From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (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 4E3E236B934 for ; Tue, 29 Sep 2026 16:47:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.156.1 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790700470; cv=none; b=UqptGAA4b0TAqz7dieGHciKvNWjYS6xFo2tR8aQy3pVFXVE3/1FgOfBmwFoIlxP0he2bdVyBY57rZm8Xc/NpEawNuD4zxswlp4oSGSdneHI800im6qFSy44P8lPCxkrsSD57rdx+WTZ+nrBGSgBC9e2Xk+ICuxEq0d3OGUQiLN0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790700470; c=relaxed/simple; bh=N9BsgCfXNS6LgrDy+6OUjxhiGTmVw8ZoB8nAhYxzmSY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=WPbY5xBYYVohTljf7OYv3jXq3WX/X99wwpbxkJez0OZMRNgUcvsTIzFlNv32dweWVWD2XLEBIYFibNVGMgbxMB3GcvDveELOl9D8CpqJX5zSv2Y8g84jpUNHUxTeWolMIPYXnFFw9A21mU9pa0rzGJovsKfWSXvR4++UkqN7weE= 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=BsoIpDHf; arc=none smtp.client-ip=148.163.156.1 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="BsoIpDHf" Received: from pps.filterd (m0360083.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 68TB5M1e4059995; Tue, 29 Sep 2026 16:47:32 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:date:from:message-id:mime-version :subject:to; s=pp1; bh=VoVozP49h13sqmExeIlGReg/E2LYwmRl9ePEfAxbI ao=; b=BsoIpDHfrocRF3+HJiNz/MZvPxTbjYca8NJZ1UNvklq+8E0aVnMucFo0t y20LVX2GubuQ7zwjtoUHDoL6/gtCTPrRqXf37u5xLdJjV3b9s65MRyxEbo7hxjJz 96d7m5hec3hE5lJMZahIGVzVu1WHeVowD6aAldS70mYoZ5MtpZqLFPkgs3uRqUHD lRJIxc7azuMLf2C0JRuBJIV8AQW2425cQTXfdQqU8my94akKZMTDLoVzgN/NNfO0 5aIxSTA8aWeJ/EZBsEoo16kMiRuNclRM0QF+weew015EDAtqyL96rgI6WwhqF8FE fhjpS45dtF7a7LQ6shRL6NywuO5EA== Received: from ppma22.wdc07v.mail.ibm.com (5c.69.3da9.ip4.static.sl-reverse.com [169.61.105.92]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4gx5j589qb-1 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Tue, 29 Sep 2026 16:47:31 +0000 (GMT) Received: from pps.filterd (ppma22.wdc07v.mail.ibm.com [127.0.0.1]) by ppma22.wdc07v.mail.ibm.com (8.18.1.11/8.18.1.11) with ESMTP id 68TF1t9D1617010; Tue, 29 Sep 2026 16:47:30 GMT Received: from smtprelay07.fra02v.mail.ibm.com ([9.218.2.229]) by ppma22.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4gxrrwapfb-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 29 Sep 2026 16:47:30 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (smtpav02.fra02v.mail.ibm.com [10.20.54.101]) by smtprelay07.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 68TGlPoc51380610 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 29 Sep 2026 16:47:25 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BF1032004B; Tue, 29 Sep 2026 16:47:25 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A0C9820043; Tue, 29 Sep 2026 16:47:20 +0000 (GMT) Received: from li-7bb28a4c-2dab-11b2-a85c-887b5c60d769.ibm.com.com (unknown [9.124.214.246]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 29 Sep 2026 16:47:20 +0000 (GMT) From: Shrikanth Hegde To: linux-kernel@vger.kernel.org, mingo@kernel.org, peterz@infradead.org, llvm@lists.linux.dev, nathan@kernel.org Cc: sshegde@linux.ibm.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, tglx@kernel.org, yury.norov@gmail.com, kprateek.nayak@amd.com, vschneid@redhat.com, iii@linux.ibm.com, rostedt@goodmis.org, dietmar.eggemann@arm.com, elver@google.com Subject: [PATCH] sched/core: Fix context analysis errors in non-preferred CPU push Date: Tue, 29 Sep 2026 22:17:12 +0530 Message-ID: <20260929164712.1054883-1-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTI5MDA2NiBTYWx0ZWRfX3dROm87Wfw4p Ii+87R6zSfmt9mNjDivd6PUIlUC8XDQOS3ZmHUmRd704y3dbiBk+ngLf/7C6CHZeS4rKHE1gyfU j74pdR9YRARUqafyoL+xE3cGM3YDM0s= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTI5MDA2NiBTYWx0ZWRfX3koUZ/pNmXMb E3HYk1brGDS/VwQfuKSp8gUzGeK2iW8vXr2T45Aqos1erqIEV40DIA7UXjRdPvRSSeZrilhRefk VAdroQv5ToYwGIR1Vd62dktTAFoz9q1kPx2zD761Zi3IOYC4sI9bMPrKyGyE6TApItOTgaCDylW NqOVRVPZLxICN+wua+HWyKL7okIo0cQ3AAUUn5H3yMwh8BVyYgawg5lftjY1j5XrzjxmR3BGJaE xat+Uew3YM+owC7AnzTZ+Wz8jatFQJxceyfklvvbZCJMQfl3wQ6p39mqH+5y21MA1HpDRVuSVTc jTaobiI7s5aVZ1QK4/slDumVkYzzeZY9jHB5rf33ylmelv9OWz3JA3B2RON9WXRaQ0oLNhBvbpt sFc0ntHp8kc52Lx1O9C2ZZxmYUNe1oaakNOU+BfN2aJGUp2go1+bUxJyxhi3s1IfJcK/uHKPDm0 KcCJOPh5egFFPHUlqBA== X-Proofpoint-GUID: xRmHktG5Ks4uYC-49UnQekYhqAeS6FN0 X-Authority-Analysis: v=2.4 cv=RKcmjIi+ c=1 sm=1 tr=0 ts=6abbeba3 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=_XkI2SlThOc_OxJ9TIcA:9 X-Proofpoint-ORIG-GUID: QNcRT8z7AX3TpUa2h2SumYlU8z71b8f6 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=2026-09-29_04,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 priorityscore=1501 spamscore=0 bulkscore=0 impostorscore=0 adultscore=0 lowpriorityscore=0 suspectscore=0 malwarescore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609290066 Nathan reported build failure with clang23 when CONFIG_PREFERRED_CPU=y. kernel/sched/core.c:11298:3: error: releasing raw_spinlock 'rq_lockp(rq)' that was not held [-Werror,-Wthread-safety-analysis] 11298 | rq_unlock(rq, &rf); | ^ kernel/sched/core.c:11303:1: error: raw_spinlock 'rq_lockp(__this_rq())' is not held on every path through here [-Werror,-Wthread-safety-analysis] context_unsafe_alias(rq) was placed after rq_lock(), by which point it had already associated the lock with the original rq alias. Move the alias barrier before rq_lock() so that the changing rq alias is accounted for before acquiring the lock. Fixes: 74699f56ebcf ("sched/core: Push current task from non preferred CPU") Reported-by: Nathan Chancellor Closes: https://lore.kernel.org/all/20260929121838.GA1814129@ax162/ Signed-off-by: Shrikanth Hegde --- base commit: tip/sched/core 1fb28c664a19 ("virt/steal_governor: Enable the driver") kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 0bb86a43a592..23677d76f9d2 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -11283,10 +11283,10 @@ static int sched_non_preferred_cpu_push_stop(void *arg) * safely bail out. */ cpu = select_fallback_rq(rq->cpu, p); + context_unsafe_alias(rq); rq_lock(rq, &rf); rq->npc_push_work_pending = false; update_rq_clock(rq); - context_unsafe_alias(rq); if (task_rq(p) == rq && task_on_rq_queued(p)) { struct rq *dest_rq = __migrate_task(rq, &rf, p, cpu); -- 2.52.0