From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from CY3PR05CU001.outbound.protection.outlook.com (mail-westcentralusazon11013059.outbound.protection.outlook.com [40.93.201.59]) (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 78D5D349AFA; Mon, 22 Dec 2025 22:26:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.93.201.59 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766442398; cv=fail; b=djgsP+QbLwQtqSIYlWoXO3cLD24BJXSmUvxGZE+4K8s7NatFFmvXuYfNG1stmdh5dBv4OTaNQFLMMkyP0UHZBLMGGJQ//4aWEnTRtORhIRdS1+Qd1Y+3WPT3i7z1P/xpV3GkImfnlDQt4Sh/gAJNU8gSuTczMeYPub/Go5zFTRU= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766442398; c=relaxed/simple; bh=BwzoqCm2G1SvnBb25ciSuNbSvxLkqgkS/rlxRtc3JcQ=; h=Message-ID:Date:Subject:To:Cc:References:From:In-Reply-To: Content-Type:MIME-Version; b=Uejfq5YEjAdBp6XZ9YwEvVz0/ByslNzpRLWE/rAvi5Hv0hZ5vqUVJHGVa/CPjahMceLhUPx8gtwR6vwp1TFGbLPPNQLzqZ5Yc1eFMBs+WNpLsm+KamBCLBOyPkZUc6bYEL5hkGY8JPIusRx8qvYE1T4xZ2HYw7aFK6DXyCWeqQU= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com; spf=fail smtp.mailfrom=nvidia.com; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b=DILbVDVK; arc=fail smtp.client-ip=40.93.201.59 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=nvidia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b="DILbVDVK" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=YlCSYXE0yeglPOA++Wf/ywNQwoJVDMmK6FZunICVXCze/hgRIuPu36im5YgvNHWXZAyW6xIrH3Ji3lJ4zQvFy+Q3K3R74H95uq7trAiJQL8/NnagF9C2DumyxJPNtXOCQ3m5R4Qv0HR9iMj2mJEbtwe0Ncy0GxdyR0FKUqoJ9F4iUatSNc/K77tvJieB8J9Km3NoknYgqjwqDu9TuNJzogmHesZd7rkMOL0H2pLA+KMc/nQS9S/+EdTEOWLYtMivTnYLOlEO8mqK/FjIM+s8LBUm66N8fUW8N7jmIAxTPonucl589e2GFXfbDkpHlCyyNPo4r7sG9tQXSfG4y3kImw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=yKkKQyUGHtTZtaiX8jlqe8IfNiohfdvICFYy16UnCaI=; b=riZvrOyUz0TOSO+22yz9ivmEAur/uSRSxkOEU9319nVNxS4Hqcb66Dh3qRBJVhhgxa8R9fJjVaNHBptuozQwbykti1JVfm2403bnwJG7UtfrH+xTSa7XYfqMV5td/o2fTf3hzK6aeTtTMWd8aIg7xyBEc129i43eU1/qHH48V0+OxIt07wmnDFOSv2j2P3a5RKZvD0wLfq9xveWW/RlzFml51LMrxS3zYWPNyQbvny4EvfUGru5vPvLlMlVN0BMx0zOBed47NaRcDZ8aFqOjnJGMwFHwGwmLjJ95QJYN2gIYrwH7rTbsJnLKkN5Rw5+nEHj+Fya5/M8ZhA1jKNCb2Q== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=yKkKQyUGHtTZtaiX8jlqe8IfNiohfdvICFYy16UnCaI=; b=DILbVDVKLWoJTFFvQMSa6vgraiS6RQ0E9KgrzmyYF1veyMi9Ew3MFRvGOT0TO2QWXaUzY6OJhuvYnUoldgLDvsyk2gj2U62y5msnyLMbD7PyWtY+0qh13DNCN3Ru4gpqBfm/cx+RD/OAjLjutU/CkRLtlmdmc+Q2G3azkooz9bSTUBL47htOCM48e9ru+Wm7RtjYZYbRnn1HtoXwbhaU8HBt32cu++4j+LjOoXLhJSrC65jbjXmTgGfBdoloX7roxYowSguP+UtE82w0cx14TbGl8ZH9O9pg2EOfehCNWefbRI9l8KzRzm1ttNdYbiu4buXMNGXJxu4zdBqccUOWEg== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from SN7PR12MB8059.namprd12.prod.outlook.com (2603:10b6:806:32b::7) by DS7PR12MB5720.namprd12.prod.outlook.com (2603:10b6:8:73::21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9434.11; Mon, 22 Dec 2025 22:26:29 +0000 Received: from SN7PR12MB8059.namprd12.prod.outlook.com ([fe80::4ee2:654e:1fe8:4b91]) by SN7PR12MB8059.namprd12.prod.outlook.com ([fe80::4ee2:654e:1fe8:4b91%2]) with mapi id 15.20.9434.009; Mon, 22 Dec 2025 22:26:29 +0000 Message-ID: Date: Mon, 22 Dec 2025 17:26:29 -0500 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] rcu: Fix rcu_read_unlock() deadloop due to softirq To: Yao Kai Cc: rcu@vger.kernel.org, liuyongqiang13@huawei.com, paulmck@kernel.org, frederic@kernel.org, neeraj.upadhyay@kernel.org, josh@joshtriplett.org, boqun.feng@gmail.com, urezki@gmail.com, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, qiang.zhang@linux.dev, linux-kernel@vger.kernel.org, yujiacheng3@huawei.com References: <20251222080600.201867-1-yaokai34@huawei.com> Content-Language: en-US From: Joel Fernandes In-Reply-To: <20251222080600.201867-1-yaokai34@huawei.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BL1PR13CA0443.namprd13.prod.outlook.com (2603:10b6:208:2c3::28) To SN7PR12MB8059.namprd12.prod.outlook.com (2603:10b6:806:32b::7) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SN7PR12MB8059:EE_|DS7PR12MB5720:EE_ X-MS-Office365-Filtering-Correlation-Id: f1f0f063-9559-423f-1178-08de41a926c4 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|376014|7416014; X-Microsoft-Antispam-Message-Info: =?utf-8?B?b3BHYnRQaGgvRjM3bFdWMEpIc1luYjNOS01qdkRIYjNSUW5mbGtYZWhaZ21C?= =?utf-8?B?dXRtbXBHaHZCNkNsK3QvVzFRS09qTStDVE5ROCtjQVdTeXFHUC8rSS81Q1Za?= =?utf-8?B?ck44T2JoV25oc2VkN055Q2dNcTJyZzFBV3BiSFp1Qk8vWS9yNGVMUElaN2Ni?= =?utf-8?B?WE5jVEZ1TmFKL3lDQ1ByODhiWGFuRVJEcG1iTFVkcTZocUlOWWNEeC9ySEZC?= =?utf-8?B?amU2VTNDeTlveStQVENMa3kwRXFVL2IyZ3Y3QUpNMldySS9SQXhOdnVaanRE?= =?utf-8?B?VEhmRnIrbEJueFh2VTdZVzdBOTEvT3p4K29vRk80b1BTT2hnL2U3cFkvRWho?= =?utf-8?B?VWtqMWRWcnNOa01NK210MlFJc0pQdWFjVWFMUVNLNG9DaGNqeGt6ZFJrL2lI?= =?utf-8?B?WXZCWTRsckJhZTBFakptd090ZHZTZ09oR2RlZGVxb083WU93NmorOFBYOFFJ?= =?utf-8?B?aGNpVlFoY3FzL0JEbFZLWnE3eHRHUE5tWFVDaDlBWm5veHBnZXgvWURXcnhW?= =?utf-8?B?aGlkQ2xiTGh0RUdQUWRZcTNtK3lKZXZYUzdDUGY0ZXFDR2NLL3NNM2daWnd5?= =?utf-8?B?UzZZL21zK3RkUUpQWVJVamJnWHJrNjdRak9wb3FRV1RNcEJBMGJOZmhJcjZJ?= =?utf-8?B?dGVXUjlFcU05SW11QnFRai82NGtCbTZ0VkhuOTNYRk5DZEhYUFBlZGR4NUJU?= =?utf-8?B?ZjRnRkFEL3U4TER5eUttdUVwTjZON0IrWE9yZTI2S3loQlBOWlZHenNXS1Qr?= =?utf-8?B?a21SUTFOOTNrUW9oSG55ZE9HNlpSTHNUQVJvM0h3SHlxdjVLTC8yU1VaU1lB?= =?utf-8?B?RmVRSlZqNmxXSUtpYVF1SWZDQWUyc1JlRHJPUWtqUUNTS2VzRVJFVGQ4cEZk?= =?utf-8?B?aHMyRU9md0tieUZQa1FtL2hhbXZHUG8vUlZqSVdZMC9UdVZnVzg0SFZWOFB0?= =?utf-8?B?c2hJenIzaXpMQ2U4V08yTkdHdkEwa2JCSjlreEpmd1VPWEpLNTNqcUQxUlov?= =?utf-8?B?OThXSWk0dGlQd1ZTdnl0RjJyQ1hqMk1aczVSVnRQYmlLVENUcG41cnBKaFhJ?= =?utf-8?B?dm9tQzVqRXJSYmpOclRMeThSZ1VGRWtqRFhFbTUra2t3dEdWbFVOaEdpSlNK?= =?utf-8?B?ODFNR3FKaHdMSlcrM0ZuV3ZrbTRvUElYdVpWQVVvdmNidE1pU3hhZ2RUWUN0?= =?utf-8?B?a012SFFOSThTUDY4MU5ZNytBd1dkZS9rdUM1OGtLbldFQTNYck9JOGtQWk9Y?= =?utf-8?B?MUIyOFdKTUlTQzBtMDl2dmVMSjBVVG9XN1UvbkxDa1BGb3hjT2N1YVowZW1V?= =?utf-8?B?cjdkUXlzaC9RVkNNZzBTS01tZ1F0T0ZGMjJ2VVV1RitIY1ptS1g0QmxOVUEw?= =?utf-8?B?Y0ZYZHY1d21IQ0MvUkZLRjhjdXJnVnNEbldyQVdmWWVKamVjYWQrTGF1cGlU?= =?utf-8?B?aVhMQU94SGdMVUEvVzN3amF0TlorVmkzUjB2SERxU01YZHU1V0ZUUjZBZTgy?= =?utf-8?B?aE4zc3c2QmlZb1hIck5Vb2I3ZjN0RDNzUThPR1g4REcvNExFV1pwZDhjdjRK?= =?utf-8?B?NWNKdlZXYjdFbzEzdlhiSjB1bFFLcVdPc2JjVGZpZG1pSU9UL1lIcVU4NWlF?= =?utf-8?B?N2pNWEU2VHgyemlTMExGQU5rNnduMHgyRDVMMW56VHBIcXdVSmdhNUp2WWs4?= =?utf-8?B?dXF5M01wMlJtYmszZVJXT3pPbmdQTG9lVXQ0MTdqVXExZit1NFkwclRPSkpu?= =?utf-8?B?S2tsclhKTitQWk5RTmY1UnpNWkpoU3hHdTUxejVFdVAzdWkxWGZlS0tycitt?= =?utf-8?B?MVJXa2lLTWpSc3JpYnR1ZFBwOTRrZEtEUlZzOEE2MDgrdlY1cmd0eUlsUS93?= =?utf-8?B?WExLMW1yVEtkMDBUY0ZjM1prd1hmNUVGNFVPZ2dQK0NEUjZKZzZPNWFPb1V1?= =?utf-8?Q?ck/bVu9fdpbFzb7/gWWe3izY7VGHFBlU?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:SN7PR12MB8059.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(366016)(376014)(7416014);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?dWpYWXdDSXdxWmFURUduM1lxTUx6SUtSNGhiWXVaNXpOaktXRnFDZ0loS1Yr?= =?utf-8?B?M1JoaVBMd2I5ZVNpUG1DM0s3Nmdjd2hOajNJVVFYTnRSWnJ0NTVIQVZYa3Qy?= =?utf-8?B?N0ZzTlFraHRsUUFGL0k5MVdrVnB5YjBUbHo1U01mckpBNUFwdWp0NDZueHI2?= =?utf-8?B?T0I5b3pjbkZldjNOL2I0b0dNVUxSTXRtUWovaVVVYUpET0VqUVppaXN1enZy?= =?utf-8?B?V2dldHhSeHpxaUpCdlpINlpOekxyTVRtYmdHOERXL0RiL0plMHdFTFRoSVkx?= =?utf-8?B?eGxnUHFxQjRoWkpQbExVQU5SQWFwYVcvbnFNakxYdXk5VzlPSDVRZ1p6eUl4?= =?utf-8?B?Tk9XdE9uUTU3UUd6dUowZzZhNHRoM1Z3QjJra0RiV01oQ1QwVjU3ajVRZGtp?= =?utf-8?B?aFk2WEZRbmFQM0UyN2FXS2tiTDE4K0wxMktmL1pMVGRYd1ZDb3dxbm54dFpm?= =?utf-8?B?bWVsenhxeUF4Ty90RkI2UmdNTU5sZ2N5ZHBjb0tzdVBQYzhYMEFyQjdDSWZz?= =?utf-8?B?RDBDczkxNmVhaEpFSCtvTUMzTlB5UkJqQ0puZGFHOWppa2NYc3dsTlhkRzFJ?= =?utf-8?B?WXZZWmh5aXBiazdpSW0rZG5BMC96VnU3SjFvcXdBU0xoK0QzM2dtUzlBN0JB?= =?utf-8?B?VE5BS291NU5GbXBuZGtpNUd5TjBpeFcrZ1BIOXFwRm91dWJIdUl2VlFjSDN3?= =?utf-8?B?bS9lVkNLRlhERnF0eFBQVDVpb3FVdmlTWkgvZldpVFY0V2NjUnlHdnE0RGdU?= =?utf-8?B?VVVscG80M1JobDNyUmRaTHlndnJucEQ0aVoxL3BPd3I5N3pRWUtNVkhiNnV2?= =?utf-8?B?WWlyd0lPZjRmZVFFQ2s0SXFJNTZDYUcxejV3ZDJKUTRLdm9uMG42UVFTc2Fv?= =?utf-8?B?bTh6M29TSWk1bm9kekpQNFZoQ2JySkdkVlllNHhUNjFtejNlNnhYQ1kzZXg3?= =?utf-8?B?Sk15MW03UTROV0oyTlFTbk9zUWdreHZQWGZWUmtEa2E3YnNhOGwvcUhtQWp0?= =?utf-8?B?akhUSE9naFQxUEFOUVEwaTJYZWhjTDlER3dwVjlqcy9KTlZtNjJ2NlMra3hk?= =?utf-8?B?dnpxdXJRK1AyUk5BTlUwUGs4blpZeGlpcnpTSzlKMjhJcWFHTTVaSmNsOVlU?= =?utf-8?B?L0xLdmt6eUxPSXloRWtWREpSZk1TS0tqb3l0d2NLelltaXZqMWxoQU5KY0h4?= =?utf-8?B?MEswbEdLTlllc0U3RTdrYXdmd2N0am84MFgvOU9XL09RUnU2SEYzaG52eGsz?= =?utf-8?B?RHI4T1hjbXM1bG4wejZIUDYzVEFOeE1yQjNEcUo4Tm9Ld1BNOFN6YVh6RmND?= =?utf-8?B?clRwU2pGWGxOR0x0RGpZUjZIKzJyUi9OVEFJa0s4cjhyZ1RVbDNZRnBURTZ2?= =?utf-8?B?MktGOEtHazZ6QjlWZ1VYUHJRSnJFa091eGxycGFsWkRZMHlaYVlPb3hKRXo5?= =?utf-8?B?UzdLVzVGWWFkLzBEVWhYSUw5OWIzVEZQaVR5TjFvNkhTNTc1UnRKNnluVi8v?= =?utf-8?B?OGdzaUd6cGhpRncxYkVsNCtYMUNHcHhOK3hKZFlYbzkvSTI5R3Ntdkl5bEV3?= =?utf-8?B?Sm5OMGx1RnpQVmVNa0VWVVp2QTM3Y2JYMHhuTkJZdUlXUFJzZmhNNGJidVRh?= =?utf-8?B?NnArdTNnQ3pDZ1VFMlZqQTRxREhDTkRUbERseGFBSVdBSFJJTnBETWt6a3NX?= =?utf-8?B?ZlN3MS9rSkdidkxGY1kxTUY0QS9YTEtPaVRQcGdJZVZpK1htbHBkT0xlWk9l?= =?utf-8?B?aXh1SzVJWWZIbFcwSStiZTBwMFlXL0RrYzhEbThkZG9XK3dBT3ZmN3gyWkFh?= =?utf-8?B?dVFhWVU1WXd4NmVqZjluNllSOEw3NlErUTVMaWRNenNNa1krWXBhQ0ttN0wx?= =?utf-8?B?TEhWRU1TMkdsVnI4S2NzSlhma3UvdEFmS1RGQjQzdWNJb1pNbmt1ZUtNd1dM?= =?utf-8?B?MFZxT2lsb3FHQUdPMjJROHdSSGtBaFpockdjd2M5LzhqczNraEsvaEhPayt3?= =?utf-8?B?dlZjQ1NocFdxdWExRmxKdVpKcXhzNWhSL0VSMzFFMGl5WGsvNlp1RVlPaWor?= =?utf-8?B?NitpbG9UWTZLRk9Xd2xhVFVMemVSMmsxc2U1Z0lsUnVUL1FyemM1aitGVmhB?= =?utf-8?B?ZGZsOG4vYkpGVFVnc2xPVzFOcXdjMmZOY1I4cElGaTFlMkZoT0M5K0NnbTJE?= =?utf-8?B?REtVSE83TTVRa29OOG1ZZXdxM2luLzE4Ny9OSzg4MmxqQXZBZUx4N2k4a1By?= =?utf-8?B?QjROdmhZS0FVQmo3cWFjTm1mNE5HUnkvUTF6dW03NStSelhEZHg4aGxEQzJp?= =?utf-8?B?ZVQ4YmVDWFlrNVdqa2tOcXhJNmdDOVZRMXVyazU2b0l1clRCeXR3UT09?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: f1f0f063-9559-423f-1178-08de41a926c4 X-MS-Exchange-CrossTenant-AuthSource: SN7PR12MB8059.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Dec 2025 22:26:28.9910 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: s+eb6auenDqX02maCOIGZyYXJdgQPWVo0xA1kjHMddYfZlPdCrJOILck70Jo/pf1bH2H0zZZo7MnLKYBt/WpEQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB5720 On 12/22/2025 3:06 AM, Yao Kai wrote: > Commit 5f5fa7ea89dc ("rcu: Don't use negative nesting depth in > __rcu_read_unlock()") removes the recursion-protection code from > __rcu_read_unlock(). Therefore, we could invoke the deadloop in > raise_softirq_irqoff() with ftrace enabled as follows: > > WARNING: CPU: 0 PID: 0 at kernel/trace/trace.c:3021 __ftrace_trace_stack.constprop.0+0x172/0x180 > Modules linked in: my_irq_work(O) > CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G O 6.18.0-rc7-dirty #23 PREEMPT(full) > Tainted: [O]=OOT_MODULE > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 > RIP: 0010:__ftrace_trace_stack.constprop.0+0x172/0x180 > RSP: 0018:ffffc900000034a8 EFLAGS: 00010002 > RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000000000 > RDX: 0000000000000003 RSI: ffffffff826d7b87 RDI: ffffffff826e9329 > RBP: 0000000000090009 R08: 0000000000000005 R09: ffffffff82afbc4c > R10: 0000000000000008 R11: 0000000000011d7a R12: 0000000000000000 > R13: ffff888003874100 R14: 0000000000000003 R15: ffff8880038c1054 > FS: 0000000000000000(0000) GS:ffff8880fa8ea000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 000055b31fa7f540 CR3: 00000000078f4005 CR4: 0000000000770ef0 > PKRU: 55555554 > Call Trace: > > trace_buffer_unlock_commit_regs+0x6d/0x220 > trace_event_buffer_commit+0x5c/0x260 > trace_event_raw_event_softirq+0x47/0x80 > raise_softirq_irqoff+0x6e/0xa0 > rcu_read_unlock_special+0xb1/0x160 > unwind_next_frame+0x203/0x9b0 > __unwind_start+0x15d/0x1c0 > arch_stack_walk+0x62/0xf0 > stack_trace_save+0x48/0x70 > __ftrace_trace_stack.constprop.0+0x144/0x180 > trace_buffer_unlock_commit_regs+0x6d/0x220 > trace_event_buffer_commit+0x5c/0x260 > trace_event_raw_event_softirq+0x47/0x80 > raise_softirq_irqoff+0x6e/0xa0 > rcu_read_unlock_special+0xb1/0x160 > unwind_next_frame+0x203/0x9b0 > __unwind_start+0x15d/0x1c0 > arch_stack_walk+0x62/0xf0 > stack_trace_save+0x48/0x70 > __ftrace_trace_stack.constprop.0+0x144/0x180 > trace_buffer_unlock_commit_regs+0x6d/0x220 > trace_event_buffer_commit+0x5c/0x260 > trace_event_raw_event_softirq+0x47/0x80 > raise_softirq_irqoff+0x6e/0xa0 > rcu_read_unlock_special+0xb1/0x160 > unwind_next_frame+0x203/0x9b0 > __unwind_start+0x15d/0x1c0 > arch_stack_walk+0x62/0xf0 > stack_trace_save+0x48/0x70 > __ftrace_trace_stack.constprop.0+0x144/0x180 > trace_buffer_unlock_commit_regs+0x6d/0x220 > trace_event_buffer_commit+0x5c/0x260 > trace_event_raw_event_softirq+0x47/0x80 > raise_softirq_irqoff+0x6e/0xa0 > rcu_read_unlock_special+0xb1/0x160 > __is_insn_slot_addr+0x54/0x70 > kernel_text_address+0x48/0xc0 > __kernel_text_address+0xd/0x40 > unwind_get_return_address+0x1e/0x40 > arch_stack_walk+0x9c/0xf0 > stack_trace_save+0x48/0x70 > __ftrace_trace_stack.constprop.0+0x144/0x180 > trace_buffer_unlock_commit_regs+0x6d/0x220 > trace_event_buffer_commit+0x5c/0x260 > trace_event_raw_event_softirq+0x47/0x80 > __raise_softirq_irqoff+0x61/0x80 > __flush_smp_call_function_queue+0x115/0x420 > __sysvec_call_function_single+0x17/0xb0 > sysvec_call_function_single+0x8c/0xc0 > > > Commit b41642c87716 ("rcu: Fix rcu_read_unlock() deadloop due to IRQ work") > fixed the infinite loop in rcu_read_unlock_special() for IRQ work by > setting a flag before calling irq_work_queue_on(). We fix this issue by > setting the same flag before calling raise_softirq_irqoff() and rename the > flag to defer_qs_pending for more common. > > Fixes: 5f5fa7ea89dc ("rcu: Don't use negative nesting depth in __rcu_read_unlock()") > Reported-by: Tengda Wu > Signed-off-by: Yao Kai > Reviewed-by: Joel Fernandes Thank you. I will apply this patch, I am preparing a few other RCU patches from me and others. Will send it in a series for review/testing for 7.0. - Joel