Re: [PATCH 00/11] mm/cma: charge cma allocation to memcg using per area counters

[Mike Rapoport <rppt@kernel.org>]

Hi Eric,

On Fri, Aug 21, 2026 at 02:56:52PM -0400, Eric Chanudet wrote:
> CMA allocations are currently unaccounted for by cgroup memory
> controllers. As system resources, they should fall under memcg, but CMA
> areas partition the available space for different purposes and memcg
> doesn't have a good representation for that.
> 
> Add a memory_cma_accounting cgroupfs option in preparation for the
> following new behavior. Make it disabled by default since it will
> account for CMA allocations in memcg which may affect existing systems.
> 
> Provide CMA charge/uncharge functions to memcg that introduce a CMA area
> specific counter per CMA area. Charges are issued to memcg and to a page
> counter for the CMA area used. The allocation's folios are marked with
> the cgroup via commit_charge() (once for large folios, per-page for
> 0-order ones) so they can be later uncharged correctly.
> 
> Add the new memcg calls into the cma allocator under __cma_alloc_frozen,
> for both cma and hugetlb_cma allocations accounting.
> 
> Finally register the per-area usage counters in the cgroupfs. Each CMA
> area creates a memory.cma.<area>.{current,max} pair for reporting and
> limitation for each area.
> 
> Selftests and a vmtest script are added to this series for convenience.
> The tests are simple accounting and limit enforcement verification using
> the default reserved CMA area (cma=) and hugetlb_cma.
> 
> Signed-off-by: Eric Chanudet <echanude@redhat.com>
> ---
> Eric Chanudet (11):
>       mm/cma: drop const for struct page on release API
>       mm/cma: include linux/cma.h in cma.h
>       cgroup: add memory_cma_accounting mount option
>       memcg: add cma charge/uncharge functions for area counters
>       mm/cma: charge cma allocation to memcg per area counters
>       memcg: register per-area usage counters in cgroupfs
>       selftests: cgroup: add cma configs for cgroup selftest suite
>       selftests: cgroup: add memcg cma tests
>       selftests: cgroup: add a vmtest script for memcg
>       selftests: cgroup: add memcg hugetlb_cma tests
>       selftests: cgroup: amend vmtest-memcg to run the hugetlb cma tests

CI found issues:
 
https://github.com/linux-mm/linux-mm/actions/runs/32519133924

>  Documentation/admin-guide/cgroup-v2.rst         |  35 +++
>  include/linux/cgroup-defs.h                     |   5 +
>  include/linux/cma.h                             |   4 +-
>  include/linux/memcontrol.h                      |  19 ++
>  kernel/cgroup/cgroup.c                          |  15 +-
>  mm/cma.c                                        |  14 +-
>  mm/cma.h                                        |   6 +
>  mm/cma_debug.c                                  |   1 -
>  mm/cma_sysfs.c                                  |   1 -
>  mm/memcontrol.c                                 | 205 ++++++++++++
>  tools/testing/selftests/cgroup/.gitignore       |   1 +
>  tools/testing/selftests/cgroup/Makefile         |   2 +
>  tools/testing/selftests/cgroup/config           |   5 +
>  tools/testing/selftests/cgroup/test_cma_memcg.c | 402 ++++++++++++++++++++++++
>  tools/testing/selftests/cgroup/vmtest-memcg.sh  | 197 ++++++++++++
>  15 files changed, 903 insertions(+), 9 deletions(-)
> ---
> base-commit: 98f21c54f99519329c18e2625b0ea6db14524d09
> change-id: 20260706-cma-memcg-regions-696cb5ef7998
> 
> Best regards,
> -- 
> Eric Chanudet <echanude@redhat.com>
> 

-- 
Sincerely yours,
Mike.