From mboxrd@z Thu Jan 1 00:00:00 1970 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 A26543112C1; Fri, 20 Feb 2026 08:35:47 +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=1771576547; cv=none; b=VFz+3Hga8+iZDpG6kY7Z3osVZQQNa5fbwZTHgt4iKpjYgwVXK4g1s2HL6t4b+Zjpmc9YmZ+6AkzyRWX3vKpn74hrAl/MqbjSzAfG7byIsnw7n+6eFs7hMnz8i2Du7v8nKX5lc8hDuHK0Jr08F09GVEreZ6CfyP1CIEyv4/DB2gU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771576547; c=relaxed/simple; bh=zEl1Pub19ZEEgLZLHZr68KrNJy/dx8AW6TQrZwJfB5Q=; h=Date:From:To:Cc:Subject:Message-Id:Mime-Version:Content-Type; b=pBAcASxUeFEHF4r3x3ii5IR0UYr6SZwe9WbNsLRude7oDzDiqsQRPk7EwR9Srs3ySHx1NmS84oTMOc3o8LGIYVQJcA3PcBfMhx8m8vnFM2rYZsOmQmRbd8NTdwI8TWY/hkeobWTlQ2RTJe2vBZUBaEOsl/6EPg96lV/vkZgtqRU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BnQ0wDKX; 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="BnQ0wDKX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 80BDDC116D0; Fri, 20 Feb 2026 08:35:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771576547; bh=zEl1Pub19ZEEgLZLHZr68KrNJy/dx8AW6TQrZwJfB5Q=; h=Date:From:To:Cc:Subject:From; b=BnQ0wDKX1WkmTo6X/55vAjuyuArxMlRYmPsng+jqO0gftihqqxvyxAkPCcy1GrQZQ WpSRYlgQVXkUvyDtZveC/JdcY4OynDlB8HlR8QFIopS9NvVf5icJ8WKCDkUaOE5/wz exngV8EspDbOyGf+F5NBCDQVSrZyyhc6yf2FVaJ5Re5xjIHNOttKekX2pzuR5bGhUP wo/iOuMtSYnQSCYD6N+InmKlldHAOS94fvmow6FmYRGzfv1tf0kWkUrf4zUPHZ2Ptq Gh7+Qt/CmJQ8mdd8kObc0e/cfSjjSKMdWOO6fcylvZ4FtynPcwzJdoC7EotqT27mzr vN8JCVY4JS1Eg== Date: Fri, 20 Feb 2026 17:35:44 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, Linux Trace Kernel , Mathieu Desnoyers Subject: [BUG] suspicious RCU usage in event_filter_pid_sched_process_fork() Message-Id: <20260220173544.11d66361d0e2fa5fe1ff8816@kernel.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Hi, On the latest tracing/for-next branch, I hit the following suspicious RCU usage in event_filter_pid_sched_process_fork(). It seems that kernel_clone() calls back this event without holding rcu_read_lock(). [37] event tracing - restricts events based on pid notrace filtering[ 156.217609] [ 156.218272] ============================= [ 156.219569] WARNING: suspicious RCU usage [ 156.220887] 6.19.0-09924-g9678e53179aa #38 Not tainted [ 156.222336] ----------------------------- [ 156.223481] kernel/trace/trace_events.c:1057 suspicious rcu_dereference_check() usage! [ 156.225660] [ 156.225660] other info that might help us debug this: [ 156.225660] [ 156.227958] [ 156.227958] rcu_scheduler_active = 2, debug_locks = 1 [ 156.229815] no locks held by ftracetest/4360. [ 156.231103] [ 156.231103] stack backtrace: [ 156.232415] CPU: 1 UID: 0 PID: 4360 Comm: ftracetest Not tainted 6.19.0-09924-g9678e53179aa #38 PREEMPT(lazy) [ 156.232418] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 [ 156.232419] Call Trace: [ 156.232422] [ 156.232425] dump_stack_lvl+0x67/0x90 [ 156.232430] lockdep_rcu_suspicious+0x154/0x1a0 [ 156.232436] event_filter_pid_sched_process_fork+0x9a/0xd0 [ 156.232440] kernel_clone+0x367/0x3a0 [ 156.232448] __x64_sys_clone+0x116/0x140 [ 156.232454] do_syscall_64+0x158/0x460 [ 156.232457] ? entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 156.232459] ? trace_irq_disable+0x1d/0xc0 [ 156.232464] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 156.232466] RIP: 0033:0x4697c3 [ 156.232470] Code: 1f 84 00 00 00 00 00 64 48 8b 04 25 10 00 00 00 45 31 c0 31 d2 31 f6 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 89 c2 85 c0 75 2c 64 48 8b 04 25 10 00 00 [ 156.232472] RSP: 002b:00007ffd8a0c1d58 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 [ 156.232474] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004697c3 [ 156.232476] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 [ 156.232477] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000026970990 [ 156.232478] R10: 000000002696e690 R11: 0000000000000246 R12: 0000000000000001 [ 156.232479] R13: 0000000026989103 R14: 0000000000000001 R15: 0000000000000000 [ 156.232484] [ 156.232495] [ 156.268667] ============================= [ 156.269872] WARNING: suspicious RCU usage [ 156.271089] 6.19.0-09924-g9678e53179aa #38 Not tainted [ 156.272544] ----------------------------- [ 156.273704] kernel/trace/trace_events.c:1060 suspicious rcu_dereference_check() usage! [ 156.275903] [ 156.275903] other info that might help us debug this: [ 156.275903] [ 156.278122] [ 156.278122] rcu_scheduler_active = 2, debug_locks = 1 [ 156.279962] no locks held by ftracetest/4360. [ 156.281216] [ 156.281216] stack backtrace: [ 156.282551] CPU: 1 UID: 0 PID: 4360 Comm: ftracetest Not tainted 6.19.0-09924-g9678e53179aa #38 PREEMPT(lazy) [ 156.282553] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 [ 156.282555] Call Trace: [ 156.282558] [ 156.282560] dump_stack_lvl+0x67/0x90 [ 156.282566] lockdep_rcu_suspicious+0x154/0x1a0 [ 156.282572] event_filter_pid_sched_process_fork+0xcd/0xd0 [ 156.282576] kernel_clone+0x367/0x3a0 [ 156.282584] __x64_sys_clone+0x116/0x140 [ 156.282589] do_syscall_64+0x158/0x460 [ 156.282592] ? entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 156.282594] ? trace_irq_disable+0x1d/0xc0 [ 156.282600] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 156.282602] RIP: 0033:0x4697c3 [ 156.282606] Code: 1f 84 00 00 00 00 00 64 48 8b 04 25 10 00 00 00 45 31 c0 31 d2 31 f6 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 89 c2 85 c0 75 2c 64 48 8b 04 25 10 00 00 [ 156.282608] RSP: 002b:00007ffd8a0c1d58 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 [ 156.282610] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004697c3 [ 156.282611] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 [ 156.282612] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000026970990 [ 156.282613] R10: 000000002696e690 R11: 0000000000000246 R12: 0000000000000001 [ 156.282615] R13: 0000000026989103 R14: 0000000000000001 R15: 0000000000000000 [ 156.282621] Thanks, -- Masami Hiramatsu (Google)