linux-kernel - Re: [PATCH] drm/msm: skip re-emitting IBs for unusable VMs

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Message-ID: <272d2a39-19ce-4ac5-b3c6-3e3d6d9985c5@oss.qualcomm.com>
Date: Mon, 18 Aug 2025 17:40:42 +0530
From: Akhil P Oommen <akhilpo@....qualcomm.com>
To: Antonino Maniscalco <antomani103@...il.com>,
        Rob Clark <robin.clark@....qualcomm.com>, Sean Paul <sean@...rly.run>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Dmitry Baryshkov <lumag@...nel.org>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Jessica Zhang <jessica.zhang@....qualcomm.com>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/msm: skip re-emitting IBs for unusable VMs

On 8/13/2025 6:34 PM, Antonino Maniscalco wrote:
> When a VM is marked as an usuable we disallow new submissions from it,
> however submissions that where already scheduled on the ring would still
> be re-sent.
> 
> Since this can lead to further hangs, avoid emitting the actual IBs.
> 
> Fixes: 6a4d287a1ae6 ("drm/msm: Mark VM as unusable on GPU hangs")
> Signed-off-by: Antonino Maniscalco <antomani103@...il.com>
> ---
>  drivers/gpu/drm/msm/msm_gpu.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
> index c317b25a8162edba0d594f61427eac4440871b73..e6cd85c810bd2314c8bba53644a622464713b7f2 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.c
> +++ b/drivers/gpu/drm/msm/msm_gpu.c
> @@ -553,8 +553,15 @@ static void recover_worker(struct kthread_work *work)
>  			unsigned long flags;
>  
>  			spin_lock_irqsave(&ring->submit_lock, flags);
> -			list_for_each_entry(submit, &ring->submits, node)
> +			list_for_each_entry(submit, &ring->submits, node) {
> +				/*
> +				 * If the submit uses an unusable vm make sure
> +				 * we don't actually run it
> +				 */
> +				if (to_msm_vm(submit->vm)->unusable)
> +					submit->nr_cmds = 0;

Just curious, why not just retire this submit here?

-Akhil

>  				gpu->funcs->submit(gpu, submit);
> +			}
>  			spin_unlock_irqrestore(&ring->submit_lock, flags);
>  		}
>  	}
> 
> ---
> base-commit: 8290d37ad2b087bbcfe65fa5bcaf260e184b250a
> change-id: 20250813-unusable_fix_b4-10bde6f3b756
> 
> Best regards,