linux-kernel - RE: [PATCH] scsi: storvsc: Ratelimit warning logs to prevent VM denial of service

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Message-ID:
 <SN6PR02MB41576E90A65C9ADA0FA14BCCD4122@SN6PR02MB4157.namprd02.prod.outlook.com>
Date: Wed, 8 Jan 2025 05:32:18 +0000
From: Michael Kelley <mhklinux@...look.com>
To: Easwar Hariharan <eahariha@...ux.microsoft.com>, "K. Y. Srinivasan"
	<kys@...rosoft.com>, Haiyang Zhang <haiyangz@...rosoft.com>, Wei Liu
	<wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>, Long Li
	<longli@...ux.microsoft.com>, Long Li <longli@...rosoft.com>, "James E.J.
 Bottomley" <James.Bottomley@...senPartnership.com>, "Martin K. Petersen"
	<martin.petersen@...cle.com>
CC: Mitchell Levy <levymitchell0@...il.com>, Mitchell Levy
	<mitchelllevy@...ux.microsoft.com>, "linux-hyperv@...r.kernel.org"
	<linux-hyperv@...r.kernel.org>, "linux-scsi@...r.kernel.org"
	<linux-scsi@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, Vijay Balakrishna
	<vijayb@...ux.microsoft.com>
Subject: RE: [PATCH] scsi: storvsc: Ratelimit warning logs to prevent VM
 denial of service


From: Easwar Hariharan <eahariha@...ux.microsoft.com> Sent: Tuesday, January 7, 2025 9:29 AM
> 
> If there's a persistent error in the hypervisor, the scsi warning for
> failed IO can flood the kernel log and max out CPU utilization,
> preventing troubleshooting from the VM side. Ratelimit the warning so
> it doesn't DOS the VM.
> 
> Closes:
> https://github.com/microsoft/WSL/issues/9173
> Signed-off-by: Easwar Hariharan <eahariha@...ux.microsoft.com>
> ---
> If there's a persistent error in the hypervisor, the scsi warning for
> failed IO can overwhelm the kernel log and max out CPU utilization,
> preventing troubleshooting. Ratelimit the warning so it doesn't DOS the
> VM.
> 
> This is not super critical and can be deferred to an 6.14 rc since it
> mostly occurs when there's a problem with the host disk or filesystem.
> ---
>  drivers/scsi/storvsc_drv.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
> index
> 45665d4aca925a10ce4293edf40cebdc4d4997f2..5a101ac06c478aad9b01072e7a6c
> 5af48219f5c8 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -171,6 +171,12 @@ do {
> 	\
>  		dev_warn(&(dev)->device, fmt, ##__VA_ARGS__);	\
>  } while (0)
> 
> +#define storvsc_log_ratelimited(dev, level, fmt, ...)				\
> +do {										\
> +	if (do_logging(level))							\
> +		dev_warn_ratelimited(&(dev)->device, fmt, ##__VA_ARGS__);	\
> +} while (0)
> +
>  struct vmscsi_request {
>  	u16 length;
>  	u8 srb_status;
> @@ -1176,7 +1182,7 @@ static void storvsc_on_io_completion(struct storvsc_device *stor_device,
>  		int loglevel = (stor_pkt->vm_srb.cdb[0] == TEST_UNIT_READY) ?
>  			STORVSC_LOGGING_WARN : STORVSC_LOGGING_ERROR;
> 
> -		storvsc_log(device, loglevel,
> +		storvsc_log_ratelimited(device, loglevel,
>  			"tag#%d cmd 0x%x status: scsi 0x%x srb 0x%x hv 0x%x\n",
>  			scsi_cmd_to_rq(request->cmd)->tag,
>  			stor_pkt->vm_srb.cdb[0],
> 
> ---
> base-commit: 4e16367cfe0ce395f29d0482b78970cce8e1db73
> change-id: 20241023-eahariha-ratelimit-storvsc-b3fe53f02a58
> 
> Best regards,
> --
> Easwar Hariharan <eahariha@...ux.microsoft.com>
> 

Reviewed-by: Michael Kelley <mhklinux@...look.com>