From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from APC01-PSA-obe.outbound.protection.outlook.com (mail-psaapc01on2077.outbound.protection.outlook.com [40.107.255.77]) (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 CC7D1184529; Thu, 1 Aug 2024 11:08:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.255.77 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722510508; cv=fail; b=oof+FHmq769uiqxRRW5rqvBbr+8d5pATYoz3o72qPBgD3ltUzcw3xKTHnEPJ9HvOItVuCFPQuA+pdcoEs9gakVDbHbn+B4a96g41A/Khf6Z1QnynfnzrB2wU7p9X0JWIipG9kMo5mEfn/F7f+fRyL5exC4zdDemRbM9wrPvwptY= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722510508; c=relaxed/simple; bh=3v8D6RpMTzqIuv7alTxA94CF4/3igc5LjRARJp9S17Q=; h=Message-ID:Date:Subject:To:Cc:References:From:In-Reply-To: Content-Type:MIME-Version; b=Y3SOV2XnNiDPc0hTuox7GcxYlCEqvoZUkChuG/R1+Vw7DzWfZ9xKunHoBF0/Gic3CARV29MMaq+KbBGiYCr3pp28LExl1OkqHwuz3YjusBXIK5HCwHEoPCvulTqXg92ldLOThHH8CGFF3DJU5DyZ0A52GmGQNWVVlbFp65e4HjI= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=vivo.com; spf=pass smtp.mailfrom=vivo.com; dkim=pass (2048-bit key) header.d=vivo.com header.i=@vivo.com header.b=cwJxBMDQ; arc=fail smtp.client-ip=40.107.255.77 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=vivo.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=vivo.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=vivo.com header.i=@vivo.com header.b="cwJxBMDQ" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=AFgVw143XjQQ2A0Fh7FupGgg4gCwS6v5zwJaohkOhiXXmKvk/5e8UE13yIm9ILqRlyIuUbmGkr3jIKsqf8p3R/7JSs1IRTSwTqWx2+wdhFDtNzXe4gxyPFCkzF7FNNDOZjB/6qV4ltFebEZvyyOYISh9znn3Q5cxmW6h4nPACXSCjrYnB+AgdnYXxgtq/XQbakU5OD/yTexoBJOiMjVTPVFdRX5jkVE3tUAgthHE1ZzBj4X5yKCfMF6Z2dx0Oqw9pMvUIoFgiazQTlQlSPuHn07IVh5JoCdJPy9VVIq6MyNVvyaWqnJyZsrPTtdclKk4xfkggmumv4lLVPoplyoIgg== 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=6LGKzB3QSRswVLJxrr1Yluc4BnPkdQcHMtaPPdjLdkM=; b=B0zbAnP1tg5EkPdskapuc7hvFjkF1CF6XEEHIX4IS9NZFvrd7MYE1wI3gciwHx2pjmtWEMYPh/Qb0chdkYR3+fmMriuS/pwTeSJ5m25+zDvfnEzX4fTUmnq7QCaAgU7Vhtrh2DFYZYmsWyvQFJW3XITKmzGKSh9X/um1l0Ev/t+uSpuUF1nEx2jndS0gepagHn5qHXLoloqqbJ1vNOreo1ThLRO9jlfDCoSHbNfjDHebGs6OKdAvVgMvMuKrD739s58h1hwB77osWfMBm+oNJ/kL9hL06wy2dymRE+OmsFp8qWzyrh+Ft4+nkuRwt3W996pwW7UJmKtYVZrcL+kD/w== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=vivo.com; dmarc=pass action=none header.from=vivo.com; dkim=pass header.d=vivo.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=vivo.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=6LGKzB3QSRswVLJxrr1Yluc4BnPkdQcHMtaPPdjLdkM=; b=cwJxBMDQj84D/0boTaO+vaYIeLghFomCiv56VK5r4qimMwEd07hIFC+gampBurZXCGShOEg2VqXo3Dw+a7h7KsspZoCNNRpq6FZ9+lfvttAAne3EpHWhIiMj7l2Bpvs4/84+9GwJGk4B1NvPZoNhT5rsavSNFyBiE8t2bpj6iJtwkC4lOs/b5BZER6JMoTaTB6Bm1W5dj5IgBfcrrqj94Jeh5sdj+kr/2jLnJYjsoDjp7F7CwVki9n/WT8dmYX3Dokrk4OQ3+9hjIt7n+EHlIibVLvUOqWSCeRVi+AWY3/Xb/XGdCpE/pgPpsx4akUr6FBtEDbFDMpI+ZOst8hW7NQ== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=vivo.com; Received: from PUZPR06MB5676.apcprd06.prod.outlook.com (2603:1096:301:f8::10) by SEYPR06MB6506.apcprd06.prod.outlook.com (2603:1096:101:169::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.7828.21; Thu, 1 Aug 2024 11:08:18 +0000 Received: from PUZPR06MB5676.apcprd06.prod.outlook.com ([fe80::a00b:f422:ac44:636f]) by PUZPR06MB5676.apcprd06.prod.outlook.com ([fe80::a00b:f422:ac44:636f%4]) with mapi id 15.20.7828.021; Thu, 1 Aug 2024 11:08:18 +0000 Message-ID: <50615530-f77d-4c91-affc-cb63b4c67d02@vivo.com> Date: Thu, 1 Aug 2024 19:08:13 +0800 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/5] udmabuf: cancel mmap page fault, direct map it To: =?UTF-8?Q?Christian_K=C3=B6nig?= , Gerd Hoffmann , Sumit Semwal , dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org Cc: opensource.kernel@vivo.com References: <20240801104512.4056860-1-link@vivo.com> <20240801104512.4056860-2-link@vivo.com> <46d00d9a-b86b-4e4d-863f-48d71060ef2a@amd.com> From: Huan Yang In-Reply-To: <46d00d9a-b86b-4e4d-863f-48d71060ef2a@amd.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: SG2PR02CA0044.apcprd02.prod.outlook.com (2603:1096:3:18::32) To PUZPR06MB5676.apcprd06.prod.outlook.com (2603:1096:301:f8::10) Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PUZPR06MB5676:EE_|SEYPR06MB6506:EE_ X-MS-Office365-Filtering-Correlation-Id: fc97b9bd-fdfe-41cd-8820-08dcb21a3f16 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|52116014|376014|38350700014; X-Microsoft-Antispam-Message-Info: =?utf-8?B?TzVjSVg1Mk1Kenh4M01uR0NJcXpJZFlZUVlZS3UyZ1FrM0JmemFTZEUwWGxL?= =?utf-8?B?dzM0bGwzQUlFVUtleWRDaVNpOC84YURJRHZ0eW5pZUQ2RjJuZ09VQkhsTk83?= =?utf-8?B?TVNUUVY5b1dibnFwU3g5M2JpUG1ER3RPRU1ZQVN1QmZmdmxSMmRlUW9ZWFF6?= =?utf-8?B?c2g4Vy8yMjhCbVp1eXgzUit1ditzb2lKa0k0eWtzUjFDMWowdFZaZFhEV2JZ?= =?utf-8?B?cy9FeGtnRlFDYjlmdWU1eXVhZUlMQzlVVE9qa3pRUTUvV1loQnBiZFZjR1Fp?= =?utf-8?B?K0liYUpRTWhjdmUrMlF1MHFMeVBXbFR2d2E0bDBEQzhld0Y0dG93VExRNzlY?= =?utf-8?B?VDZTVG1MT3hEaTZBZ0hTdC9wY1U1RGFQalVRZERvYVp4Qm81RDNwbE1jZ0Jt?= =?utf-8?B?QkNOampJSlBuZ0hpQnBUSWtaNHJtWVEzMWNYZHJuU09VclYvU3JEVUl0N2Vm?= =?utf-8?B?eXNhT0xaOGdqQ1FvdGduYXhYRFBzVm5KZUpZOFZOVThVRXFEQTFvUWY2QXc1?= =?utf-8?B?VEJld1NyVEh1ZFZRRjV3M0Y1dVZobkRRM2pVMEFwOHdzV2VTZEhESkZCRFU0?= =?utf-8?B?c3A1SkJrVlQwT1huT2d0Rzd6Z1RPNlRQc0VQWllLY2doenU2NkVxWDZZZE0v?= =?utf-8?B?aGh0aXIxNDVyL3gzZUZBc29WR3EyVHU0cXdlM0dac2JadVN0SG0rR3JGUVFt?= =?utf-8?B?Snh6WHRTZHFici9XSU9HTi95dkhvME00S3BEdUFlcHM5eG5mTllzdWVLL1JF?= =?utf-8?B?TmRmSDRlVnVORkt1QzYyZjl2VG1uVE5seExEM09zQ1pEbnhJYjFzOVlXdlRu?= =?utf-8?B?U1U3aVIvb2M0RFMxY1FyRUY4YnNYczJIM005TDZtcUJnSitNakdCL2xQWHpo?= =?utf-8?B?ZFQvQzNtVUF2NSttNWxkb0t5aFUwUTAzVmFkcHR3NGlhemdKSE9YYVJjZlZ5?= =?utf-8?B?WHR3aHFML1c4SzkvRmZmOE5jNTRqTitQLzFGMUVwU3FFbXpiZStBVm1WRnUz?= =?utf-8?B?aGdsNzlDRURLNWRiVFFRcEM2dnhkdnhPdEpBc1hCM2pzalMyY3BOUDJpWDZY?= =?utf-8?B?S1lwTXViT0xjNnliVU1CUGxNZGh6S2FFaGw0Ty95czNRbWovV25NRWdZS3dt?= =?utf-8?B?bkIzYWZBclJhT3BqYktoWUh0a2tJNCtUdWxNUHJYbE5xYS94NlVJNTN2ZEs3?= =?utf-8?B?Z05LRlNXOUpnUGRpYzlhZHJ5WHNHT0M2VGVMQnVwcFNMRTh2dEx6NnkycHpP?= =?utf-8?B?eElSaXJKRDNkUDVQZzJrRTRPZkVYTndjM01kTFdTTi9nWjFUejVyU1lRdmdq?= =?utf-8?B?RU82TW9Nc1VRVGtoYksyQUszRnVGbExPK1dKVXptZUlNSWVTeWduQWoySzdU?= =?utf-8?B?TjNZeXNxOGhna21zRWdSamYzZzZ3S21qNnVpbG9DZ21XMFYxVUFTYzhUcjVU?= =?utf-8?B?aVBpOTZaRUtHMlhZOU1oYkVoMTB6UDhDWkhqaGtQaFJoOVNVWDc0Q1V6dldP?= =?utf-8?B?QWU2YXR4am40VnFZbkE1dzRVeDFTSVBIVVNXZ2x5Mk9MaE9MalZkZXhUUFFN?= =?utf-8?B?c2xvRUYvaGRqZWpWNEtwem5EcmZKMjRvT01ObGlJZVcvcEE2dEREdTRHTkxJ?= =?utf-8?B?K3czNmgvYjVCbzk2TkF0R29GaHUvclNjT003eERhd0RQQzFlL2t3dmM1OUFv?= =?utf-8?B?VUd4emRBdU9PdFBDNmhOc1VaaTk0dlU2N0tLNXZNSXBmZ2dqbDJoNlFqY0Qx?= =?utf-8?B?Z05ITnZUT1QyWHpvZ0ZGaGpuOGgvRmJnY21iVXJ3dVBkdkJhRGsrZmQ1Njhq?= =?utf-8?B?c28rbWpFYUVheVRMTkpVVUJDSGRBRkhNZ0tWU1V4d0YwSHkvUExGSGFyNElu?= =?utf-8?B?djVNaHpDamkyWFlZbE51R2MvSE5HbGtwSzRCOHM5MHJYMGc9PQ==?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:PUZPR06MB5676.apcprd06.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(366016)(52116014)(376014)(38350700014);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?TVVGaHVab0gzQU9Tbm5GK3ZrY1ZJQTYvM0t1N0pqT1duVkxudTBDRVJHL0Vu?= =?utf-8?B?bXNaSWlIVkpVa0s3Z0hkcUg0b095UWpaaXdicGZKNGRzSVh5UVlFMVhVSFAw?= =?utf-8?B?eE0zdWFwTmFDL2lmUVBnNkVHaStGektMQzNmRG1vdG1DN3pkaDgrV2cwdEVu?= =?utf-8?B?RkVrU3JhbGxkbEpSdTQxK0xvTjBHN1JtWWlocFRCVFloWHVTZEkrd2haVnpM?= =?utf-8?B?NHd1b3BzQ1lzckZINGpVRUpwNlBNb3IxZ3VybmNTaHAxR0NxUHZRK0dSN2ZD?= =?utf-8?B?dGk2OUZTQXZPa0wvTTJyRE8vQ2dTeXF5cDlmd01GOVlqTW1HTzU1cFVXMER2?= =?utf-8?B?OGUvb2NmQUlKdlNYOEtUd1F4Mzh2bWhRakZqYk81cXBhQ3RnWjRzbDRaUlIz?= =?utf-8?B?OTBUT3Zpd3FRZ2VHbFFjYWNtenVkQmJUeG1RaEp3M3pacnFLY3h3eUVsT01l?= =?utf-8?B?VkowQkg5ZWRNancwWFdyUDJ2L2Y0Q2xsTkxZdUg0aUpoWHpaVDFTYTBQaTBK?= =?utf-8?B?SG53SkJ1cDlYWWswZWtuMSsvcElBSjA5UktKSkZMT0JvMHZYZURIdjZoOS9z?= =?utf-8?B?L3g1SXlpUDZyd3QvZHh6QUMyaU9zOTd1ay8yZFhqYUZSRUorWHFZa01oSEEv?= =?utf-8?B?STZvdHN1Z2VrckJjeEFuR2pEakxPMCtjNURnajkzTVVYQml4S0N1bmgyRjhw?= =?utf-8?B?c21FMHV1aDJqSE5lajJQSXVZZ3BaUG4xaFhnR2JpdGtJYXVjbmFSMXlmbmZt?= =?utf-8?B?TmlETjlRQlB1MVZpOUxMSGdrWW1wUFlucVhmU1IzZGVJeTdRTGpsUnRPRmJa?= =?utf-8?B?cW5ucmNHZmFueHRTNzJzNjVhY1BaRWZnaUlhWjlyMWgrMHlNemVHWU9oV0xQ?= =?utf-8?B?SWtyejlZVU9GN1ltcEVSaHc0aCtiT0RaRDdobnVqNGsxT0RkdGFXWmJualRt?= =?utf-8?B?dGZySFpzTnc0NnFCWk5manVYYW1JbWF5a0txTE5QRUlSTEtiYzI3ckdXcWls?= =?utf-8?B?NmxsYmR1TU1WQVRMMklXT0ZpKzVhalRlZ25ZNW1kMHRkL0R4aDF3ajZ0YXJi?= =?utf-8?B?RTNUVWwzTko3ZHRqWU9MdUFFU3p4L21qMzdtNUY4ZW1jbVEzNzRrV1ZIMElj?= =?utf-8?B?UzZ3Uzh3SDM1RWlZQnFXSkFndklOYzMwYUlZcUlNVk9NMm5JZk1Ea0NZS3FQ?= =?utf-8?B?QnJBUDNhRTNPWmRHdlBNR1BsL1RqS1ppVS9NWXhGSjBPVFp0YnIzaEFyRHQ0?= =?utf-8?B?cUdVclo0aVVOeXdZeXQ4K0V5ZFB0ZHgrZXA1WTYvbDNlWGNhSDZCVVo4OHlj?= =?utf-8?B?c3JsbGNRS2xLdHBvc29rcVlacGxFU2wvMW9JbWhIRWwrVjN4YmxURTc3WGhn?= =?utf-8?B?M0xWME5vdUZQTS9FYVdNZ21rZ3JOd2RQb1lINVNnakYyRkxkclltMUV4UkM2?= =?utf-8?B?Qms1QUVldDJRZlc1a25aT3ZiOWxhNzBIdE5mbUt3T2xrcSt3aFcrTE5WRVNr?= =?utf-8?B?NTBpWERmRFNidHpGbzhqZGVOWGRPNnRjSThRQkpWNjcwRlQ4TVFUdDNhVGcv?= =?utf-8?B?MEJyNjR6UDRlQWR4OWRlRFg4MzZmNGsySWVZQ1I1bzZnY0JIbndjbjlGbi9T?= =?utf-8?B?dzRQZGVXbzcrdDErYWhvRGJUNHlPNFBVVlNJQmVoR3g2RWd2YkxPZzBKdVlu?= =?utf-8?B?WTkrR1dSNVFjeHd5YzlmUU5tUS9SYWwreEhhMGs5VFpXcUVkc2R4bmlWQm9N?= =?utf-8?B?R1ZsYmtmVmtTazdFTWMyZTZSVkFtRW9zQVRBeWErUTVBQVordGI1djJZOXBn?= =?utf-8?B?MWdLUjNQODBabFk3eG84VnZqSVdGcmVNblRhODllcExlcWZmMndKRU5Mand4?= =?utf-8?B?aE1wZzY0K01BMEdvcEZiQStJbjdRU0VjU2I1T1MzOXRJYWZqRTdyWFc5cHNU?= =?utf-8?B?WGRHanB0NGRuTmxBSFQ5V3dTZ1Nic3lxdWhabmY2ZUVjTVptMXJFZzk1UDI5?= =?utf-8?B?aU5UVU5WTDcrdEtWRnoweFJmbUtHZW56SG9QN1c3Y2JHeW9YWnRtbExsRkda?= =?utf-8?B?ODdhMmJtRUQwbDE4R29qekpPMjhoTkE3L3loNG1JTm4yMmxLMnBJUHZLTU10?= =?utf-8?Q?5zO2sg2nsdlvGaCvTplkEU4ul?= X-OriginatorOrg: vivo.com X-MS-Exchange-CrossTenant-Network-Message-Id: fc97b9bd-fdfe-41cd-8820-08dcb21a3f16 X-MS-Exchange-CrossTenant-AuthSource: PUZPR06MB5676.apcprd06.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 01 Aug 2024 11:08:17.9243 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 923e42dc-48d5-4cbe-b582-1a797a6412ed X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 0ya5p4fLoQWKVig6WDFBtexIn0h+50Tf9GFwPGygH+DsggPvBfEjpBNO4HOhSftGGP4r5KDY1w1p6SJ+VlNPeQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SEYPR06MB6506 在 2024/8/1 18:50, Christian König 写道: > Am 01.08.24 um 12:45 schrieb Huan Yang: >> The current udmabuf mmap uses a page fault mechanism to populate the >> vma. >> >> However, the current udmabuf has already obtained and pinned the folio >> upon completion of the creation.This means that the physical memory has >> already been acquired, rather than being accessed dynamically. The >> current page fault method only saves some page table memory. >> >> As a result, the page fault mechanism has lost its purpose as a >> demanding >> page. Due to the fact that page fault requires trapping into kernel mode >> and filling in when accessing the corresponding virtual address in mmap, >> this means that user mode access to virtual addresses needs to trap into >> kernel mode. >> >> Therefore, when creating a large size udmabuf, this represents a >> considerable overhead. >> >> Therefore, the current patch removes the page fault method of mmap and >> instead fills it directly when mmap is triggered. >> >> Signed-off-by: Huan Yang >> --- >>   drivers/dma-buf/udmabuf.c | 70 ++++++++++++++++++++++----------------- >>   1 file changed, 39 insertions(+), 31 deletions(-) >> >> diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c >> index 047c3cd2ceff..d69aeada7367 100644 >> --- a/drivers/dma-buf/udmabuf.c >> +++ b/drivers/dma-buf/udmabuf.c >> @@ -38,36 +38,39 @@ struct udmabuf_folio { >>       struct list_head list; >>   }; >>   -static vm_fault_t udmabuf_vm_fault(struct vm_fault *vmf) >> -{ >> -    struct vm_area_struct *vma = vmf->vma; >> -    struct udmabuf *ubuf = vma->vm_private_data; >> -    pgoff_t pgoff = vmf->pgoff; >> -    unsigned long pfn; >> - >> -    if (pgoff >= ubuf->pagecount) >> -        return VM_FAULT_SIGBUS; >> - >> -    pfn = folio_pfn(ubuf->folios[pgoff]); >> -    pfn += ubuf->offsets[pgoff] >> PAGE_SHIFT; >> - >> -    return vmf_insert_pfn(vma, vmf->address, pfn); >> -} >> - >> -static const struct vm_operations_struct udmabuf_vm_ops = { >> -    .fault = udmabuf_vm_fault, >> -}; >> +static struct sg_table *get_sg_table(struct device *dev, struct >> dma_buf *buf, >> +                     enum dma_data_direction direction); >>     static int mmap_udmabuf(struct dma_buf *buf, struct >> vm_area_struct *vma) >>   { >>       struct udmabuf *ubuf = buf->priv; >> +    struct sg_table *table = ubuf->sg; >> +    unsigned long addr = vma->vm_start; >> +    struct sg_page_iter piter; >> +    int ret; >>         if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0) >>           return -EINVAL; >>   -    vma->vm_ops = &udmabuf_vm_ops; >> -    vma->vm_private_data = ubuf; >> -    vm_flags_set(vma, VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP); >> +    if (!table) { >> +        table = get_sg_table(NULL, buf, 0); >> +        if (IS_ERR(table)) >> +            return PTR_ERR(table); >> +        ubuf->sg = table; >> +    } >> + >> +    for_each_sgtable_page(table, &piter, vma->vm_pgoff) { > > That might not work correctly. We intentionally remove the pages from > the sgtable when it is shared between devices. > > Additional to that the sgtable is *not* a page container, but rather a > DMA address container. So that here is also a rather bad idea from the > design side. Sorry for that and patch 1 3 4's ops. I was not aware of this before. All idea to do this in mmap/vmap is just like system_heap and any other heaps that I learned. But well to learn it. BTW, sgtable is a wrong idea to maintain page, maybe we need to both setup page's array(order 0 page), and folio's array(only the folio, use for unpin)? Or else, mapping page to vm_off and vma solely through folio's array is quite challenging. Moreover, even in this way, the memory overhead is smaller than the current unpin list. Thanks for your correct.:) > > Regards, > Christian. > >> +        struct page *page = sg_page_iter_page(&piter); >> + >> +        ret = remap_pfn_range(vma, addr, page_to_pfn(page), PAGE_SIZE, >> +                      vma->vm_page_prot); >> +        if (ret) >> +            return ret; >> +        addr += PAGE_SIZE; >> +        if (addr >= vma->vm_end) >> +            return 0; >> +    } >> + >>       return 0; >>   } >>   @@ -126,6 +129,10 @@ static struct sg_table *get_sg_table(struct >> device *dev, struct dma_buf *buf, >>           sg_set_folio(sgl, ubuf->folios[i], PAGE_SIZE, >>                    ubuf->offsets[i]); >>   +    // if dev is NULL, no need to sync. >> +    if (!dev) >> +        return sg; >> + >>       ret = dma_map_sgtable(dev, sg, direction, 0); >>       if (ret < 0) >>           goto err_map; >> @@ -206,20 +213,21 @@ static int begin_cpu_udmabuf(struct dma_buf *buf, >>   { >>       struct udmabuf *ubuf = buf->priv; >>       struct device *dev = ubuf->device->this_device; >> -    int ret = 0; >> +    struct sg_table *sg; >>   -    if (!ubuf->sg) { >> -        ubuf->sg = get_sg_table(dev, buf, direction); >> -        if (IS_ERR(ubuf->sg)) { >> -            ret = PTR_ERR(ubuf->sg); >> -            ubuf->sg = NULL; >> -        } >> -    } else { >> +    if (ubuf->sg) { >>           dma_sync_sg_for_cpu(dev, ubuf->sg->sgl, ubuf->sg->nents, >>                       direction); >> +        return 0; >>       } >>   -    return ret; >> +    sg = get_sg_table(dev, buf, direction); >> +    if (IS_ERR(sg)) >> +        return PTR_ERR(sg); >> + >> +    ubuf->sg = sg; >> + >> +    return 0; >>   } >>     static int end_cpu_udmabuf(struct dma_buf *buf, >