From nobody Sat Jul 25 15:51:51 2026 Received: from mx0a-0031df01.pphosted.com (mx0a-0031df01.pphosted.com [205.220.168.131]) (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 B6A1341D4D9 for ; Thu, 16 Jul 2026 11:52:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.168.131 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784202729; cv=none; b=V8zFJuRlKeb7ndo6VSkJzO44sSlvshN1phTy4NOsQRyVORVHnPLmY6P/2ADlQzj8mHem843kfOONthV0E/LPsN+JRdKUNxCf1TmLpPyVjcCoQwxiCr+XPFqwZhgiC6Is1VWbTdcZ5U+v6m8PJqiaQRgZOaVCgFESwUdR1Nda2AE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784202729; c=relaxed/simple; bh=HYna8fn7t2KA7gRid/Wc1EDMEsLvCN2XW1uoIOUWEDE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=e4EiAnJ0MvfeGsV2db9znPxR8lHNt/OYW38dRn+p/YmbCg7xkfO4cUhL+15/znTEoHWa7MVOak5NzN5y6VleSIlVDQvb0TkIAp/qwUeGRVF8zIkT7MfRtAm0wVTxRLl6mKX6MOp7ubONmsDEAUsI66xO9rPYHiv4Myuju+yH8w8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com; spf=pass smtp.mailfrom=oss.qualcomm.com; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b=Atm7+S0s; dkim=pass (2048-bit key) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com header.b=UFjFec2w; arc=none smtp.client-ip=205.220.168.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b="Atm7+S0s"; dkim=pass (2048-bit key) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com header.b="UFjFec2w" Received: from pps.filterd (m0279865.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 66GBiPxC2824077 for ; Thu, 16 Jul 2026 11:52:07 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qualcomm.com; h= cc:content-transfer-encoding:date:from:message-id:mime-version :subject:to; s=qcppdkim1; bh=iKq0++/woNlx+aXAGS5PFN7c8L7JOhXQvmy HSz6bOiQ=; b=Atm7+S0sGr35PbHte6pf546y8ZkLsfTrZoabHggGCXxofDSLHMj QJATD/Z3iKD9xHRuBiR+p0jjkHmQf2z+PiCLW5/m5rHYz62/1HPOEUIjIylzY92U MCQ0eIXfWwS8flkzbTlU7PVw4SLahGdBR5Xqt5djnUv8QuEdLm2HjFg+QrBNG2qR fADqSG+YfJUpeAmTt83L858bb1oQ9bfD6kz5mlYyDoteA2VLID+rIzyl0c6s7QuX IxCRPCfA2ZXhegoj1zGNWswrLEAtKL6L6ZAliDx0R9bA1rI1+deQl0QoCn5GHBVg pVkU1ZiMxQu7e///33YivwH9/LaIm7ExKNA== Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 4fetcf16s5-1 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NOT) for ; Thu, 16 Jul 2026 11:52:06 +0000 (GMT) Received: by mail-pg1-f200.google.com with SMTP id 41be03b00d2f7-cab3e9cd922so2724525a12.0 for ; Thu, 16 Jul 2026 04:52:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oss.qualcomm.com; s=google; t=1784202726; x=1784807526; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=iKq0++/woNlx+aXAGS5PFN7c8L7JOhXQvmyHSz6bOiQ=; b=UFjFec2ws+ngBw7c55fWcNOlPCQYdLkQVyEVqeWknmDw02Vrna/0XoMhJderdad9W/ 2vKDiWkzSq0AwaIRzI6F9KfUDS1FipoyHfibeD+D+XncW6ZrslrxngaTRvL6I95mu3Vs QN2saYw8BNgp/z0SfeMyptiKe+KT4T0Qv9CqFhuB8EA4CzaEbwSim4+wO4LAkklUmT+3 OZ+x5F0v53R0B6EWGl0+KLkUPsY4puH4VWVrrVupBO7skvn7CYA6bDk4CemYUUtQW0PY s/BKQLOstTmVaTWYm70dXsanlshHbfxQQ/TH2beJbTS0uHs2mbqTQMvm4qLysmStayPo F9Sg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1784202726; x=1784807526; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=iKq0++/woNlx+aXAGS5PFN7c8L7JOhXQvmyHSz6bOiQ=; b=hfau59zo41auWG//+d60hV+n1Ar9hP5Cl+SVOA0uUp72NnkVzcS47RPSJ7CjX0J1DG oq8aKTWLbOZGHVPDhq4G3IbxQ7xPTw1Z3gWvFFVsrRnqPQ2WokwF0mmZ4EMKIk6dGp5j q2jY85i9Jauq1I4LprFUZK+Yzo1Jxu9PW2b7/o6DJWFa/RPPexlx9DedlLbPG//r5FyC 5d1HfNMJ3KAZcDoMabig5F58magFdWQDrgHKLp06hWmP4ndw8aqvl1UaUScCIee78LQJ eegxs6EySmhlq1uFvIdcvT1n8UruZ6AP9hHipxPy5ch38jHrcnFnpjcxeKVL26uPVpOp EItw== X-Forwarded-Encrypted: i=1; AHgh+Ro+dbhy3+EqxclODV9NnQYhSmLaDJhnNbzd8sXQfHKGJ2Wt8w1iTQBAA05PU1vlu29KdckuwTMiL6hLiFY=@vger.kernel.org X-Gm-Message-State: AOJu0YyTTMh/AJTmiitnPK6YRlXCLUtOLOOECU/driIpZe3UJRI87ELB 8UUV2asgGgRikyEBa1Yi6MASIFg0u9NNU42cBFm7CZv287n2WwD5cu6XhF53zHv18f1efOjLaQQ KuTekO4/K5ahCo1PcSD7UwJQb7EOL8cg0HgpSO7tDPGiuYb3jNOw0fgjg3rPooSgrp+I= X-Gm-Gg: AfdE7ckIs7HeSXwdplI/8Oa8zCslCLRl8fkA/fhvFiYPDt1YESEJY+P3ZI/+O2eI/jd TRwUoIoZQBZPPvOBjrW2hRvSaFtQ4Si8d6R4v74IjwNofW2NHlIHgi+Sb3GRpHF8qsdhNOCax1B pEIcq0sYesQHZzzrW4PnxbFLoRPHSxLg0p9gGeCCmsUuq+z6aRl5nBEZFy6WnjnDSzbsrwJhD1f HXKnduU5x6LY9l1btNVXnBGTDU05DDnpDLELytxFAzrZgoqMWdnxzKAy5lB+QekswscskRRpB7U a+Ol9HR/zRaEAo4qU5FNLaxvvmyNvH1YX2hDE++5XXRscUldhhp7nGPktOx/7Xa//YrTx866q8n vsDVJL/EvtexMdTfc5+HSpdoTCEMMKGxLcp1Jyw88TZ4hP//vxReMj+P65npMXfEKR6s= X-Received: by 2002:a05:6a20:4307:b0:3c3:7dfd:22c6 with SMTP id adf61e73a8af0-3c37dfd2500mr4604568637.73.1784202726223; Thu, 16 Jul 2026 04:52:06 -0700 (PDT) X-Received: by 2002:a05:6a20:4307:b0:3c3:7dfd:22c6 with SMTP id adf61e73a8af0-3c37dfd2500mr4604549637.73.1784202725782; Thu, 16 Jul 2026 04:52:05 -0700 (PDT) Received: from zhonhan-gv.qualcomm.com (tpe-colo-wan-fw-bordernet.qualcomm.com. [103.229.16.4]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cb258ff402asm1631213a12.22.2026.07.16.04.52.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Jul 2026 04:52:05 -0700 (PDT) From: Zhongqiu Han To: rafael@kernel.org, viresh.kumar@linaro.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, christian.loehle@arm.com, liaochang1@huawei.com Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, zhongqiu.han@oss.qualcomm.com, stable@vger.kernel.org Subject: [PATCH] cpufreq: schedutil: Publish util hooks only after all sg_cpu are initialized Date: Thu, 16 Jul 2026 19:51:58 +0800 Message-ID: <20260716115159.848403-1-zhongqiu.han@oss.qualcomm.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Proofpoint-ORIG-GUID: w3q3I7JyF8JwElW4ApZO1-W5TWwSoyJ3 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzE2MDEyMiBTYWx0ZWRfX0RBRequjnNjM HAbFGRsmzNW1+MBbiH+BJn+aTMtRCGw27L54cPAB/QglS65pIGFw16b4MqLUC2cjKuEp/qTu3rc 5ImZ28mzBPvWY1IxpRjJGnMg1cPqgCptUPaOL+P4PwDUVgR1uP6OMfzo6YHI2Vwira5DcdBcotT Ch8iBuiWfYDQ2jWWYiVvMcH/zLa+/KNnpHe8wDU315n5KcScojDPqiK+hIvaCf18lHkzHRimqPo fw+Z6HPfzc4TMhqIWDDUitt+kfmVSFk8Af6yxcAprMOec2pbougOiA45zAOAMoEHw4Dt9Ka+eag srWNSWP9QHIos2xhTJl0myYu+MbJHZlJ0Dxct42yUY5G4hXOEDkXtkWEao0qmfPhxNKJ+/Pf5Kd ucIZ3MA0AclDvt3vVGoSbV+kmHm1S4dnm9Hgoh9393fBmoD3PlM0zGop60a1SyOi8UtTD1jKFd7 E96Ei79Hya9YUp7np9w== X-Authority-Analysis: v=2.4 cv=f8R4wuyM c=1 sm=1 tr=0 ts=6a58c5e6 cx=c_pps a=oF/VQ+ItUULfLr/lQ2/icg==:117 a=nuhDOHQX5FNHPW3J6Bj6AA==:17 a=RAioF0-LDSMA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=Um2Pa8k9VHT-vaBCBUpS:22 a=VwQbUJbxAAAA:8 a=EUspDBNiAAAA:8 a=cKKUN8DYBXwKWaGdE6wA:9 a=3WC7DwWrALyhR5TkjVHa:22 X-Proofpoint-GUID: w3q3I7JyF8JwElW4ApZO1-W5TWwSoyJ3 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzE2MDEyMiBTYWx0ZWRfXylxlCVYmkxAG kDPCallUvWb72TJ6FLVUb5T33po6Kz8nM8zQFvtPpoxRZpwOMB4CzzepcuYr5bXFkhmpFdorXJf d6SS2Vrq4IbokMJ0zhmkuaQIGVQm7zQ= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-16_04,2026-07-15_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 clxscore=1015 impostorscore=0 priorityscore=1501 bulkscore=0 phishscore=0 suspectscore=0 lowpriorityscore=0 malwarescore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607160122 Content-Type: text/plain; charset="utf-8" Commit 16a03c71bba0 ("cpufreq: schedutil: Merge initialization code of sg_cpu in single loop") merged the per-CPU initialization and the utilization-hook registration into a single loop in sugov_start(). For a shared cpufreq policy this re-introduces the race originally fixed by commit ab2f7cf141aa ("cpufreq: schedutil: Fix sugov_start() versus sugov_update_shared() race"). The scheduler's util path reaches the hook under RCU-sched and never takes policy->rwsem, so the rwsem held across sugov_start() cannot serialize the two. Once the first CPU's hook is published, sugov_update_shared() may run and, via sugov_next_freq_shared(), read/write each sibling sugov_cpu (iowait_boost, util, bw_min, ...) concurrently with the memset() still initializing them, with no lock common to both sides: the update side holds sg_policy->update_lock while the init side holds only policy->rwsem, which the scheduler's util path never takes. The walk only accesses scalar members, never a pointer like ->sg_policy, so it does not crash today; it merely uses stale (or zero on first start) values that skew the frequency selection and tracepoints. It is still a genuine data race, and a latent crash once any pointer member is dereferenced there. Restore the two-phase approach: initialize all per-CPU structures first, and only then publish the per-CPU utilization update hooks. Fixes: 16a03c71bba0 ("cpufreq: schedutil: Merge initialization code of sg_c= pu in single loop") Cc: stable@vger.kernel.org Signed-off-by: Zhongqiu Han Reviewed-by: Christian Loehle --- kernel/sched/cpufreq_schedutil.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedu= til.c index dc0835ceee98..6ad080de8644 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -872,8 +872,19 @@ static int sugov_start(struct cpufreq_policy *policy) memset(sg_cpu, 0, sizeof(*sg_cpu)); sg_cpu->cpu =3D cpu; sg_cpu->sg_policy =3D sg_policy; + } + + /* + * Publish the hooks only after all per-CPU data is initialized, so a + * shared policy's sugov_update_shared() never reads an uninitialized + * sibling sugov_cpu. + */ + for_each_cpu(cpu, policy->cpus) { + struct sugov_cpu *sg_cpu =3D &per_cpu(sugov_cpu, cpu); + cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util, uu); } + return 0; } =20 --=20 2.43.0