Re: [PATCH 0/7] V3 of the async function call patches

From: Pavel Machek
Date: Fri Jan 16 2009 - 14:15:11 EST



> > My dmesg shows:
> >
> > [ 2.264955] sd 5:0:0:0: [sdb] Write cache: enabled, read cache:
> > enabled, doesn't support DPO or FUA [ 2.264958] sdb:<6>Freeing
> > unused kernel memory: 408k freed
> >
> > Ouch. How come that "Freeing unused kernel memory" got done in the
> > middle of the sdb partition thing?
> >
> > There's a async_synchronize_full() there before the free_initmem(),
> > but I'm worrying that it just isn't working. Hmm? What am I missing?
> >
>
> ok this part looks funny but it's not really (and it's safe I think).
>
> The async sata thing launches another async thing (the scsi partition
> scan).
> The synchronize_full() waits for the sata to complete, but doesn't wait
> for things that the sata async schedules after the wait started.
>
> is this a problem? not right now, but it means we have a rule that if
> an async item schedules another async item, the second one cannot be
> __init. (which is ok right now.. scsi already had some of this async
> anyway).
>
> I could make the async_full() be more strict if that makes you feel
> better, but for this specific purpose it would be over-synchronizing.

Really? If you run userspace before partitions are ready, its attempts
to read partitions will result in problems, right?

--
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