linux-kernel - Re: [PATCH bpf-next v3 05/17] bpf: mark struct oom_control's memcg field as TRUSTED_OR

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Message-ID: <CALOAHbBLEqqs3iP=QFCs7BMX-YZXu6p+D-vmQg12S2Kyq12Frw@mail.gmail.com>
Date: Tue, 27 Jan 2026 14:06:20 +0800
From: Yafang Shao <laoar.shao@...il.com>
To: Roman Gushchin <roman.gushchin@...ux.dev>
Cc: bpf@...r.kernel.org, Michal Hocko <mhocko@...e.com>, 
	Alexei Starovoitov <ast@...nel.org>, Matt Bobrowski <mattbobrowski@...gle.com>, 
	Shakeel Butt <shakeel.butt@...ux.dev>, JP Kobryn <inwardvessel@...il.com>, 
	linux-kernel@...r.kernel.org, linux-mm@...ck.org, 
	Suren Baghdasaryan <surenb@...gle.com>, Johannes Weiner <hannes@...xchg.org>, 
	Andrew Morton <akpm@...ux-foundation.org>, Kumar Kartikeya Dwivedi <memxor@...il.com>
Subject: Re: [PATCH bpf-next v3 05/17] bpf: mark struct oom_control's memcg
 field as TRUSTED_OR_NULL

On Tue, Jan 27, 2026 at 10:49 AM Roman Gushchin
<roman.gushchin@...ux.dev> wrote:
>
> Struct oom_control is used to describe the OOM context.
> It's memcg field defines the scope of OOM: it's NULL for global
> OOMs and a valid memcg pointer for memcg-scoped OOMs.
> Teach bpf verifier to recognize it as trusted or NULL pointer.
> It will provide the bpf OOM handler a trusted memcg pointer,
> which for example is required for iterating the memcg's subtree.
>
> Signed-off-by: Roman Gushchin <roman.gushchin@...ux.dev>
> Acked-by: Kumar Kartikeya Dwivedi <memxor@...il.com>

Acked-by: Yafang Shao <laoar.shao@...il.com>

> ---
>  kernel/bpf/verifier.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index c2f2650db9fd..cca36edb460d 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -7242,6 +7242,10 @@ BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct vm_area_struct) {
>         struct file *vm_file;
>  };
>
> +BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct oom_control) {
> +       struct mem_cgroup *memcg;
> +};
> +
>  static bool type_is_rcu(struct bpf_verifier_env *env,
>                         struct bpf_reg_state *reg,
>                         const char *field_name, u32 btf_id)
> @@ -7284,6 +7288,7 @@ static bool type_is_trusted_or_null(struct bpf_verifier_env *env,
>         BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket));
>         BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct dentry));
>         BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct vm_area_struct));
> +       BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct oom_control));
>
>         return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id,
>                                           "__safe_trusted_or_null");
> --
> 2.52.0
>
>


-- 
Regards
Yafang