From nobody Sun Feb 8 11:43:43 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 289F230DD31; Mon, 26 Jan 2026 23:12:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769469173; cv=none; b=A942lV2DjJ4D1gAzwAeGWA2t+r6XCR7e7EiDDbcbk/g/U2CVFb6GF3RiJdheubfST/hARXU7ZABrfw8wscO0m3BpeRc2cEkF6ZkYv7152Sa8VDNR7BLzCG9xqcdJoH7XSaYTxyZ2btKKtjO0QnZJv6mnCqqVR9G/Zrx/kUOzn/k= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769469173; c=relaxed/simple; bh=Btlf+O4AfMiaH+Tpkc8CIcpEHiL8iAmq3ZoEmAb2gv0=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=fouRd2ciIBiLvdjZ7kX8dP9YE4NjP8sHwrTQR2tPIFWQs42tTJ51V62Sg8DWBHKATT/XozMOAEf6mn4r+aH7nzEWvNFJg/PFTRgOqa28f4it6kpbL5y12tI6JeZy0D7MsDqX73AaL8eEjvCWdM4kgKBoaOQS8aOwiE5Ypc80oAA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ukLTe/M6; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ukLTe/M6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D41CBC2BCB2; Mon, 26 Jan 2026 23:12:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769469172; bh=Btlf+O4AfMiaH+Tpkc8CIcpEHiL8iAmq3ZoEmAb2gv0=; h=Date:From:To:Cc:Subject:References:From; b=ukLTe/M6RA57QeBDYaGRFsS143CWJq9ZGx48JoI8CVHjJteczIcE3WXi0CoUgstg3 Mnd2ec/rv4VJ0r3u945EMlW2uFrZ261gRp6uDLrHr7lu1jLxOvV2cK2F43/dKijglA nPXbBL02c6ygNQRzcgg5kC3m2zxvV/X9n9dPtUtOvimHIxA8r9WNgt/mMgats1Oy4+ 1asLUClDXL3XStu10IJ77j7aNyqB76rnuj0WaWU3SI0Iz1501QmbVx1USrxCdNEOc5 wxFDLql+p/zKj4EoIW3L8V3TRDUMjYHQOMhmlYfouDSfbduhyNqa/l5xfiHQyzVjZM NnTT6IjD7o3RA== Received: from rostedt by gandalf with local (Exim 4.99.1) (envelope-from ) id 1vkVlQ-00000000C0m-20cu; Mon, 26 Jan 2026 18:12:56 -0500 Message-ID: <20260126231256.335034877@kernel.org> User-Agent: quilt/0.68 Date: Mon, 26 Jan 2026 18:11:47 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , "Paul E. McKenney" , Sebastian Andrzej Siewior , Alexei Starovoitov , Alexei Starovoitov Subject: [PATCH v6 2/3] bpf: Have __bpf_trace_run() use rcu_read_lock_dont_migrate() References: <20260126231145.728172709@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Steven Rostedt In order to switch the protection of tracepoint callbacks from preempt_disable() to srcu_read_lock_fast() the BPF callback from tracepoints needs to have migration prevention as the BPF programs expect to stay on the same CPU as they execute. Put together the RCU protection with migration prevention and use rcu_read_lock_dont_migrate() in __bpf_trace_run(). This will allow tracepoints callbacks to be preemptible. Link: https://lore.kernel.org/all/CAADnVQKvY026HSFGOsavJppm3-Ajm-VsLzY-OeFU= e+BaKMRnDg@mail.gmail.com/ Suggested-by: Alexei Starovoitov Signed-off-by: Steven Rostedt (Google) --- kernel/trace/bpf_trace.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index fe28d86f7c35..abbf0177ad20 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -2062,7 +2062,7 @@ void __bpf_trace_run(struct bpf_raw_tp_link *link, u6= 4 *args) struct bpf_run_ctx *old_run_ctx; struct bpf_trace_run_ctx run_ctx; =20 - cant_sleep(); + rcu_read_lock_dont_migrate(); if (unlikely(this_cpu_inc_return(*(prog->active)) !=3D 1)) { bpf_prog_inc_misses_counter(prog); goto out; @@ -2071,13 +2071,12 @@ void __bpf_trace_run(struct bpf_raw_tp_link *link, = u64 *args) run_ctx.bpf_cookie =3D link->cookie; old_run_ctx =3D bpf_set_run_ctx(&run_ctx.run_ctx); =20 - rcu_read_lock(); (void) bpf_prog_run(prog, args); - rcu_read_unlock(); =20 bpf_reset_run_ctx(old_run_ctx); out: this_cpu_dec(*(prog->active)); + rcu_read_unlock_migrate(); } =20 #define UNPACK(...) __VA_ARGS__ --=20 2.51.0