Messages in this thread | | | Subject | Re: [PATCH 05/12] mm: trylock_page | From | Peter Zijlstra <> | Date | Sat, 29 Sep 2007 17:01:34 +0200 |
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On Fri, 2007-09-28 at 13:11 +1000, Nick Piggin wrote: > On Friday 28 September 2007 17:42, Peter Zijlstra wrote: > > Replace raw TestSetPageLocked() usage with trylock_page() > > I have such a thing queued too, for the lock bitops patches for when 2.6.24 > opens, Andrew promises me :). > > I guess they should be identical, except I don't like doing trylock_page in > place of SetPageLocked, for memory ordering performance and aesthetic > reasons... I've got an init_page_locked (or set_page_locked... I can't > remember, the patch is at home).
Sure, that might work, or we could just make it so that add_to_*_cache is never passed an unlocked page. But sure...
> Fine idea to lockdep the page lock, anyway. Does it show up any of the > buffered write deadlock possibilities? :)
Not yet, it might just be that the concessions done to annotate this type of lock were too severe.
What I basically did was treat all the page locks as a single recursive lock.
> buffer lock is another notable bit-mutex that might be converted (I have > the patch to do the similar nice !tas->trylock conversion for that too). I > think it is used widely enough by tricky code that it would be useful to > annotate as well.
Not at all familiar with that lock, but yeah, we could have a look at doing that too.
> Unfortunately we can't convert bit_spinlock.h easily, I guess?
Yeah, the space constraints make that rather hard. Each of these locks needs some form of external meta-data.
For the page lock I used one lock instance per file system type.
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