Re: Regression: x86/mm: new _PTE_SWP_SOFT_DIRTY bit conflicts with existing use

From: Andi Kleen
Date: Wed Aug 21 2013 - 19:43:16 EST


Cyrill Gorcunov <gorcunov@xxxxxxxxx> writes:
>
> Hi all, I worked on patch which would not touch PSE bit for dirty page
> tracking and the result is not that good:
>
> - 2level pages now always page dirty if page is swapped in and out, because
> there is no space left in PTE (other than PSE bit)

Maybe just don't support soft dirty for 2 level page tables?

2 level page tables should be really on the way out anyways, as they
have severe limits and do not support NX. With 3 levels there is enough
space.

-Andi

--
ak@xxxxxxxxxxxxxxx -- Speaking for myself only
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