Messages in this thread | | | Date | Thu, 01 Jun 2006 02:26:46 +1000 | From | Nick Piggin <> | Subject | Re: [rfc][patch] remove racy sync_page? |
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Linus Torvalds wrote:
> And I suspect your objection to unplugging is not really about unplugging > itself. It's literally about the fact that we use the same page lock for > IO and for the ->mapping thing, isn't it?
Nearly, but not quite that far: it's that we sync_page in lock_page.
I don't think using the single lock for both is too bad (in many ways they are related eg. you don't want the page to be truncated while IO is in progress).
> > IOW, you don't actually dislike plugging itself, you dislike it due to the > effects of a totally unrelated locking issue, namely that we use the same > lock for two totally independent things. If the ->mapping thing were to > use a PG_map_lock that didn't affect plugging one way or the other, you > wouldn't have any issues with unplugging, would you? > > And I think _that_ is what really gets us to the problem.
No I don't dislike plugging at all ;) Just this tangle as you say.
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