From: "Florent Revest" <florent.revest@linux.dev>
To: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>,
<bpf@vger.kernel.org>, "Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Andrii Nakryiko" <andrii@kernel.org>
Cc: "Martin KaFai Lau" <martin.lau@linux.dev>,
"Eduard Zingerman" <eddyz87@gmail.com>,
"Kumar Kartikeya Dwivedi" <memxor@gmail.com>,
"Song Liu" <song@kernel.org>,
"Yonghong Song" <yonghong.song@linux.dev>,
"Jiri Olsa" <jolsa@kernel.org>, "KP Singh" <kpsingh@kernel.org>,
"John Fastabend" <john.fastabend@gmail.com>,
"Leon Hwang" <leon.hwang@linux.dev>,
"Junseo Lim" <zirajs7@gmail.com>,
"Sechang Lim" <rhkrqnwk98@gmail.com>,
"Puranjay Mohan" <puranjay@kernel.org>,
"Xu Kuohai" <xukuohai@huaweicloud.com>,
"Ilya Leoshkevich" <iii@linux.ibm.com>,
"Hari Bathini" <hbathini@linux.ibm.com>,
"Christophe Leroy" <chleroy@kernel.org>,
"Naveen N Rao" <naveen@kernel.org>,
"Björn Töpel" <bjorn@kernel.org>, "Pu Lehui" <pulehui@huawei.com>,
"Tiezhu Yang" <yangtiezhu@loongson.cn>,
"Hengqi Chen" <hengqi.chen@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf v3 2/3] bpf: Skip the progs of trampoline images that are being freed
Date: Fri, 25 Sep 2026 09:23:31 +0000 [thread overview]
Message-ID: <DLOADU4BBAUV.3HU4BSEG87ZOS@linux.dev> (raw)
In-Reply-To: <DLNZ5JQGHKP6.3TN7S6R9IFH5C@gmail.com>
On Fri Sep 25, 2026 at 12:35 AM UTC, Alexei Starovoitov wrote:
> On Thu Sep 24, 2026 at 5:05 PM UTC, Florent Revest (Anthropic) wrote:
> > call sequences, which replaces ip_after_call. Tasks that are still in an
> > image that was put skip all of its progs from then on, including the
> > ones that are still attached, like they already skipped its fexit
> > progs. The call to the original function is left alone, a task that is
> > before it in the image still has to run it.
>
> So I slept on it and you were right to argue that skipping fmod_ret
> is a bad idea. bpf-ci explains it well.
>
> So let's patch only the progs that are being detached instead of all.
> Pretty much what you had in v2, but also explain why list is needed
> and why just patching previous tramp is not enough.
Ack, I will respin in v4 with a better explanation than I had in v2.
> Also see CI re: lower limit for x86.
Yes, I could reproduce it. I'll lower the limit to 36 on x86.
> Adjusting BPF_MAX_TRAMP_LINKS for large page sizes is a bigger change.
> Ignore it for now.
Alright!
next prev parent reply other threads:[~2026-09-25 9:23 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-24 17:05 [PATCH bpf v3 0/3] bpf: Fix use-after-free of progs detached from busy trampolines Florent Revest (Anthropic)
2026-09-24 17:05 ` [PATCH bpf v3 1/3] bpf: Wait for an RCU tasks grace period before freeing trampoline progs Florent Revest (Anthropic)
2026-09-24 17:05 ` [PATCH bpf v3 2/3] bpf: Skip the progs of trampoline images that are being freed Florent Revest (Anthropic)
2026-09-24 18:07 ` bot+bpf-ci
2026-09-25 9:52 ` Florent Revest
2026-09-25 0:35 ` Alexei Starovoitov
2026-09-25 9:23 ` Florent Revest [this message]
2026-09-24 17:05 ` [PATCH bpf v3 3/3] selftests/bpf: Detach a trampoline prog while a task sleeps before it Florent Revest (Anthropic)
2026-09-24 17:53 ` bot+bpf-ci
2026-09-25 9:59 ` Florent Revest
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