From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from SN4PR2101CU001.outbound.protection.outlook.com (mail-southcentralusazon11012014.outbound.protection.outlook.com [40.93.195.14]) (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 D8FFE34EEEE; Tue, 29 Sep 2026 12:03:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.93.195.14 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790683404; cv=fail; b=jC1bqUuCpWaKtb8P7bW8WsSKI3PgKTXNSU52A0LL8VZsJg393aWFW3PHwSW3A9ScaH5a/wDV0WXNgcLb5DECPJJR56l26+1oTgdFfYPGKdl8VtPz3E4650pnwSUOURiUo2/czz/93jbWOSZBZ/9VcKKH5TzwRc6M+dXYX565yoM= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790683404; c=relaxed/simple; bh=+WnZcngnrvAMCiVbjmk5xXWyT8Ktm7D9vahJsfsBiko=; h=Date:From:To:Cc:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:MIME-Version; b=RVI+epErxzDepoLhc8fjEo6q1zprv9ZyvygN7QifXDtGbHQpWJzNo6rKy/WQiHlip125ckFEV3Wy1bvDE8Fda5Vvybu6gbUXnQVxmhsjcKk60yRNuqucsUtZ02rMlEPdZEy8d2z2E/ggiQmnu7VLp60/cMYBauYHvxRqO20IkLQ= 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=di+LRluI; arc=fail smtp.client-ip=40.93.195.14 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="di+LRluI" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=EueHNRcVQac84xhTf5mGEcwMUSXc+64uiCNfAMQ/WYaEro0wxZmE+Q8SwlbznWZNi4PhbQiNRiGls5sNNKjr3BNJ9Mg9Rfg5zGMqd3wca/iyuYP0eC9RWlR/WMDsj1l/IA22DXLRk2AoZ4piZ64P+7AcnrxN8ivCHR1DF4C59L04e/A7cg2n0OzBumzRmXglm/KDcUe3b8ZG435gd3QTpQS5u/z6pUvSAhBZlhhy40KrZGrOvASOnSzMnJ78Iq+Ynes9BIUYj3lFE38+k9vE8iLlrS4SZr9BTEeNUaQl4qHltt0osdH8CQiGuSjFycptUKflSPNgRSrhmYcGPIpYDg== 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=al/UBYHE+/xo9e5AfOmSk1P7TrhRh5H1m/yoTabharw=; b=eKIu4pSav6YcL1oJOrkKIcwP01PvoRmoXtQgwvmt5lIlUy5T2AJQcuGQJxm/zkd391NDa2dKbXks7b8yGf1JvwHVIBGR8ejAQAOrHA/c/oqoX9d14a616UC/+kWNPiveWfThswR4Oq2xKL6UK4hf+fwo0ADj3PCNnH8dgYLe1LNuZ7ndl+8mhKX70H4rlWe9zV0kV1UhC4UY8/yLeH6fEmlkNIO2skxPIxi7PffE2O6hU3QRRVV/DYhjP2jWtR57efB/iJiVMC1kQiM5b1nEeR22kMFbb4SNE6xym9nWILllp21ssT2GRK4B4lVb1W0dOT+VpFAzurkz2EM65Fsydg== 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=al/UBYHE+/xo9e5AfOmSk1P7TrhRh5H1m/yoTabharw=; b=di+LRluIdURrpxsABOB1oWi5L51I1NtizpnBY7u2JKw1xCZVAiZTRSRefF5i/MNCxTGVD1A33yqLjUT4dV16YJ1NaXGWtq5l12/X/GpliaeodN6NfQ2AhUtE/+sZIwPVn7JgXarKAmqXuLl/J2PFcvNFprTHWOcI5+9TBk5twZH1j6ntDCUszkXXrqErkCj8BOqqaP/eMRhfP74Z5H1UBC5dsKXAv/7BwMXGK/TOHa0g+I1doBbyG36f/oDCOs0R6LZwHkMIUqZzuFUaGVcqiHs1u/QZWjDJ1Oejgw75nrYGsNTR2kzllIh2g00D5g7Et/EKv2otc1vYlp9BeU9/Xg== Authentication-Results: mx.microsoft.com 1; dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from CHBPR12MB731189.namprd12.prod.outlook.com (2603:10b6:610:33d::12) by IA0PPF0C93AC97B.namprd12.prod.outlook.com (2603:10b6:20f:fc04::bc7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.451.18; Tue, 29 Sep 2026 12:03:18 +0000 Received: from CHBPR12MB731189.namprd12.prod.outlook.com ([fe80::b0e5:123d:fe06:e10d]) by CHBPR12MB731189.namprd12.prod.outlook.com ([fe80::b0e5:123d:fe06:e10d%6]) with mapi id 15.21.0451.024; Tue, 29 Sep 2026 12:03:18 +0000 Date: Tue, 29 Sep 2026 09:03:17 -0300 From: Jason Gunthorpe To: Karl Mehltretter Cc: sashiko-bot@kernel.org, Gerd Hoffmann , Vivek Kasireddy , Sumit Semwal , Christian =?utf-8?B?S8O2bmln?= , dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] udmabuf: respect the device's maximum segment size Message-ID: <20260929120317.GH1616761@nvidia.com> References: <20260929054835.94118-1-kmehltretter@gmail.com> <20260929060028.371041F00893@smtp.kernel.org> <20260929065601.99518-1-kmehltretter@gmail.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260929065601.99518-1-kmehltretter@gmail.com> X-ClientProxiedBy: BL1PR13CA0228.namprd13.prod.outlook.com (2603:10b6:208:2bf::23) To CHBPR12MB731189.namprd12.prod.outlook.com (2603:10b6:610:33d::12) 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: CHBPR12MB731189:EE_|IA0PPF0C93AC97B:EE_ X-MS-Office365-Filtering-Correlation-Id: 56cbfd87-9cc0-49be-30eb-08df1e21a670 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|7416014|1800799024|23010399003|376014|4143699003|22082099003|18002099003|11063799006|10067099003|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:CHBPR12MB731189.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(7416014)(1800799024)(23010399003)(376014)(4143699003)(22082099003)(18002099003)(11063799006)(10067099003)(56012099006);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?5fHCFwXod6qKncq59WtT4XPVLnsS8o3zt2UORQIjlg2f6QtmouO5WhVA3hNu?= =?us-ascii?Q?IBUh+lE37aSvm3XU1cAReunJQZUOkiUqGY+bRQb58GszP+Mzt5oIigcnWZnH?= =?us-ascii?Q?Yh9FkUETnIbLBWkv74Gq5vv7Y+e/OBqFFX2QdmY+N6jApwVPoPkNSuSFTNPx?= =?us-ascii?Q?RpTuXxJ0EG1476IeSGFD799bb3zneuDIfAVWxerUel9a4EocgT6098wx8/PE?= =?us-ascii?Q?Grb/i+WycR9zbMWLJ6ohBr6sPbHtqCIWjDmQeRF3cR/3kAknSZrYQ3LcxgLZ?= =?us-ascii?Q?wVmJGsFE17x6rBm4pVilyK0qfYSNjquf6ql8z4ztZV0WP3NHUn7v5se1wo4f?= =?us-ascii?Q?0Xs6OSzJvUExVx5OXZg0tm1PeFLmX48X+TqkWbiv0M2lXHctMsSiYoDJF+RH?= =?us-ascii?Q?iqN1ul8iRvYNV6+FtKrgWPQaX4DhSXt5yPk1+OwiqeLNWGNMjhUo9Sp7Ooy/?= =?us-ascii?Q?8EXkMnosuu2FheXvmwLKH9uoJ+IGqPRsiCryL10pXUbTwAv2ZpGZczk9lfec?= =?us-ascii?Q?q3j+qv2RbC57o9Y/piJRV2I4/szxAd4TSEYNfHwMkwA4aFOG3KxxIyBHA4Tz?= =?us-ascii?Q?9qnOlcp3hZjfeFx9uQu+wOm5nBqzo879MYFl9lGVogp0P4E6Wze4obPbviOv?= =?us-ascii?Q?fwbg/0VIWozm0Jy3wOFztY0lXtgJQySwDSJtQ9zeJdYw5MeWPpdnVsSwL0Cm?= =?us-ascii?Q?/gYTD+nFRiNhZq8G5ZjgyLXDNvZkTcW9vSXAM2+DD9UUfmy/gMwIZ4wL2AOQ?= =?us-ascii?Q?g8/YMi/3AnkBWHNsK+lr7+PGYUQbAMP4TsBRgl3oC5KG8aCKc5y6srROkA/s?= =?us-ascii?Q?p/rH0wUZC48jQLAZyNjy26biXsyOholdngZxr3Bk4ASJ9wEbtmirs4e17Jon?= =?us-ascii?Q?uL6my3hDVR8sj4b6MRWf0is4cN4FY8Wt3I80f0Ksg1mD2WWUJoLSrb8gC5uS?= =?us-ascii?Q?ZzOtqsR4w+vAIjAyjSLWX9ilMF5x6bwqJwE8q2kkANUmbiLnBSOjrX/gJqx/?= =?us-ascii?Q?F2N6JpBMHKSDTACYS/Ao0JgDquTPK86J+CgIXCYGPD7fmAVSC4sNJJpiLBG3?= =?us-ascii?Q?3HeODP4l3WHJyoBpk9ZAy0NazNrR2rTasfvfTkyI/n5shU0/DAKNDRT27ew/?= =?us-ascii?Q?o2sgT93JKf0NDJ3H62ikBrw7oPRW8Ljvlc/6dlGH16s4udfJTe5XqPDa9X91?= =?us-ascii?Q?aLFCCP3S9Mb5NVqRtu/W0XE2/3KLGCEM9ZbntBDpPN/F9TAfCVcOWjXqeOhR?= =?us-ascii?Q?aKGodkjy6i2f3YCuk8pOpcWtDCowMXppKingTNOWZrT1DBYK/M2bcLsHcLLd?= =?us-ascii?Q?QFWajYqsWjb7Y1tAQvXo+NvfPlKEJ+do4v3csn6zeM/fN6o/qUHlVmEakiAo?= =?us-ascii?Q?uwOBaQ7FUt5EwjMU2JG5WMzESEo4KeaxlGZRD5rP3PHITGNiRgfyJiv7Er+C?= =?us-ascii?Q?RXfkeh1B8glZQmggJiCYqeXxkTdduEe4XowGuvRTe7/3cCXobf0/8ZiyIA6Y?= =?us-ascii?Q?aPsorCtZpinhvzRtSx9pST5n4lTBpOBFHO7mPisXmfmFJ7eDG/r4DiUb9+P/?= =?us-ascii?Q?CLGjgPznHqymmUYH2l4/1Lzgd0KwIHRdg1XqYFT1t8scwEYQv6TGl8IzyFqr?= =?us-ascii?Q?xJKlmDsfRHqffcaQlENaMRIQ/u9essuGDzXPvaV00fY0/wWdxMJjI2D1JEs+?= =?us-ascii?Q?K9RjkMSjvcNXfuHdDQbF34Oxst1LSji9LOjEdCOwLZ09p8qz?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 56cbfd87-9cc0-49be-30eb-08df1e21a670 X-MS-Exchange-CrossTenant-AuthSource: CHBPR12MB731189.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Sep 2026 12:03:18.5770 (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: ODHmMjz7E2aHPCqIkFU6tI9oSrCOPT+XUnOsBaGb5U163cdeYxJpWGiGz6KoG+YI X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA0PPF0C93AC97B On Tue, Sep 29, 2026 at 08:56:01AM +0200, Karl Mehltretter wrote: > On Tue, Sep 29, 2026 at 06:00:27AM +0000, sashiko-bot@kernel.org wrote: > > On architectures with a 256KB PAGE_SIZE (such as Hexagon or PowerPC), this > > new validation evaluates to 65536 < 262144, unconditionally returning > > -EINVAL and breaking all CPU mappings. > > Right, the misc device has no dma_parms, so it gets the 64K default and > sync fails with 256K pages I would ignore this, it seems fictional to me, and if someone really needs to support this rediculous combination it should be done inside sg_alloc_table_from_pages_segment(:) > The misc device has no real segment limit, so for v3 I'll give it > dma_parms with an unlimited max segment size and keep the -EINVAL for > importers that report a limit below PAGE_SIZE. The params have to come from the *importing* device, not the udmabuf misc device. You don't get to control what they are, and there is no reason to put a dma_parms on a misc deivce. Jason