Re: [PATCH v5 02/14] mm: shmem: shmem_getattr(): set blksize to highest supported THP order

[Zi Yan]

On 29 May 2026, at 10:55, Luiz Capitulino wrote:

> Today, shmem_getattr() sets stat->blksize to PMD size whenever
> shmem_huge_global_enabled() returns non-zero. While this works fine
> for the normal THP-enabled case as explained by Baolin in [1], this
> has two problems:
>
>  1. Theoretically, when shmem is configured for within_size, this
>     could set blksize to PMD size even though the allocation may
>     be a smaller mTHP order
>
>  2. A future commit will allow shmem THP support to be enabled
>     even when the CPU doesn't support PMD-sized pages. We should
>     not allow blksize to be set to PMD size in this case
>
> In order to fix #1 and prepare for #2, this commit sets blksize
> to the size of the highest supported order returned by
> shmem_huge_global_enabled().
>
>   [1] https://lore.kernel.org/linux-mm/6591a74c-7ef9-4614-9ae9-cb2fbed86ebf@xxxxxxxxxxxxxxxxx/
>
> Suggested-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Luiz Capitulino <luizcap@xxxxxxxxxx>
> ---
>  mm/shmem.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>

Make sense.

Acked-by: Zi Yan <ziy@xxxxxxxxxx>

Best Regards,
Yan, Zi