> From: John Garry <john.garry@xxxxxxxxxx> > Sent: Thursday, October 7, 2021 2:42 PM > > On 07/10/2021 18:49, 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 (the below numbers may differ in different kernel versions): > > in drivers/scsi/storvsc_drv.c, storvsc_drv_init() sets > > 'max_outstanding_req_per_channel' to 352, and storvsc_probe() sets > > 'max_sub_channels' to (416 - 1) / 4 = 103 and sets scsi_driver.can_queue to > > 352 * (103 + 1) * (100 - 10) / 100 = 32947, which exceeds SHRT_MAX. > > I think that you just need to mention that if can_queue exceeds > SHRT_MAX, then there is a data truncation issue. I just hoped the explanation how the too big 'can_queue' value is generated is helpful. OK, I think I can change the commit log to: After commit ea2f0f77538c, a 416-CPU VM running on Hyper-V hangs during boot because the hv_storvsc driver sets scsi_driver.can_queue to an "int" value that exceeds SHRT_MAX, and hence scsi_add_host_with_dma() sets shost->cmd_per_lun to a negative "short" number. Use min_t(int, ...) to fix the issue. > It looks ok, I'd just like to test it a bit more. > > Thanks, > John Thanks! I'll post v3 with the above commit log, and I look forward to your review/test. > > v2 directly fixes the scsi core change instead as Michael Kelley and > > John Garry suggested (refer to the above link). > > To be fair, it was Michael's suggestion Yeah. Michael always gives good suggstions when reviewing patches. :-)
