From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Cathy Avery <cavery@redhat.com>
Cc: kys@microsoft.com, hch@infradead.org, haiyangz@microsoft.com,
jejb@linux.vnet.ibm.com, martin.petersen@oracle.com,
sthemmin@microsoft.com, dan.carpenter@oracle.com,
devel@linuxdriverproject.org, linux-kernel@vger.kernel.org,
linux-scsi@vger.kernel.org, longli@microsoft.com, tj@kernel.org
Subject: Re: [PATCH V3] scsi: storvsc: Allow only one remove lun work item to be issued per lun
Date: Fri, 03 Nov 2017 12:28:30 -0400 [thread overview]
Message-ID: <yq1y3nn5ntd.fsf@oracle.com> (raw)
In-Reply-To: <1509454326-11118-1-git-send-email-cavery@redhat.com> (Cathy Avery's message of "Tue, 31 Oct 2017 08:52:06 -0400")
Cathy,
> When running multipath on a VM if all available paths go down the
> driver can schedule large amounts of storvsc_remove_lun work items to
> the same lun. In response to the failing paths typically storvsc
> responds by taking host->scan_mutex and issuing a TUR per lun. If
> there has been heavy IO to the failed device all the failed IOs are
> returned from the host. A remove lun work item is issued per failed
> IO. If the outstanding TURs have not been completed in a timely manner
> the scan_mutex is never released or released too late. Consequently
> the many remove lun work items are not completed as scsi_remove_device
> also tries to take host->scan_mutex. This results in dragging the VM
> down and sometimes completely.
>
> This patch only allows one remove lun to be issued to a particular lun
> while it is an instantiated member of the scsi stack.
Applied to 4.15/scsi-queue.
Next time the change log needs to go after a "---" delimiter.
Thank you!
> Changes since v1:
> Use single threaded workqueue to serialize work in
> storvsc_handle_error [Christoph Hellwig]
>
> Changes since v2:
> Replaced create_singlethread_workqueue with
> alloc_ordered_workqueue [Christoph Hellwig]
>
> Added reviewed by's.
--
Martin K. Petersen Oracle Linux Engineering
prev parent reply other threads:[~2017-11-03 16:29 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-31 12:52 [PATCH V3] scsi: storvsc: Allow only one remove lun work item to be issued per lun Cathy Avery
2017-11-03 16:28 ` Martin K. Petersen [this message]
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