From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f198.google.com (mail-qt0-f198.google.com [209.85.216.198]) by kanga.kvack.org (Postfix) with ESMTP id 5717E6B0038 for ; Wed, 29 Nov 2017 15:51:08 -0500 (EST) Received: by mail-qt0-f198.google.com with SMTP id r51so3088408qtj.17 for ; Wed, 29 Nov 2017 12:51:08 -0800 (PST) Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com. [148.163.156.1]) by mx.google.com with ESMTPS id l5si2651432qtf.461.2017.11.29.12.51.07 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 29 Nov 2017 12:51:07 -0800 (PST) Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id vATKnbhM146670 for ; Wed, 29 Nov 2017 15:51:06 -0500 Received: from e18.ny.us.ibm.com (e18.ny.us.ibm.com [129.33.205.208]) by mx0a-001b2d01.pphosted.com with ESMTP id 2ej205nykm-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 29 Nov 2017 15:51:05 -0500 Received: from localhost by e18.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 29 Nov 2017 15:51:02 -0500 Date: Wed, 29 Nov 2017 12:50:59 -0800 From: "Paul E. McKenney" Subject: Re: WARNING: suspicious RCU usage (3) Reply-To: paulmck@linux.vnet.ibm.com References: <94eb2c03c9bcc3b127055f11171d@google.com> <20171128133026.cf03471c99d7a0c827c5a21c@linux-foundation.org> <20171128223041.GZ3624@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Message-Id: <20171129205059.GI3624@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Dmitry Vyukov Cc: Andrew Morton , syzbot , Christoph Lameter , Joonsoo Kim , LKML , Linux-MM , Pekka Enberg , David Rientjes , syzkaller-bugs@googlegroups.com, Herbert Xu On Wed, Nov 29, 2017 at 07:25:32AM +0100, Dmitry Vyukov wrote: > On Tue, Nov 28, 2017 at 11:30 PM, Paul E. McKenney > wrote: > > On Tue, Nov 28, 2017 at 01:30:26PM -0800, Andrew Morton wrote: > >> On Tue, 28 Nov 2017 12:45:01 -0800 syzbot wrote: > >> > >> > Hello, > >> > > >> > syzkaller hit the following crash on > >> > b0a84f19a5161418d4360cd57603e94ed489915e > >> > git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master > >> > compiler: gcc (GCC) 7.1.1 20170620 > >> > .config is attached > >> > Raw console output is attached. > >> > > >> > Unfortunately, I don't have any reproducer for this bug yet. > >> > > >> > WARNING: suspicious RCU usage > >> > >> There's a bunch of other info which lockdep_rcu_suspicious() should > >> have printed out, but this trace doesn't have any of it. I wonder why. > > > > Yes, there should be more info printed, no idea why it would go missing. > > I think that's because while reporting "suspicious RCU usage" kernel hit: > > BUG: unable to handle kernel NULL pointer dereference at 0000000000000074 > > and the rest of the report is actually about the NULL deref. > > syzkaller hits too many crashes at the same time. And it's a problem > for us. We get reports with corrupted/intermixed titles, > corrupted/intermixed bodies, reports with same titles but about > different bugs, etc. Got it, thank you! Thanx, Paul -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org