Re: [PATCH bpf-next v11 1/2] mm/bpf: Add bpf_proactive_reclaim kfunc

[Shakeel Butt <shakeel.butt@linux.dev>]

On Tue, Sep 15, 2026 at 08:29:35PM +0800, Hui Zhu wrote:
> From: Hui Zhu <zhuhui@kylinos.cn>
> 
> BPF programs can observe memory pressure on a cgroup, e.g. refault
> stats via bpf_mem_cgroup_page_state(), but cannot act on it:
> triggering reclaim requires writing to memory.reclaim, which BPF
> cannot do.
> 
> Add bpf_proactive_reclaim(), a sleepable kfunc performing one
> proactive reclaim pass on a memcg, like a write to memory.reclaim
> but without retrying until the target is reached, so that when and
> how hard to reclaim is BPF policy rather than hard-coded thresholds.
> The reclaim target of a single call is capped at MEMCG_CHARGE_BATCH,
> as high_work_func() does for memory.high; reclaiming more is left to
> the program, which can call the kfunc once per bpf_wq callback and
> stop at any point. It is limited to BPF_PROG_TYPE_SYSCALL, because
> other sleepable programs may run with filesystem locks held, on
> which the reclaim path could deadlock via filesystem shrinkers.
> 
> Convert MIN_SWAPPINESS, MAX_SWAPPINESS and SWAPPINESS_ANON_ONLY from
> macros to an enum so that they are emitted into BTF and usable from
> BPF programs via vmlinux.h.
> 
> Signed-off-by: Hui Zhu <zhuhui@kylinos.cn>

Acked-by: Shakeel Butt <shakeel.butt@linux.dev>