Hi Jens, upon further testing with your blk-mq-sched branch I hit a queue stall during requeing: [ 202.340959] sd 3:0:4:1: tag#473 Send: scmd 0xffff880422e7a440 [ 202.340962] sd 3:0:4:1: tag#473 CDB: Test Unit Ready 00 00 00 00 00 00 [ 202.341161] sd 3:0:4:1: tag#473 Done: ADD_TO_MLQUEUE Result: hostbyte=DID_OK driverbyte=DRIVER_OK [ 202.341164] sd 3:0:4:1: tag#473 CDB: Test Unit Ready 00 00 00 00 00 00 [ 202.341167] sd 3:0:4:1: tag#473 Sense Key : Unit Attention [current] [ 202.341171] sd 3:0:4:1: tag#473 Add. Sense: Power on, reset, or bus device reset occurred [ 202.341173] sd 3:0:4:1: tag#473 scsi host busy 1 failed 0 [ 202.341176] sd 3:0:4:1: tag#473 Inserting command ffff880422e7a440 into mlqueue ... and that is the last ever heard of that device. The 'device_busy' count remains at '1' and no further commands will be sent to the device. Debugging continues. Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@xxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
