# Re: \[PATCH 02/13\] mm/filemap: convert fault and readahead logic to use vma\_flags\_t

- From: Barry Song \<baohua@kernel.org\>
- Date: 2026-11-08 07:20:37 
- List: linux-trace-kernel
- Page: https://ratatoskr.run/linux-trace-kernel/2026/11/17891634
- Thread: https://ratatoskr.run/sashiko-reviews/2026/11/17877962/t.md

```text
On Fri, Nov 6, 2026 at 7:53 PM Lorenzo Stoakes (ARM) [ref] wrote:
[...]
> > --
> > Sashiko AI review · https://sashiko.dev/#/patchset/20261105-late-2026-vma-flags-v1-0-0d3cd15ab75f@kernel.org?part=2
>
> It seems these are valid, oops!
>
> Andrew suggested a fix off-list, and I agreed to this as an in-place fixup to
> avoid respin.
>
> I have also updated the series locally to reflect this change:

Seems like a reasonable fix. maybe_unlock_mmap_for_io()
could have released mmap_lock, leaving the VMA
unprotected. but  ra->size *= 2 is still going there no matter
if the vma has disappeared

For the original patch combined with the fix,

Reviewed-by: Barry Song <baohua@kernel.org>

>
> ----8<----
>  mm/filemap.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> --- a/mm/filemap.c~mm-filemap-convert-fault-and-readahead-logic-to-use-vma_flags_t-fix
> +++ a/mm/filemap.c
> @@ -3410,6 +3410,7 @@ static struct file *do_sync_mmap_readahe
>
>         if (force_thp_readahead) {
>                 unsigned long folio_nr_pages = 1UL << thp_order;
> +               const bool random_read = vma_test(vma, VMA_RAND_READ_BIT);
>
>                 fpin = maybe_unlock_mmap_for_io(vmf, fpin);
>                 ractl._index &= ~(folio_nr_pages - 1);
> @@ -3418,7 +3419,7 @@ static struct file *do_sync_mmap_readahe
>                  * Fetch two folios so we get the chance to actually
>                  * readahead, unless we've been told not to.
>                  */
> -               if (!vma_test(vma, VMA_RAND_READ_BIT))
> +               if (!random_read)
>                         ra->size *= 2;
>                 ra->async_size = folio_nr_pages;
>                 ra->order = thp_order;
> @@ -3438,7 +3439,6 @@ static struct file *do_sync_mmap_readahe
>                  * pad that might exist between sections, which would be a waste
>                  * of memory.
>                  */
> -               struct vm_area_struct *vma = vmf->vma;
>                 const unsigned long start = vma_start_pgoff(vma);
>                 const unsigned long end = vma_end_pgoff(vma);
>                 unsigned long ra_end;
> _
>

Thanks,
Barry
```