Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753846AbbFXUOd (ORCPT ); Wed, 24 Jun 2015 16:14:33 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:52582 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932168AbbFXUOX (ORCPT ); Wed, 24 Jun 2015 16:14:23 -0400 From: Stephen Boyd To: Catalin Marinas , Will Deacon Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, John Stultz , Steven Rostedt , "Paul E. McKenney" , Nicolas Pitre Subject: [PATCH] ARM64: smp: Silence suspicious RCU usage with ipi tracepoints Date: Wed, 24 Jun 2015 13:14:18 -0700 Message-Id: <1435176858-9568-1-git-send-email-sboyd@codeaurora.org> X-Mailer: git-send-email 2.3.0.rc1.33.g42e4583 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1905 Lines: 54 John Stultz reported an RCU splat on ARM with ipi trace events enabled. It looks like the same problem exists on ARM64. At this point in the IPI handling path we haven't called irq_enter() yet, so RCU doesn't know that we're about to exit idle and properly warns that we're using RCU from an idle CPU. Use trace_ipi_entry_rcuidle() instead of trace_ipi_entry() so that RCU is informed about our exit from idle. Cc: John Stultz Cc: Steven Rostedt Cc: Paul E. McKenney Cc: Nicolas Pitre Fixes: 45ed695ac10a "ARM64: add IPI tracepoints" Signed-off-by: Stephen Boyd --- I haven't confirmed this, but it looks an awful lot like the same problem exists on ARM64. arch/arm64/kernel/smp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 4b2121bd7f9c..a1883bfdd9d6 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -693,7 +693,7 @@ void handle_IPI(int ipinr, struct pt_regs *regs) struct pt_regs *old_regs = set_irq_regs(regs); if ((unsigned)ipinr < NR_IPI) { - trace_ipi_entry(ipi_types[ipinr]); + trace_ipi_entry_rcuidle(ipi_types[ipinr]); __inc_irq_stat(cpu, ipi_irqs[ipinr]); } @@ -736,7 +736,7 @@ void handle_IPI(int ipinr, struct pt_regs *regs) } if ((unsigned)ipinr < NR_IPI) - trace_ipi_exit(ipi_types[ipinr]); + trace_ipi_exit_rcuidle(ipi_types[ipinr]); set_irq_regs(old_regs); } -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/