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

[Matt Bobrowski <mattbobrowski@google.com>]

On Mon, Jan 26, 2026 at 06:44:08PM -0800, Roman Gushchin 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.

This is fine. Feel free to add:

Acked-by: Matt Bobrowski <mattbobrowski@google.com>

> Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
> Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.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
>