From: Leon Hwang <leon.hwang@linux.dev>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: bot+bpf-ci@kernel.org, bpf@vger.kernel.org, ast@kernel.org,
daniel@iogearbox.net, andrii@kernel.org, eddyz87@gmail.com,
memxor@gmail.com, martin.lau@linux.dev, song@kernel.org,
yonghong.song@linux.dev, jolsa@kernel.org, emil@etsalapatis.com,
ihor.solodrai@linux.dev, shuah@kernel.org,
linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
martin.lau@kernel.org, clm@meta.com
Subject: Re: [PATCH bpf-next v2] selftests/bpf: Avoid flaky resize value test for percpu data
Date: Tue, 25 Aug 2026 13:17:10 +0800 [thread overview]
Message-ID: <b8f1e71d-0fe6-47b5-bf59-0e077e5806ad@linux.dev> (raw)
In-Reply-To: <CAEf4BzZY-C3WtoRkdi+U7XFAMv59JeJ2R0yMi8+FGM4sLTsnQQ@mail.gmail.com>
On 25/8/26 04:04, Andrii Nakryiko wrote:
> On Sun, Aug 23, 2026 at 10:02 PM Leon Hwang <leon.hwang@linux.dev> wrote:
[...]
>>>
>> It is to verify the mmap change in libbpf's bpf_map_mmap_resize() for
>> percpu data map, like those subtests in global_map_resize.c.
>>
>
> this didn't explain much, but I think what you are trying to say is
> that this won't work for PERCPU arrays with PAGE_SIZE=64KB, because
> PERCPU value is limited to 32KB today, is that right?
>
Right. Limiting PAGE_SIZE=4KB is to avoid the
test_global_percpu_data__load() failure due to PERCPU value 32KB limit
when PAGE_SIZE is 64KB.
>
> so maybe actually model that in the test itself, expect -E2BIG if
> PAGE_SIZE > 32KB or something, and otherwise check the resize?
>
How about skipping test_percpu_data_on_cpus() when
test_global_percpu_data__load() returns -E2BIG? Because
bpf_map__set_value_size() has already been verified before calling
test_global_percpu_data__load(). Afterward, it's unnecessary to check
PAGE_SIZE value.
Thanks,
Leon
next prev parent reply other threads:[~2026-08-25 5:17 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-18 15:32 [PATCH bpf-next v2] selftests/bpf: Avoid flaky resize value test for percpu data Leon Hwang
2026-08-18 16:15 ` bot+bpf-ci
2026-08-19 1:44 ` Leon Hwang
2026-08-21 17:58 ` Andrii Nakryiko
2026-08-24 5:02 ` Leon Hwang
2026-08-24 20:04 ` Andrii Nakryiko
2026-08-25 5:17 ` Leon Hwang [this message]
2026-08-25 18:29 ` Andrii Nakryiko
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