linux-kernel - Re: [PATCH][v2] Drivers: hv: Change flag to write log level in panic msg to false

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Date:   Mon, 29 Jun 2020 10:32:23 +0000
From:   Wei Liu <wei.liu@...nel.org>
To:     Joseph Salisbury <joseph.salisbury@...rosoft.com>
Cc:     kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
        sashal@...nel.org, wei.liu@...nel.org, mikelley@...rosoft.com,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH][v2] Drivers: hv: Change flag to write log level in panic
 msg to false

On Fri, Jun 26, 2020 at 03:28:17PM -0700, Joseph Salisbury wrote:
> When the kernel panics, one page of kmsg data may be collected and sent to
> Hyper-V to aid in diagnosing the failure.  The collected kmsg data typically
>  contains 50 to 100 lines, each of which has a log level prefix that isn't
> very useful from a diagnostic standpoint.  So tell kmsg_dump_get_buffer()
> to not include the log level, enabling more information that *is* useful to
> fit in the page.
> 
> Requesting in stable kernels, since many kernels running in production are
> stable releases.
> 
> Cc: stable@...r.kernel.org
> Signed-off-by: Joseph Salisbury <joseph.salisbury@...rosoft.com>

Applied to hyperv-fixes with Michael's review from v1. Thanks.

> ---
>  drivers/hv/vmbus_drv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 9147ee9d5f7d..d69f4efa3719 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -1368,7 +1368,7 @@ static void hv_kmsg_dump(struct kmsg_dumper *dumper,
>  	 * Write dump contents to the page. No need to synchronize; panic should
>  	 * be single-threaded.
>  	 */
> -	kmsg_dump_get_buffer(dumper, true, hv_panic_page, HV_HYP_PAGE_SIZE,
> +	kmsg_dump_get_buffer(dumper, false, hv_panic_page, HV_HYP_PAGE_SIZE,
>  			     &bytes_written);
>  	if (bytes_written)
>  		hyperv_report_panic_msg(panic_pa, bytes_written);
> -- 
> 2.17.1
>