Re: [PATCH V2 01/29] powerpc/mm: add _PAGE_HASHPTE similar to 4K hash

Paul Mackerras [off-list ref] writes:

On Mon, Feb 08, 2016 at 02:50:13PM +0530, Aneesh Kumar K.V wrote:

quoted

Not really needed. But this brings it back to as it was before

If it's not really needed, what's the motivation for putting this
patch in?  You need to explain where you are heading with this patch.

I explained this in the last review.

What confused me in the beginning was difference between 4k and 64k
page size. I was trying to find out whether we miss a hpte flush in any
scenario because of this. ie, a pte update on a linux pte, for which we
are doing a parallel hash pte insert. After looking at it closer my
understanding is this won't happen because pte update also look at
_PAGE_BUSY and we will wait for hash pte insert to finish before going
ahead with the pte update. But to avoid further confusion I was wondering
whether we should keep this closer to what we have with __hash_page_4k.
Hence the statement "Not really needed".

I will add more information in the commit message.

quoted

Check this
41743a4e34f0777f51c1cf0675b91508ba143050

The SHA1 is useful, but you need to be more explicit - something like

"This partially reverts commit 41743a4e34f0 ("powerpc: Free a PTE bit
on ppc64 with 64K pages", 2008-06-11)."

ok

-aneesh