On Thu, 6 Nov 2008, Brian Kysela wrote: > On 2008-11-06 at 14:36 -0500, Alan Stern wrote: > > On Thu, 6 Nov 2008, Andrew Morton wrote: > > > > > > The error message: > > > > > > > > > [ 152.701070] usb-storage: Error in queuecommand: us->srb = ffff88007dfd0680 > > > > > > > > means that the SCSI layer has told usb-storage to start a new command > > > > before the old one completed. This could happen, for example, if the > > > > SCSI layer had gotten confused and tried to cancel a command that > > > > wasn't running -- then it would think usb-storage was idle when in fact > > > > it was still busy. (This was the failure mechanism resulting from the > > > > timeout changes.) > > > > > > > > > > OK, thanks. I'll cc linux-scsi, but I have this-wont-be-getting-fixed > > > feelings on this one :( > > > > > > I wonder what's special about Brian's setup. > > > > Brian, if you can use usbmon to monitor what happens during the file > > copy and subsequent error, it might provide a clue. Instructions are > > in the kernel source file Documentation/usb/usbmon.txt. > > Since it's a large file, I have posted the content of usbmon here: > > http://www.kysela.org/pub/1.mon.out > > I also got another kernel bug and system freeze on that copy, after the > copy process hung, when I pulled the drive out: This is exactly the failure mechanism I described earlier. The usbmon log shows that a communications error occurred and usb-storage tried to carry out error recovery. The drive apparently did not reset itself, because when the READ was reissued no data was received. In fact, the log _ends_ at the point where the READ was reissued; no more data was transferred in either direction. Presumably the next thing to occur was a command timeout. And since the block-layer timeout code in 2.6.28-rc2 is known to be buggy, it's not surprising that the copy process hung at that point. It would be better to run this test under 2.6.27; that way we might learn something new. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
