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Mon, 20 Sep 2021 14:39:36 +0000 (GMT) Received: from b03ledav001.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AE8396E05D; Mon, 20 Sep 2021 14:39:36 +0000 (GMT) Received: from localhost (unknown [9.211.63.177]) by b03ledav001.gho.boulder.ibm.com (Postfix) with ESMTP; Mon, 20 Sep 2021 14:39:36 +0000 (GMT) From: Nathan Lynch To: Christophe Leroy , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH 2/3] powerpc/cpuhp: BUG -> WARN conversion in offline path In-Reply-To: <47f36467-ae04-6472-741a-0851506a2d73@csgroup.eu> References: <20210920135504.1792219-1-nathanl@linux.ibm.com> <20210920135504.1792219-3-nathanl@linux.ibm.com> <47f36467-ae04-6472-741a-0851506a2d73@csgroup.eu> Date: Mon, 20 Sep 2021 09:39:36 -0500 Message-ID: <87mto7nwev.fsf@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-GUID: YV2uI9GV9He-cSW5IJ5SYIYGf_sA6XGt X-Proofpoint-ORIG-GUID: feZuGgIsImCadTYW8nYI4vHmLxPpEGJ_ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.182.1,Aquarius:18.0.790,Hydra:6.0.391,FMLib:17.0.607.475 definitions=2021-09-20_07,2021-09-20_01,2020-04-07_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 priorityscore=1501 mlxscore=0 mlxlogscore=999 impostorscore=0 suspectscore=0 phishscore=0 clxscore=1015 spamscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2109030001 definitions=main-2109200093 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: , Cc: danielhb413@gmail.com, tyreld@linux.ibm.com, ldufour@linux.ibm.com, aneesh.kumar@linux.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Christophe Leroy writes: > Le 20/09/2021 =C3=A0 15:55, Nathan Lynch a =C3=A9crit=C2=A0: >> If, due to bugs elsewhere, we get into unregister_cpu_online() with a CPU >> that isn't marked hotpluggable, we can emit a warning and return an >> appropriate error instead of crashing. > > Is it only a bug situation, or is it something that can happen in real=20 > life ? > > If it can happen in real life, kernels with panic_on_warn will still be=20 > impacted. I only found this by inspection, and it can happen only due to a bug in CPU device registration at boot. The flag must not be set if the platform or CPU can't support going offline.