From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from SN4PR0501CU005.outbound.protection.outlook.com (mail-southcentralusazon11011006.outbound.protection.outlook.com [40.93.194.6]) (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 AEA663B2FCE for ; Mon, 15 Jun 2026 07:32:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.93.194.6 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781508736; cv=fail; b=I8gQ0rJ4lib5l1wK8Q3oTjuT6HRD48/EOKLYDFBII01NBWhZvTDmXHKOGUXDUDa/R8m3UFF5dDZThm8YBBqE9DtffBto0//z+AZJ9KnFXqWAuHwL0d8c4HXGVAuZDvkRdG8L/AwZJyv7HlWvjFjUf2DRmWTFRp94qeZNSnvS8Og= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781508736; c=relaxed/simple; bh=NS9cECxMUxKCLpeFKb9KSon4/ERmgP6Ao2GHFO/UOWQ=; h=Date:From:To:Cc:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:MIME-Version; b=AYkmpy/aj59a5EnJxX6E3ITq2v2bnosbCgvalMwghyTio+7j8XkuOkVzOQK/wWKFiMnTxfzERxh2UHLM+qu07Eo1HXBVwP4O64JWJhSFpQlbhdP27xVAf+LaX+FGDYL/lH8s3o9PPuDdrQdiLXCiu9JAzk1K3I9Q1hOmlb6smJI= 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=NdWPXjhr; arc=fail smtp.client-ip=40.93.194.6 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="NdWPXjhr" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=qvBiIKlI1X4Qu5nQt1/6fT7rWur0VRv142Yl9q97A8dPey6nRNrrKk5gZ6lGdW0GUeXBBchfD0WIlmxVZNjnWGV1SzyD2W3HNYlpPuk6C0um2mvMIByDkezhWVWbASm8HosQZkW1WhcNOx64KS/9cMUoNDwxXuSwql3Zj4mBvVy4tXqGjYiRAwXZFL0Nj5A7UN9JlDlPiVN0QgcceaDtrmXM+P36jiNIgx++Y+l5GF2gqRc9FCkkyCNIdD36qUMSEBgUNkHB8am3A15BfG2usI8D8stbr+bnRyNrHwnSHiM45ue37Qi0JBG5QJYO5thsbbqTI9mXnQ/8gtrS0Pducg== 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=RmUGvP6lhBRTapQ+1WOhIOT+MfxoJ7o8pDm0CQkKHtk=; b=JLzjkEt3gG34EO0aYCe+5W2KTEe5fphmOzY3VFMi41v1q9dP6kG3n9lEknVQ8Rpdkyr5dTYdTmO7k3H9OTh4jK5yXbgMVmPpAFg3i/QbnCpTkTp7wFJQqwa3mEY0xlNl3NwmXvMRGfz09ZiA4uqBrKqK5uSHvVA4ROJKn1JkAcVzW13LDxhHPqkQ9x2cUMty3VcJFJAf6vN2B7KNcCtZ+muJlTSet4O9/PTVBsK/0ikVmMngK57b34KipDE7wYuvHv5MbYGM6bilsHVQuHGvb2WBMb/hB4ozsbjxGbUcML3S8B+O0/UP0R4Vefv7h/YNxeUSwrrhfvlAcrsvEZhlkA== 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=RmUGvP6lhBRTapQ+1WOhIOT+MfxoJ7o8pDm0CQkKHtk=; b=NdWPXjhr8SgeWuwcPS+pDjzNATdTMfXUyFq5V739wVfGP6wk1pn7/8hK0drK2tLAq/7jUspFpm862DaaKIla6GOfMAD8nvAMSZNo3adMAJtt0QZ1syIiWtazsAfL0SZfW1IG68di6MoIxXZwxA/rgcqv243AE5k0msp896rPIP26XWFC286ejfG3rQBfzyvcBGi39y/I/EfX3iHX8/AxHrx9CBcLEmRRIzaGpICxZ9Cg4YHc+L77kuDPW4GuOug5lvsrb+Rnxg8m3dHKnKvt4VDeN2Ni2pT/J+Y4jubPZmdBB2v1YA5I37i1G1DO/rphddstOUiE//3mw4zXzKnOCg== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from SA3PR12MB7901.namprd12.prod.outlook.com (2603:10b6:806:306::12) by PH0PR12MB7792.namprd12.prod.outlook.com (2603:10b6:510:281::21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.113.18; Mon, 15 Jun 2026 07:32:11 +0000 Received: from SA3PR12MB7901.namprd12.prod.outlook.com ([fe80::6f7f:5844:f0f7:acc2]) by SA3PR12MB7901.namprd12.prod.outlook.com ([fe80::6f7f:5844:f0f7:acc2%6]) with mapi id 15.21.0113.014; Mon, 15 Jun 2026 07:32:11 +0000 Date: Mon, 15 Jun 2026 10:32:02 +0300 From: Ido Schimmel To: Wongi Lee Cc: netdev@vger.kernel.org, David Ahern , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , asml.silence@gmail.com, dhowells@redhat.com, willemb@google.com, Jungwoo Lee Subject: Re: [PATCH net v3 1/2] ipv4: account for fraggap on the paged allocation path Message-ID: <20260615073202.GB338677@shredder> References: Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: FR4P281CA0363.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:f8::19) To SA3PR12MB7901.namprd12.prod.outlook.com (2603:10b6:806:306::12) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SA3PR12MB7901:EE_|PH0PR12MB7792:EE_ X-MS-Office365-Filtering-Correlation-Id: ec6db602-dc47-4f1f-fcfe-08decab036a6 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|23010399003|376014|366016|1800799024|56012099006|11063799006|4143699003|18002099003|22082099003; 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:SA3PR12MB7901.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(7416014)(23010399003)(376014)(366016)(1800799024)(56012099006)(11063799006)(4143699003)(18002099003)(22082099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?FChT4Ld52p4RgYZvHw4PVlUpsY1L3bIIr+dfXGTLIXk3ikhtXolfdcTRkPT2?= =?us-ascii?Q?75/KOFrCsUHQKMlKOoto+uZTjWvLriyTHHFYzKPiRqwpW9EV4Uk6d1OQw9j1?= =?us-ascii?Q?Qb1hnIHw3bFbaRlJh4GdpRfghQuci+6pthzgs78+Xn1/EA3pdFUjJLVglEnp?= =?us-ascii?Q?idyovrSOTC/3p1wFzb2U+aer+kCjoNg9qttQeAOY0E50lk+jFXgEpCKivet8?= =?us-ascii?Q?LDhA4nhVoWAHvZ77eYr4TvFonhLs342u8ww8hK9cGvHkoaYgv0tjz+Wqo0Ir?= =?us-ascii?Q?DO8V1n64LFLzT9YhGr318FqhOGwzZubAo2pVFdfbkuyNdgJrU/QAc1xHFrPz?= =?us-ascii?Q?f76CqUwncAvhHK+wyFhALeRaV3mrg/bmP5vbOyQXokkRZfg4UjMOKNYlTVwy?= =?us-ascii?Q?zbt6Z8ck/PfuTJJw/YlrAd0DTw6WR5892080sOflI7hhaq30e56FiK0f4bfG?= =?us-ascii?Q?LeLhsyouswB8m5H4Z+gB0SwF63ZiH/6kdSSw+hu9SmU3sdqzPYQv8gqzvLAO?= =?us-ascii?Q?vcfxes5G7a8cpVqYqY9CznbisKD3juXz2tJLDuXEahtdgGUC4o2f+08CdM0x?= =?us-ascii?Q?I5tBcLq6l0wMLo2tfalV6d8xSEpY31ldSzl78UqdzY5aXI0T/2ay4Pm/oVTm?= =?us-ascii?Q?Q12qFVkGxtvkm5T4eBm2afF0fec0MfvoDHZ7w0zi0n+QInGaFRlTTzyEWHLJ?= =?us-ascii?Q?O1zYV+WlNaF9Vg5rY4cNo5TfAo56Lit+mVD0rcEl59n890qILBGg1qbLOv9+?= =?us-ascii?Q?D6GpBuAj+YQ3Uf8hl8teIzBL8LyvtEjrLQEDK37lODmrLVM5gW2eUYZSqyRj?= =?us-ascii?Q?PDrwwwNSSJ106i9Xozbm7h2mLIS7MyS7J84E45pvFg03DmTwzceRpShKGDxs?= =?us-ascii?Q?/lWB17iSLcYTTiaWfgLh4RtwoV/ksC98t7yO5cYH8s1TiU20qcB6253TjftX?= =?us-ascii?Q?TSfg1SJ5bDyy/ijLoYiutszPM2ijgT0lblG+pCWftSXgoTJZcLkVj+JyMRDY?= =?us-ascii?Q?T1Rct4AkMSermvTpQFhz13BKn4+W5SzKDqBC0CeUf8SKXPPDg+CyY66pciej?= =?us-ascii?Q?TZM5pI+Cqgfcent1L4A2xWMnQuesBvZOv1FAiwbvnpk8jPunjSH445SyTZke?= =?us-ascii?Q?+XQt8IpTHm2UYIA4fYknJxVnucMUKybN6mTymEReihXMVjOi0EU1e1nlXSbl?= =?us-ascii?Q?kbOxxYSIKumj7Tg5gGxCSacIXty+e6s7VeU0JLHCnsLuL0Gf11ON4kKCvF+P?= =?us-ascii?Q?PnSzM/2vmcJd0JNgovwDG135EecuPoftPePgsT8zvU8n/FvMwFIdjEGyvwo/?= =?us-ascii?Q?hlkv7KcE6tdAczfwr5qZJikJVa9P90tkZuOtuyfI8Fh8Dw5kKfypdLCgxu8a?= =?us-ascii?Q?SvpRi0ETIl8fl0Y6b+fYKuy+h4wAbFTpLwO/quLl0Um34L25l8u7pWjwGO7i?= =?us-ascii?Q?1VDjn8Q5wPMul5KeXqsTsOY9BoXtCyxZ71NL5tR3QDES7BHhIxGQmN6w/gUO?= =?us-ascii?Q?yiruqxYBxYkbAzDIwiU4wDmeYapsl+aMW+ISt+ewVISlxIsXUKW2ByYfpleK?= =?us-ascii?Q?tBNuMIbcu/e85Dtrncc00kugi4AjzK1DoTqatY5V1lrjoxcfMMZvRRxQPANH?= =?us-ascii?Q?330oEeQYW/fRPhM5I1jQJUvoXp7RT5v2uWE5mZrqLXPKf3p0+TW7lLgpSC23?= =?us-ascii?Q?mgBl6G5XqvgQjOl1Vzdsu/+zha2FnZd5u7nAdZCmzTa2a35W?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: ec6db602-dc47-4f1f-fcfe-08decab036a6 X-MS-Exchange-CrossTenant-AuthSource: SA3PR12MB7901.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Jun 2026 07:32:11.5808 (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: 9pBvtmJjIBMxrICk5N3sLTaoMRw9VYtBWBNQF9P0vNjKlUnPM+YpWyBv3D6y/sA2tsWfx9ItgagzfQ+LDGN39Q== X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR12MB7792 On Thu, Jun 11, 2026 at 10:32:39PM +0900, Wongi Lee wrote: > In __ip_append_data(), when the paged-allocation branch is taken, > alloclen and pagedlen are computed as > > alloclen = fragheaderlen + transhdrlen; > pagedlen = datalen - transhdrlen; > > datalen already includes fraggap, but the fraggap bytes carried over > from the previous skb are copied into the new skb's linear area at > offset transhdrlen by the subsequent skb_copy_and_csum_bits(). The > linear area is therefore undersized by fraggap bytes while pagedlen is > overstated by the same amount. > > The non-paged branch sets alloclen to fraglen, which already accounts > for fraggap because datalen does. Bring the paged branch in line by > adding fraggap to alloclen and subtracting it from pagedlen. > > After this adjustment, copy no longer collapses to -fraggap on the > paged path, so remove the stale comment describing that old arithmetic. > > Fixes: 8eb77cc73977 ("ipv4: avoid partial copy for zc") > Signed-off-by: Jungwoo Lee > Signed-off-by: Wongi Lee Reviewed-by: Ido Schimmel