mm/mmap.c: rb_parent is not necessary in __vma_link_list()

Now we use rb_parent to get next, while this is not necessary. When prev is NULL, this means vma should be the first element in the list. Then next should be current first one (mm->mmap), no matter whether we have parent or not. After removing it, the code shows the beauty of symmetry. Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Wei Yang <[email protected]> Acked-by: Andrew Morton <[email protected]> Cc: Mel Gorman <[email protected]> Cc: Vlastimil Babka <[email protected]> Cc: Matthew Wilcox <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
vieko · Dec 1, 2019 · aba6dfb · aba6dfb
1 parent 1b9fc5b
commit aba6dfb
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Showing 4 changed files with 5 additions and 9 deletions.
diff --git a/mm/internal.h b/mm/internal.h
@@ -290,7 +290,7 @@ static inline bool is_data_mapping(vm_flags_t flags)
 
 /* mm/util.c */
 void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
-		struct vm_area_struct *prev, struct rb_node *rb_parent);
+		struct vm_area_struct *prev);
 void __vma_unlink_list(struct mm_struct *mm, struct vm_area_struct *vma);
 
 #ifdef CONFIG_MMU

diff --git a/mm/mmap.c b/mm/mmap.c
@@ -641,7 +641,7 @@ __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 	struct vm_area_struct *prev, struct rb_node **rb_link,
 	struct rb_node *rb_parent)
 {
-	__vma_link_list(mm, vma, prev, rb_parent);
+	__vma_link_list(mm, vma, prev);
 	__vma_link_rb(mm, vma, rb_link, rb_parent);
 }
 

diff --git a/mm/nommu.c b/mm/nommu.c
@@ -648,7 +648,7 @@ static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
 	if (rb_prev)
 		prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
 
-	__vma_link_list(mm, vma, prev, parent);
+	__vma_link_list(mm, vma, prev);
 }
 
 /*

diff --git a/mm/util.c b/mm/util.c
@@ -271,7 +271,7 @@ void *memdup_user_nul(const void __user *src, size_t len)
 EXPORT_SYMBOL(memdup_user_nul);
 
 void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
-		struct vm_area_struct *prev, struct rb_node *rb_parent)
+		struct vm_area_struct *prev)
 {
 	struct vm_area_struct *next;
 
@@ -280,12 +280,8 @@ void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
 		next = prev->vm_next;
 		prev->vm_next = vma;
 	} else {
+		next = mm->mmap;
 		mm->mmap = vma;
-		if (rb_parent)
-			next = rb_entry(rb_parent,
-					struct vm_area_struct, vm_rb);
-		else
-			next = NULL;
 	}
 	vma->vm_next = next;
 	if (next)