From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D728CC43441 for ; Fri, 9 Nov 2018 20:13:06 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2631120855 for ; Fri, 9 Nov 2018 20:13:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2631120855 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 42sBD00hpFzF3VL for ; Sat, 10 Nov 2018 07:13:04 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.ibm.com Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=linux.vnet.ibm.com (client-ip=148.163.158.5; helo=mx0a-001b2d01.pphosted.com; envelope-from=paulmck@linux.vnet.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.ibm.com Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 42sB9m0FGvzF3dP for ; Sat, 10 Nov 2018 07:11:07 +1100 (AEDT) Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id wA9KB3uk062425 for ; Fri, 9 Nov 2018 15:11:04 -0500 Received: from e17.ny.us.ibm.com (e17.ny.us.ibm.com [129.33.205.207]) by mx0a-001b2d01.pphosted.com with ESMTP id 2nney5n4a2-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 09 Nov 2018 15:11:02 -0500 Received: from localhost by e17.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 9 Nov 2018 20:10:34 -0000 Received: from b01cxnp22033.gho.pok.ibm.com (9.57.198.23) by e17.ny.us.ibm.com (146.89.104.204) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 9 Nov 2018 20:10:32 -0000 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp22033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id wA9KAV0Y46465056 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 9 Nov 2018 20:10:31 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5D018B205F; Fri, 9 Nov 2018 20:10:31 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3E2A0B2064; Fri, 9 Nov 2018 20:10:31 +0000 (GMT) Received: from paulmck-ThinkPad-W541 (unknown [9.85.161.168]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Fri, 9 Nov 2018 20:10:31 +0000 (GMT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id F04EC16C5D5F; Fri, 9 Nov 2018 12:10:30 -0800 (PST) Date: Fri, 9 Nov 2018 12:10:30 -0800 From: "Paul E. McKenney" To: Christophe LEROY Subject: Re: UBSAN: Undefined behaviour in kernel/rcu/tree_plugin.h in 4.20-rc1 References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18110920-0040-0000-0000-0000048FCCEA X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010016; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000270; SDB=6.01115069; UDB=6.00577119; IPR=6.00895168; MB=3.00024093; MTD=3.00000008; XFM=3.00000015; UTC=2018-11-09 20:10:34 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18110920-0041-0000-0000-00000898D413 Message-Id: <20181109201030.GI4170@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2018-11-09_07:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1811090181 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: paulmck@linux.ibm.com Cc: "linuxppc-dev@lists.ozlabs.org" , "linux-kernel@vger.kernel.org" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Fri, Nov 09, 2018 at 06:11:20PM +0100, Christophe LEROY wrote: > (Resending due to error in Paul's address) > > Paul > > I get the following UBSAN reports in 4.20-rc1 on an MPC8321E > (powerpc/book3s/32) > > I bisected it to 3e31009898699dfc ("rcu: Defer reporting RCU-preempt > quiescent states when disabled") Fixed by dfdc33585b0a ("rcu: Avoid signed integer overflow in rcu_preempt_deferred_qs()") in my -rcu tree and in -next, which I intend to push into the next merge window. Thanx, Paul > Thanks > Christophe > > [ 4.919995] ================================================================================ > [ 4.928428] UBSAN: Undefined behaviour in kernel/rcu/tree_plugin.h:623:28 > [ 4.935198] signed integer overflow: > [ 4.938766] 0 - -2147483648 cannot be represented in type 'int' > [ 4.944678] CPU: 0 PID: 119 Comm: mkdir Not tainted > 4.19.0-rc1-s3k-dev-00005-g5a60513 #214 > [ 4.952908] Call Trace: > [ 4.955382] [dec4fd20] [c02cb0d0] ubsan_epilogue+0x18/0x74 (unreliable) > [ 4.962003] [dec4fd30] [c02cb5e0] handle_overflow+0xd0/0xe0 > [ 4.967588] [dec4fdb0] [c007b424] rcu_preempt_deferred_qs+0xc0/0xc8 > [ 4.973857] [dec4fdd0] [c007be28] rcu_note_context_switch+0x74/0x608 > [ 4.980217] [dec4fe10] [c064b790] __schedule+0x58/0x6e0 > [ 4.985448] [dec4fe50] [c064bfdc] preempt_schedule_common+0x48/0x9c > [ 4.991717] [dec4fe70] [c01308c8] handle_mm_fault+0x10fc/0x1ecc > [ 4.997639] [dec4fee0] [c001339c] do_page_fault+0x10c/0x760 > [ 5.003225] [dec4ff40] [c001234c] handle_page_fault+0x14/0x40 > [ 5.008968] --- interrupt: 401 at 0xff9cff8 > [ 5.008968] LR = 0xfeefd78 > [ 5.016170] ================================================================================ > [ 5.024591] ================================================================================ > [ 5.033005] UBSAN: Undefined behaviour in kernel/rcu/tree_plugin.h:627:28 > [ 5.039775] signed integer overflow: > [ 5.043342] -2147483648 + -2147483648 cannot be represented in type 'int' > [ 5.050118] CPU: 0 PID: 119 Comm: mkdir Not tainted > 4.19.0-rc1-s3k-dev-00005-g5a60513 #214 > [ 5.058348] Call Trace: > [ 5.060813] [dec4fd20] [c02cb0d0] ubsan_epilogue+0x18/0x74 (unreliable) > [ 5.067433] [dec4fd30] [c02cb5e0] handle_overflow+0xd0/0xe0 > [ 5.073014] [dec4fdb0] [c007b408] rcu_preempt_deferred_qs+0xa4/0xc8 > [ 5.079283] [dec4fdd0] [c007be28] rcu_note_context_switch+0x74/0x608 > [ 5.085640] [dec4fe10] [c064b790] __schedule+0x58/0x6e0 > [ 5.090871] [dec4fe50] [c064bfdc] preempt_schedule_common+0x48/0x9c > [ 5.097139] [dec4fe70] [c01308c8] handle_mm_fault+0x10fc/0x1ecc > [ 5.103059] [dec4fee0] [c001339c] do_page_fault+0x10c/0x760 > [ 5.108642] [dec4ff40] [c001234c] handle_page_fault+0x14/0x40 > [ 5.114385] --- interrupt: 401 at 0xff9cff8 > [ 5.114385] LR = 0xfeefd78 > [ 5.121588] ================================================================================ >