Re: [PATCH] mm: Save soft-dirty bits on swapped pages

[Cyrill Gorcunov]

On Wed, Jul 24, 2013 at 11:21:46AM -0700, Andy Lutomirski wrote:
> >
> > I fear for tracking soft-dirty-bit for swapped entries we sinply have
> > no other place than pte (still i'm quite open for ideas, maybe there
> > are a better way which I've missed).
> 
> I know approximately nothing about how swap and anon_vma work.
> 
> For files, sticking it in struct page seems potentially nicer,
> although finding a free bit might be tough.  (FWIW, I have plans to
> free up a page flag on x86 some time moderately soon as part of a
> completely unrelated project.)  I think this stuff really belongs to
> the address_space more than it belongs to the pte.

Well, some part of information already lays in pte (such as 'file' bit,
swap entries) so it looks natural i think to work on this level. but
letme think if use page struct for that be more convenient...

> 
> How do you handle the write syscall?

I fear I somehow miss your point here, could please alaborate a bit?
There is no additional code I know of being write() specific, just
a code for #PF exceptions.
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