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

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.. 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>
This commit is contained in:
Linus Torvalds 2018-07-21 14:48:45 -07:00
parent 3928d4f5ee
commit 95faf6992d
3 changed files with 7 additions and 11 deletions
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10
kernel/fork.c
View file

@ -315,7 +315,13 @@ struct vm_area_struct *vm_area_alloc(void)
struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig) 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) 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); tmp = vm_area_dup(mpnt);
if (!tmp) if (!tmp)
goto fail_nomem; goto fail_nomem;
*tmp = *mpnt;
INIT_LIST_HEAD(&tmp->anon_vma_chain);
retval = vma_dup_policy(mpnt, tmp); retval = vma_dup_policy(mpnt, tmp);
if (retval) if (retval)
goto fail_nomem_policy; goto fail_nomem_policy;

7
mm/mmap.c
View file

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

1
mm/nommu.c
View file

@ -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 */ /* most fields are the same, copy all, and then fixup */
*new = *vma;
*region = *vma->vm_region; *region = *vma->vm_region;
new->vm_region = region; new->vm_region = region;