linux-kernel - Re: [PATCH bpf-next v6 2/2] bpf: Hold the perf callchain entry until used completely

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Message-ID: <7b82e322-eab7-4fc2-9de1-d10ad8251378@linux.dev>
Date: Wed, 26 Nov 2025 17:29:12 +0800
From: Tao Chen <chen.dylane@...ux.dev>
To: Yonghong Song <yonghong.song@...ux.dev>, peterz@...radead.org,
 mingo@...hat.com, acme@...nel.org, namhyung@...nel.org,
 mark.rutland@....com, alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
 irogers@...gle.com, adrian.hunter@...el.com, kan.liang@...ux.intel.com,
 Andrii Nakryiko <andrii@...nel.org>, Alexei Starovoitov <ast@...nel.org>,
 Daniel Borkmann <daniel@...earbox.net>, Eduard Zingerman
 <eddyz87@...il.com>, Song Liu <song@...nel.org>,
 Martin KaFai Lau <martin.lau@...ux.dev>
Cc: linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
 bpf@...r.kernel.org
Subject: Re: [PATCH bpf-next v6 2/2] bpf: Hold the perf callchain entry until
 used completely

在 2025/11/14 00:01, Yonghong Song 写道:
> 
> 
> On 11/12/25 8:31 AM, Tao Chen wrote:
>> As Alexei noted, get_perf_callchain() return values may be reused
>> if a task is preempted after the BPF program enters migrate disable
>> mode. The perf_callchain_entres has a small stack of entries, and
>> we can reuse it as follows:
>>
>> 1. get the perf callchain entry
>> 2. BPF use...
>> 3. put the perf callchain entry
>>
>> And Peter suggested that get_recursion_context used with preemption
>> disabled, so we should disable preemption at BPF side.
>>
>> Signed-off-by: Tao Chen <chen.dylane@...ux.dev>
> 
> Acked-by: Yonghong Song <yonghong.song@...ux.dev>
> 

Hi eBPF maintainers,

This patch appears to have missed the eBPF maintainers on the list, 
please review it again, thanks.

-- 
Best Regards
Tao Chen