[PATCH V3 1/6] powerpc/mm/book3s: Update pmd_present to look at _PAGE_PRESENT bit

[Aneesh Kumar K.V]

On 08/24/2018 11:30 AM, Aneesh Kumar K.V wrote:
> With this patch we use 0x8000000000000000UL (_PAGE_PRESENT) to indicate a valid
> pgd/pud/pmd entry. We also switch the p**_present() to look at this bit.
> 
> With pmd_present, we have a special case. We need to make sure we consider a
> pmd marked invalid during THP split as present. Right now we clear the
> _PAGE_PRESENT bit during a pmdp_invalidate. Inorder to consider this special
> case we add a new pte bit _PAGE_INVALID (mapped to _RPAGE_SW0). This bit is
> only used with _PAGE_PRESENT cleared. Hence we are not really losing a pte bit
> for this special case. pmd_present is also updated to look at _PAGE_INVALID.
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>

Changese from V2:
* Rebased to mpe/merge
* Also fixup new WARN_ON with pte_present looking at _PAGE_INVALID now.

-aneesh