Re: [PATCH 2/2] Fix console handling during suspend/resume

Nigel Cunningham
2006-06-16T02:50:01Z

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Hi.

On Friday 16 June 2006 12:28, Linus Torvalds wrote:
> On Fri, 16 Jun 2006, Benjamin Herrenschmidt wrote:
> > You can't save a consistent system image if your drivers aren't all
> > stopped and DMA is stopped.
>
> Read the whole thread to an end.
>
> You don't _need_ to save a consistent system image. There's no "single
> snapshot in time" needed.

Yes, you do. If you save an image that has, say, pages in the lru that are
also in the free lists or a similar situation with driver data, you're going
to get an oops some time after resume at best, and possibly ruin your
filesystem at worst.

That said, consistency doesn't need to equal atomicity. As I'm sure you know,
what we're after is something that's effectively atomic, which is why I've
happily saved the lru separate to the atomically copied pages for the last 4
or so years. It works because I can be sure nothing's going to change the lru
contents, so the image is effectively atomic.

Regards,

Nigel
--
Nigel, Michelle and Alisdair Cunningham
5 Mitchell Street
Cobden 3266
Victoria, Australia

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