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Subject: Re: [PATCH/RFC] Rework ptep_set_access_flags and fix sun4c
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Hugh Dickins <hugh@veritas.com>
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Date: Wed, 23 May 2007 14:21:45 +1000
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On Wed, 2007-05-23 at 05:03 +0100, Hugh Dickins wrote:
> 
> No, I wasn't meaning the optimization, but the significance of the
> boolean __changed that's returned.  If ptep_set_access_flags does
> not change the pte (because !dirty or !safely_writable or whatever
> that arch calls it), then ideally it ought to return false.

Hrm... I prefer keeping the existing semantics. The old code used to
always update_mmu_cache() on those archs and I'd rather let it continue
do so unless the arch maintainer who knows better changes it :-)
 
> But it doesn't affect correctness if it sometimes says true not
> false, and these arches happen to have an empty update_mmu_cache
> (with lazy_mmu_prot_update currently under separate review), and
> what you have follows what was already being done, and sun4c
> already has to "lie": so it's rather theoretical. 

Ok.

Cheers,
Ben.