On Tue, Jun 1, 2021 at 2:11 PM Hugh Dickins <hughd@xxxxxxxxxx> wrote:
>
> From: Jue Wang <juew@xxxxxxxxxx>
>
> Anon THP tails were already supported, but memory-failure may need to use
> page_address_in_vma() on file THP tails, which its page->mapping check did
> not permit: fix it.
>
> hughd adds: no current usage is known to hit the issue, but this does fix
> a subtle trap in a general helper: best fixed in stable sooner than later.
>
> Fixes: 800d8c63b2e9 ("shmem: add huge pages support")
> Signed-off-by: Jue Wang <juew@xxxxxxxxxx>
> Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
Reviewed-by: Yang Shi <shy828301@xxxxxxxxx>
> ---
> mm/rmap.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 144de54efc1c..e05c300048e6 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -716,11 +716,11 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
> if (!vma->anon_vma || !page__anon_vma ||
> vma->anon_vma->root != page__anon_vma->root)
> return -EFAULT;
> - } else if (page->mapping) {
> - if (!vma->vm_file || vma->vm_file->f_mapping != page->mapping)
> - return -EFAULT;
> - } else
> + } else if (!vma->vm_file) {
> + return -EFAULT;
> + } else if (vma->vm_file->f_mapping != compound_head(page)->mapping) {
> return -EFAULT;
> + }
>
> return vma_address(page, vma);
> }
> --
> 2.32.0.rc0.204.g9fa02ecfa5-goog
>
>
