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 <[email protected]>
> ---
> 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 <[email protected]>
>
--
Sincerely yours,
Mike.
