mm: make vm_area_dup() actually copy the old vma data

.. and re-initialize th eanon_vma_chain head.

This removes some boiler-plate from the users, and also makes it clear
why it didn't need use the 'zalloc()' version.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/fork.c b/kernel/fork.c
index 0e23deb..67253e4 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -315,7 +315,13 @@ struct vm_area_struct *vm_area_alloc(void)
 
 struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
 {
-       return kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
+       struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
+
+       if (new) {
+               *new = *orig;
+               INIT_LIST_HEAD(&new->anon_vma_chain);
+       }
+       return new;
 }
 
 void vm_area_free(struct vm_area_struct *vma)
@@ -473,8 +479,6 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
                tmp = vm_area_dup(mpnt);
                if (!tmp)
                        goto fail_nomem;
-               *tmp = *mpnt;
-               INIT_LIST_HEAD(&tmp->anon_vma_chain);
                retval = vma_dup_policy(mpnt, tmp);
                if (retval)
                        goto fail_nomem_policy;

diff --git a/mm/mmap.c b/mm/mmap.c
index 4286ad2..b0ed8ce 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2624,11 +2624,6 @@ int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
        if (!new)
                return -ENOMEM;
 
-       /* most fields are the same, copy all, and then fixup */
-       *new = *vma;
-
-       INIT_LIST_HEAD(&new->anon_vma_chain);
-
        if (new_below)
                new->vm_end = addr;
        else {
@@ -3205,13 +3200,11 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
                new_vma = vm_area_dup(vma);
                if (!new_vma)
                        goto out;
-               *new_vma = *vma;
                new_vma->vm_start = addr;
                new_vma->vm_end = addr + len;
                new_vma->vm_pgoff = pgoff;
                if (vma_dup_policy(vma, new_vma))
                        goto out_free_vma;
-               INIT_LIST_HEAD(&new_vma->anon_vma_chain);
                if (anon_vma_clone(new_vma, vma))
                        goto out_free_mempol;
                if (new_vma->vm_file)

diff --git a/mm/nommu.c b/mm/nommu.c
index 006e3fe..c2560e9 100644 (file)
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1476,7 +1476,6 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
        }
 
        /* most fields are the same, copy all, and then fixup */
-       *new = *vma;
        *region = *vma->vm_region;
        new->vm_region = region;