On 11/07/2013 07:33 PM, Douglas Gilbert wrote: > On 13-11-07 01:45 AM, Hannes Reinecke wrote: >> On 11/06/2013 06:23 PM, Mike Christie wrote: >>> On 11/05/2013 10:48 PM, Hannes Reinecke wrote: >>>> On 11/05/2013 08:19 PM, Mike Christie wrote: >>>>> On 11/04/2013 11:05 PM, Hannes Reinecke wrote: >>>>>> + >>>>>> + scmd->eh_eflags |= SCSI_EH_ABORT_SCHEDULED; >>>>>> + SCSI_LOG_ERROR_RECOVERY(3, >>>>>> + scmd_printk(KERN_INFO, scmd, >>>>>> + "scmd %p abort scheduled\n", scmd)); >>>>>> + schedule_delayed_work(&scmd->abort_work, HZ / 100); >>>>>> + return SUCCESS; >>>>>> +} >>>>> >>>>> Do we want to use our own workqueue_struct with WQ_MEM_RECLAIM >>>>> set? >>>>> >>>> Errm. Yes, why? >>>> >>>> I must admit I'm not _that_ familiar with workqueues ... >>>> Care to explain? >>>> >>> >>> We all share the above workqueue_structs pool of threads, so if >>> we get >>> stuck behind code doing GFP_KERNEL allocs that end up needing to >>> write >>> data to the disk we are now trying to aborts on, then we could get >>> stuck. With WQ_MEM_RECLAIM, we have our own backup thread that gets >>> created at workqueue_struct create time which can get used in >>> cases like >>> that so we can always make forward progress. >>> >> Ah. Right. Yes, that makes sense. >> >> I guess I'll have to redo the patches _yet again_. > > I wonder if it might be useful to flag a LU (disk) > with "try really hard to recover me, perhaps at the > expense of other LUs". Seems like a LU containing the > rootfs or swap might qualify for setting such a flag. > And LUs that have this flag cleared could be assumed > to not get wedged in the fashion that Mike pointed out. > While this would be a good idea in general, I would _very much_ see to have this patch accepted first. Without that proviso any discussion is pretty much moot anyway. So I would like to defer that until the patch has been accepted. Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg) -- 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
