Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932549AbaDHOtB (ORCPT ); Tue, 8 Apr 2014 10:49:01 -0400 Received: from merlin.infradead.org ([205.233.59.134]:37460 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932217AbaDHOs5 (ORCPT ); Tue, 8 Apr 2014 10:48:57 -0400 Date: Tue, 8 Apr 2014 14:21:28 +0200 From: Peter Zijlstra To: Toralf =?iso-8859-1?Q?F=F6rster?= Cc: Michele Ballabio , linux-kernel@vger.kernel.org, fweisbec@gmail.com, mingo@kernel.org, Steven Rostedt , David Cohen , Stefan Bader , Paolo Bonzini , Borislav Petkov Subject: Re: Bisected KVM hang on x86-32 between v3.12 and v3.13 Message-ID: <20140408122128.GC13658@twins.programming.kicks-ass.net> References: <5341707F.5000406@katamail.com> <20140407150337.GO10526@twins.programming.kicks-ass.net> <20140407150705.GB13658@twins.programming.kicks-ass.net> <5342EB78.3060002@gmx.de> <20140407185658.GK11096@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20140407185658.GK11096@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 07, 2014 at 08:56:58PM +0200, Peter Zijlstra wrote: > On Mon, Apr 07, 2014 at 08:16:24PM +0200, Toralf F?rster wrote: > > > v3.14-10353-g2b3a8fd works fine AFAICS > > (BTW the fix is stable material, right ?) > > I'm fairly sure its not; its a rather invasive series; see: > > 2432e1364bbe x86: Nuke the supervisor_stack field in i386 thread_info > b807902a88c4 x86: Nuke GET_THREAD_INFO_WITH_ESP() macro for i386 > 0788aa6a23cb x86: Prepare removal of previous_esp from i386 thread_info structure > 198d208df437 x86: Keep thread_info on thread stack in x86_32 > > Let me see if there's anything 'simpler' we can stuff in .13+ OK.. so could someone test the below patch to see if that makes things work for .13 and .14? --- arch/x86/include/asm/preempt.h | 11 +++++++++++ include/linux/preempt.h | 4 ++++ include/linux/thread_info.h | 2 -- 3 files changed, 15 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h index c8b051933b1b..7ada46d8d4d8 100644 --- a/arch/x86/include/asm/preempt.h +++ b/arch/x86/include/asm/preempt.h @@ -5,6 +5,17 @@ #include #include +#ifdef CONFIG_X86_32 +/* + * i386's current_thread_info() depends on ESP and for interrupt/exception + * stacks this doesn't yield the actual task thread_info. + * + * We hard rely on the fact that all the TIF_NEED_RESCHED bits are + * the same, therefore use the slightly more expensive version below. + */ +#define tif_need_resched() test_tsk_thread_flag(current, TIF_NEED_RESCHED) +#endif + DECLARE_PER_CPU(int, __preempt_count); /* diff --git a/include/linux/preempt.h b/include/linux/preempt.h index de83b4eb1642..891c8f8b52fe 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -17,6 +17,10 @@ #include +#ifndef tif_need_resched +#define tif_need_resched() test_thread_flag(TIF_NEED_RESCHED) +#endif + #if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER) extern void preempt_count_add(int val); extern void preempt_count_sub(int val); diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index fddbe2023a5d..a629e4b23217 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -118,8 +118,6 @@ static inline __deprecated void set_need_resched(void) */ } -#define tif_need_resched() test_thread_flag(TIF_NEED_RESCHED) - #if defined TIF_RESTORE_SIGMASK && !defined HAVE_SET_RESTORE_SIGMASK /* * An arch can define its own version of set_restore_sigmask() to get the -- 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/