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Tue, 6 Oct 2026 14:04:49 +0000 (GMT) Received: from osiris (unknown [9.111.2.28]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTPS; Tue, 6 Oct 2026 14:04:49 +0000 (GMT) Date: Tue, 6 Oct 2026 16:04:48 +0200 From: Heiko Carstens To: Sumanth Korikkar Cc: Vasily Gorbik , Alexander Gordeev , Ilya Leoshkevich , Christian Borntraeger , Jan Polensky , linux-s390 Subject: Re: [PATCH 0/2] s390/cpum_cf: Check session cpu mask during hotplug Message-ID: <20261006140448.17402F87-hca@linux.ibm.com> References: <20261006111304.4023017-1-sumanthk@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261006111304.4023017-1-sumanthk@linux.ibm.com> X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=TOPQ2Fla c=1 sm=1 tr=0 ts=6ac50007 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=kj9zAlcOel0A:10 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=DXTpHQnePCYUjPM-eFMA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDA2MDA1NCBTYWx0ZWRfX371CxI+DWwvX 7tnr7lG58VvCn2nV+JnpgA61HAmGME0itQ2H5ZX+xyAP3cmzoKhRlIFJKCC5J9DCL86lMU4+sbd M69Wltvztt3B5vh82tGhYO96Lr8dz3Xdn9UUwttPJ2+dwvF399ohYzx2KV17XF8e5oG9RBQ/XEf riSNC+QIWSilWruAB8IVwavqxahGRUMN8mp0BPvKTyVVMy7tXsp1CUqmmk7Y4gDsLLT4hHP5+VW z73HHR/78FrHhCLXjwaoY2fVDBSVhBKY+FqrkWMG42becl6/JtBmkzbAcxPrK8MzNoGfEgA3m9k s60EdnBbHi06WQHLr0IqpdG0pCKdib/ZlI0bS8i01YQqm4KZfdJl2b4VhjVfEjbNM1LRSiDXirz g2F7Zt5EqPv4lE33RM3VqMXyTg2eFQQu6ri7OwWokmzb5LfUFeyCWKhjed69LxT7IoDfQvnOWSt kz98k0tTVUQZZbm4O8A== X-Proofpoint-GUID: 0KN_yjIY1JPBLwqZgoHe4hPy-wcmFDJg X-Proofpoint-ORIG-GUID: 0KN_yjIY1JPBLwqZgoHe4hPy-wcmFDJg X-Proofpoint-Spam-Info: AW1haW4tMjYxMDA2MDA1NCBTYWx0ZWRfX0hSbTI1mEl5z gxcAHzFN4qgzHHuo6OLgxpqTLKcdTGuibdgA5mqKtMwtplSDiJg9gkj4NX5D//EtpXLw18962mh ZW1/gP0HhPCJ55dbQ/qR+e42fm+zoK8= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-10-06_04,2026-10-06_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 priorityscore=1501 spamscore=0 adultscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 bulkscore=0 phishscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2610060054 On Tue, Oct 06, 2026 at 01:13:02PM +0200, Sumanth Korikkar wrote: > The cpu hotplug callbacks start and stop counter sets for every active > hwctr session without checking the session cpu mask. This causes a > reference count underflow when an unrelated cpu goes offline, and > silently adds cpus to a session when they come online. > > Patch 1 fixes the reference count underflow in cfset_offline_cpu() and > is suitable for stable kernels. It does not change the online behavior, > so no matching lshwc change is required. > > Patch 2 extends the mask check to cfset_online_cpu() and keeps the > userspace provided cpu mask unchanged across hotplug events. It requires > a matching lshwc change and is therefore kept separate from patch 1. > > Sumanth Korikkar (2): > s390/cpum_cf: Check session mask before cpu offline > s390/cpum_cf: Honor hwctr session cpu mask during hotplug > > arch/s390/kernel/perf_cpum_cf.c | 19 ++++++++++++------- > 1 file changed, 12 insertions(+), 7 deletions(-) Series applied. Thanks!