linux-kernel - Re: [patch 2/3] splice: implement default splice

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: <E1M4f8b-0000Tb-GI@pomaz-ex.szeredi.hu>
Date:	Thu, 14 May 2009 19:54:33 +0200
From:	Miklos Szeredi <miklos@...redi.hu>
To:	jens.axboe@...cle.com
CC:	miklos@...redi.hu, akpm@...ux-foundation.org, max@...mpel.org,
	torvalds@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [patch 2/3] splice: implement default splice_read method

On Thu, 14 May 2009, Jens Axboe wrote:

> > The bigger problem is that the default_file_splice_write()
> > implementation in the other patch does the same (it calls
> > buf->ops->map() on all buffers).
> 
> Yep that's even worse, as that should go BUG() pretty much immediately
> when the KM_USER0 slot is reused!

No, ->map() calls plain kmap() if "atomic" argument is zero.
Nevertheless the deadlock due to multiple kmaps is still possible.

> > Hmm.  Simple solution would be to do a write() for each buffer.  But
> > this only affects HIGHMEM kernels, so it's a bit pointless to do that
> > on all archs.  Sigh...
> 
> It is unfortunate, we are going to be stuck with that for some time
> still...

I'm going to be offline till next monday, I'll post a fix after that.

Thanks,
Miklos
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/