From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from SJ2PR03CU001.outbound.protection.outlook.com (mail-westusazon11012025.outbound.protection.outlook.com [52.101.43.25]) (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 4C1AD289E17 for ; Mon, 26 Jan 2026 20:22:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.43.25 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769458979; cv=fail; b=bGpIcTtVdI4lV3pIR8FRQBkG2WZxDO+rqwfPD7Xg1z3Ihv4pHlW/pWQLCdq8vcA7ZkFhU/iol9F21wcZuWjf1N6v0ILHjE4q1YME10wucj6J0/ap/9rljNzrm7YmbpFtNfwBiat86+XxmqH3Zknp7FGPgMoWA4h4Gms1Zftwg8o= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769458979; c=relaxed/simple; bh=/nVB45w/nMykig0Om1R7B+y+9fSV0eHRn/oEBW91dBI=; h=Message-ID:Date:Cc:Subject:To:References:From:In-Reply-To: Content-Type:MIME-Version; b=Ifhi6YJ26ff9n7gNUVNgtUdWp6vHr87EAh/op/UzxvNv6DfLkxALZEIlHCqcBtd+jywMRC+Md61dPOruBz92x8aVoiQh5Q0CkfijBAA8uzhba1TXiwF3ZvHIrQz6aprD9wbU4BuKCeG5NGQJFP46eICuPvrg7BJRP8TStcT3aCo= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=citrix.com; spf=pass smtp.mailfrom=citrix.com; dkim=pass (1024-bit key) header.d=citrix.com header.i=@citrix.com header.b=o4+rnOd0; arc=fail smtp.client-ip=52.101.43.25 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=citrix.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=citrix.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=citrix.com header.i=@citrix.com header.b="o4+rnOd0" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=aDpOyZ4Co0Vtmf3N3eyOyGvYtb/Uub5QimEyHLHRZzKMQH3ELvO/h9xoioLQlQDyxsZNbjZE2gyMrwiCimxAXoMOOhxkWLpf1s5ysSR/MlU06jJmC1D/GM8j0KaCiKjnEiggeUz6d/tEtxo8Cvf2cNtH8mNaH6cIDduQX2TfTgd2FejE6x+tYi9ojPShPayTq+VZ/2Q5jYY+kzC54Kx476Z85BGl3nVSy9ihqSWwb5jXdv8q9k/8razt3and0UgmyXFIXU1NVaypL+3o2SB7ojaotqT/oqOkPxq2ZzzNPck7v+JLSx1QPIIw7zC2+LisE3bFQsYesD5VicJ4KfnDjw== 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=fqhYYn3ujR4c++rTS83m6BGQ6U+TphxnYmxzE34q9m4=; b=PXDCMuvsuy0VvJN0Dyj7dr602R9fQLg6qbZEBm08YUWdaxekB7QN/8DPZpPqAhC4rNcfbHdy1r2xRCDXFr3ccImlMxfhKzndgpKNwT8RX7HC3T8eDMufQZ8M21KBXKvHFWmOZeyZYa4nDUheF11apDryUe0ALv1hoaD8x5y9hvB0bWKB9tYgS7kPNsO4O69WLNt27JkoOKNLQQSqLB2xsMQfEhW4QdD652GYaKtXXKqrw7ESHqNCYyGIyEpGpIld2T6aT70sNcEAOILwjDply2auFu/JX7h0xsGJ8w2wwMgK0Sh51b1XDVxO2OXI2ZsHUeQmAQGJ1hgnidW+TIkHUA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=citrix.com; dmarc=pass action=none header.from=citrix.com; dkim=pass header.d=citrix.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=fqhYYn3ujR4c++rTS83m6BGQ6U+TphxnYmxzE34q9m4=; b=o4+rnOd0pD6fIdxC3NvBcOYgj7+VLxhyrj5AJAgKhPHOt50ubOtvVG80ZTfZWSfTlBAOwoLnBtQ8wdCZIVSAAefOj37vFBcCHDT2uVammobvuPrNYFeefhmq8B2rdsclJRGk11fG5sDZri4BmoHs+jrv+dCcboB/AEiQhLTaQyM= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=citrix.com; Received: from CH8PR03MB8275.namprd03.prod.outlook.com (2603:10b6:610:2b9::7) by BN8PR03MB5122.namprd03.prod.outlook.com (2603:10b6:408:da::24) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9542.15; Mon, 26 Jan 2026 20:22:51 +0000 Received: from CH8PR03MB8275.namprd03.prod.outlook.com ([fe80::a70d:dc32:bba8:ce37]) by CH8PR03MB8275.namprd03.prod.outlook.com ([fe80::a70d:dc32:bba8:ce37%4]) with mapi id 15.20.9542.015; Mon, 26 Jan 2026 20:22:51 +0000 Message-ID: <6adad05f-bd56-4f32-a2d5-611656863acb@citrix.com> Date: Mon, 26 Jan 2026 20:22:51 +0000 User-Agent: Mozilla Thunderbird Cc: Andrew Cooper , Andrew Morton , Marco Elver , LKML , Alexander Potapenko , Dmitry Vyukov , Thomas Gleixner , Ingo Molnar , Dave Hansen , X86 ML , "H. Peter Anvin" , Jann Horn , kasan-dev@googlegroups.com Subject: Re: [REGRESSION] x86_32 boot hang in 6.19-rc7 caused by b505f1944535 ("x86/kfence: avoid writing L1TF-vulnerable PTEs") To: Borislav Petkov , Ryusuke Konishi References: <20260106180426.710013-1-andrew.cooper3@citrix.com> <20260107151700.c7b9051929548391e92cfb3e@linux-foundation.org> <20260126195431.GDaXfGd9cSwoH2O52r@fat_crate.local> Content-Language: en-GB From: Andrew Cooper In-Reply-To: <20260126195431.GDaXfGd9cSwoH2O52r@fat_crate.local> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-ClientProxiedBy: LO4P265CA0144.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:2c4::17) To CH8PR03MB8275.namprd03.prod.outlook.com (2603:10b6:610:2b9::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: CH8PR03MB8275:EE_|BN8PR03MB5122:EE_ X-MS-Office365-Filtering-Correlation-Id: 0f0ec4ac-9bf5-4135-f033-08de5d18add7 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|376014|366016; X-Microsoft-Antispam-Message-Info: =?utf-8?B?SDRJTnJQMWpuMURvZ0hYKzhOUk52VDhYMHNWZDAxL3EvQlAxZ0NpWHN0aHpZ?= =?utf-8?B?LzJJMEdtdERoRmZMeXVOdnIvb08yWWxyNkpZTVFmZ2ROVjNiZERMc0NYc2lL?= =?utf-8?B?cCtjOUdoTHlRanhyOGR5eUc4OFhwc1NmaEs2ek54TWZsb21RU0gwR0VjRitB?= =?utf-8?B?K09qMVlWYllhNTNHcEthcDBrQmlQYStFN0dhTnY5R0xBYUF4WE42ajBkelZR?= =?utf-8?B?UXVCdlMrUTY4bHlIZmVBVVBtcmpld0ltVUdpZ2JmM013czNvaGJEVHlpdWwz?= =?utf-8?B?VjJMWW9VeTNsT3ExMkxiaHhSNVEvQUtGR1F0UUU2ckhYZHJjYUp0NDZsd3pP?= =?utf-8?B?KysxazBNamhuZk9HSUUrcmR1VkVKaUxNNVlwWHk2aTRjNGZrZDRHM3dUWkRE?= =?utf-8?B?L3I5QWgrdVFzV0hhU2pxT3BHaG9lcVNBMjNNa0M5OUFQeXlxWWNtdmpPUkNX?= =?utf-8?B?VHZBZTJDbnU2QUEvdHhyZWQza21NSks3a1hLZ28zc1h2V1h0WEViaFN1TXhJ?= =?utf-8?B?eU5RNGxqMExyR0k4U2dHNFBpMDkzaFAvVXZBTHZHckRPc1hhMm0vYVJaRUYz?= =?utf-8?B?VjR5MW5ma3ZSUkFLNDMvcklOZW5zbXBGbU95cEFpYmwyOFVxRXFvQ1gwdzhQ?= =?utf-8?B?c3Q0Y2kwV3ExVGdKZlV0c1VFVU1JTy9hVkFsUFloditCMWlhVC9VZ0ovUDEr?= =?utf-8?B?UVJpb0JyOVRrc1pmeWRnbFFudkE1L1QwSG95ZGRVVHlLcXJDZ3NBK3ZsbFQy?= =?utf-8?B?OVNrYVRhYVFzNDFoaS8yZDVFM0Zab1MzUldQeVMyd0o5L25YYndhOTdSRlNj?= =?utf-8?B?TFRubDZkUXFFQnRET3p4OWRTOFNMOHNla3lLeE1pVXpzMlhRY3dmbXA0Yjg4?= =?utf-8?B?WUdIbmV3d3VMS1o5L0xVbVg1b0doOEl1S2dmM0Q2Znhzc3piYzBYZFN0Qm5F?= =?utf-8?B?T09TR0dZM09MTVl5MmV1SmxadndCNTg4VkMxRzF6MlVEYTVHZis5bUM4SGZ0?= =?utf-8?B?a01ydC81RG1UYzZ3bkkrQ3RMZmNLdzZiV083eUlDN0l5UkV1OEVaZDNrd3JW?= =?utf-8?B?MUh5MEN1OFFMSXI3YlNZRk51b0IveTRydkhac3pXc09sdWxZbUVpN3daMlF4?= =?utf-8?B?eWtlMDlZdkRGYzQ1WGVzZ2tZajZIZkhabGo1SVlMUTB5UGdJMGowMnozd2pm?= =?utf-8?B?b0ovRjN6N3RaeTl5QmVBRjZ4bzhaSjQwc3pMOXp4SHltSVhlVWFDckg4dmtn?= =?utf-8?B?YmZFalBZWTVmRDNIUTVyV1BHNE1jb0lyUkwzSDRxN1JaSmprdCtSN1JGUTBW?= =?utf-8?B?cWdyYXYrZi9oNmJtcW9sY04rVVBLUW5YRUxJcWhSd2VacUMyMWFHeWVEWHhz?= =?utf-8?B?SkY4QVp1WmVKcTJZanJhclZDYkxxNnhLMUxMVjZyelo0dTBBamtYdm5KdmE0?= =?utf-8?B?cTN3RkxHNHVocGlSQ1M2SDJKR2VWNWZrZ2ViaFpkcmxUZWxFQS92R1Q1QytO?= =?utf-8?B?ZFJIVDFHZ2pVV1I2Tk1MbkJyR0Y2VTIyMmNoZmFteTFsRTkzdFlLVGRtZXlL?= =?utf-8?B?N3ZiWEJjRUZ1bEk2RHkzMWZEa1NsMVpzQWozNXdIRUNHeDBaUTlGeC85ZE1Y?= =?utf-8?B?aVplNmpEMHR0azcwK291d1dvZU9lU3R0NFkra3IvYjRSS0JEM1VFcG5FV01J?= =?utf-8?B?dyt6NER4SjdQZmQvTVhHSW5ISzAra3l6NnA0SmRJaU55aFVpQnQxcXVkelZF?= =?utf-8?B?REZQdVE0Smd4NXBCUTNGMTBkNXYrRFF4aHpCbG9PaFp1WWoycU9jVnQ2czh5?= =?utf-8?B?Y2V5WjBWVzYyQ2hJeXdEMzF5SzJEajN6UHYya3dGa3JZNVRVZ3Q3UlhyWlh2?= =?utf-8?B?WWR5OU9oOE1LYmtrOUJvS2YreGMxdUJlV0hJMzVVcTE0THd1RnA2TVhNc3B5?= =?utf-8?B?NTNaMUNESDdiNHAwVnRlb1p4eEQ3dDNmM2NKTjI0b1A1aVdpalFSOEVYM0FX?= =?utf-8?B?S0FjejJPa1NGcTRzUW12Njh0dW53VElaZ1V1TW9IVUlHa2dRMEczOG5HYmUw?= =?utf-8?B?bTRicXB2ZUZUQjRPcndJY05MK0VBUERuOVl2SWpHQ1J6MGRmb0hVUkozTVQy?= =?utf-8?Q?1rZY=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CH8PR03MB8275.namprd03.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(7416014)(376014)(366016);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?NDI0TUhqYm9JN1lyTzNmS2Z5NFFDeVp3ZE1OK3ppZzNvaEM0Z09ubUpBZjRK?= =?utf-8?B?TzNHbDhCRmZDOUsyRzJJaFNkZ28yRmY3cmFWUUJVbWRBSzFYejN0RjExMUtD?= =?utf-8?B?Q25IK3phUC84SFoxZlhuK29IcGRZaVZNd1BURUJpbVhDNi82NXZhMi9nbXVt?= =?utf-8?B?VnVzRDdIR2ttZloyZUdZOXo0Y2Z2MnFNcFJockxKeUZnSlRXV3BKVEZ6dlZp?= =?utf-8?B?cEl6VkJkTUFFSG9jYkw3V3hvUitaL2E1WlBUbkZhNlh3dWthYm9najB2WWp6?= =?utf-8?B?MU1lTlJ6Q3RRMmZheGxaNEJLT2loU0pIY0NHNmNQRWJnT3htUHZ1TEp4ektX?= =?utf-8?B?QzBOa2QwYVdwRnNVOFlSdnB0VzR1SWlLSytOTWY0dGFkTjFQNmxPYnh2RGVC?= =?utf-8?B?azRMOXo2TFRNQzVucnU5VGRPQVR3aDh3a3gvOVNZdWNHSDlIUUNYUFNBMVk5?= =?utf-8?B?eFFoK0h4a01kMUdsakNRdVJnTFIyY0swaUsvZHV3N0IwY3MxYkZIblF1OTVR?= =?utf-8?B?UzVWZE5CTVRlcWdzODhvNnhicXlwempYNkphanBNTkJaemRnNFhoWkhQN3NT?= =?utf-8?B?MWI3MC9vNWlyOHVGclFRWW9GWWpPejNxQzhzalRwNG42bWpodEFvK3lNTGVB?= =?utf-8?B?RklTNTEvSCt6VktweHdFNExNVmJmUmM2M3luT2VpR2FBeHdBT0pZNnowLzlG?= =?utf-8?B?a3BtRTVvM2RPRE55elZFN3R5WGlKWTloK3UzcC8veTNnR0NpYk1HUktjcXVB?= =?utf-8?B?UGpadzlTK0xBSy9DL1hBWkVBSHRoTUV0TFNTMXBIeDJpWnlCUTdlYVhjSDdR?= =?utf-8?B?RnJWVExBZ3dnOVRSMXNjdlpPNll3WmNDd3NWSDNKRmFJSEd1Q1VOY2ZqTWty?= =?utf-8?B?VHlCOVErTFRxaTlwY3VzV2s3VXYycHJua1ZmeHN2MDBhUmRHeXlud1Y2RGFw?= =?utf-8?B?aXBaVnBHeStmMGZ3NkVZR0pZVGhDSGs0Smt3SElEVWFIZmx2MWRXVmYwSitJ?= =?utf-8?B?dFd5SUh0N3pWeXQvRzhrVFJpdTN0Q1FLdXh0VGlKamFkb2xDNGprNTJSc3Zr?= =?utf-8?B?SFlSeW5rLzdHMHJlUy9ITWt2RDZFRnU3MllpUzlVV0dvdCs2Q2xUNDJFL0J4?= =?utf-8?B?WFVlZ29jbDc0VlUrcS90aU5sN2Y2TS8wN2hWeGI2bXlpZHdrVVg5SHA5WUxU?= =?utf-8?B?L1BadlFHYUFtQS9vK21lTlc1OGVEWDNRZTUwN3VCL1RYNlRQRUxOeURWcnd5?= =?utf-8?B?blhUUVhWVWJkNW9oYzJvNzBpbnlwOG9WSllNZCs0Y1BqTEc1MTlXbW1JWlgx?= =?utf-8?B?djdsWjNUbm5OVzh4YzFIWjBzR1V6OHpmRUNXeTVOcTd3WmdUcWFCUGgyeUdI?= =?utf-8?B?K1RoUnJORXIvT2VvOGtNalUxNzA5K3JyVVRNVHNWNEtETFozbWI3bUZhN2lK?= =?utf-8?B?YU5YWmRnd1J2Qk1nKzZGZ3lLb1ZPeWU5UVU0L1ZHQlRIVnBabWlqREhDL2Vz?= =?utf-8?B?UzU4KzVxUFJEOXliL3J6c1U1VVRGR3U0ZDhJTjBDanRaOGs5SSttN0R1Ui83?= =?utf-8?B?cGlFVkRUOGdVNSs2YTJnUmlKOTBxOGdCc3ZlcG5Qa0tJOUs2a3UyWUJyWjBI?= =?utf-8?B?QkxoaFBuRFNwK0NkalROU05vTTJjR3UrZmhMbFl1NElnRGVrMXVzbGJLYkJa?= =?utf-8?B?NklCNFIzTmtFYWFwQWxYY0dyNnZnZUNnU0F5UW1URmJTdUUzdUpWdlQxVE9B?= =?utf-8?B?NzRsTFVHVDdrYjVIQmsxVWJUbmUwUkZBMmZxVHdwelg1b1pJdkVYZGNRc01X?= =?utf-8?B?UjhnVllJNnBlWll1elJiSkQ3REZWK2IxRjB3TlFEZFNoL3RaanduMnFvTjY1?= =?utf-8?B?azJxandManNyUDhNVG9LL1VHUnFXWWZZU1E5NjM4d2NZRmtuMytLek5neUZW?= =?utf-8?B?MCtjR3Y1aXRhSnlUVTdGcnM5Zy8xeUlPNDVFcUlUSnVvUXBlbCtGa01POHk3?= =?utf-8?B?NDQyWmVYUmhjWHRNUmxueFNXRGhVMnRrVHQ1QklHZER5ZlA2Z2ZrQ3Y0clpK?= =?utf-8?B?NXNMMTJ4ZmdJSmlkdEUrOVJ2Tmp2YnBMVnBLV1lvd01ydWxOYjZqaXpGbVhq?= =?utf-8?B?MldEdm9UYVZ4Y0JJcHhBeWZnSTZncWlKYzhUVnpIak1ubHJEQXlVNGExeHhx?= =?utf-8?B?WFR1eWVETkQvcDM5Njd0VmJJeXg2YXYwMlhFTHRNd2hnVTMxdGJIMm1FV21V?= =?utf-8?B?amlQNUxtSFpqdVpGbU5qWE8rRkY1c0h4bHNmTGpEbC9wSGRLWnhiTHBtQmVx?= =?utf-8?B?QU9ZRDgyay9lT0R0dldodWNjekZ6aVFPTGxuVWdZOERDYmxNNktFdz09?= X-OriginatorOrg: citrix.com X-MS-Exchange-CrossTenant-Network-Message-Id: 0f0ec4ac-9bf5-4135-f033-08de5d18add7 X-MS-Exchange-CrossTenant-AuthSource: CH8PR03MB8275.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 Jan 2026 20:22:51.1024 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 335836de-42ef-43a2-b145-348c2ee9ca5b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: Q9IXVYikJ+2N0z8QQGkw4V24ePnTeFuqYK9jvJ2md0f0PCLnvc4SCzK39fQan2bo4gHoFrXIy5wCRj8M4NeSwSathy3IF0fiO0eeyz8FNlI= X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN8PR03MB5122 On 26/01/2026 7:54 pm, Borislav Petkov wrote: > On Tue, Jan 27, 2026 at 04:07:04AM +0900, Ryusuke Konishi wrote: >> Hi All, >> >> I am reporting a boot regression in v6.19-rc7 on an x86_32 >> environment. The kernel hangs immediately after "Booting the kernel" >> and does not produce any early console output. >> >> A git bisect identified the following commit as the first bad commit: >> b505f1944535 ("x86/kfence: avoid writing L1TF-vulnerable PTEs") > I can confirm the same - my 32-bit laptop experiences the same. The guest > splat looks like this: > > [ 0.173437] rcu: srcu_init: Setting srcu_struct sizes based on contention. > [ 0.175172] ------------[ cut here ]------------ > [ 0.176066] kernel BUG at arch/x86/mm/physaddr.c:70! > [ 0.177037] Oops: invalid opcode: 0000 [#1] SMP > [ 0.177914] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.19.0-rc7+ #1 PREEMPT(full) > [ 0.179509] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 > [ 0.181363] EIP: __phys_addr+0x78/0x90 > [ 0.182089] Code: 89 c8 5b 5d c3 2e 8d 74 26 00 0f 0b 8d b6 00 00 00 00 89 45 f8 e8 08 a4 1d 00 84 c0 8b 55 f8 74 b0 0f 0b 8d b4 26 00 00 00 00 <0f> 0b 8d b6 00 00 00 00 0f 0b 66 90 8d 74 26 00 2e 8d b4 26 00 00 > [ 0.185723] EAX: ce383000 EBX: 00031c7c ECX: 31c7c000 EDX: 034ec000 > [ 0.186972] ESI: c1ed3eec EDI: f21fd101 EBP: c2055f78 ESP: c2055f70 > [ 0.188182] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00210086 > [ 0.189503] CR0: 80050033 CR2: ffd98000 CR3: 029cf000 CR4: 00000090 > [ 0.191045] Call Trace: > [ 0.191518] kfence_init+0x3a/0x94 > [ 0.192177] start_kernel+0x4ea/0x62c > [ 0.192894] i386_start_kernel+0x65/0x68 > [ 0.193653] startup_32_smp+0x151/0x154 > [ 0.194397] Modules linked in: > [ 0.194987] ---[ end trace 0000000000000000 ]--- > [ 0.195879] EIP: __phys_addr+0x78/0x90 > [ 0.196610] Code: 89 c8 5b 5d c3 2e 8d 74 26 00 0f 0b 8d b6 00 00 00 00 89 45 f8 e8 08 a4 1d 00 84 c0 8b 55 f8 74 b0 0f 0b 8d b4 26 00 00 00 00 <0f> 0b 8d b6 00 00 00 00 0f 0b 66 90 8d 74 26 00 2e 8d b4 26 00 00 > [ 0.200231] EAX: ce383000 EBX: 00031c7c ECX: 31c7c000 EDX: 034ec000 > [ 0.201452] ESI: c1ed3eec EDI: f21fd101 EBP: c2055f78 ESP: c2055f70 > [ 0.202693] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00210086 > [ 0.204011] CR0: 80050033 CR2: ffd98000 CR3: 029cf000 CR4: 00000090 > [ 0.205235] Kernel panic - not syncing: Attempted to kill the idle task! > [ 0.206897] ---[ end Kernel panic - not syncing: Attempted to: kill the idle task! ]--- Ok, we're hitting a BUG, not a TLB flushing problem.  That's: BUG_ON(slow_virt_to_phys((void *)x) != phys_addr); so it's obviously to do with the inverted pte.  pgtable-2level.h has /* No inverted PFNs on 2 level page tables */ and that was definitely an oversight on my behalf.  Sorry. Does this help? diff --git a/arch/x86/include/asm/kfence.h b/arch/x86/include/asm/kfence.h index acf9ffa1a171..310e0193d731 100644 --- a/arch/x86/include/asm/kfence.h +++ b/arch/x86/include/asm/kfence.h @@ -42,7 +42,7 @@ static inline bool kfence_protect_page(unsigned long addr, bool protect)  {         unsigned int level;         pte_t *pte = lookup_address(addr, &level); -       pteval_t val; +       pteval_t val, new;           if (WARN_ON(!pte || level != PG_LEVEL_4K))                 return false; @@ -61,7 +61,8 @@ static inline bool kfence_protect_page(unsigned long addr, bool protect)          * L1TF-vulnerable PTE (not present, without the high address bits          * set).          */ -       set_pte(pte, __pte(~val)); +       new = val ^ _PAGE_PRESENT; +       set_pte(pte, __pte(flip_protnone_guard(val, new, PTE_PFN_MASK)));           /*          * If the page was protected (non-present) and we're making it Only compile tested.  flip_protnone_guard() seems the helper which is a nop on 2-level paging. ~Andrew