mm: cleanup *pte_alloc* interfaces

There are few things about *pte_alloc*() helpers worth cleaning up:

 - 'vma' argument is unused, let's drop it;

 - most __pte_alloc() callers do speculative check for pmd_none(),
   before taking ptl: let's introduce pte_alloc() macro which does
   the check.

   The only direct user of __pte_alloc left is userfaultfd, which has
   different expectation about atomicity wrt pmd.

 - pte_alloc_map() and pte_alloc_map_lock() are redefined using
   pte_alloc().

[sudeep.holla@arm.com: fix build for arm64 hugetlbpage]
[sfr@canb.auug.org.au: fix arch/arm/mm/mmu.c some more]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memory.c b/mm/memory.c
index 0e24764..1974fc0 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -562,8 +562,7 @@
 	}
 }
 
-int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
-		pmd_t *pmd, unsigned long address)
+int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
 {
 	spinlock_t *ptl;
 	pgtable_t new = pte_alloc_one(mm, address);
@@ -3419,12 +3418,11 @@
 	}
 
 	/*
-	 * Use __pte_alloc instead of pte_alloc_map, because we can't
+	 * Use pte_alloc() instead of pte_alloc_map, because we can't
 	 * run pte_offset_map on the pmd, if an huge pmd could
 	 * materialize from under us from a different thread.
 	 */
-	if (unlikely(pmd_none(*pmd)) &&
-	    unlikely(__pte_alloc(mm, vma, pmd, address)))
+	if (unlikely(pte_alloc(mm, pmd, address)))
 		return VM_FAULT_OOM;
 	/*
 	 * If a huge pmd materialized under us just retry later.  Use
diff --git a/mm/mremap.c b/mm/mremap.c
index e30c8a6..3fa0a467 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -213,8 +213,7 @@
 				continue;
 			VM_BUG_ON(pmd_trans_huge(*old_pmd));
 		}
-		if (pmd_none(*new_pmd) && __pte_alloc(new_vma->vm_mm, new_vma,
-						      new_pmd, new_addr))
+		if (pte_alloc(new_vma->vm_mm, new_pmd, new_addr))
 			break;
 		next = (new_addr + PMD_SIZE) & PMD_MASK;
 		if (extent > next - new_addr)
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 806b0c7..9f3a029 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -230,8 +230,7 @@
 			break;
 		}
 		if (unlikely(pmd_none(dst_pmdval)) &&
-		    unlikely(__pte_alloc(dst_mm, dst_vma, dst_pmd,
-					 dst_addr))) {
+		    unlikely(__pte_alloc(dst_mm, dst_pmd, dst_addr))) {
 			err = -ENOMEM;
 			break;
 		}