)
- pm_runtime_get(>pdev->dev);
-
- pm_runtime_get_sync(>pdev->dev);
+ pm_runtime_force_resume(>pdev->dev);
gpu->active_submits = active_submits;
mutex_unlock(>active_lock);
--
2.43.0
