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From:   "Rafael J. Wysocki" <rjw@rjwysocki.net>
To:     decui@microsoft.com
Cc:     linux-pm@vger.kernel.org, len.brown@intel.com, pavel@ucw.cz,
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Subject: Re: [PATCH] PM: hibernate: Freeze kernel threads in software_resume()
Date:   Sun, 26 Apr 2020 18:24:14 +0200
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On Friday, April 24, 2020 5:40:16 AM CEST Dexuan Cui wrote:
> Currently the kernel threads are not frozen in software_resume(), so
> between dpm_suspend_start(PMSG_QUIESCE) and resume_target_kernel(),
> system_freezable_power_efficient_wq can still try to submit SCSI
> commands and this can cause a panic since the low level SCSI driver
> (e.g. hv_storvsc) has quiesced the SCSI adapter and can not accept
> any SCSI commands: https://lkml.org/lkml/2020/4/10/47
> 
> At first I posted a fix (https://lkml.org/lkml/2020/4/21/1318) trying
> to resolve the issue from hv_storvsc, but with the help of
> Bart Van Assche, I realized it's better to fix software_resume(),
> since this looks like a generic issue, not only pertaining to SCSI.
> 
> Cc: Bart Van Assche <bvanassche@acm.org>
> Cc: stable@vger.kernel.org
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
> ---
>  kernel/power/hibernate.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index 86aba8706b16..30bd28d1d418 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -898,6 +898,13 @@ static int software_resume(void)
>  	error = freeze_processes();
>  	if (error)
>  		goto Close_Finish;
> +
> +	error = freeze_kernel_threads();
> +	if (error) {
> +		thaw_processes();
> +		goto Close_Finish;
> +	}
> +
>  	error = load_image_and_restore();
>  	thaw_processes();
>   Finish:
> 

Applied as a fix for 5.7-rc4, thanks!