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.
Doug Gilbert
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