Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751458AbaLZHDF (ORCPT ); Fri, 26 Dec 2014 02:03:05 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:39604 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751140AbaLZHDC (ORCPT ); Fri, 26 Dec 2014 02:03:02 -0500 Message-ID: <549D07CD.8000204@oracle.com> Date: Fri, 26 Dec 2014 02:01:33 -0500 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Li Bin , Peter Zijlstra CC: Ingo Molnar , LKML , Dave Jones , rui.xiang@huawei.com, wengmeiling.weng@huawei.com 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> <549D03F6.9090607@huawei.com> In-Reply-To: <549D03F6.9090607@huawei.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Source-IP: ucsinet22.oracle.com [156.151.31.94] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/26/2014 01:45 AM, Li Bin wrote: > 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"); Could you explain a bit more why do you think it's needed? Thanks, Sasha -- 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/