[PATCH] mm: remove a redundant check in do_munmap()

[Wei Yang <richard.weiyang@gmail.com>]

A non-NULL vma returned from find_vma() implies:

   vma->vm_start <= start

Since len != 0, the following condition always hods:

   vma->vm_start < start + len = end

This means the if check would never be true.

This patch removes this redundant check and fix two typo in comment.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
---
 mm/mmap.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 8d6449e74431..94660ddfa2c1 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -414,7 +414,7 @@ static void vma_gap_update(struct vm_area_struct *vma)
 {
 	/*
 	 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
-	 * function that does exacltly what we want.
+	 * function that does exactly what we want.
 	 */
 	vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
 }
@@ -1621,7 +1621,7 @@ SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
 
 /*
- * Some shared mappigns will want the pages marked read-only
+ * Some shared mappings will want the pages marked read-only
  * to track write events. If so, we'll downgrade vm_page_prot
  * to the private version (using protection_map[] without the
  * VM_SHARED bit).
@@ -2705,12 +2705,8 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
 	if (!vma)
 		return 0;
 	prev = vma->vm_prev;
-	/* we have  start < vma->vm_end  */
-
-	/* if it doesn't overlap, we have nothing.. */
+	/* we have vma->vm_start <= start < vma->vm_end */
 	end = start + len;
-	if (vma->vm_start >= end)
-		return 0;
 
 	/*
 	 * If we need to split any vma, do it now to save pain later.
-- 
2.15.1