[v6 08/15] mm: zero struct pages during initialization

[Pasha Tatashin]

> I believe this deserves much more detailed explanation why this is safe.
> What actually prevents any pfn walker from seeing an uninitialized
> struct page? Please make your assumptions explicit in the commit log so
> that we can check them independently.

There is nothing prevents pfn walkers from walk over any struct pages 
deferred and non-deferred. However, during boot before deferred pages 
are initialized we have just a few places that do that, and all of those 
cases are fixed in this patchset.

> Also this is done with some purpose which is the perfmance, right? You
> have mentioned that in the cover letter but if somebody is going to read
> through git logs this wouldn't be obvious from the specific commit.
> So add that information here as well. Especially numbers will be
> interesting.

I will add more performance data to this patch comment.