From: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>
To: <mikeba@sentinelone.com>,
"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>,
"John Fastabend" <john.fastabend@gmail.com>,
"Shuah Khan" <shuah@kernel.org>, <bpf@vger.kernel.org>,
<linux-kselftest@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RFC bpf-next 0/2] bpf: Do not let preemption cause false recursion drops in trampoline progs
Date: Fri, 30 Oct 2026 22:22:24 +0000 [thread overview]
Message-ID: <DMIIV9CE0PN4.309YUGIXQUZNF@gmail.com> (raw)
In-Reply-To: <20261025-b4-bpf-trampoline-preempt-v1-0-198dcdc0c6ac@sentinelone.com>
On Sun, Oct 25, 2026 at 04:02 AM Mike Bazov via B4 Relay <devnull+mikeba.sentinelone.com@kernel.org> wrote:
> Is disabling preemption in __bpf_prog_enter_recur() on !PREEMPT_RT the
> preferred fix for fentry/fexit, or would you prefer a different
> mechanism for reconciling preemptible execution with prog->active and
> the per-CPU private stack?
No.
We cannot disable preemption, since progs are not short
with may_goto they can take 1/4 sec.
Sounds like private stack is the culprit.
Should we disable it?
pw-bot: cr
prev parent reply other threads:[~2026-10-30 22:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-25 11:02 [PATCH RFC bpf-next 0/2] bpf: Do not let preemption cause false recursion drops in trampoline progs Mike Bazov via B4 Relay
2026-10-25 11:02 ` [PATCH RFC bpf-next 1/2] bpf: Keep recursion-checked trampoline programs non-preemptible on !PREEMPT_RT Mike Bazov via B4 Relay
2026-10-25 11:02 ` [PATCH RFC bpf-next 2/2] selftests/bpf: Add trampoline preemption false-recursion test Mike Bazov via B4 Relay
2026-10-30 22:22 ` Alexei Starovoitov [this message]
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