mm/madvise: reduce code duplication in error handling paths

madvise_behavior() converts -ENOMEM to -EAGAIN in several places using
identical code.

Move that code to a common error handling path.

No functional changes.

Link: http://lkml.kernel.org/r/1564640896-1210-1-git-send-email-rppt@linux.ibm.comSigned-off-by: NMike Rapoport <rppt@linux.ibm.com>
Acked-by: NPankaj Gupta <pagupta@redhat.com>
Reviewed-by: NAnshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/madvise.c

@@ -107,28 +107,14 @@ static long madvise_behavior(struct vm_area_struct *vma,
 	case MADV_MERGEABLE:
 	case MADV_UNMERGEABLE:
 		error = ksm_madvise(vma, start, end, behavior, &new_flags);
-		if (error) {
-			/*
-			 * madvise() returns EAGAIN if kernel resources, such as
-			 * slab, are temporarily unavailable.
-			 */
-			if (error == -ENOMEM)
-				error = -EAGAIN;
-			goto out;
-		}
+		if (error)
+			goto out_convert_errno;
 		break;
 	case MADV_HUGEPAGE:
 	case MADV_NOHUGEPAGE:
 		error = hugepage_madvise(vma, &new_flags, behavior);
-		if (error) {
-			/*
-			 * madvise() returns EAGAIN if kernel resources, such as
-			 * slab, are temporarily unavailable.
-			 */
-			if (error == -ENOMEM)
-				error = -EAGAIN;
-			goto out;
-		}
+		if (error)
+			goto out_convert_errno;
 		break;
 	}
 
@@ -154,15 +140,8 @@ static long madvise_behavior(struct vm_area_struct *vma,
 			goto out;
 		}
 		error = __split_vma(mm, vma, start, 1);
-		if (error) {
-			/*
-			 * madvise() returns EAGAIN if kernel resources, such as
-			 * slab, are temporarily unavailable.
-			 */
-			if (error == -ENOMEM)
-				error = -EAGAIN;
-			goto out;
-		}
+		if (error)
+			goto out_convert_errno;
 	}
 
 	if (end != vma->vm_end) {
@@ -171,15 +150,8 @@ static long madvise_behavior(struct vm_area_struct *vma,
 			goto out;
 		}
 		error = __split_vma(mm, vma, end, 0);
-		if (error) {
-			/*
-			 * madvise() returns EAGAIN if kernel resources, such as
-			 * slab, are temporarily unavailable.
-			 */
-			if (error == -ENOMEM)
-				error = -EAGAIN;
-			goto out;
-		}
+		if (error)
+			goto out_convert_errno;
 	}
 
 success:
@@ -187,6 +159,14 @@ static long madvise_behavior(struct vm_area_struct *vma,
 	 * vm_flags is protected by the mmap_sem held in write mode.
 	 */
 	vma->vm_flags = new_flags;
+
+out_convert_errno:
+	/*
+	 * madvise() returns EAGAIN if kernel resources, such as
+	 * slab, are temporarily unavailable.
+	 */
+	if (error == -ENOMEM)
+		error = -EAGAIN;
 out:
 	return error;
 }