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
