linux-kernel - Re: [patch 3/3] mm: fault handler to replace nopage and populate

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Date:	Mon, 09 Oct 2006 22:11:16 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Nick Piggin <npiggin@...e.de>
Cc:	Andrew Morton <akpm@...l.org>,
	Linux Memory Management <linux-mm@...ck.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [patch 3/3] mm: fault handler to replace nopage and populate

On Mon, 2006-10-09 at 14:09 +0200, Nick Piggin wrote:
> On Mon, Oct 09, 2006 at 01:58:36PM +0200, Nick Piggin wrote:
> > > > > > > It also needs update_mmu_cache() I suppose.
> > > > > > 
> > > > > > Hmm, but it might not be called from a pagefault. Can we get away
> > > > > > with not calling it? Or is it required by some architectures?
> > > > > 
> > > > > I think some architectures might be upset if it's not called...
> > > > 
> > > > But would any get upset if it is called from !pagefault path?
> > > 
> > > Probably not... the PTE has been filled so it should be safe, but then,
> > > I don't know the details of what non-ppc archs do with that callback.
> 
> I guess we can make the rule that it only be called from the ->fault
> handler anyway. If they want that functionality from ->mmap, then they
> can use remap_pfn_range, because it isn't so performance critical.

Yup. The whole point of the discussion is for cases where we can't just
setup a static mapping at mmap time.

Ben.


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