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

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Date:	Mon, 9 Oct 2006 13:45:27 +0200
From:	Nick Piggin <npiggin@...e.de>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
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, Oct 09, 2006 at 09:32:59PM +1000, Benjamin Herrenschmidt wrote:
> > 
> > You'll want to clear VM_PFNMAP after unmapping all pages from it, before
> > switching to struct page backing.
> 
> Which means having a list of all vma's ... I suppose I can look at the
> truncate code to do that race free but I was hoping I could avoid it
> (that's the whole point of using unmap_mapping_range() in fact).

Yeah I don't think there is any other way to do it.

> > > 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?
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