Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933284AbcDKNvZ (ORCPT ); Mon, 11 Apr 2016 09:51:25 -0400 Received: from mx2.suse.de ([195.135.220.15]:37473 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932391AbcDKNX7 (ORCPT ); Mon, 11 Apr 2016 09:23:59 -0400 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Dave Jones , Andi Kleen , Thomas Gleixner , Jiri Slaby Subject: [PATCH 3.12 40/98] x86/apic: Fix suspicious RCU usage in smp_trace_call_function_interrupt() Date: Mon, 11 Apr 2016 15:22:42 +0200 Message-Id: <6da4a8d451bde1a7a136468d259d4ecdc5fa33c0.1460380917.git.jslaby@suse.cz> X-Mailer: git-send-email 2.8.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2503 Lines: 70 From: Dave Jones 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit 7834c10313fb823e538f2772be78edcdeed2e6e3 upstream. Since 4.4, I've been able to trigger this occasionally: =============================== [ INFO: suspicious RCU usage. ] 4.5.0-rc7-think+ #3 Not tainted Cc: Andi Kleen Link: http://lkml.kernel.org/r/20160315012054.GA17765@codemonkey.org.uk Signed-off-by: Thomas Gleixner Signed-off-by: Jiri Slaby ------------------------------- ./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 = 1 RCU used illegally from extended quiescent state! no locks held by swapper/3/0. stack backtrace: CPU: 3 PID: 0 Comm: swapper/3 Not tainted 4.5.0-rc7-think+ #3 ffffffff92f821e0 1f3e5c340597d7fc ffff880468e07f10 ffffffff92560c2a ffff880462145280 0000000000000001 ffff880468e07f40 ffffffff921376a6 ffffffff93665ea0 0000cc7c876d28da 0000000000000005 ffffffff9383dd60 Call Trace: [] dump_stack+0x67/0x9d [] lockdep_rcu_suspicious+0xe6/0x100 [] do_trace_write_msr+0x127/0x1a0 [] native_apic_msr_eoi_write+0x23/0x30 [] smp_trace_call_function_interrupt+0x38/0x360 [] trace_call_function_interrupt+0x90/0xa0 [] ? cpuidle_enter_state+0x1b4/0x520 Move the entering_irq() call before ack_APIC_irq(), because entering_irq() tells the RCU susbstems to end the extended quiescent state, so that the following trace call in ack_APIC_irq() works correctly. Suggested-by: Andi Kleen Fixes: 4787c368a9bc "x86/tracing: Add irq_enter/exit() in smp_trace_reschedule_interrupt()" Signed-off-by: Dave Jones Signed-off-by: Thomas Gleixner --- 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 1d2091a226bc..29559831c94f 100644 --- a/arch/x86/include/asm/apic.h +++ b/arch/x86/include/asm/apic.h @@ -699,8 +699,8 @@ static inline void entering_irq(void) static inline void entering_ack_irq(void) { - ack_APIC_irq(); entering_irq(); + ack_APIC_irq(); } static inline void exiting_irq(void) -- 2.8.1