Re: [PATCH bpf-next v11 3/8] bpf: allow non-owning list-node args via __nonown_allowed

[Kaitao Cheng <kaitao.cheng@linux.dev>]

在 2026/5/21 12:08, bot+bpf-ci@kernel.org 写道:
>> diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst
>> index 75e6c078e0e7..3a9db1108b95 100644
>> --- a/Documentation/bpf/kfuncs.rst
>> +++ b/Documentation/bpf/kfuncs.rst
> 
> [ ... ]
> 
>> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
>> index 8dd79b735a69..f3cf8d85bea0 100644
>> --- a/kernel/bpf/verifier.c
>> +++ b/kernel/bpf/verifier.c
> 
> [ ... ]
> 
>> @@ -12244,6 +12249,13 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
>>  			return ret;
>>  		break;
>>  	case KF_ARG_PTR_TO_LIST_NODE:
>> +		if (is_kfunc_arg_nonown_allowed(btf, &args[i]) &&
>> +		    type_is_non_owning_ref(reg->type) && !reg->ref_obj_id) {
>> +			/* Allow bpf_list_front/back return value for
>> +			 * __nonown_allowed list-node arguments.
>> +			 */
>> +			goto check_ok;
>> +		}
>>  		if (reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
>>  			verbose(env, "%s expected pointer to allocated object\n",
>>  				reg_arg_name(env, argno));
>>  @@ -12253,6 +12265,7 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
>>  			verbose(env, "allocated object must be referenced\n");
>>  			return -EINVAL;
>>  		}
>> +check_ok:
>>  		ret = process_kf_arg_ptr_to_list_node(env, reg, argno, meta);
>>  		if (ret < 0)
>>  			return ret;
> 
> This isn't a bug, but the multi-line comment doesn't match the BPF
> subsystem style. The BPF guide requires multi-line comments to have the
> opening /* on its own line for files under kernel/bpf/. Should this be:
> 
>   /*
>    * Allow bpf_list_front/back return value for
>    * __nonown_allowed list-node arguments.
>    */

This file uses this comment style extensively, so I followed the
existing convention here.

> Eduard Zingerman raised a related nit in v10 RESEND: the check
> '!reg->ref_obj_id' appears redundant. Would type_is_non_owning_ref() be
> sufficient here?
> 
> Reference: https://lore.kernel.org/bpf/0419643c9a04bf0824066742e52e3f197b43909b.camel@gmail.com/
> 

Sorry, I missed that. If needed, I can fix it in the next version.

> AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
> See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
> 
> CI run summary: https://github.com/kernel-patches/bpf/actions/runs/26204125015

-- 
Thanks
Kaitao Cheng