Re: [PATCH v4 1/2] mm/page_io: use sio->len for PSWPIN accounting in sio_read_complete()

David Hildenbrand (Arm)
2026-04-02T07:12:48Z

On 4/2/26 08:14, David Carlier wrote:
> sio_read_complete() uses sio->pages to account global PSWPIN vm events,
> but sio->pages tracks the number of bvec entries (folios), not base
> pages.
>
> While large folios cannot currently reach this path (SWP_FS_OPS and
> SWP_SYNCHRONOUS_IO are mutually exclusive, and mTHP swap-in allocation
> is gated on SWP_SYNCHRONOUS_IO), the accounting is semantically
> inconsistent with the per-memcg path which correctly uses
> folio_nr_pages().
>
> Use sio->len >> PAGE_SHIFT instead, which gives the correct base page
> count since sio->len is accumulated via folio_size(folio).
>
> Signed-off-by: David Carlier <devnexen@gmail.com>
> ---

Acked-by: David Hildenbrand (Arm) <david@kernel.org>

--
Cheers,

David