Re: [PATCH 14/16] mm/shmem: fix truncate loop after boundary swapin failure

[Kiryl Shutsemau]

On Mon, Oct 26, 2026 at 10:40:47AM +0100, David Hildenbrand (Arm) wrote:
> If swapping in a large entry at the new EOF fails, shmem_undo_range()
> leaves the entry in place. Its final scan skips the entry, then restarts
> from the same start index and finds it again. Truncation can loop forever
> while holding i_rwsem.
> 
> Advance start past the skipped entry so that a restarted scan can finish,
> as we already do for folios that cannot be split.
> 
> Note that this does not fix the missing zeroing when boundary swapin fails,
> it merely prevents the endless loop.
> 
> Fixes: 8a1968bd997f ("mm/shmem, swap: fix race of truncate and swap entry split")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>

Okay, one more stop-gap:

Acked-by: Kiryl Shutsemau (Meta) <kas@xxxxxxxxxx>

-- 
  Kiryl Shutsemau / Kirill A. Shutemov