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 <hu...@google.com> > Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") > Cc: sta...@vger.kernel.org # v5.4+ Acked-by: Johannes Weiner <han...@cmpxchg.org>