From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 45A4A3CC314; Thu, 13 Aug 2026 09:34:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.158.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786613648; cv=none; b=VHWipVRM4AZgDNZZH8VnQaW3LIJ2IoMkYhaTanH4QFm0T2QPV0kMi0S4XI5wiUovoSi2AR6QrGv2rIYmaXUBPYYacduatFT8/+KvtEhMIqVvrRrDVyY0uF6MOwm2QzZAjlliW+hF6/zc8kGHNlfI2IQFuZZnRgntb9udHLHDH3c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786613648; c=relaxed/simple; bh=WZcKegKusGSYc+j1Wkf8jKtJ41TaZy/jhhpAMK5Js9Q=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=duWaH95pLnSUGAibeNsEqsyzs2Xo47lWMsxPtuS5hYQlSgtzjm+EMJZG/nLdkKuugdRtV8tyF1LUX0zn3cWT976qIr7HTikdW9Iac+LdWr+2WyYz0u7mNP0ZwV6J/vbI1O1hp3/EDz1IvQ7yh0yTwpPYmvdII/HTRiXEAdYU8Fs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=bpJcrEAp; arc=none smtp.client-ip=148.163.158.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="bpJcrEAp" Received: from pps.filterd (m0360072.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 67D98vfb1949754; Thu, 13 Aug 2026 09:34:05 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=128j5y xQWpx+4Nfn3fGJu3UpPbXfHhXb3HJpm34WKW8=; b=bpJcrEApNS76irch0XiVze zvywkgTvvPhOcAZayMwVefelhe5S7OGw8GtUf4Im5Dbes0fwOnMub9ZRrmPQBf5T EEGTijZVeyUdBlpgy8d55HZgDMjPN2/wDf3/qkL58xrO8VpBjCmBLKyQ8n3XRgfx L5Z91bBrzsyBSDjo9i0gm7ekUX23wtXphC6xBUbtKRcSidekVY6ogwnc5hBexjLB ivy8icc5Lbkl5Kr4XMVJN9sJyaFhUeIzQ93l6JgVDZ8SOGKqmPbbYPW1uTGZVsfh zHxLvKi8lyM0CiHJPLDBiHx4COYqKsaxxgOLIAkQht6I5IBAuR8dw6CcIdwERJLA == Received: from ppma23.wdc07v.mail.ibm.com (5d.69.3da9.ip4.static.sl-reverse.com [169.61.105.93]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4fwvnwe83x-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 13 Aug 2026 09:34:04 +0000 (GMT) Received: from pps.filterd (ppma23.wdc07v.mail.ibm.com [127.0.0.1]) by ppma23.wdc07v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 67D9QWa9022756; Thu, 13 Aug 2026 09:34:04 GMT Received: from smtprelay01.fra02v.mail.ibm.com ([9.218.2.227]) by ppma23.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4fxg9hac1j-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 13 Aug 2026 09:34:03 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (smtpav04.fra02v.mail.ibm.com [10.20.54.103]) by smtprelay01.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 67D9Y05l31981954 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 13 Aug 2026 09:34:00 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1C8C420043; Thu, 13 Aug 2026 09:34:00 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E6E6020040; Thu, 13 Aug 2026 09:33:59 +0000 (GMT) Received: from [9.224.77.157] (unknown [9.224.77.157]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 13 Aug 2026 09:33:59 +0000 (GMT) Message-ID: Date: Thu, 13 Aug 2026 11:33:59 +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] s390/pai: Handle multiple PMU stop callback invocations To: sashiko-reviews@lists.linux.dev Cc: Alexander Gordeev , Christian Borntraeger , Heiko Carstens , linux-s390@vger.kernel.org, Vasily Gorbik References: <20260813070815.2692398-1-tmricht@linux.ibm.com> <20260813072156.9C4311F000E9@smtp.kernel.org> Content-Language: en-US From: Thomas Richter Organization: IBM In-Reply-To: <20260813072156.9C4311F000E9@smtp.kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=RsP16imK c=1 sm=1 tr=0 ts=6a7d8f8c cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VwQbUJbxAAAA:8 a=_CkJLOUM1Kt26T3VhsEA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: -jr7y3OyPJoaeNEZmAZqNyzNu3SZ1tp2 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODEzMDA2NiBTYWx0ZWRfX9ozMIUZ0Qz+n 1nDEgL13ElsSrxpbT5WA5ZoNy+qvGzJJVgdoLdTPbbhQ0mVJa9eS29QZaSZG/AP321n9Cwit4/M 9W7QOH4yZcIntxJIexiU945wpvz61WRcv+cuLw2rc6pJZA9osKfiQnBU6Hhn4S2tK9KXnCyWs64 +wwE9cngF4RlBIZ02TEuvArDAyqBLcQN5ZKYTfJKgpL6fAWVFkntUNYTGDXSc0gPOwL19u/pTWv NwRTI0sRuJqKYlcF+Mp/MS3rwjmGArdtGOg+fXfw0c1rnIlkgq77AAO8swNSFRaVdzCDHxadaXj JWAg3UTbcCG5cRPJtZ3bSLdGs7UiV8VC+hny6stndvSV2BxRhPnT/bawZOWKOxqYHxvoVnHusg/ mHxxsxFYWorNRH1IZ65OAauOlD29g+zvwbUoOFWoaORYiZFCA0QPDae/Mv9vXY8yL2dQ0PabLJx L25JebjIiyUAskhawyg== X-Proofpoint-ORIG-GUID: -jr7y3OyPJoaeNEZmAZqNyzNu3SZ1tp2 X-Proofpoint-Spam-Info: AW1haW4tMjYwODEzMDA2NiBTYWx0ZWRfX4FHbjM9QdaUO ySAxdxkhTb472Gf1jUwf9ZLRtltE2KdJ97OHFSLRt3oLKT9/SXaTYVJ1gr/Rj9cgIb/mPsJHSVA /eJGIXiTsEtB74OmGzSYED96VDBvBvI= 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=2026-08-13_03,2026-08-12_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 impostorscore=0 suspectscore=0 clxscore=1015 malwarescore=0 phishscore=0 adultscore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608130066 On 8/13/26 09:21, sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: > > Pre-existing issues: > - [High] Unsafe iteration over `cpump->syswide_list` in `pai_have_samples()` leads to a kernel crash (LIST_POISON dereference) if an event overflows and is synchronously throttled during the loop. > -- This can not happen. The syswide_list is anchored by per-CPU pai_map::syswide_list and tracks all events which are bound to that particular CPU. The event was installed only on that particular CPU and does not move with the process/task. Each CPU has its own list anchored by pai_map::syswide_list. The call chains are either paicrypt_sched_task() or paiext_sched_task +--> pai_have_samples() iterates over syswide_list and calls +--> pai_have_sample or pai_stop() +--> list_del() to remove the event from that CPU. Since a CPU can only execute one given code path at any one time: - either schedule out - or stop the event both can not happen at the same time. PAI PMU does not install an interrupt handler, there is no supoprt for interrupts. I think this is safe or am I mistaken? ... -- 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