linux-kernel - Re: [PATCH v4 0/4] Implement dmabuf direct I/O via copy_file

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <09c8fb7c-a337-4813-9f44-3a538c4ee8b1@amd.com>
Date: Tue, 3 Jun 2025 15:14:20 +0200
From: Christian König <christian.koenig@....com>
To: Christoph Hellwig <hch@...radead.org>, wangtao <tao.wangtao@...or.com>
Cc: sumit.semwal@...aro.org, kraxel@...hat.com, vivek.kasireddy@...el.com,
 viro@...iv.linux.org.uk, brauner@...nel.org, hughd@...gle.com,
 akpm@...ux-foundation.org, amir73il@...il.com,
 benjamin.gaignard@...labora.com, Brian.Starkey@....com, jstultz@...gle.com,
 tjmercier@...gle.com, jack@...e.cz, baolin.wang@...ux.alibaba.com,
 linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 linaro-mm-sig@...ts.linaro.org, linux-kernel@...r.kernel.org,
 linux-fsdevel@...r.kernel.org, linux-mm@...ck.org, bintian.wang@...or.com,
 yipengxiang@...or.com, liulu.liu@...or.com, feng.han@...or.com
Subject: Re: [PATCH v4 0/4] Implement dmabuf direct I/O via copy_file_range

On 6/3/25 15:00, Christoph Hellwig wrote:
> This is a really weird interface.  No one has yet to explain why dmabuf
> is so special that we can't support direct I/O to it when we can support
> it to otherwise exotic mappings like PCI P2P ones.

With udmabuf you can do direct I/O, it's just inefficient to walk the page tables for it when you already have an array of all the folios.

Regards,
Christian.