Re: [RFC v7 PATCH 1/4] mm: refactor do_munmap() to extract the common part

On Fri, Aug 10, 2018 at 07:36:00AM +0800, Yang Shi wrote:

+static inline bool addr_ok(unsigned long start, size_t len)

Maybe munmap_range_ok()?  Otherwise some of the conditions here don't make
sense for such a generic sounding function.

 {
-	unsigned long end;
-	struct vm_area_struct *vma, *prev, *last;
-
 	if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
-		return -EINVAL;
+		return false;
 
-	len = PAGE_ALIGN(len);
-	if (len == 0)
-		return -EINVAL;
+	if (PAGE_ALIGN(len) == 0)
+		return false;
+
+	return true;
+}
+
+/*
+ * munmap_lookup_vma: find the first overlap vma and split overlap vmas.
+ * @mm: mm_struct
+ * @start: start address
+ * @end: end address
+ *
+ * returns the pointer to vma, NULL or err ptr when spilt_vma returns error.

kernel-doc prefers:

 * Return: %NULL if no VMA overlaps this range.  An ERR_PTR if an
 * overlapping VMA could not be split.  Otherwise a pointer to the first
 * VMA which overlaps the range.

+ */
+static struct vm_area_struct *munmap_lookup_vma(struct mm_struct *mm,
+			unsigned long start, unsigned long end)
+{
+	struct vm_area_struct *vma, *prev, *last;
 
 	/* Find the first overlapping VMA */
 	vma = find_vma(mm, start);
 	if (!vma)
-		return 0;
-	prev = vma->vm_prev;
-	/* we have  start < vma->vm_end  */
+		return NULL;
 
+	/* we have  start < vma->vm_end  */

Can you remove the duplicate spaces here?