From: Greg KH <gregkh@linuxfoundation.org>
To: Dexuan Cui <decui@microsoft.com>
Cc: kys@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org,
jejb@linux.ibm.com, martin.petersen@oracle.com,
haiyangz@microsoft.com, ming.lei@redhat.com, bvanassche@acm.org,
john.garry@huawei.com, linux-scsi@vger.kernel.org,
linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH] scsi: storvsc: Cap scsi_driver.can_queue to fix a hang issue during boot
Date: Wed, 6 Oct 2021 09:17:57 +0200 [thread overview]
Message-ID: <YV1NpdaVYJFHPml7@kroah.com> (raw)
In-Reply-To: <20211006070345.51713-1-decui@microsoft.com>
On Wed, Oct 06, 2021 at 12:03:45AM -0700, Dexuan Cui wrote:
> After commit ea2f0f77538c, a 416-CPU VM running on Hyper-V hangs during
> boot because scsi_add_host_with_dma() sets shost->cmd_per_lun to a
> negative number:
> 'max_outstanding_req_per_channel' is 352,
> 'max_sub_channels' is (416 - 1) / 4 = 103, so in storvsc_probe(),
> scsi_driver.can_queue = 352 * (103 + 1) * (100 - 10) / 100 = 32947, which
> is bigger than SHRT_MAX (i.e. 32767).
>
> Fix the hang issue by capping scsi_driver.can_queue.
>
> Add the below Fixed tag though ea2f0f77538c itself is good.
>
> Fixes: ea2f0f77538c ("scsi: core: Cap scsi_host cmd_per_lun at can_queue")
> Cc: stable@vger.kernel.org
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
> ---
> drivers/scsi/storvsc_drv.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
> index ebbbc1299c62..ba374908aec2 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -1976,6 +1976,16 @@ static int storvsc_probe(struct hv_device *device,
> (max_sub_channels + 1) *
> (100 - ring_avail_percent_lowater) / 100;
>
> + /*
> + * v5.14 (see commit ea2f0f77538c) implicitly requires that
No need to put a version number in a comment, they do not track well
when people backport changes all over the place in other kernel trees.
If you want to refer to a commit, please do so in the documented way.
For this case, that would be:
ea2f0f77538c ("scsi: core: Cap scsi_host cmd_per_lun at can_queue")
thanks,
greg k-h
next prev parent reply other threads:[~2021-10-06 7:18 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-06 7:03 [PATCH] scsi: storvsc: Cap scsi_driver.can_queue to fix a hang issue during boot Dexuan Cui
2021-10-06 7:17 ` Greg KH [this message]
2021-10-06 8:17 ` John Garry
2021-10-06 15:01 ` Michael Kelley
2021-10-06 16:03 ` John Garry
2021-10-06 16:08 ` Michael Kelley
2021-10-06 16:24 ` John Garry
2021-10-06 17:28 ` Dexuan Cui
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