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    Subject[PATCH 4.17 299/324] mm: make vm_area_dup() actually copy the old vma data
    Date
    4.17-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Linus Torvalds <torvalds@linux-foundation.org>

    [ Upstream commit 95faf6992df468f617edb788da8c21c6eed0dfa7 ]

    .. 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>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    kernel/fork.c | 10 +++++++---
    mm/mmap.c | 7 -------
    mm/nommu.c | 1 -
    3 files changed, 7 insertions(+), 11 deletions(-)

    --- a/kernel/fork.c
    +++ b/kernel/fork.c
    @@ -315,7 +315,13 @@ struct vm_area_struct *vm_area_alloc(voi

    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(str
    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;
    --- a/mm/mmap.c
    +++ b/mm/mmap.c
    @@ -2624,11 +2624,6 @@ int __split_vma(struct mm_struct *mm, st
    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 v
    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)
    --- a/mm/nommu.c
    +++ b/mm/nommu.c
    @@ -1476,7 +1476,6 @@ int split_vma(struct mm_struct *mm, stru
    }

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


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