Re: [PATCH] mm/cma_sysfs: Skip inactive CMA areas in sysfs

[Muchun Song]

On Fri, May 22, 2026 at 9:15 PM Kaitao Cheng <kaitao.cheng@xxxxxxxxx> wrote:
>
> From: Kaitao Cheng <chengkaitao@xxxxxxxxxx>
>
> cma_activate_area() can fail after a CMA area has already been added to
> cma_areas[].  In that case the area is left in the global array, but it
> does not reach the point where CMA_ACTIVATED is set.
>
> cma_sysfs_init() currently walks all cma_area_count entries and creates
> sysfs files for every area, including ones that failed activation.  These
> areas are not usable CMA areas and should not be exposed to userspace as
> valid CMA regions.
>
> Skip CMA areas that did not reach CMA_ACTIVATED when creating the sysfs
> objects.  Since inactive entries can now be skipped, make the error
> unwind tolerate entries that never had cma_kobj initialized.
>
> Fixes: 43ca106fa8ec ("mm: cma: support sysfs")

Actually, this is not a fix since there is no serious issue when accessing those
sysfs files. I think it is an improvement.

> Reported-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>
> Reported-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> Closes: https://lore.kernel.org/linux-mm/55481a8b-dcfc-4bef-ba59-aa0b43dca88b@xxxxxxxxxx/
> Signed-off-by: Kaitao Cheng <chengkaitao@xxxxxxxxxx>

Acked-by: Muchun Song <muchun.song@xxxxxxxxx>

Thanks.