linux-kernel - Re: [PATCH bpf-next v3 1/3] bpf: Add bpf_jit_supports

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Message-Id: <97fd7e67669f887badde4e276fc501a5969ff9dac703a6dccedda386dacd25f1@mail.kernel.org>
Date: Thu, 29 Jan 2026 14:54:30 +0000 (UTC)
From: bot+bpf-ci@...nel.org
To: leon.hwang@...ux.dev,bpf@...r.kernel.org
Cc: ast@...nel.org,daniel@...earbox.net,andrii@...nel.org,martin.lau@...ux.dev,eddyz87@...il.com,song@...nel.org,yonghong.song@...ux.dev,john.fastabend@...il.com,kpsingh@...nel.org,sdf@...ichev.me,haoluo@...gle.com,jolsa@...nel.org,puranjay@...nel.org,xukuohai@...weicloud.com,catalin.marinas@....com,will@...nel.org,shuah@...nel.org,menglong8.dong@...il.com,leon.hwang@...ux.dev,linux-arm-kernel@...ts.infradead.org,linux-kernel@...r.kernel.org,linux-kselftest@...r.kernel.org,kernel-patches-bot@...com,ast@...nel.org,andrii@...nel.org,daniel@...earbox.net,martin.lau@...nel.org,eddyz87@...il.com,yonghong.song@...ux.dev,clm@...a.com,ihor.solodrai@...ux.dev
Subject: Re: [PATCH bpf-next v3 1/3] bpf: Add bpf_jit_supports_fsession()

> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index e7ff8394e0..6e0693ac72 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -24874,6 +24874,9 @@ int bpf_check_attach_target(struct bpf_verifier_log *log,
>  	case BPF_TRACE_FENTRY:
>  	case BPF_TRACE_FEXIT:
>  	case BPF_TRACE_FSESSION:
> +		if (prog->expected_attach_type == BPF_TRACE_FSESSION &&
> +		    !bpf_jit_supports_fsession())
> +			return -EOPNOTSUPP;

This isn't a bug, but other similar bpf_jit_supports_*() checks in
this file include a bpf_log() message before returning an error. For
example:

  bpf_jit_supports_kfunc_call() -> "JIT does not support calling kernel function"
  bpf_jit_supports_exceptions() -> "JIT does not support calling kfunc..."
  bpf_jit_supports_arena()      -> "JIT doesn't support arena"
  bpf_jit_supports_private_stack() -> "Private stack not supported by jit"

Should this check also include a message like "JIT does not support
fsession" for consistency with other similar checks in the verifier?


---
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/21482297342

AI-authorship-score: low
AI-authorship-explanation: The commit demonstrates specific debugging context with actual test output and errno values, correct understanding of kernel BPF conventions, and follows established patterns - typical of experienced human kernel developers.
issues-found: 1
issue-severity-score: low
issue-severity-explanation: Minor consistency issue - missing bpf_log() error message compared to similar checks in the same file; does not affect functionality or stability.