On Fri 11-03-16 12:56:10, Tejun Heo wrote: > Hello, Jan. > > On Thu, Mar 03, 2016 at 10:33:10AM +0100, Jan Kara wrote: > > > Ugh... that's nasty. I wonder whether the right thing to do is making > > > writeback workers non-freezable. IOs are supposed to be blocked from > > > lower layer anyway. Jan, what do you think? > > > > Well no, at least currently IO is not blocked in lower layers AFAIK - for > > that you'd need to freeze block devices & filesystems and there are issues > > At least libata does and I think SCSI does too, but yeah, there > probably are drivers which depend on block layer blocking IOs, which > btw is a pretty fragile way to go about as upper layers might not be > the only source of activities. > > > with that (Jiri Kosina was the last one which was trying to make this work > > AFAIR). And I think you need to stop writeback (and generally any IO) to be > > generated so that it doesn't interact in a strange way with device drivers > > being frozen. So IMO until suspend freezes filesystems & devices properly > > you have to freeze writeback workqueue. > > I still think the right thing to do is plugging that block layer or > low level drivers. It's like we're trying to plug multiple sources > when we can plug the point where they come together anyway. I agree that freezing writeback workers is a workaround for real issues at best and ideally we shouldn't have to do that. But at least for now I had the impression that it is needed for suspend to work reasonably reliably. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
