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Date: Fri, 4 Sep 2026 11:03:08 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: "Hui Zhu" <hui.zhu@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>, JP Kobryn
 <inwardvessel@gmail.com>, Shakeel Butt <shakeel.butt@linux.dev>, Andrii
 Nakryiko <andrii@kernel.org>, Eduard Zingerman <eddyz87@gmail.com>, Ihor
 Solodrai <ihor.solodrai@linux.dev>, Alexei Starovoitov <ast@kernel.org>,
 Daniel Borkmann <daniel@iogearbox.net>, Kumar Kartikeya Dwivedi
 <memxor@gmail.com>, Martin KaFai Lau <martin.lau@linux.dev>, Song Liu
 <song@kernel.org>, Yonghong Song <yonghong.song@linux.dev>, Jiri Olsa
 <jolsa@kernel.org>, Emil Tsalapatis <emil@etsalapatis.com>, Shuah Khan
 <shuah@kernel.org>, Barry Song <baohua@kernel.org>, Geliang Tang
 <geliang@kernel.org>, linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
 linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Hui Zhu
 <zhuhui@kylinos.cn>
Subject: Re: [PATCH bpf-next v7 1/2] mm/bpf: Add bpf_proactive_reclaim kfunc
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On Fri,  4 Sep 2026 18:20:19 +0800 "Hui Zhu" <hui.zhu@linux.dev> wrote:

> @@ -159,6 +160,74 @@ __bpf_kfunc void bpf_mem_cgroup_flush_stats(struct mem_cgroup *memcg)
>  	mem_cgroup_flush_stats(memcg);
>  }
>  
> +/*
> + * Reclaim must not recurse: try_to_free_mem_cgroup_pages() overwrites
> + * current->reclaim_state, so a nested call would corrupt the outer
> + * reclaim state. Reclaim windows are marked with PF_MEMALLOC;
> + * reclaim_state is also checked because it is installed slightly
> + * before PF_MEMALLOC.
> + */
> +static bool bpf_in_reclaim_context(void)
> +{
> +	return (current->flags & PF_MEMALLOC) || current->reclaim_state;
> +}
> +

Would life improve if try_to_free_mem_cgroup_pages() didn't do that? 
If try_to_free_mem_cgroup_pages() (or some variant of it) were to
permit nesting?

	rs = new_thing(current, &sc.reclaim_state);
	...
	set_task_reclaim_state(current, rs);

?