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From: Daniel Phillips <phillips@bonn-fries.net>
To: Linus Torvalds <torvalds@transmeta.com>,
        Rik van Riel <riel@conectiva.com.br>
Subject: Re: [RFC] Page table sharing
Date: Tue, 19 Feb 2002 03:22:21 +0100
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On February 19, 2002 03:05 am, Linus Torvalds wrote:
> On Mon, 18 Feb 2002, Rik van Riel wrote:
> >
> > The swapout code can remove a page from the page table
> > while another process is in the process of unsharing
> > the page table.
> 
> Ok, I'll buy that. However, looking at that, the locking is not the real
> issue at all:
> 
> When the swapper does a "ptep_get_and_clear()" on a shared pmd, it will
> end up having to not just synchronize with anybody doing unsharing, it
> will have to flush all the TLB's on all the mm's that might be implicated.
> 
> Which implies that the swapper needs to look up all mm's some way anyway,

Ick.  With rmap this is straightforward, but without, what?  flush_tlb_all?
Maybe page tables should be unshared on swapin/out after all, only on arches
that need special tlb treatment, or until we have rmap.

> so the locking gets solved that way.

-- 
Daniel
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