linux-kernel - Re: [PATCH bpf-next v12 2/7] bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu

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Message-ID: <26c4677b-aeff-4516-85f4-87b5d1a9f6ee@meta.com>
Date: Wed, 26 Nov 2025 10:56:04 -0500
From: Chris Mason <clm@...a.com>
To: Leon Hwang <leon.hwang@...ux.dev>, bot+bpf-ci@...nel.org,
        bpf@...r.kernel.org
Cc: ast@...nel.org, andrii@...nel.org, daniel@...earbox.net, jolsa@...nel.org,
        yonghong.song@...ux.dev, song@...nel.org, eddyz87@...il.com,
        dxu@...uu.xyz, deso@...teo.net, martin.lau@...ux.dev,
        john.fastabend@...il.com, kpsingh@...nel.org, sdf@...ichev.me,
        haoluo@...gle.com, shuah@...nel.org, kerneljasonxing@...il.com,
        chen.dylane@...ux.dev, willemb@...gle.com, paul.chaignon@...il.com,
        a.s.protopopov@...il.com, memxor@...il.com, yatsenko@...a.com,
        tklauser@...tanz.ch, kernel-patches-bot@...com,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        martin.lau@...nel.org, ihor.solodrai@...ux.dev
Subject: Re: [PATCH bpf-next v12 2/7] bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS
 flags support for percpu_array maps



On 11/26/25 10:24 AM, Leon Hwang wrote:
> 
> 
> On 2025/11/26 23:11, bot+bpf-ci@...nel.org wrote:
>>> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
>>> index d84af3719..01a99e3a3 100644
>>> --- a/include/linux/bpf.h
>>> +++ b/include/linux/bpf.h
>>
>> [ ... ]
>>
>>> diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
>>> index 1eeb31c5b..67e9e811d 100644
>>> --- a/kernel/bpf/arraymap.c
>>> +++ b/kernel/bpf/arraymap.c
>>
>> [ ... ]
>>
>>> @@ -398,10 +405,11 @@ int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
>>>  	struct bpf_array *array = container_of(map, struct bpf_array, map);
>>>  	u32 index = *(u32 *)key;
>>>  	void __percpu *pptr;
>>> -	int cpu, off = 0;
>>> +	void *ptr, *val;
>>>  	u32 size;
>>> +	int cpu;
>>>
>>> -	if (unlikely(map_flags > BPF_EXIST))
>>> +	if (unlikely((map_flags & BPF_F_LOCK) || (u32)map_flags > BPF_F_ALL_CPUS))
>>>  		/* unknown flags */
>>>  		return -EINVAL;
>>>
>>> @@ -409,7 +417,7 @@ int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
>>>  		/* all elements were pre-allocated, cannot insert a new one */
>>>  		return -E2BIG;
>>>
>>> -	if (unlikely(map_flags & BPF_NOEXIST))
>>> +	if (unlikely(map_flags == BPF_NOEXIST))
>>                               ^^
>>
> 
> ?
> 
> No such change in this version.
> 
> It seems that this change was inferred from v11 to v12 by AI itself

Thanks for flagging this, I'll try to find this section of the logs to
see how the false positive checks failed to catch it.

-chris