Re: [PATCH] mm,thp: stop leaking unreleased file pages

[Johannes Weiner]

On Sat, May 23, 2020 at 06:50:15PM -0700, Hugh Dickins wrote:
> When collapse_file() calls try_to_release_page(), it has already
> isolated the page: so if releasing buffers happens to fail (as it
> sometimes does), remember to putback_lru_page(): otherwise that page is
> left unreclaimable and unfreeable, and the file extent uncollapsible.

Oof, I could imagine that was painful to debug (unless you already
suspected file THP due to a targeted test or similar). Kudos.

> Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
> Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
> Cc: stable@xxxxxxxxxxxxxxx # v5.4+

Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>