Re: [PATCH -next] PM: hibernate: add retry mechanism for S4 image loading failures

[Pavel Machek <pavel@ucw.cz>]

> During the S4 resume process, there's a rare chance of image loading
> failure. We provide three retries to load it successfully. If the
> recovery fails after these attempts, print out the handle CRC32
> value. When the CRC32 value obtained on each retry are inconsistent,
> there may be a memory anomaly. When the values are consistent, it
> might indicate corrupted swapped memory data.
> 
> Signed-off-by: Xueqin Luo <luoxueqin@kylinos.cn>

NAK. If machine is so broken it can't load memory image, it is not
safe to  continue.

								Pavel
> ---
>  kernel/power/hibernate.c |  8 ++++++++
>  kernel/power/swap.c      | 14 ++++++++------
>  2 files changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index 43b1a82e800c..d9bcf38221ef 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -703,6 +703,7 @@ static int load_image_and_restore(void)
>  {
>  	int error;
>  	unsigned int flags;
> +	int cnt = 0;
>  
>  	pm_pr_dbg("Loading hibernation image.\n");
>  
> @@ -713,7 +714,14 @@ static int load_image_and_restore(void)
>  		goto Unlock;
>  	}
>  
> +retry:
>  	error = swsusp_read(&flags);
> +	if (error && (cnt++ < 3)) {
> +		pr_err("Failed to load hibernation image, trying to load again...\n");
> +		swsusp_free();
> +		goto retry;
> +	}
> +
>  	swsusp_close();
>  	if (!error)
>  		error = hibernation_restore(flags & SF_PLATFORM_MODE);
> diff --git a/kernel/power/swap.c b/kernel/power/swap.c
> index 5bc04bfe2db1..4b866c645cd7 100644
> --- a/kernel/power/swap.c
> +++ b/kernel/power/swap.c
> @@ -1489,15 +1489,17 @@ static int load_compressed_image(struct swap_map_handle *handle,
>  		ret = snapshot_write_finalize(snapshot);
>  		if (!ret && !snapshot_image_loaded(snapshot))
>  			ret = -ENODATA;
> -		if (!ret) {
> -			if (swsusp_header->flags & SF_CRC32_MODE) {
> -				if(handle->crc32 != swsusp_header->crc32) {
> -					pr_err("Invalid image CRC32!\n");
> -					ret = -ENODATA;
> -				}
> +	}
> +	if (!ret) {
> +		if (swsusp_header->flags & SF_CRC32_MODE) {
> +			if (handle->crc32 != swsusp_header->crc32) {
> +				pr_err("Invalid image CRC32, swsusp header CRC32: %u, handle CRC32: %u\n",
> +					 swsusp_header->crc32, handle->crc32);
> +				ret = -ENODATA;
>  			}
>  		}
>  	}
> +
>  	swsusp_show_speed(start, stop, nr_to_read, "Read");
>  out_clean:
>  	hib_finish_batch(&hb);
> 2.25.1