Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933707AbaKSV42 (ORCPT ); Wed, 19 Nov 2014 16:56:28 -0500 Received: from mail-pa0-f42.google.com ([209.85.220.42]:37939 "EHLO mail-pa0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756343AbaKSV4Y (ORCPT ); Wed, 19 Nov 2014 16:56:24 -0500 From: Andy Lutomirski To: Dave Jones , Linus Torvalds Cc: Don Zickus , Thomas Gleixner , Linux Kernel , x86@kernel.org, Peter Zijlstra , Andy Lutomirski Subject: [PATCH] x86, syscall: Fix _TIF_NOHZ handling in syscall_trace_enter_phase1 Date: Wed, 19 Nov 2014 13:56:19 -0800 Message-Id: X-Mailer: git-send-email 1.9.3 In-Reply-To: <546D0530.8040800@mit.edu> References: <546D0530.8040800@mit.edu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org TIF_NOHZ is 19 (i.e. _TIF_SYSCALL_TRACE | _TIF_NOTIFY_RESUME | _TIF_SINGLESTEP), not (1<<19). This code is involved in Dave's trinity lockup, but I don't see why it would cause any of the problems he's seeing, except inadvertently by causing a different path through entry_64.S's syscall handling. Signed-off-by: Andy Lutomirski --- arch/x86/kernel/ptrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 749b0e423419..e510618b2e91 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -1484,7 +1484,7 @@ unsigned long syscall_trace_enter_phase1(struct pt_regs *regs, u32 arch) */ if (work & _TIF_NOHZ) { user_exit(); - work &= ~TIF_NOHZ; + work &= ~_TIF_NOHZ; } #ifdef CONFIG_SECCOMP -- 1.9.3 -- 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/