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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 26 Apr 2019 14:07:39 +0100 Received: from d06av24.portsmouth.uk.ibm.com (d06av24.portsmouth.uk.ibm.com [9.149.105.60]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x3QD7cmY30212172 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 26 Apr 2019 13:07:38 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8F43442045; Fri, 26 Apr 2019 13:07:38 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 465114203F; Fri, 26 Apr 2019 13:07:38 +0000 (GMT) Received: from osiris (unknown [9.152.212.21]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Fri, 26 Apr 2019 13:07:38 +0000 (GMT) Date: Fri, 26 Apr 2019 15:07:36 +0200 From: Heiko Carstens To: Prarit Bhargava , Jessica Yu Cc: linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, Cathy Avery Subject: [-next] system hangs likely due to "modules: Only return -EEXIST for modules that have finished loading" MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-TM-AS-GCONF: 00 x-cbid: 19042613-0008-0000-0000-000002E0837B X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19042613-0009-0000-0000-0000224CE125 Message-Id: <20190426130736.GB8646@osiris> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-04-26_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 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=8.0.1-1810050000 definitions=main-1904260090 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Prarit, it looks like your commit f9a75c1d717f ("modules: Only return -EEXIST for modules that have finished loading") _sometimes_ causes hangs on s390. This is unfortunately not 100% reproducible, however the mentioned commit seems to be the only relevant one in modules.c. What I see is a hanging system with messages like this on the console: [ 65.876040] rcu: INFO: rcu_sched self-detected stall on CPU [ 65.876049] rcu: 7-....: (5999 ticks this GP) idle=eae/1/0x4000000000000002 softirq=1181/1181 fqs=2729 [ 65.876078] (t=6000 jiffies g=-471 q=17196) [ 65.876084] Task dump for CPU 7: [ 65.876088] systemd-udevd R running task 0 731 721 0x06000004 [ 65.876097] Call Trace: [ 65.876113] ([<0000000000abb264>] __schedule+0x2e4/0x6e0) [ 65.876122] [<00000000001ee486>] finished_loading+0x4e/0xb0 [ 65.876128] [<00000000001f1ed6>] load_module+0xcce/0x27a0 [ 65.876134] [<00000000001f3af0>] __s390x_sys_init_module+0x148/0x178 [ 65.876142] [<0000000000ac0766>] system_call+0x2aa/0x2c8 crash's backtrace of this task looks like this: PID: 731 TASK: 1e79ba000 CPU: 7 COMMAND: "systemd-udevd" LOWCORE INFO: -psw : 0x0704c00180000000 0x0000000000ab666a -function : memcmp at ab666a -prefix : 0x7fe32000 -cpu timer: 0x7fffff5784d0f048 -clock cmp: 0xd60757081cd70d00 -general registers: 0x0000000000000009 0x0000000000000009 0x000003ff80347321 000000000000000000 0x000003ff8034f321 000000000000000000 0x000000000000001e 0x000003ff8c592708 0x000003e0047da900 0x000003ff8034f318 0x0000000000000001 0x0000000000000009 0x000003ff80347300 0x0000000000ad81b8 0x00000000001ee062 0x000003e004357cb0 [...] #0 [3e004357cf0] load_module at 1f1eb0 #1 [3e004357dd0] __se_sys_init_module at 1f3af0 #2 [3e004357ea8] system_call at ac0766 PSW: 0705000180000000 000003ff8c27ad3e (user space) GPRS: 000002aa280d2fb0 000003ff8c27ad3c 0000000000000080 00000000000035fd 000003ff8c592708 000002aa280c8770 0000000000000000 000002aa280d7130 0000000000020000 000002aa28915760 000003ff8c592708 000002aa280c00b0 000003ff8c8fff80 000002aa280c00b0 000003ff8c58a456 000003ffe9cfde90 I did not look any further into the dump, however since the commit touches exactly the code path which seems to be looping... ;)