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

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 <redacted>

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

-aneesh