From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from PH0PR06CU001.outbound.protection.outlook.com (mail-westus3azon11011062.outbound.protection.outlook.com [40.107.208.62]) (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 D4D08419308; Fri, 5 Jun 2026 09:30:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.208.62 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780651820; cv=fail; b=FrhUPrDHY6d7nCyXlL3wAp+ZPbD7th3bN87iZYsbqYPfhNISDgBJv+rCwXiKYPLm1KTUL0SRfki2opxgUG0bChfAMp/GyBRgdE6VCP8CAlkA+JTCjHmzXHKhxDSsyeICFTswNGeG6JMxedH5b21OK+nZmutpHQwOGa6oCoOFXig= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780651820; c=relaxed/simple; bh=9itIK9+RaF52U9sWHIIBdh0etrA9E1Y6dosirCkj+Jw=; h=Message-ID:Date:Subject:To:Cc:References:From:In-Reply-To: Content-Type:MIME-Version; b=XB6JT1KccrOgiOu/c0Ak9TkhOWV2gMGmbFR/gnIfSk1V1JJC70f18U097dWn/bacZKxMe872ecmij7CW2ohK1lhvSp/5y4A7KkhpWkD8ypFXZ0fgbruGyGMAVF07s55Lz+zPq9nmyp7NvD6QOOgzReU24sf3VUDSemnIIZL/6xA= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com; spf=fail smtp.mailfrom=amd.com; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b=Cg5Fq9EL; arc=fail smtp.client-ip=40.107.208.62 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=amd.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b="Cg5Fq9EL" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=D3zyGfM6odtnJ1egNo8wn+a+Ye77wn6dJO4NTWAN8kHRb/nLwuaOfL7IR+mUJZoryavuZXqglXHBldlfOltNgWeVpc884InllgiQFwcd1iZqUK3i7tCHWOtX/TBVEcD2qqv4F/6TPlfJ0R0vXP8iPxa16uLbfl45978sjJwg1KDUdgtBk5MlenlsfM8UApZoNYJukWoa1Xqa70s9KFa1R3UB5rNmj2yTINzbFhnkC3CdKrk5a2TF/y1G3riEbO949IOKFL3hpXx/FRvK9lrxZjw59ueYOQaGYWbGu6d4647FAWKdIh2yEEx8J/Boziz9kIJP2NxgGv0XDVab9KbuUg== 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=IhLkNZCcebkEx2sF7NdJqEiZnF4QK85a1ARSeqABH5M=; b=rWUzvUqlv3GeNFaELBQG/xftlNR6VpSZQqaF4/YV4oiapcFYXyByS6W8JU8mLyO8FagEgAWlhsxImxIGEzhfogQygh7WEPi4MPaonmkao0vcFZ5AqNCQeRUEOYDPc48hNWkTd3Q0OwsCZj0Ol5xfuLyR1iKE+9TBlCqXVkGkY+P+kEkBGIYewPkKYYQVvyjvlJnyWUEEacAuzdBQE23M48X8YkATxmYFIzMvEBtXbqX0DMSE1/w5g8DUOwWzGiuXqljUEQ6IHeRoCVGJkFZgpfnbnE+hqfp7ph7bwIrrlslvebPHvufDCLbeElZeSwmlBH9+tNJLg+cv0dhSPHY0ww== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=amd.com; dmarc=pass action=none header.from=amd.com; dkim=pass header.d=amd.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=IhLkNZCcebkEx2sF7NdJqEiZnF4QK85a1ARSeqABH5M=; b=Cg5Fq9ELpBXjGBKMjVDMbVKzXwBSp5F/5OMMZgdgBFqsfkni80ajuQ7VMupdKjeBTRzQ9LIiTN7k8Wz4YMBl8X1/8xPE+2wSnPi1S98LcswBinNt6/KfuetKm0XK/se/HYLI4/SraCj+s4lh8lns2w40b6/OARsW5hNF0TPODi4= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from PH7PR12MB5685.namprd12.prod.outlook.com (2603:10b6:510:13c::22) by SAWPR12MB999139.namprd12.prod.outlook.com (2603:10b6:806:4e0::10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.71.13; Fri, 5 Jun 2026 09:30:16 +0000 Received: from PH7PR12MB5685.namprd12.prod.outlook.com ([fe80::ce69:cfae:774d:a65c]) by PH7PR12MB5685.namprd12.prod.outlook.com ([fe80::ce69:cfae:774d:a65c%5]) with mapi id 15.21.0092.006; Fri, 5 Jun 2026 09:30:15 +0000 Message-ID: Date: Fri, 5 Jun 2026 11:30:07 +0200 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next 2/4] udmabuf: emit one sg entry per pinned folio To: Bobby Eshleman , Donald Hunter , Jakub Kicinski , "David S. Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Andrew Lunn , Gerd Hoffmann , Vivek Kasireddy , Sumit Semwal , Shuah Khan Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-kselftest@vger.kernel.org, sdf@fomichev.me, razor@blackwall.org, daniel@iogearbox.net, almasrymina@google.com, matttbe@kernel.org, skhawaja@google.com, dw@davidwei.uk, Bobby Eshleman References: <20260603-tcpdm-large-niovs-v1-0-f37a4ac6726c@meta.com> <20260603-tcpdm-large-niovs-v1-2-f37a4ac6726c@meta.com> Content-Language: en-US From: =?UTF-8?Q?Christian_K=C3=B6nig?= In-Reply-To: <20260603-tcpdm-large-niovs-v1-2-f37a4ac6726c@meta.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BL1PR13CA0011.namprd13.prod.outlook.com (2603:10b6:208:256::16) To PH7PR12MB5685.namprd12.prod.outlook.com (2603:10b6:510:13c::22) 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: PH7PR12MB5685:EE_|SAWPR12MB999139:EE_ X-MS-Office365-Filtering-Correlation-Id: e9f98924-d258-40f2-5d23-08dec2e50d20 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|1800799024|366016|921020|18002099003|22082099003|6133799003|10063799003|4143699003|11063799006|56012099006; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:PH7PR12MB5685.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(376014)(7416014)(1800799024)(366016)(921020)(18002099003)(22082099003)(6133799003)(10063799003)(4143699003)(11063799006)(56012099006);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?bmYzNHVNSm5pQTd4ZFN0VW5SS3BZLzVEZUd0WU9SaXhYdWNaOG9DVERjSnZa?= =?utf-8?B?T2R4VTJKWit3ckJKbldsbkw4MjdHRWdtdHNwRmw0d0lKTHY3MVVqd0ZHQmdw?= =?utf-8?B?QXExN0tQeFUyRFZOY01MZDE5S3JEektZYU1BV1BpenVFSU14WkppVnBKTGJ5?= =?utf-8?B?OHA2bmZKRzZ6cVhXUmtTaFgzS2hLcUNFUWVNNUZZUXlVeDhJTUs1NkVoZ0da?= =?utf-8?B?ZUJDMUphR0ZVVUkyZkJ4R2Z1SU8wNk44akR2d0NhWmFGQ2IrZWJRdnQzRWpS?= =?utf-8?B?RVZ3Ulh6Y2YxZFN1L25kOG5pMGtiVCsveTNhblNhMHN0OW52SjZrOXlLNnNT?= =?utf-8?B?dHhna0lpeUU4eC91VktOQXYreTNpSUNtU1p4M1FwU1VyVmFqTHByZFVQV3Uz?= =?utf-8?B?Kys1Y1FYOW1EbisxUXBXRFd5NWxVSUhMbndtYndKd05UZUFSU0VOdlJ4K3M5?= =?utf-8?B?blVTNTBBYWNsQ09JWGJOcElGUVhmQktpWTE1bnJsTXlpcXBLZTY2WUgwSTly?= =?utf-8?B?aWhaQ3RTeFB3U0RFQ3ZlcUdzNGU3TFQ1WXJDcXdTS0FzN2VwVzZyaFBGQmtL?= =?utf-8?B?VERpbXloSWE0SG5xeEJXQU1MTzVacWxRR2Z0VWN2NExJb250YVJXN2Z2R2kv?= =?utf-8?B?cDFmczRpcVljQXBxMGM5TmtIZi9qcGhZNWtIR1o5bU9ORUhYcGJyZVgrUXdU?= =?utf-8?B?WXJ0OUpjWVlnT25IOFhHVDdTb1ZiSHRSbWhuOGdrVWVCOEthaFhGT1gxeUVP?= =?utf-8?B?YVpadStKOHRCMzBsdVlnZ0J2Tkp6cDBmSld1eXVHbGN6SmdOSlBDQ3VxVkt0?= =?utf-8?B?dzNDVi9yWll6NmEzSjR6ejFmcVJRSDlJeVJ6ZXhxY3JMR2dwOHNQZVR0SnNz?= =?utf-8?B?YXdqcUFDd2pxSmR5WjMxa2V2SFRhdEFhZHVZUjVkNW43KzlIclFuR3hDSWoy?= =?utf-8?B?N01xNTZ1REtyaTdvRi9ZOXJIbzRYR3F4bkJJVzdJQ2h4UmpwVm5IMlpIWFla?= =?utf-8?B?TEx4RHlmNzVueUJkcUM4aE11NTdXdW5ickV4ZG5EVktnTk5wU2I3VmpBZWx0?= =?utf-8?B?c3Z4ZDlHSktELzBUVXlNNzNvVXdUQTY4a0hBTTZYWFJkdFRKaDJCUWlkVDdR?= =?utf-8?B?dVhTTXpUenJCN0FoRlpwdWphRzFHSTJjb1VrZTdleWF5SWtjWTN6SmdHVzYr?= =?utf-8?B?NW44eXQ5WktPV3RNMlJieTFWYmJBbHVvY2FzWVQ2bkJrRXhuRUphcFhaUnZQ?= =?utf-8?B?SlhacTU4bGhPNFE2SDFPQWtVV3RUMm8xbmVRK2RWNzk2dXloaTRGa0t0QW5v?= =?utf-8?B?dkFrQnVKOVR0a3E0YXdKVWJYTkhrTS9sL3U5VG9QcnJZMmJUVXREWThRL1lC?= =?utf-8?B?V1ZNZjVQbUhPbjFBdHM3aVIvbk93WWcyTFEyOGJ2QUlXeCs2V0pscWZUcURB?= =?utf-8?B?c29uRVN2Y29qZEtud2c1TXBHM1B6QjE3M1JUY0FGNjBKaCtGaWF5SHliS3Bx?= =?utf-8?B?MmU1aWxpR0xvdVlpUk9pa1dDZGQzOVhMaE5VUDV0R2dxZzBmMGErS2xUYURB?= =?utf-8?B?SEppTm1FR0tIQlZ4bXlPOTYvT0NqaitHek5UNzJDeDM4bFZwUmhvYWE1UzFS?= =?utf-8?B?QUNoczdML0tpeXhkSWpocCt5ZjA5ZktjcHgyNDZPajFOb2pUNWFIVzdGSXZ2?= =?utf-8?B?MzNDMExjd2lPNmdxQzhCVlNBN3FkWVJtaFFWS2xtNlNnQUZXMVZKd1dYUEsy?= =?utf-8?B?N0hlWFZrdG8vek5DazIveUwvZjh6ditIa1JzbU1WbThjcjRCdS9aL0dwVEpT?= =?utf-8?B?YTh5UnY5eVhXemkxRkhFbXBVcEtqY1g0WWZyc1Z6S25TaWtWZUpqNHFGYmtE?= =?utf-8?B?WVFyMVN5NjNqdFpRZGVqTC93YjM0c3F4cUYyRUt1d3JpWkp4RldtalJuVjlD?= =?utf-8?B?cHNZSG9ZQ1Fva0Z4bytvTFRHN3pEbDB1VE1SS1BwQUt0NXFKc1RWUm1hRUc1?= =?utf-8?B?U0k3K09BRDRrZVJLR2c4RmNOU20rRktlUElkbVdWUTJCOEFMQ3ZwSURjTkV0?= =?utf-8?B?Sno3ZmdvcE1hRGhGL3VZMVJ4d0pUY29MRWRLeW1XSmV6Vlg3N3M4VUk1bHJK?= =?utf-8?B?RUVMZHp3RUMrbVJjdFYxbUFNS2Z5Q0hsU0JSWjVYeGZLbklEa0N5Qm5xbkRX?= =?utf-8?B?QzJiRkJRVnNpeUUxeGxVVVQwZ0FsM2prQXBtMVJ5S2lNVFFmQUhPMDlLRGxZ?= =?utf-8?B?TlhoMFFlUk55SEtWTGRrMGYvbmVwV3dVaEh5S0tIcEl2Q3ZLQlBCVUUwNDFE?= =?utf-8?Q?CGtv1MKLDCsEuZSaMs?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: e9f98924-d258-40f2-5d23-08dec2e50d20 X-MS-Exchange-CrossTenant-AuthSource: PH7PR12MB5685.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Jun 2026 09:30:15.8483 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: aw2SXT0jfji5bf8SbdTkNqv0CC4DMeBy+7KHp/Mhs1tVyz7qEWZoxzYvgVlChKkq X-MS-Exchange-Transport-CrossTenantHeadersStamped: SAWPR12MB999139 On 6/4/26 02:42, Bobby Eshleman wrote: > From: Bobby Eshleman > > get_sg_table() emitted one PAGE_SIZE sg entry per page even when the > underlying folio was larger. > > Instead, walk folios[] and emit one sg entry per folio. When folios > represent large pages (as is for MFD_HUGETLB), each sg entry is a large > page. Normal PAGE_SIZE sg tables are unchanged. > > Required by net/core/devmem to support rx-buf-size > PAGE_SIZE with > udmabuf. That doesn't explain why this is required. Please note that accessing the pages/folio of an sg-table returned by DMA-buf is illegal and strictly forbidden! Regards, Christian. > Signed-off-by: Bobby Eshleman > --- > drivers/dma-buf/udmabuf.c | 47 ++++++++++++++++++++++++++++++++++++++++++----- > 1 file changed, 42 insertions(+), 5 deletions(-) > > diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c > index 94b8ecb892bb..f28dd3788ada 100644 > --- a/drivers/dma-buf/udmabuf.c > +++ b/drivers/dma-buf/udmabuf.c > @@ -141,26 +141,63 @@ static void vunmap_udmabuf(struct dma_buf *buf, struct iosys_map *map) > vm_unmap_ram(map->vaddr, ubuf->pagecount); > } > > +/* Return the number of contiguous pages backed by the folio at @i. > + * A udmabuf may map only part of a folio, or reference the same folio > + * in multiple non-contiguous runs, so folio_nr_pages() can't be used. > + */ > +static pgoff_t udmabuf_folio_nr_pages(struct udmabuf *ubuf, pgoff_t i) > +{ > + struct folio *f = ubuf->folios[i]; > + pgoff_t j; > + > + for (j = 1; i + j < ubuf->pagecount; j++) { > + if (ubuf->folios[i + j] != f) > + break; > + /* Same folio, but not a sequential offset within it. */ > + if (ubuf->offsets[i + j] != ubuf->offsets[i] + j * PAGE_SIZE) > + break; > + } > + return j; > +} > + > +/* Count the contiguous folio runs in @ubuf, one sg entry per run. */ > +static unsigned int udmabuf_sg_nents(struct udmabuf *ubuf) > +{ > + unsigned int nents = 0; > + pgoff_t i; > + > + for (i = 0; i < ubuf->pagecount; i += udmabuf_folio_nr_pages(ubuf, i)) > + nents++; > + return nents; > +} > + > static struct sg_table *get_sg_table(struct device *dev, struct dma_buf *buf, > enum dma_data_direction direction) > { > struct udmabuf *ubuf = buf->priv; > - struct sg_table *sg; > struct scatterlist *sgl; > - unsigned int i = 0; > + struct sg_table *sg; > + pgoff_t i, run; > + unsigned int nents; > int ret; > > + nents = udmabuf_sg_nents(ubuf); > + > sg = kzalloc_obj(*sg); > if (!sg) > return ERR_PTR(-ENOMEM); > > - ret = sg_alloc_table(sg, ubuf->pagecount, GFP_KERNEL); > + ret = sg_alloc_table(sg, nents, GFP_KERNEL); > if (ret < 0) > goto err_alloc; > > - for_each_sg(sg->sgl, sgl, ubuf->pagecount, i) > - sg_set_folio(sgl, ubuf->folios[i], PAGE_SIZE, > + sgl = sg->sgl; > + for (i = 0; i < ubuf->pagecount; i += run) { > + run = udmabuf_folio_nr_pages(ubuf, i); > + sg_set_folio(sgl, ubuf->folios[i], run << PAGE_SHIFT, > ubuf->offsets[i]); > + sgl = sg_next(sgl); > + } > > ret = dma_map_sgtable(dev, sg, direction, 0); > if (ret < 0) > > -- > 2.53.0-Meta >