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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 62070E77188 for ; Thu, 16 Jan 2025 05:58:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C1F8F6B007B; Thu, 16 Jan 2025 00:58:52 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id BA7ED280001; Thu, 16 Jan 2025 00:58:52 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9D39E6B0085; Thu, 16 Jan 2025 00:58:52 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 7BC266B007B for ; Thu, 16 Jan 2025 00:58:52 -0500 (EST) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 2887643825 for ; Thu, 16 Jan 2025 05:58:52 +0000 (UTC) X-FDA: 83012261304.06.5D7E3E2 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.18]) by imf01.hostedemail.com (Postfix) with ESMTP id 18F3A40003 for ; Thu, 16 Jan 2025 05:58:47 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=UDo932NC; spf=pass (imf01.hostedemail.com: domain of vivek.kasireddy@intel.com designates 198.175.65.18 as permitted sender) smtp.mailfrom=vivek.kasireddy@intel.com; dmarc=pass (policy=none) header.from=intel.com; arc=pass ("microsoft.com:s=arcselector10001:i=1") ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1737007128; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=eLBNDRgvC3cFpUNSk/UbGEQJDeup/98oznfAvJqjYs8=; b=p+xLuCKLMzKX7dJuH9YV0zbeU49MI3crygkhUEofKw4KPndMRyeqGeDzBEpxKHvXYbKJcc cm5kJu7Umfufc3K2t3WvUluTHNxamZ5LBwaGvGO4MZ/skAdS0OcXFhAObvdXkVW5uF6qE3 tgRWYhvTLyk9Yslg+4vwAUDJyvtQIhI= ARC-Authentication-Results: i=2; imf01.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=UDo932NC; spf=pass (imf01.hostedemail.com: domain of vivek.kasireddy@intel.com designates 198.175.65.18 as permitted sender) smtp.mailfrom=vivek.kasireddy@intel.com; dmarc=pass (policy=none) header.from=intel.com; arc=pass ("microsoft.com:s=arcselector10001:i=1") ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1737007128; a=rsa-sha256; cv=pass; b=d8c1sk+dGyQ2wTnGirf+1o92PTrdBd/8cNEQB3dpil6HJ3z35p7XQkGkJJq8MaWUTYsSps hjFG3XwXt94YC1xeeitJhqyqjyq/aILvL5EJDSNyC8iH2BgtiyyzchUUOEa22zHTkUq854 aASf58gsGHG+GqMYp1WnPKEbVhQpJp4= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1737007129; x=1768543129; h=from:to:cc:subject:date:message-id:references: in-reply-to:content-transfer-encoding:mime-version; bh=xQaYDVB47u2jat6WJ5AqHmbI5tDO4BmXKFNbKA0DSOM=; b=UDo932NCsCRpbNqypxbgryDU6kYsMhSTo/+ds3dFPOgl9Jbm+eIjFHHr taznnKMwBbRMGso65PxERbVhZiiuq3jIX6ISS6gTsvFfUuINl877euLn7 bk3ZW848nNy2oenBMqlUeMsvRNxwSIFmQyPEFr44y7c225IA7eySCS9SO FjI3TtVrQeqRENh3xzPX17uLWF11sh01M5Z/J+uRWV0eVY11xXtIby6E5 a5Il8xKUN7YE+K/V/1dUqYT0GT5DJXESaXt/VVX4+2ex/ek62wTWeRZ7O o4htIOAbXHLVTqxRwQd+oRBcTcs1Q93MyBLZsQxk4PXHaqBXzsd1XEKoS Q==; X-CSE-ConnectionGUID: wwCe+bbdTf2y1qaZVyXHTw== X-CSE-MsgGUID: eqluXpoyTqig6hhn+jN5LQ== X-IronPort-AV: E=McAfee;i="6700,10204,11314"; a="37494226" X-IronPort-AV: E=Sophos;i="6.12,310,1728975600"; d="scan'208";a="37494226" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by orvoesa110.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Jan 2025 21:58:47 -0800 X-CSE-ConnectionGUID: XLhNvcQjSvCUwNolrYlS4A== X-CSE-MsgGUID: 100LmuSWQmylUziehc+45A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.13,208,1732608000"; d="scan'208";a="136219046" Received: from orsmsx603.amr.corp.intel.com ([10.22.229.16]) by orviesa002.jf.intel.com with ESMTP/TLS/AES256-GCM-SHA384; 15 Jan 2025 21:58:47 -0800 Received: from orsmsx601.amr.corp.intel.com (10.22.229.14) by ORSMSX603.amr.corp.intel.com (10.22.229.16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.44; Wed, 15 Jan 2025 21:58:46 -0800 Received: from orsedg603.ED.cps.intel.com (10.7.248.4) by orsmsx601.amr.corp.intel.com (10.22.229.14) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.44 via Frontend Transport; Wed, 15 Jan 2025 21:58:46 -0800 Received: from NAM11-CO1-obe.outbound.protection.outlook.com (104.47.56.174) by edgegateway.intel.com (134.134.137.100) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.44; Wed, 15 Jan 2025 21:58:46 -0800 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=uy2V7QL3alKJa+QJWexYAUsRRZzZ4FC7eIBjFwBI+p/EWSqdj8HlOBlo3NLs0W9lZzcVZf1ZKGtUEtucmIeZWrOQpwGU9B+BPPjDKnG4igOndhMIjNDYkNYbK45O8/UXezf9/rbgiqh/Am7dPMAHmmX0MygOwMZpEd89RBjks1LjF935XMVwdvKawGcMohuwmDwHjjbVAuKT+yQwQsoH1Q5b9fMoLkwe4kebSvyh7NvVQ+PX19UOD0ipOq5D2m++olTJn0qqEERK+T/mMvB93NtYwo9hcMAXE5ejRLlTUVhivl4BzeoJ6zeALOLek9jwyhC8XunQuMfe2228AG072A== 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=eLBNDRgvC3cFpUNSk/UbGEQJDeup/98oznfAvJqjYs8=; b=uUaK3KE3NpeKrKKAibEpX0T5cMSmagyN5nuU4tlm1K39lddcnMXZMpcTo9Kt6MFnnOq/QNTnOVBYalrP2fFZtPp2TtJnKG0XKrbForzZSHF0FR3kS/YJbxjfdOAABFGAF/sgergTgeMQfI8naEthOn7or2cVU674RNIbh1b7hFWkAMjI3PDCs76UU3e/EcxF8XkxgLlbuCezEouo+hRwhZHBVpBHWb+oQo41HJl8KK40tX5iPrNh/rnaNCCoBaUpeio9v7ICPmo8yuf9wWphEpqQUpx3W2H8ILJVpIq7ykZ+g9GjONogu1VCmFSQFoc5S3Eug6d5DvLkDIMxEXnJOA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=intel.com; dmarc=pass action=none header.from=intel.com; dkim=pass header.d=intel.com; arc=none Received: from IA0PR11MB7185.namprd11.prod.outlook.com (2603:10b6:208:432::20) by DS0PR11MB7650.namprd11.prod.outlook.com (2603:10b6:8:151::21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8356.14; Thu, 16 Jan 2025 05:58:04 +0000 Received: from IA0PR11MB7185.namprd11.prod.outlook.com ([fe80::dd3b:ce77:841a:722b]) by IA0PR11MB7185.namprd11.prod.outlook.com ([fe80::dd3b:ce77:841a:722b%4]) with mapi id 15.20.8356.010; Thu, 16 Jan 2025 05:58:03 +0000 From: "Kasireddy, Vivek" To: Andrew Morton CC: "dri-devel@lists.freedesktop.org" , "linux-mm@kvack.org" , "syzbot+a504cb5bae4fe117ba94@syzkaller.appspotmail.com" , Steve Sistare , Muchun Song , "David Hildenbrand" Subject: RE: [PATCH v2 1/2] mm/memfd: reserve hugetlb folios before allocation Thread-Topic: [PATCH v2 1/2] mm/memfd: reserve hugetlb folios before allocation Thread-Index: AQHbZl+3lfkNkaG2WE6j0iGvFEUcbrMXL5UAgAE2+xA= Date: Thu, 16 Jan 2025 05:58:03 +0000 Message-ID: References: <20250114080927.2616684-1-vivek.kasireddy@intel.com> <20250114080927.2616684-2-vivek.kasireddy@intel.com> <20250114193256.c1cdb555ba24afc9790a40c8@linux-foundation.org> In-Reply-To: <20250114193256.c1cdb555ba24afc9790a40c8@linux-foundation.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-publictraffictype: Email x-ms-traffictypediagnostic: IA0PR11MB7185:EE_|DS0PR11MB7650:EE_ x-ms-office365-filtering-correlation-id: bc0e0e55-4980-4ce9-464b-08dd35f2bdaf x-ms-exchange-senderadcheck: 1 x-ms-exchange-antispam-relay: 0 x-microsoft-antispam: BCL:0;ARA:13230040|1800799024|376014|366016|38070700018; x-microsoft-antispam-message-info: =?us-ascii?Q?fxA+hLhKPMVN99lHN/BgOGyH7L5NYcYPTOApbwi5nPEmPiJQQpUTWTxkmguZ?= =?us-ascii?Q?zLSI1b6iPhv0qW9Du7PxIduBd6F2SiDtv1BaZyWMbZyvftYOgWqL9J0N4MBI?= =?us-ascii?Q?Zu2YZg/m4+AlD7zYddh5uX0cyGufzPoyIYGz8TTP0WR8jP5ixFJwTndKTx9j?= =?us-ascii?Q?jEfIEChcLo5VQJwh/Nn9F3RFBTehG/s+I95/uVPniPCKKYH/0EkFQf/hEjug?= =?us-ascii?Q?x4UpiJjXU5S8Tu3Cxu6PgB82DECnXjIzggFNJZibT8gGHD/B5umJGp3zUGK+?= =?us-ascii?Q?eizbgWv/cUVJCakYxAZyYLmOBA58qDVwqjVjsnKJ/4t+YJNKxqXiJ0TAyDwN?= =?us-ascii?Q?kdiZ2kceLrGi4E+u5wF3LM5f5jUFOrKjcdK74wTOvzbnskkgYSp5I25dSvId?= =?us-ascii?Q?2s40XgPHkxT45TKG4jGGnL9NoT6/BoIy4Y5kFGt39ExuvSdIrw6JCfJZDnWB?= =?us-ascii?Q?RgdPBKJogL8MFs6P5im/kOUQya0whaM5I7TuaO47oiwJxCJyIK+uolu2FoDw?= =?us-ascii?Q?WQa7hSLz7ffrf6CTYu9X/ipN0qcgdoulOxNL9vf3TkjukU27O+s9u0NI2Q4B?= =?us-ascii?Q?V5skyZHRo+cuIyGNpEJwIw4IVGBIxQEVzRFCZCohdJED+22NQv4M+7uU957B?= =?us-ascii?Q?1MiDqsFb2u+So/i7GOwufA4G9qUfMrNw4HytyLJ4V3dNcZWwmSxykQaniY2l?= =?us-ascii?Q?O7IiJejd1SgIPWfUH5xXfel2LBOlXcx1z1pI1kfq2FtedLXWrTHy/RJYoNa8?= =?us-ascii?Q?xs0TPpVLs5n3mGv2p2mlBLnoskgMn0NOQV+anPqCDH2ZQnXUZAKY5DjkG/yc?= =?us-ascii?Q?CkWvqCuP7vlZmEti+Idh9/pqzIsLv72Eo6uruNN7hk8ylwXpzvG9QYXihal/?= =?us-ascii?Q?XIRHHXOcabxRCe/kHo4QW1iS5eaNeUSXHBW958KiqCoqlncnRno2UGHj3YQI?= =?us-ascii?Q?IcF3ANSBi2k6C1EgKOykvWwRtFVa7n/eqS9pOw0owvC+pQkxA/SO2Dlt3ZL7?= =?us-ascii?Q?uKHKZPxjdE0sjCrZ3ET4pKNldgSNObuAbBNVtkz4M2h+mcq9D08ocRrBuTzq?= =?us-ascii?Q?3LbGoI5tN28bZGpqkrLH3gy5x5vHXcgkbdbyfDPtEKqX7/Qlm3hdj+PbmlD5?= =?us-ascii?Q?IFmUZTVZRRlAj9pqbwOseAw1CpVukOrxLmdfa5mPDb+4rGlQPIEWaXioFRRB?= =?us-ascii?Q?YrSZaskzLFHBZ6M88qLWb2C5wKxVjF5bOQ9p2xuKl/qMJn+JPjF6dgWVrFZH?= =?us-ascii?Q?lt3V7DYWusPjMzFrefjv87AZm//8RIN2bY4aNCnF3NQ26jfLOUX9SDqSI62k?= =?us-ascii?Q?dDm9cEWIgm9ZH5NMWpFT6amgN867BOCebmg/L4F9I6+zU3GeqZuRAXY1vCRf?= =?us-ascii?Q?OeiK1njKPGyFLVaZkqEN/fjE406Un2Yv3ye4H/gE7Of+h3kDmg0GUAbttewh?= =?us-ascii?Q?q+SPQz22VjlsN7gusi8ly2Pw9T76Dvgt?= x-forefront-antispam-report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:IA0PR11MB7185.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(376014)(366016)(38070700018);DIR:OUT;SFP:1101; x-ms-exchange-antispam-messagedata-chunkcount: 1 x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?4bbo0fLYWYg6/03KWwSeT/oHEXqCsjW8uXJS3xzMJBdq76H5hRK7sVhWRghA?= =?us-ascii?Q?lOle55BvoXjHgDYTqkD5dk0YO87KNeA3ulmwDoWkgHpAbW2PXbGDNvRl6Rhb?= =?us-ascii?Q?ddIes9UHvmMk3XWwuO3u5C9gKmW+rdTJ+qi7geh9pw0wYWqb7KmAAKRqR8Zi?= =?us-ascii?Q?G9RoZ0JUN4h2hvVOFZXwLC3Ns1r8T4fvWQyR1s1zOD4Cw7Md/G4XU5FmYsrT?= =?us-ascii?Q?lU+m6uUjT4kxQRod4TrU/wGycd4Awq7TPCwFKlvZvBmGJRlPHmtMrBp+G0Eo?= =?us-ascii?Q?5ONUyj1fSRLdrUISbHirboegellzd6wsfVE8JYoDc0lxYEtNmELJrwBjr+d2?= =?us-ascii?Q?IqVLjejTde+eGi7PKoY2VepbW7F3ZW63dvsseju7TKIyovIP5E6uckScYlqi?= =?us-ascii?Q?FIlXi/YPp4XNSQvR595bVpc9k6sVcjDFfvX0KasVeG7BTlP26izc8Yks635q?= =?us-ascii?Q?aHMFQgPhjLK40Hs75uiBvaldu1Nyac6xHLOP1lV0h8M8ez6rNH0xz+aJ52mQ?= =?us-ascii?Q?7Bsul2K7WUxtwuY4Rx9ZyAL7GRXuU3DP0IyKRGLYll1zS4ZP4s30yFOvbqPg?= =?us-ascii?Q?rkbXI2I4GeHwoBDBCAKTJCvIBhflSzlihIWwM2stXqkfvaV+qBj9HA+vE720?= =?us-ascii?Q?XOeJEp5q+mgjFTMypMgH/o4ftGB6aGGT13l9GoKD6kq2vI8QEAYpW7+G9a9S?= =?us-ascii?Q?g8F3vnQDsSQRs3/KlSbWYLY027CKILitWV6RXxmlT+yZzg0v9pLgYM83c6gO?= =?us-ascii?Q?uanPjrneN6fTuZSRJC7gjx71Jl+ahLi8hFDiiilLRZvmGl4GqetKfhVSno2t?= =?us-ascii?Q?5o4zwyMx1wrGctItjGL2kE+2yZMH2zBU5u/V92jhXah9UQvNxcUZzXG8kaWG?= =?us-ascii?Q?GrBDmWeqM4MWkhjHq4uZmtwGF+yGEOgsFoL4D2VmQT1iUqoOstG6Knus4DPa?= =?us-ascii?Q?kOjPJTdFBTw2rka+TF+dYEiRZZjbdMk9uFMv15t2mCXxcmKD4SVlB3xOkyW/?= =?us-ascii?Q?FJovrPl7b7v5I2ZpUzVhhgcCjLRlVVjTpvBFEclAsxHWSZujn0HBQGwehHt3?= =?us-ascii?Q?IHfgW6mdJF2hFqwXLbRS++TUqaWBAhkvio5jdOTbr1sBasEM1vGCN0xC01M2?= =?us-ascii?Q?lh1in0+uvTmX/ouKPz140lTJBpJxMm53jUcVedr9uc0/QRw5t2zOW+A792bf?= =?us-ascii?Q?7bHAJZinLVqKXojueUDbIgTNBOXfLe2EPwqkggg38a3ogZljiXHO0giZRhk9?= =?us-ascii?Q?5bQd8IeT4cxxRIh59SNWSL0YCgOCR+0KbTRlWK3SCGBuBoIoTb/Ltv3SKAqf?= =?us-ascii?Q?XysYMnJHOgEkV79vGz3NQgPUDsRSChWBQlCl8CArMSpXV760R1LLW0J96437?= =?us-ascii?Q?gXzssFCURsCyw5KRvX723Qq4JFdF4POwkVUw7l0YXFfv+PxTBPj/iUAsHicz?= =?us-ascii?Q?rFmEDcNgvTY3DwmHiAzphm3rcr/z/fsnxrXCx5Z7+mplqbwDTxDqIPOUfeCV?= =?us-ascii?Q?UNVirWSBzhwwkHpHsrcgfkdZcpjnZvFSQwOeKf7OB6oH8t3b9tATsL/YV1Bz?= =?us-ascii?Q?6ieGp3aeI99OrsThh1pX5AZ26nYEu+7C2zxVziEI?= Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: IA0PR11MB7185.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: bc0e0e55-4980-4ce9-464b-08dd35f2bdaf X-MS-Exchange-CrossTenant-originalarrivaltime: 16 Jan 2025 05:58:03.6844 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: mzLA0OrHyuU45EgxbuVg4xrMlkIhqNQtGFIHml4Sd/JYzjxrzCEbCizXv77BGauQx3cSjQw4B4T/vB0F6j1Ww4zzlStkM/LQoeWDrRefD9M= X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR11MB7650 X-OriginatorOrg: intel.com X-Rspamd-Queue-Id: 18F3A40003 X-Stat-Signature: jxhhtk7netcrkm5inwme4m6buxg54mcf X-Rspamd-Server: rspam08 X-Rspam-User: X-HE-Tag: 1737007127-897527 X-HE-Meta: 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 uJor/LVS 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Andrew, > Subject: Re: [PATCH v2 1/2] mm/memfd: reserve hugetlb folios before > allocation >=20 >=20 > > There are cases when we try to pin a folio but discover that it has > > not been faulted-in. So, we try to allocate it in memfd_alloc_folio() > > but there is a chance that we might encounter a crash/failure > > (VM_BUG_ON(!h->resv_huge_pages)) if there are no active reservations > > at that instant. This issue was reported by syzbot: > > > > kernel BUG at mm/hugetlb.c:2403! > > > > ... > > > > Therefore, to avoid this situation and fix this issue, we just need > > to make a reservation (by calling hugetlb_reserve_pages()) before > > we try to allocate the folio. This will ensure that we are properly > > doing region/subpool accounting associated with our allocation. > > > > While at it, move subpool_inode() into hugetlb header and also > > replace the VM_BUG_ON() with WARN_ON_ONCE() as there is no need to > > crash the system in this scenario and instead we could just warn > > and fail the allocation. > > > > ... > > > > @@ -2397,12 +2392,15 @@ struct folio *alloc_hugetlb_folio_reserve(struc= t > hstate *h, int preferred_nid, > > struct folio *folio; > > > > spin_lock_irq(&hugetlb_lock); > > + if (WARN_ON_ONCE(!h->resv_huge_pages)) { > > + spin_unlock_irq(&hugetlb_lock); > > + return NULL; > > + } > > + >=20 > What is is that we're warning of here? The warning serves two purposes: 1) To flag a situation that is unexpected at that instant 2) To alert the callers (mostly future) that they need to somehow reserve their hugetlb folios before calling this function > Is there any action which > either kernel developers or the user can take to prevent this warning > from being issued? Yeah, the callers of this function need to make a reservation and ensure th= at hugetlb_reserve_pages() gets called (probably via hugetlbfs_file_mmap() or other possible means) before they get their folios allocated via this funct= ion. >=20 > IOW, maybe the WARN shouldn't be present? Instead of silently failing, warning the caller about the failure mode seem= s like the right thing to do in this situation. However, I am OK if this warn= ing is not present (given that this not a common use-case as of now) but do you see any concern if it stays? Thanks, Vivek