linux-kernel - Re: [RFC PATCH] nvmet-tcp: Don't kmap() pages which can't come from HIGHMEM

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: <YvvpJbOT9iv6rnm2@kbusch-mbp.dhcp.thefacebook.com>
Date:   Tue, 16 Aug 2022 12:59:49 -0600
From:   Keith Busch <kbusch@...nel.org>
To:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>
Cc:     Christoph Hellwig <hch@....de>, Sagi Grimberg <sagi@...mberg.me>,
        Chaitanya Kulkarni <kch@...dia.com>,
        linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Ira Weiny <ira.weiny@...el.com>
Subject: Re: [RFC PATCH] nvmet-tcp: Don't kmap() pages which can't come from
 HIGHMEM

On Tue, Aug 16, 2022 at 11:18:08AM +0200, Fabio M. De Francesco wrote:
> 
> Therefore, I have two questions: am I right about thinking that the pages
> mapped in nvmet_tcp_map_pdu_iovec() are allocated with GFP_KERNEL? 

I think you are correct.

> If so, can anyone with more knowledge than mine please say if my changes make
> any sense?

I think it does make sense. I like the code simplification, though this use
was't really paying the kmap penalty since, as you mentioned, this is never
highmem.

You should also remove the cmd's 'nr_mapped' field while you're at it,
otherwise you'll hit the WARN in nvmet_tcp_free_cmd_buffers().