From: Timur Tabi <timur.tabi@ammasso.com>
To: Dave Hansen <haveblue@us.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>,
linux-mm <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
kernelnewbies@nl.linux.org
Subject: Re: get_user_pages() still broken in 2.6
Date: Wed, 29 Sep 2004 09:46:38 -0500 [thread overview]
Message-ID: <415ACACE.1020008@ammasso.com> (raw)
In-Reply-To: <1096413678.16198.16.camel@localhost>
Dave Hansen wrote:
> You probably want mlock(2) to keep the kernel from messing with the ptes
> at all.
mlock() can only be called via sys_mlock(), which is a user-space call.
Not only that, but only root can call sys_mlock(). This is not
compatible with our needs.
> But, you should probably really be thinking about why you're
> accessing the page tables at all. I count *ONE* instance in drivers/
> where page tables are accessed directly.
I access PTEs to get the physical addresses of a user-space buffer, so
that we can DMA to/from it directly.
--
Timur Tabi
Staff Software Engineer
timur.tabi@ammasso.com
WARNING: multiple messages have this Message-ID (diff)
From: Timur Tabi <timur.tabi@ammasso.com>
To: Dave Hansen <haveblue@us.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>,
linux-mm <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
kernelnewbies@nl.linux.org
Subject: Re: get_user_pages() still broken in 2.6
Date: Wed, 29 Sep 2004 09:46:38 -0500 [thread overview]
Message-ID: <415ACACE.1020008@ammasso.com> (raw)
In-Reply-To: <1096413678.16198.16.camel@localhost>
Dave Hansen wrote:
> You probably want mlock(2) to keep the kernel from messing with the ptes
> at all.
mlock() can only be called via sys_mlock(), which is a user-space call.
Not only that, but only root can call sys_mlock(). This is not
compatible with our needs.
> But, you should probably really be thinking about why you're
> accessing the page tables at all. I count *ONE* instance in drivers/
> where page tables are accessed directly.
I access PTEs to get the physical addresses of a user-space buffer, so
that we can DMA to/from it directly.
--
Timur Tabi
Staff Software Engineer
timur.tabi@ammasso.com
--
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next prev parent reply other threads:[~2004-09-29 15:13 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-28 22:40 get_user_pages() still broken in 2.6 Timur Tabi
2004-09-28 22:40 ` Timur Tabi
2004-09-28 23:03 ` Christoph Hellwig
2004-09-28 23:03 ` Christoph Hellwig
2004-09-28 23:21 ` Dave Hansen
2004-09-28 23:21 ` Dave Hansen
2004-09-29 14:46 ` Timur Tabi [this message]
2004-09-29 14:46 ` Timur Tabi
2004-09-29 14:48 ` Timur Tabi
2004-09-29 14:48 ` Timur Tabi
2004-09-29 15:01 ` Christoph Hellwig
2004-09-29 15:01 ` Christoph Hellwig
2004-09-29 4:49 ` opening a file inside the kernel module Rakesh Jagota
2004-09-29 4:49 ` Rakesh Jagota
2004-09-29 5:00 ` Jeff Garzik
2004-09-29 5:00 ` Jeff Garzik
2004-09-29 5:56 ` Rakesh Jagota
2004-09-29 5:56 ` Rakesh Jagota
2004-09-29 15:52 ` Stuart MacDonald
2004-09-29 15:52 ` Stuart MacDonald, linux-kernel-owner
[not found] <2JyXo-77W-19@gated-at.bofh.it>
[not found] ` <2JzgH-7rT-11@gated-at.bofh.it>
[not found] ` <2JOpu-1y1-21@gated-at.bofh.it>
2004-09-29 15:41 ` get_user_pages() still broken in 2.6 Andi Kleen
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