Re: [PATCH 1/4] mm: Assert the mmap_lock is held in __anon_vma_prepare()

[Suren Baghdasaryan <surenb@google.com>]

On Fri, Apr 26, 2024 at 7:45 AM Matthew Wilcox (Oracle)
<willy@infradead.org> wrote:
>
> Convert the comment into an assertion.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Reviewed-by: Suren Baghdasaryan <surenb@google.com>

> ---
>  mm/rmap.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 2608c40dffad..619d4d65d99b 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -182,8 +182,6 @@ static void anon_vma_chain_link(struct vm_area_struct *vma,
>   * for the new allocation. At the same time, we do not want
>   * to do any locking for the common case of already having
>   * an anon_vma.
> - *
> - * This must be called with the mmap_lock held for reading.
>   */
>  int __anon_vma_prepare(struct vm_area_struct *vma)
>  {
> @@ -191,6 +189,7 @@ int __anon_vma_prepare(struct vm_area_struct *vma)
>         struct anon_vma *anon_vma, *allocated;
>         struct anon_vma_chain *avc;
>
> +       mmap_assert_locked(mm);
>         might_sleep();
>
>         avc = anon_vma_chain_alloc(GFP_KERNEL);
> --
> 2.43.0
>