Re: [PATCH for-7.4 0/9] memcg: remove the v1 soft limit

[Lorenzo Stoakes (ARM)]

On Tue, Aug 11, 2026 at 01:31:54PM -0700, Shakeel Butt wrote:
> Syzbot reported [1] a set_mm_walk() warning from kswapd. Soft limit
> reclaim is the only thing that runs shrink_lruvec() from kswapd with a
> target memcg set, and thus the only way kswapd can reach
> lru_gen_shrink_lruvec() and in turn set_mm_walk(). The offender,
> mem_cgroup_shrink_node(), has long carried a "Only used by soft limit
> reclaim. Do not reuse for anything else." comment and a priority hack,
> and it simply never got taught about MGLRU.
>
> Rather than teach it, let's delete it. The v1 soft limit was deprecated
> in v6.12 by commit 569c4f62d84a ("memcg: initiate deprecation of v1
> soft limit"). Nobody has reported depending on it in the ~21 months
> since, and v2 has covered the same ground for a long time with
> memory.low and memory.min.
>
> Link: https://lore.kernel.org/all/6a7a6929.b50370da.49fe0.005e.GAE@xxxxxxxxxx/ [1]
>
> Shakeel Butt (9):
>   memcg: make the v1 soft limit knob inert
>   memcg: remove v1 soft limit reclaim
>   memcg: remove mem_cgroup_shrink_node()
>   memcg: remove the soft limit reclaim tracepoints
>   memcg: remove the soft limit rbtree
>   memcg: remove lru_gen_soft_reclaim()
>   memcg: remove the per-node soft limit tree fields
>   memcg: remove mem_cgroup->soft_limit
>   memcg: simplify v1 event ratelimiting
>
>  .../admin-guide/cgroup-v1/memory.rst          |  49 +-
>  include/linux/memcontrol.h                    |  27 --
>  include/linux/mmzone.h                        |  30 +-
>  include/trace/events/vmscan.h                 |  14 -
>  mm/internal.h                                 |   4 -
>  mm/memcontrol-v1.c                            | 435 ++----------------
>  mm/memcontrol-v1.h                            |  12 +-
>  mm/memcontrol.c                               |   7 +-
>  mm/vmscan.c                                   |  96 +---
>  9 files changed, 66 insertions(+), 608 deletions(-)

This is a gorgeous diffstat :)

Obviously not my area but looking over it, all LGTM so feel free to add:

Acked-by: Lorenzo Stoakes (ARM) <ljs@xxxxxxxxxx>

To the whole series!

>
> --
> 2.53.0-Meta
>

--
Cheers, Lorenzo