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 523d2a3ee923e5f34ce45fa29d504d4321a88111..a246c516ade275413545bbc5ce0c4574cf8b0915 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 148b175352c97d0fca6373a80032baca9405839c..311b08f780ce90c1a15f9a4665a734a39fe52afa 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 47a58b32fdc99bbd6c0849512ebc26f40c7c0522..bd2b4e5ef14457eab36c1905ee558eea5e33f213 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 7fbaadb7fb1f1492c002ab939c9f9cddcb467e54..988d11e6c17cbc1cb8b0004efafc63a9cd10b2c7 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)