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Wed, 19 Aug 2026 09:15:03 +0000 (GMT) Received: from [9.224.77.157] (unknown [9.224.77.157]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 19 Aug 2026 09:15:03 +0000 (GMT) Message-ID: <3dadc544-5836-4472-9365-90d91a0c2618@linux.ibm.com> Date: Wed, 19 Aug 2026 11:15:02 +0200 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] s390/pai: Handle multiple PMU stop callback invocations To: sashiko-reviews@lists.linux.dev Cc: linux-s390@vger.kernel.org, Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Heiko Carstens , Thomas Richter References: <20260819055855.1001578-1-tmricht@linux.ibm.com> <20260819061147.9E2851F00ACA@smtp.kernel.org> Content-Language: en-US From: Thomas Richter Organization: IBM In-Reply-To: <20260819061147.9E2851F00ACA@smtp.kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: JrTHG1paNPar3rm3whWVUcRMM4HLJIcq X-Proofpoint-GUID: JrTHG1paNPar3rm3whWVUcRMM4HLJIcq X-Authority-Analysis: v=2.4 cv=RoX16imK c=1 sm=1 tr=0 ts=6a85741c cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VwQbUJbxAAAA:8 a=vNTNgnaILCbdAc7DXJgA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Info: AW1haW4tMjYwODE5MDA2OCBTYWx0ZWRfXz1eb4S+lzw5m 3/WZkgNNMqL3Qjhz0gObptNsChI4evm78he6a5sa7mWis5+LMqVSmlCq8jRMQAMuhATuDgbi4Qd KPun7YnCKUSG9ehRHFBDjgRCCq72KLk= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODE5MDA2OCBTYWx0ZWRfX/Vq2r2TE7pme kDsLycO3JDLTpvGta2LAfh1Cav3g7aZ87Ebqw94RPeGrsSdEeCUhMD9KX5yGaI0zbXs38J+TxM2 2rdX5BZuyEjXgNmz9BehWZysetI1oIOKjV/LkmtVpFgx44QcqyPy8unYKSFIBdzlh/70IREogDy EtnJp0nOMjeTlOyYH8Ge553ve5rXbl17KCDWanLlYcUnA7Jlo7SLiJhhALG7M8tNoe1NVnpXPoR ykQMHdtLZDz6jutxaE5htJF8BKMaCn4uiQZLZBgXjBlrGDu9kdzEYfsqQcxp/0cru6dpTzg9PGN CTZb3V/1h5SzgF0Ur2+c7Cv42LfG2e7LQQZ8W3uNxiaXpQrjT1dOytBXidFnzQFOPqmz9YzEnhk JBay0C/qKgDY72jVE6gXb3CvBpuxMBE5tyatRQx6F3SzHZ98UnAQBWCXiTL2rGkPpkuvhvIirW9 C2oMV2anilcjZL8ZtQQ== 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=2026-08-19_02,2026-08-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 suspectscore=0 malwarescore=0 adultscore=0 clxscore=1015 phishscore=0 spamscore=0 bulkscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608190068 On 8/19/26 08:11, sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider: > > Pre-existing issues: > - [Medium] `list_for_each_entry_safe` in `pai_have_samples()` is insufficient to prevent list corruption (dereferencing `LIST_POISON1`) when group throttling removes sibling events concurrently. perf_event_throttle_group() walks a different list anchored by perf_event::sibling_list. The list anchored by cpuhw::syswide is a complete different list using different nodes. Since events CRYPTO_ALL and NNPA_ALL are single sampling events and the only sampling event for each PAI PMU, it makes no sense to group the same event. Events of different PMUS can not be grouped anyway. > - [Medium] The patch fails to prohibit setting `event_limit`, leaving the unsupported `pai_stop()` invocation pathway open via `PERF_EVENT_IOC_REFRESH`. > -- > This needs to be addressed in a follow-on patch, the invocation of perf_event_refresh() can not be blocked right now. Maybe add a new PMU call back. -- Thomas Richter, Dept 3303, IBM s390 Linux Development, Boeblingen, Germany -- IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Wolfgang Wendt Geschäftsführung: David Faller Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294