linux-kernel - Re: [PATCH 0/3] remove rw_page() from brd, pmem and btt

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: <20170731074404.GA16749@lst.de>
Date:   Mon, 31 Jul 2017 09:44:04 +0200
From:   Christoph Hellwig <hch@....de>
To:     Minchan Kim <minchan@...nel.org>
Cc:     Christoph Hellwig <hch@....de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>,
        linux-kernel@...r.kernel.org, "karam . lee" <karam.lee@....com>,
        Jerome Marchand <jmarchan@...hat.com>,
        Nitin Gupta <ngupta@...are.org>, seungho1.park@....com,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Chinner <david@...morbit.com>, Jan Kara <jack@...e.cz>,
        Jens Axboe <axboe@...nel.dk>,
        Vishal Verma <vishal.l.verma@...el.com>,
        linux-nvdimm@...ts.01.org
Subject: Re: [PATCH 0/3] remove rw_page() from brd, pmem and btt

On Mon, Jul 31, 2017 at 09:42:06AM +0200, Christoph Hellwig wrote:
> On Mon, Jul 31, 2017 at 04:36:47PM +0900, Minchan Kim wrote:
> > Do you suggest define something special flag(e.g., SWP_INMEMORY)
> > for in-memory swap to swap_info_struct when swapon time manually
> > or from bdi_queue_someting automatically?
> > And depending the flag of swap_info_struct, use the onstack bio
> > instead of dynamic allocation if the swap device is in-memory?
> 
> Currently swap always just does I/O on a single page as far
> as I can tell, so it can always just use an on-stack bio and
> biovec.

That's for synchronous I/O, aka reads of course.  For writes you'll
need to do a dynamic allocation if they are asynchronous.  But yes,
if we want to force certain devices to be synchronous we'll need
a flag for that.