mm: properly frame Xen additions with CONFIG_XEN conditionals

There's no need and no good reason to affect native kernels built from
the same sources.

Also eliminate a compiler warning triggered by various versions, and
adjust some white space.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -209,14 +209,15 @@ struct vm_operations_struct {
 	/* notification that a previously read-only page is about to become
 	 * writable, if an error is returned it will cause a SIGBUS */
 	int (*page_mkwrite)(struct vm_area_struct *vma, struct page *page);
+#ifdef CONFIG_XEN
 	/* Area-specific function for clearing the PTE at @ptep. Returns the
 	 * original value of @ptep. */
-	pte_t (*zap_pte)(struct vm_area_struct *vma, 
+	pte_t (*zap_pte)(struct vm_area_struct *vma,
 			 unsigned long addr, pte_t *ptep, int is_fullmm);
 
-        /* called before close() to indicate no more pages should be mapped */
-        void (*unmap)(struct vm_area_struct *area);
-
+	/* called before close() to indicate no more pages should be mapped */
+	void (*unmap)(struct vm_area_struct *area);
+#endif
 #ifdef CONFIG_NUMA
 	int (*set_policy)(struct vm_area_struct *vma, struct mempolicy *new);
 	struct mempolicy *(*get_policy)(struct vm_area_struct *vma,
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -409,7 +409,9 @@ struct page *vm_normal_page(struct vm_ar
 	 * and that the resulting page looks ok.
 	 */
 	if (unlikely(!pfn_valid(pfn))) {
+#ifdef CONFIG_XEN
 		if (!(vma->vm_flags & VM_RESERVED))
+#endif
 			print_bad_pte(vma, pte, addr);
 		return NULL;
 	}
@@ -665,10 +667,12 @@ static unsigned long zap_pte_range(struc
 				     page->index > details->last_index))
 					continue;
 			}
+#ifdef CONFIG_XEN
 			if (unlikely(vma->vm_ops && vma->vm_ops->zap_pte))
 				ptent = vma->vm_ops->zap_pte(vma, addr, pte,
 							     tlb->fullmm);
 			else
+#endif
 				ptent = ptep_get_and_clear_full(mm, addr, pte,
 								tlb->fullmm);
 			tlb_remove_tlb_entry(tlb, pte, addr);
@@ -1425,7 +1429,7 @@ static inline int apply_to_pte_range(str
 	spinlock_t *ptl;
 
 	pte = (mm == &init_mm) ?
-		pte_alloc_kernel(pmd, addr) :
+		ptl = NULL, pte_alloc_kernel(pmd, addr) :
 		pte_alloc_map_lock(mm, pmd, addr, &ptl);
 	if (!pte)
 		return -ENOMEM;
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1689,8 +1689,10 @@ static void unmap_region(struct mm_struc
 
 static inline void unmap_vma(struct vm_area_struct *vma)
 {
+#ifdef CONFIG_XEN
 	if (unlikely(vma->vm_ops && vma->vm_ops->unmap))
 		vma->vm_ops->unmap(vma);
+#endif
 }
 
 /*
@@ -1966,7 +1968,7 @@ EXPORT_SYMBOL(do_brk);
 void exit_mmap(struct mm_struct *mm)
 {
 	struct mmu_gather *tlb;
-	struct vm_area_struct *vma_tmp, *vma = mm->mmap;
+	struct vm_area_struct *vma = mm->mmap;
 	unsigned long nr_accounted = 0;
 	unsigned long end;
 
@@ -1974,8 +1976,11 @@ void exit_mmap(struct mm_struct *mm)
 	arch_exit_mmap(mm);
 #endif
 
-	for (vma_tmp = mm->mmap; vma_tmp; vma_tmp = vma_tmp->vm_next)
-		unmap_vma(vma_tmp);
+#ifdef CONFIG_XEN
+	for (; vma; vma = vma->vm_next)
+		unmap_vma(vma);
+	vma = mm->mmap;
+#endif
 
 	lru_add_drain();
 	flush_cache_mm(mm);