From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A73C02C324D for ; Fri, 3 Apr 2026 09:06:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775207210; cv=none; b=hZhXQ174nCmjxi9JGJlzb2zSGBV6QkVaLSXaOFgexGymdzKyuHvaXx+kQqM8L7G6uYbbDFY06JJJtU1O0kbRfDCSyF7g/nJF+jfRk7PXmv8+N3hSIwmqcIWFN3Oj9OZcUBYS/5reA0Sb+8fkAmyKda2lKYgNifY0NhP21dJq5oA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775207210; c=relaxed/simple; bh=8VNTsNLwh4pYRGyy7ABwzKsrV8s7jJb34VRUNiKfiXk=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=s9cxyXRxkQFnlZDHxp8tkg5j5klMzvsgQSYVpdXu3d6Nn5+m+4q0KQaWQcJrqM4J3QKkKMQALivQBjdXg3lXAwV+tFfDe1Fi8WzoUY6VSkhmnIaeDs6bggp6tULl31hWNtaJCZNT/+Yt71BYX5TeUxKUNDOKvf0JFUQMo5VsN+M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MS8uxI9t; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MS8uxI9t" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9CFA2C19424; Fri, 3 Apr 2026 09:06:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775207210; bh=8VNTsNLwh4pYRGyy7ABwzKsrV8s7jJb34VRUNiKfiXk=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=MS8uxI9tVsBgWSxJnntJydZYFQUQRYXC1WVZESGMXFMpfLJ9kWzZanXanp5F24u4U 46bggIW0yFZPfhymOcEmbxf5hQw44F/GldAe0aN9PRwbvhWWni/585TjhxIsFWhb/q AccmqfCVCcUqWmmJioOaPcKQWLg4eAxEVq5W9MHAxU4ZkDqIw8rWRQM5GHY9hE0Egh JoBuEiV8Tscb1fOVnof4rS6DdRcgbL7sHOkYR+iI94nEY696sd0ZsV/J0/pA0p1THN oF/4gbTwrmte+i8+VX72e7fzcklktB6dQ6bE8Wy6CyaFxNyogYdcdz5efjqligZYLI qzXk5Pys8Zi2w== From: Pratyush Yadav To: Andrew Morton Cc: Pratyush Yadav , Chenghao Duan , pasha.tatashin@soleen.com, rppt@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, jianghaoran@kylinos.cn Subject: Re: [PATCH v3 7/7] mm/memfd_luo: fix integer overflow in memfd_luo_preserve_folios In-Reply-To: <20260402105845.f4d375734c0b21a1203fb9c0@linux-foundation.org> (Andrew Morton's message of "Thu, 2 Apr 2026 10:58:45 -0700") References: <20260326084727.118437-1-duanchenghao@kylinos.cn> <20260326084727.118437-8-duanchenghao@kylinos.cn> <2vxzv7e9ftwd.fsf@kernel.org> <20260402105845.f4d375734c0b21a1203fb9c0@linux-foundation.org> Date: Fri, 03 Apr 2026 09:06:46 +0000 Message-ID: <2vxzqzowe7kp.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Thu, Apr 02 2026, Andrew Morton wrote: > On Thu, 02 Apr 2026 12:06:58 +0000 Pratyush Yadav wrote: > >> On Thu, Mar 26 2026, Chenghao Duan wrote: >> >> > In memfd_luo_preserve_folios(), two variables had types that could cause >> > silent data loss with large files: >> > >> > 1. 'size' was declared as 'long', truncating the 64-bit result of >> > i_size_read(). On 32-bit systems a 4GB file would be truncated to 0, >> > causing the function to return early and discard all data. >> >> As Pasha said, KHO and LUO are not expected to run on 32-bit systems. >> Plus, since i_size_read() returns loff_t, why use u64 when you can just >> match the type and just use loff_t (which on 64-bit is long anyway)? I >> don't get why u64 is any better than long or loff_t. >> >> > >> > 2. 'max_folios' was declared as 'unsigned int', causing overflow for >> > sparse files larger than 4TB. For example, a 16TB+4KB file would >> > calculate 0x100000001 folios but truncate to 1 when assigned to >> > max_folios, causing memfd_pin_folios() to pin only the first folio. >> >> Using unsigned int was intentional. We pass max_folios to >> memfd_pin_folios(), which expects an unsigned int. So this change is >> pointless unless you go and update memfd_pin_folios() too. >> >> I think making memfd_pin_folios() use unsigned long for max_folios makes >> a lot of sense, so can you please go update that first before making >> this change? And when you do, please match the type of the argument to >> the type you use here instead of using u64. This can be a separate, >> independent patch series. > > Thanks. I'll drop this patch. The preceding six patches are looking > well-reviewed and ready to go? Yes. The first six patches are good to go. I think the changes in this one can be split off as a separate series since it will be a bit more involved. > > Chenghao, please prepare any update for this patch against the > preceding six. Or against tomorrow's mm-unstable or mm-new or > linux-next. > -- Regards, Pratyush Yadav