From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 209F0CD343F for ; Mon, 18 May 2026 05:09:22 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4gJm7K09B9z2xPb; Mon, 18 May 2026 15:09:17 +1000 (AEST) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=148.163.158.5 ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1779080956; cv=none; b=QJlE9ik51CMEhNWeTpw+XAcyQT5LX2cDXUIlQd5/peH615JIAPygxKhAQ/TWQmvrfcfiw6USkFHm1zVJax5UWBhj81XvPDrA6ezFBTPhaAZN4TwMSCsMzEPynJb5F25JoZvyym7nAl3ufJ7eGLH+e+xdDq1Y0p338osXCKqe1q/Io6MUqetNqMzM5l4HbarRJdglv4CqT/m3HnNwcv9oYNlHXiYMTxONRa8W+/4urhmU/k2vbtkky5iPUGQ3MUjtLNkZqul7/hmlvi3dq3eqiRnQMwUlaEU5U0LN+RkouEEmNNN7tFkysmI/m8tfRShUOxOK4XvPDzfWw56OBQP7uA== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1779080956; c=relaxed/relaxed; bh=lMu/vpDdNx6Ekr3hpvhDe81ynMbqgAMOjfYi7vjOm+g=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DaWKD0wVxtSo3O7iUG5XdOA6i118vMaWuQeq8PXN9MhNB6ZBbBBhWnUOmLWBpA/M6NxledJUVTvtKmgInUEGs0S/gikIEV2RHxJnrv/7KDwd6IfBR5/Sa6Lru5XJlKH9c2+QzNs6BA6oDISGotwk5LBFLlQebwbvnuLNCRbYMmrXH+T2aw6oGf/Z+Og18/CEi3FqBx2X39AWozZQFJ9FY52neu8r0mB/qczShzs69t2bI7BwMxN17ozXWDBuDgbOU93R3JzIDYMgTu9OPCtv0G6Kjz5L+8PH57kITjuN683Hin6Q9eSOjGRA+cFmrgl2JYAarQwix6NhxPoxMQd9+Q== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; dkim=pass (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=Dv1yZRKR; dkim-atps=neutral; spf=pass (client-ip=148.163.158.5; helo=mx0b-001b2d01.pphosted.com; envelope-from=aboorvad@linux.ibm.com; receiver=lists.ozlabs.org) smtp.mailfrom=linux.ibm.com Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=Dv1yZRKR; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.ibm.com (client-ip=148.163.158.5; helo=mx0b-001b2d01.pphosted.com; envelope-from=aboorvad@linux.ibm.com; receiver=lists.ozlabs.org) Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4gJm7J0xbhz2yRF for ; Mon, 18 May 2026 15:09:15 +1000 (AEST) 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 64HBU4p64007147; Mon, 18 May 2026 05:09:10 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:date:from:in-reply-to:message-id :mime-version:references:subject:to; s=pp1; bh=lMu/vpDdNx6Ekr3hp vhDe81ynMbqgAMOjfYi7vjOm+g=; b=Dv1yZRKRNjSGTgevf9M1/H/S3YYID/QBq uWevtctWKgR5B9elr0UFYJP6gY1NBF9/YiZMBQL2WSsyVp5wr0bI3YO1Ny9tjWnt j1EWypNmeTR7az7dBnP/hhvjZAZPplTA/sherayvkqmTXxsOlVUb/EBUCvZb/eu0 boC9zv71LiHkBC1+SSGMXiYZdXBsD2aBhG1nLbPrQKpS9qw0ENLfTvZ59RDPXK1w nKHgLvLYmQDat6mrbuTcxgrD8u0Ma08sd5MEy7bzkXv8rozLkLsH+lbRR/OzY4A8 oilw9DpZLudHax+eEbh+KH5pFRNQNhCnKl5YS4xEPHDqMOmM/YoNg== Received: from ppma12.dal12v.mail.ibm.com (dc.9e.1632.ip4.static.sl-reverse.com [50.22.158.220]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4e6havwuar-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 18 May 2026 05:09:10 +0000 (GMT) Received: from pps.filterd (ppma12.dal12v.mail.ibm.com [127.0.0.1]) by ppma12.dal12v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 64I5931j026796; Mon, 18 May 2026 05:09:09 GMT Received: from smtprelay02.fra02v.mail.ibm.com ([9.218.2.226]) by ppma12.dal12v.mail.ibm.com (PPS) with ESMTPS id 4e72wpveyd-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 18 May 2026 05:09:09 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (smtpav06.fra02v.mail.ibm.com [10.20.54.105]) by smtprelay02.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 64I596Bc31850918 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 18 May 2026 05:09:06 GMT Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id EF6052004B; Mon, 18 May 2026 05:09:05 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 333A420049; Mon, 18 May 2026 05:09:03 +0000 (GMT) Received: from aboo.ibm.com.com (unknown [9.124.214.53]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 18 May 2026 05:09:02 +0000 (GMT) From: Aboorva Devarajan To: Madhavan Srinivasan , linuxppc-dev@lists.ozlabs.org Cc: Athira Rajeev , Aboorva Devarajan , Christophe Leroy , linux-kernel@vger.kernel.org, Sourabh Jain , Ritesh Harjani , Shrikanth Hegde Subject: [PATCH 1/3] powerpc/perf: fix preempt count underflow in fsl_emb_pmu_del Date: Mon, 18 May 2026 10:38:53 +0530 Message-ID: <20260518050855.1147242-2-aboorvad@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260518050855.1147242-1-aboorvad@linux.ibm.com> References: <20260518050855.1147242-1-aboorvad@linux.ibm.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTE4MDA0NiBTYWx0ZWRfX5UZOUDpGfQKu BKtrDEaj304LX8VOwCorLdh2KmIGSxYqU09IihmwPCZPEJPUXZVCm43xebjeBnDMJwor7K6ymu1 NFiTiZkAfewaeKv8ez64UyqLN6YndL9gWneXJid9tEhthvn9QDllBIQ7+KHNbsu9els1SWkxZSU d6psjtYY7An5oWeSzXRoPmDJtymm3gX3A17r1fJBKvoKb8hPGtWV/PNd2P5ke4qwtBG+zIYQ0Lk VTfqdH6hpWD5oZF6JG0ZnyXAPIOFiqpP6cP6flY76W1gdZ3GwrGJlQgxZG1AvVGb3oOw+5MeH5/ mP5EcvaKOakUPc7qoaZsVfDnJyXUcv+/c2CovPtY3jTtXgKgcv5j4eXM70dqjVQsU0gurrBEfUV cFv+cdU/PlvguJcj2yd1YmeOP/lAju/dU5tt/dX4TGUfr9MGwcIjgXl3AFApQ/vYBRK2NeDKU9P EIjs0fLt079TAGxBHrg== X-Authority-Analysis: v=2.4 cv=Np/htcdJ c=1 sm=1 tr=0 ts=6a0a9ef6 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=-qzNKB2iBSQ2TZesQmUA:9 X-Proofpoint-ORIG-GUID: R5OLhjrXBAEml8L4J0j_p_RnDPsppf7_ X-Proofpoint-GUID: 3xCLEy9P5J4PAMny0CBofMXUJhW9L5P3 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-18_01,2026-05-15_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 spamscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 lowpriorityscore=0 suspectscore=0 adultscore=0 phishscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605180046 fsl_emb_pmu_del() unconditionally calls put_cpu_var(cpu_hw_events) at the 'out:' label, but only calls the matching get_cpu_var() after the 'i < 0' early-return check. When event->hw.idx is negative the function jumps to 'out:' without having taken get_cpu_var(), and the trailing put_cpu_var() then issues an unmatched preempt_enable(), underflowing preempt_count. On a CONFIG_PREEMPT=y kernel preempt_count would underflow and eventually present as a 'scheduling while atomic' BUG. Move put_cpu_var() to pair with get_cpu_var() so the percpu access is correctly bracketed and the 'out:' label only handles perf_pmu_enable. Fixes: a11106544f33c ("powerpc/perf: e500 support") Signed-off-by: Aboorva Devarajan --- arch/powerpc/perf/core-fsl-emb.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/perf/core-fsl-emb.c b/arch/powerpc/perf/core-fsl-emb.c index 7120ab20cbfec..02b5dd74c187a 100644 --- a/arch/powerpc/perf/core-fsl-emb.c +++ b/arch/powerpc/perf/core-fsl-emb.c @@ -366,9 +366,10 @@ static void fsl_emb_pmu_del(struct perf_event *event, int flags) cpuhw->n_events--; + put_cpu_var(cpu_hw_events); + out: perf_pmu_enable(event->pmu); - put_cpu_var(cpu_hw_events); } static void fsl_emb_pmu_start(struct perf_event *event, int ef_flags) -- 2.54.0