On 09/17/2014 03:53 PM, Elliott, Robert (Server Storage) wrote: > > >> -----Original Message----- >> From: Christoph Hellwig [mailto:hch@xxxxxx] >> Sent: Saturday, 13 September, 2014 6:40 PM >> To: Jens Axboe >> Cc: Elliott, Robert (Server Storage); linux-scsi@xxxxxxxxxxxxxxx; linux- >> kernel@xxxxxxxxxxxxxxx >> Subject: blk-mq timeout handling fixes >> >> This series fixes various issues with timeout handling that Robert >> ran into when testing scsi-mq heavily. He tested an earlier version, >> and couldn't reproduce the issues anymore, although the series changed >> quite significantly since and should probably be retested. >> >> In summary we not only start the blk-mq timer inside the drivers >> ->queue_rq method after the request has been fully setup, and we >> also tell the drivers if we're timing out a reserved (internal) >> request or a real one. Many drivers including will need to handle >> those internal ones differently, e.g. for scsi-mq we don't even >> have a scsi command structure allocated for the reserved commands. > > I have rerun a variety of tests on: > * Jens' for-next tree that went into 3.17rc5 > * plus this series > * plus two patches for infinite recursion on flushes from > Ming and then Christoph This is pretty much what is queued up for 3.17 as well. It's bigger than I'd like at this point, but these are real fixes. > and have not been able to trigger the scsi_times_out req->special > NULL pointer dereference that prompted this series. Great!! > Testing includes: > * concurrent heavy workload generators: > * fio high iodepth direct 512 byte random reads (> 1M IOPS) > * programs generating large bursts of paged writes > * mkfs.ext4 (followed by e2fsck) > * mkfs.xfs (followed by xfs_check) > * ddpt > * watch -n 0 sync to generate flushes > * scsi_logging_level MLCOMPLETE set to 0 or 1 > * scsi_lib.c patched to put all the ACTION_FAIL messages > under level 1 so they can be squelched (massive error > prints cause more timeouts themselves) > * 4 hpsa and 16 mpt3sas devices (all made from SAS SSDs) > * lockless hpsa driver > * injecting errors > * device removal > * device generating infinite errors > * device generating a brief number of errors > > The filesystems don't always recover properly, but nothing in > the block or scsi midlayers crashed. > > So, you may add this to the series: > Tested-by: Robert Elliott <elliott@xxxxxx> Thanks a lot for your (continued) testing, Robert. It's a great help. -- Jens Axboe -- 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
