Re: [rfc][patch] remove racy sync_page?

Nick Piggin
2006-06-02T02:21:43Z

Linus Torvalds wrote:
>
> On Thu, 1 Jun 2006, Nick Piggin wrote:
>
>>I keep telling you. Put the unplug after submission of IO. Not before
>>waiting for IO.
>
>
> And that's exactly where we have the lock_page().

In some cases.

>
> And you ignored the list of _requirements_ I had, so you just missed the
> other place you _have_ to have the unplug, namely in the "found a page
> that was not yet up-to-date" case (look for the other lock_page()).

I know you have to unplug there. I didn't ignore anything. Where is
the problem?

> Because the person who started the IO might be off doing something else,
> and may not be unplugging now (or ever, in the case of readahead).
>
> In other words, when you start arguing, at least read my emails. Your
> suggestion would have introduced a bug by not waiting on that other place.

No. I'm saying the "person" who started IO _could_ be the one unplugging.
Always.

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SUSE Labs, Novell Inc.
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