From: Yonghong Song <yonghong.song@linux.dev>
To: bot+bpf-ci@kernel.org, bpf@vger.kernel.org
Cc: ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net,
jose.marchesi@oracle.com, kernel-team@fb.com,
martin.lau@kernel.org, eddyz87@gmail.com, clm@meta.com,
ihor.solodrai@linux.dev
Subject: Re: [PATCH bpf-next 2/9] bpf: Fix tail_call_reachable leak
Date: Tue, 21 Apr 2026 17:29:15 -0700 [thread overview]
Message-ID: <5323628d-65d6-4fbf-a302-2f5d3e2d46e1@linux.dev> (raw)
In-Reply-To: <154d4ed659716997501257309218648961b1f25de606e411a8f84cf16b95cc5a@mail.kernel.org>
On 4/21/26 11:06 AM, bot+bpf-ci@kernel.org wrote:
> commit 697f215251be114235dcf2ec469f425797a26a51
> Author: Yonghong Song <yonghong.song@linux.dev>
>
> bpf: Fix tail_call_reachable leak
>
> This commit fixes a leak of the local tail_call_reachable flag across
> sibling subprogs during the DFS traversal in
> check_max_stack_depth_subprog(), which caused the JIT to emit
> unnecessary tail call counter preservation code for subprogs that
> could not be reached via a tail call path.
>
> Should this commit carry a Fixes: tag? The buggy pattern (set
> tail_call_reachable to true on push, never reset on pop, then mark all
> currently-on-stack frames) appears to have been introduced by commit
> ebf7d1f508a7 ("bpf, x64: rework pro/epilogue and tailcall handling in
> JIT") which originally added tail_call_reachable tracking to the
> stack-depth DFS.
>
> Something like:
>
> Fixes: ebf7d1f508a7 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT")
The above fix tag is in 2020 so it has been 5+ years. BTW, this is not
really a bug although in certain cases it may cause more stack space than needed.
I would skip Fixes tag for this patch.
>
>
> ---
> 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/24736686700
next prev parent reply other threads:[~2026-04-22 0:29 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-21 17:19 [PATCH bpf-next 0/9] bpf: Prepare to support stack arguments Yonghong Song
2026-04-21 17:19 ` [PATCH bpf-next 1/9] bpf: Remove unused parameter from check_map_kptr_access() Yonghong Song
2026-04-21 17:19 ` [PATCH bpf-next 2/9] bpf: Fix tail_call_reachable leak Yonghong Song
2026-04-21 18:06 ` bot+bpf-ci
2026-04-22 0:29 ` Yonghong Song [this message]
2026-04-21 17:19 ` [PATCH bpf-next 3/9] bpf: Remove WARN_ON_ONCE in check_kfunc_mem_size_reg() Yonghong Song
2026-04-21 17:19 ` [PATCH bpf-next 4/9] bpf: Refactor to avoid redundant calculation of bpf_reg_state Yonghong Song
2026-04-21 21:40 ` Amery Hung
2026-04-21 23:42 ` Yonghong Song
2026-04-21 17:19 ` [PATCH bpf-next 5/9] bpf: Refactor to handle memory and size together Yonghong Song
2026-04-21 17:19 ` [PATCH bpf-next 6/9] bpf: Rename existing argno to arg Yonghong Song
2026-04-21 17:20 ` [PATCH bpf-next 7/9] bpf: Prepare verifier logs for upcoming kfunc stack arguments Yonghong Song
2026-04-21 22:07 ` Alexei Starovoitov
2026-04-21 23:56 ` Yonghong Song
2026-04-22 0:37 ` Alexei Starovoitov
2026-04-22 1:20 ` Yonghong Song
2026-04-22 1:52 ` Alexei Starovoitov
2026-04-21 17:20 ` [PATCH bpf-next 8/9] bpf: Introduce bpf register BPF_REG_PARAMS Yonghong Song
2026-04-21 22:10 ` Alexei Starovoitov
2026-04-22 0:09 ` Yonghong Song
2026-04-22 0:42 ` Alexei Starovoitov
2026-04-22 1:10 ` Yonghong Song
2026-04-21 17:20 ` [PATCH bpf-next 9/9] bpf: Reuse MAX_BPF_FUNC_ARGS for maximum number of arguments Yonghong Song
2026-04-21 17:52 ` bot+bpf-ci
2026-04-21 19:13 ` [PATCH bpf-next 0/9] bpf: Prepare to support stack arguments Kumar Kartikeya Dwivedi
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