Re: [PATCH v2 14/14] mm/shmem: fix truncation of files containing only swapin-error markers

[Baolin Wang]

On 10/27/26 9:03 PM, David Hildenbrand (Arm) wrote:
> It might not be very common, but we can end up with shmem files that are
> composed only of swapin-error/poison markers.
>
> Such markers are not counted in info->alloced. Consequently,
> shmem_setattr() can skip shmem_truncate_range(), leaving the markers
> behind.
>
> Truncating the file to zero and growing it again will result in reads
> failing with -EIO instead of returning zeroes.
>
> Check whether the mapping contains entries, in addition to
> info->alloced, before skipping the truncation. Keep the info->alloced
> check so that shmem_recalc_inode(), called at the end of
> shmem_undo_range(), can fix up accounting after reclaim has emptied the
> mapping.
>
> Fixes: 6cec2b95dadf ("mm/shmem: fix infinite loop when swap in shmem error at swapoff time")
> Cc: stable@xxxxxxxxxxxxxxx
> Tested-by: Gregory Price (Meta) <gourry@xxxxxxxxxx>
> Signed-off-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>
> ---

LGTM.
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>