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/20190813032656.16625-1-richardw.yang@linux.intel.com
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/internal.h b/mm/internal.h
index 523d2a3..a246c51 100644 (file)
--- 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
index 148b175..311b08f 100644 (file)
--- 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
index 47a58b3..bd2b4e5 100644 (file)
--- 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
index 7fbaadb..988d11e 100644 (file)
--- 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)