ACK: [focal:linux-azure][PATCH v2] Revert "video: hyperv_fb: Fix hibernation for the deferred IO feature"

[Thadeu Lima de Souza Cascardo]

On Mon, Aug 17, 2020 at 04:48:21PM -0300, Marcelo Henrique Cerri wrote:
> BugLink: https://bugs.launchpad.net/bugs/1891931

Acked-by: Thadeu Lima de Souza Cascardo <cascardo at canonical.com>

> 
> This reverts commit 0a14dbaa0736a6021c02e74d42cf3a7ca5438da6.
> 
> This commit was included as part of bug #1880032 ([linux-azure] Enable
> Hibernation on The 18.04 and 20.04 5.4 Kernels), however this change
> wasn't necessary because the base feature is not present in our 5.4
> kernel. The unnecessary commit causes a panic when triggering
> hibernation in some azure instances.
> 
> The panic can be reproduced in E and D instances types in azure. And
> Reverting the commit solves the issue.
> 
> After the revert hibernation succeeds on instances under high memory
> utilization, up to 70%, when tested with stress-ng (ie, stress-ng --vm
> 8 --vm-bytes 50% -t 1d).
> 
> Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri at canonical.com>
> ---
>  drivers/video/fbdev/hyperv_fb.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
> index 5017b4b20781..fe4731f97df7 100644
> --- a/drivers/video/fbdev/hyperv_fb.c
> +++ b/drivers/video/fbdev/hyperv_fb.c
> @@ -891,7 +891,6 @@ static int hvfb_suspend(struct hv_device *hdev)
>  	fb_set_suspend(info, 1);
>  
>  	cancel_delayed_work_sync(&par->dwork);
> -	cancel_delayed_work_sync(&info->deferred_work);
>  
>  	par->update_saved = par->update;
>  	par->update = false;
> @@ -925,7 +924,6 @@ static int hvfb_resume(struct hv_device *hdev)
>  	par->fb_ready = true;
>  	par->update = par->update_saved;
>  
> -	schedule_delayed_work(&info->deferred_work, info->fbdefio->delay);
>  	schedule_delayed_work(&par->dwork, HVFB_UPDATE_DELAY);
>  
>  	/* 0 means do resume */
> -- 
> 2.25.1
> 
> 
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