From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933861AbcIOGWL (ORCPT ); Thu, 15 Sep 2016 02:22:11 -0400 Received: from mail-pa0-f66.google.com ([209.85.220.66]:36045 "EHLO mail-pa0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933182AbcIOGWH (ORCPT ); Thu, 15 Sep 2016 02:22:07 -0400 From: Wanpeng Li X-Google-Original-From: Wanpeng Li To: linux-kernel@vger.kernel.org Cc: Wanpeng Li , Thomas Gleixner , Peter Zijlstra Subject: [PATCH] x86/apic: Fix suspicious RCU usage in smp_trace_call_function_interrupt Date: Thu, 15 Sep 2016 14:22:00 +0800 Message-Id: <1473920520-12220-1-git-send-email-wanpeng.li@hotmail.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wanpeng Li =============================== [ INFO: suspicious RCU usage. ] 4.8.0-rc6+ #5 Not tainted ------------------------------- ./arch/x86/include/asm/msr-trace.h:47 suspicious rcu_dereference_check() usage! other info that might help us debug this: RCU used illegally from idle CPU! rcu_scheduler_active = 1, debug_locks = 0 RCU used illegally from extended quiescent state! no locks held by swapper/2/0. stack backtrace: CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.8.0-rc6+ #5 Hardware name: Dell Inc. OptiPlex 7020/0F5C5X, BIOS A03 01/08/2015 0000000000000000 ffff8d1bd6003f10 ffffffff94446949 ffff8d1bd4a68000 0000000000000001 ffff8d1bd6003f40 ffffffff940e9247 ffff8d1bbdfcf3d0 000000000000080b 0000000000000000 0000000000000000 ffff8d1bd6003f70 Call Trace: [] dump_stack+0x99/0xd0 [] lockdep_rcu_suspicious+0xe7/0x120 [] do_trace_write_msr+0x135/0x140 [] native_write_msr+0x20/0x30 [] native_apic_msr_eoi_write+0x1d/0x30 [] smp_trace_call_function_interrupt+0x1e/0x270 [] trace_call_function_interrupt+0x96/0xa0 [] ? cpuidle_enter_state+0xe4/0x360 [] ? cpuidle_enter_state+0xcf/0x360 [] cpuidle_enter+0x17/0x20 [] cpu_startup_entry+0x338/0x4d0 [] start_secondary+0x154/0x180 This can be reproduced readily by running ftrace test case of kselftest. Move the irq_enter() call before ack_APIC_irq(), because irq_enter() tells the RCU susbstems to end the extended quiescent state, so that the following trace call in ack_APIC_irq() works correctly. Cc: Thomas Gleixner Cc: Peter Zijlstra Signed-off-by: Wanpeng Li --- arch/x86/include/asm/apic.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h index 1243577..71c1fe2 100644 --- a/arch/x86/include/asm/apic.h +++ b/arch/x86/include/asm/apic.h @@ -650,8 +650,8 @@ static inline void entering_ack_irq(void) static inline void ipi_entering_ack_irq(void) { - ack_APIC_irq(); irq_enter(); + ack_APIC_irq(); } static inline void exiting_irq(void) -- 1.9.1