Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751371AbaLZGpc (ORCPT ); Fri, 26 Dec 2014 01:45:32 -0500 Received: from szxga03-in.huawei.com ([119.145.14.66]:35488 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751046AbaLZGpb (ORCPT ); Fri, 26 Dec 2014 01:45:31 -0500 Message-ID: <549D03F6.9090607@huawei.com> Date: Fri, 26 Dec 2014 14:45:10 +0800 From: Li Bin User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.0.1 MIME-Version: 1.0 To: Peter Zijlstra , Sasha Levin CC: Ingo Molnar , LKML , "Dave Jones" , , Subject: Re: sched: spinlock recursion in sched_rr_get_interval References: <53B98709.3090603@oracle.com> <20140707083016.GA19379@twins.programming.kicks-ass.net> <53BAA6DF.5060409@oracle.com> <20140707200550.GA6758@twins.programming.kicks-ass.net> In-Reply-To: <20140707200550.GA6758@twins.programming.kicks-ass.net> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.177.25.181] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020202.549D0412.00CC,ss=1,re=0.001,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 54712ec9e065671cceeb6ad884f48a18 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014/7/8 4:05, Peter Zijlstra wrote: > On Mon, Jul 07, 2014 at 09:55:43AM -0400, Sasha Levin wrote: >> I've also had this one, which looks similar: >> >> [10375.005884] BUG: spinlock recursion on CPU#0, modprobe/10965 >> [10375.006573] lock: 0xffff8803a0fd7740, .magic: dead4ead, .owner: modprobe/10965, .owner_cpu: 15 >> [10375.007412] CPU: 0 PID: 10965 Comm: modprobe Tainted: G W 3.16.0-rc3-next-20140704-sasha-00023-g26c0906-dirty #765 > > Something's fucked; so we have: > > debug_spin_lock_before() > SPIN_BUG_ON(lock->owner == current, "recursion"); > Hello， Does ACCESS_ONCE() can help this issue? I have no evidence that its lack is responsible for the issue, but I think here need it indeed. Is that right? SPIN_BUG_ON(ACCESS_ONCE(lock->owner) == current, "recursion"); Thanks, Li Bin > Causing that, _HOWEVER_ look at .owner_cpu and the reporting cpu!! How > can the lock owner, own the lock on cpu 15 and again contend with it on > CPU 0. That's impossible. > > About when-ish did you start seeing things like this? Lemme go stare > hard at recent changes. > -- 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/