From patchwork Thu May 26 16:09:08 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Zijlstra X-Patchwork-Id: 821272 Received: from canuck.infradead.org (canuck.infradead.org [134.117.69.58]) by demeter1.kernel.org (8.14.4/8.14.3) with ESMTP id p4QG9gKZ014125 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Thu, 26 May 2011 16:10:08 GMT Received: from localhost ([127.0.0.1] helo=canuck.infradead.org) by canuck.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1QPd4J-0001wS-JU; Thu, 26 May 2011 16:05:51 +0000 Received: from j77219.upc-j.chello.nl ([24.132.77.219] helo=dyad.programming.kicks-ass.net) by canuck.infradead.org with esmtpsa (Exim 4.76 #1 (Red Hat Linux)) id 1QPd4F-0001wF-Im for linux-arm-kernel@lists.infradead.org; Thu, 26 May 2011 16:05:47 +0000 Received: by dyad.programming.kicks-ass.net (Postfix, from userid 65534) id 287C31D5EA; Thu, 26 May 2011 18:09:34 +0200 (CEST) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on dyad X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED autolearn=unavailable version=3.3.1 Received: from [IPv6:::1] (dyad [192.168.0.60]) by dyad.programming.kicks-ass.net (Postfix) with ESMTP id 721161D5E8; Thu, 26 May 2011 18:09:32 +0200 (CEST) Subject: Re: [BUG] "sched: Remove rq->lock from the first half of ttwu()" locks up on ARM From: Peter Zijlstra To: Oleg Nesterov In-Reply-To: <1306425584.2497.81.camel@laptop> References: <1306260792.27474.133.camel@e102391-lin.cambridge.arm.com> <1306272750.2497.79.camel@laptop> <1306343335.21578.65.camel@twins> <1306358128.21578.107.camel@twins> <1306405979.1200.63.camel@twins> <1306407759.27474.207.camel@e102391-lin.cambridge.arm.com> <1306409575.1200.71.camel@twins> <1306412511.1200.90.camel@twins> <20110526154508.GA13788@redhat.com> <1306425584.2497.81.camel@laptop> Date: Thu, 26 May 2011 18:09:08 +0200 Message-ID: <1306426148.2497.83.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Cc: Marc Zyngier , Frank Rowand , linux-kernel@vger.kernel.org, Yong Zhang , Ingo Molnar , linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter1.kernel.org [140.211.167.41]); Thu, 26 May 2011 16:10:08 +0000 (UTC) On Thu, 2011-05-26 at 17:59 +0200, Peter Zijlstra wrote: > On Thu, 2011-05-26 at 17:45 +0200, Oleg Nesterov wrote: > > Stupid question. Can't we fix this problem if we do > > > > - if (p == current) > > + if (cpu == raw_smp_processor_id()) > > > > ? > > > > I forgot the rules... but iirc task_cpu(p) can't be changed under us? > > Easy enough to test.. brain gave out again,. hold on ;-) The below seems to run all-right so far, I'll let it run for a while. --- arch/x86/include/asm/system.h | 2 ++ kernel/sched.c | 3 ++- kernel/sched_debug.c | 7 +++++++ 3 files changed, 11 insertions(+), 1 deletions(-) diff --git a/arch/x86/include/asm/system.h b/arch/x86/include/asm/system.h index c2ff2a1..2c597e8 100644 --- a/arch/x86/include/asm/system.h +++ b/arch/x86/include/asm/system.h @@ -10,6 +10,8 @@ #include #include +#define __ARCH_WANT_INTERRUPTS_ON_CTXSW + /* entries in ARCH_DLINFO: */ #if defined(CONFIG_IA32_EMULATION) || !defined(CONFIG_X86_64) # define AT_VECTOR_SIZE_ARCH 2 diff --git a/kernel/sched.c b/kernel/sched.c index 2d12893..f3627e5 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2636,7 +2636,8 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) * to spin on ->on_cpu if p is current, since that would * deadlock. */ - if (p == current) { + if (cpu == smp_processor_id()) { + p->sched_contributes_to_load = 0; ttwu_queue(p, cpu); goto stat; } diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c index a6710a1..f0ff1de 100644 --- a/kernel/sched_debug.c +++ b/kernel/sched_debug.c @@ -332,6 +332,13 @@ static int sched_debug_show(struct seq_file *m, void *v) (int)strcspn(init_utsname()->version, " "), init_utsname()->version); +#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW + SEQ_printf(m, "__ARCH_WANT_INTERRUPTS_ON_CTXSW\n"); +#endif +#ifdef __ARCH_WANT_UNLOCKED_CTXSW + SEQ_printf(m, "__ARCH_WANT_UNLOCKED_CTXSW\n"); +#endif + #define P(x) \ SEQ_printf(m, "%-40s: %Ld\n", #x, (long long)(x)) #define PN(x) \