powerpc/mm/book3s: Check for pmd_large instead of pmd_trans_huge

Update few code paths to check for pmd_large.

set_pmd_at:
We want to use this to store swap pte at pmd level. For swap ptes we don't want
to set H_PAGE_THP_HUGE. Hence check for pmd_large in set_pmd_at. This remove
the false WARN_ON when using this with swap pmd entry.

pmd_page:
We don't really use them on pmd migration entries. But they can also work with
migration entries and we don't differentiate at the pte level. Hence update
pmd_page to work with pmd migration entries too

__find_linux_pte:
lockless page table walk need to handle pmd migration entries. pmd_trans_huge
check will return false on them. We don't set thp = 1 for such entries, but
update hpage_shift correctly. Without this we will walk pmd migration entries
as a pte page pointer which is wrong.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/hugetlbpage.c

@@ -837,8 +837,12 @@ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
 				ret_pte = (pte_t *) pmdp;
 				goto out;
 			}
-
-			if (pmd_huge(pmd)) {
+			/*
+			 * pmd_large check below will handle the swap pmd pte
+			 * we need to do both the check because they are config
+			 * dependent.
+			 */
+			if (pmd_huge(pmd) || pmd_large(pmd)) {
 				ret_pte = (pte_t *) pmdp;
 				goto out;
 			} else if (is_hugepd(__hugepd(pmd_val(pmd))))

arch/powerpc/mm/pgtable-book3s64.c

@@ -75,7 +75,7 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
 	 */
 	WARN_ON(pte_val(pmd_pte(*pmdp)) & _PAGE_PRESENT);
 	assert_spin_locked(pmd_lockptr(mm, pmdp));
-	WARN_ON(!(pmd_trans_huge(pmd) || pmd_devmap(pmd)));
+	WARN_ON(!(pmd_large(pmd) || pmd_devmap(pmd)));
 #endif
 	trace_hugepage_set_pmd(addr, pmd_val(pmd));
 	return set_pte_at(mm, addr, pmdp_ptep(pmdp), pmd_pte(pmd));

arch/powerpc/mm/pgtable_64.c

@@ -306,7 +306,7 @@ struct page *pud_page(pud_t pud)
  */
 struct page *pmd_page(pmd_t pmd)
 {
-	if (pmd_trans_huge(pmd) || pmd_huge(pmd) || pmd_devmap(pmd))
+	if (pmd_large(pmd) || pmd_huge(pmd) || pmd_devmap(pmd))
 		return pte_page(pmd_pte(pmd));
 	return virt_to_page(pmd_page_vaddr(pmd));
 }