[PATCH] dup_mmap: update comment on new vma

Remove part of comment on linking new vma in dup_mmap: since anon_vma rmap
came in, try_to_unmap_one knows the vma without needing find_vma.  But add
a comment to note that here vma is inserted without mmap_sem.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

kernel/fork.c

@@ -250,8 +250,9 @@ static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm)
 
 		/*
 		 * Link in the new vma and copy the page table entries:
-		 * link in first so that swapoff can see swap entries,
-		 * and try_to_unmap_one's find_vma find the new vma.
+		 * link in first so that swapoff can see swap entries.
+		 * Note that, exceptionally, here the vma is inserted
+		 * without holding mm->mmap_sem.
 		 */
 		spin_lock(&mm->page_table_lock);
 		*pprev = tmp;