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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 17 Apr 2020 08:01:07 +0100 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 03H71QiW53149902 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 17 Apr 2020 07:01:26 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0F69611C058; Fri, 17 Apr 2020 07:01:26 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 866AF11C050; Fri, 17 Apr 2020 07:01:25 +0000 (GMT) Received: from localhost (unknown [9.85.75.158]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 17 Apr 2020 07:01:25 +0000 (GMT) Date: Fri, 17 Apr 2020 12:31:20 +0530 From: "Naveen N. Rao" Subject: Re: POWER9 crash due to STRICT_KERNEL_RWX (WAS: Re: Linux-next POWER9 NULL pointer NIP...) To: Qian Cai , Michael Ellerman , Russell Currey Cc: LKML , linuxppc-dev , Nicholas Piggin , Steven Rostedt References: <15AC5B0E-A221-4B8C-9039-FA96B8EF7C88@lca.pw> <87eeszlb6u.fsf@mpe.ellerman.id.au> <0675B22E-8F32-432C-9378-FDE159DD1729@lca.pw> <20200407093054.3eb23e45@gandalf.local.home> <20200409101413.35d9c72d@gandalf.local.home> <06A2EA93-B730-4DB1-819F-D27E7032F0B3@lca.pw> <161662E3-5D9C-4C15-919C-CFEFE4CC35CB@lca.pw> <69F0448F-CA5B-497D-B8AF-2848175B9477@lca.pw> In-Reply-To: <69F0448F-CA5B-497D-B8AF-2848175B9477@lca.pw> MIME-Version: 1.0 User-Agent: astroid/v0.15-13-gb675b421 (https://github.com/astroidmail/astroid) Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8BIT X-TM-AS-GCONF: 00 x-cbid: 20041707-0012-0000-0000-000003A603D0 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 20041707-0013-0000-0000-000021E34692 Message-Id: <1587106774.1oa2whm69m.naveen@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.676 definitions=2020-04-17_01:2020-04-14,2020-04-17 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 malwarescore=0 mlxlogscore=936 adultscore=0 priorityscore=1501 clxscore=1011 lowpriorityscore=0 spamscore=0 mlxscore=0 suspectscore=2 impostorscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004170046 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Qian, Qian Cai wrote: > OK, reverted the commit, > > c55d7b5e6426 (“powerpc: Remove STRICT_KERNEL_RWX incompatibility with RELOCATABLE”) > > or set STRICT_KERNEL_RWX=n fixed the crash below and also mentioned in this thread, > > https://lore.kernel.org/lkml/15AC5B0E-A221-4B8C-9039-FA96B8EF7C88@lca.pw/ Do you see any errors logged in dmesg when you see the crash? STRICT_KERNEL_RWX changes how patch_instruction() works, so it would be interesting to see if there are any ftrace-related errors thrown before the crash. - Naveen