Re: chasing the four level page table

From: Dave Jones
Date: Thu Jan 06 2005 - 16:54:47 EST


On Thu, Jan 06, 2005 at 03:05:49PM -0500, Jon Smirl wrote:
> On 6 Jan 2005 20:38:27 +0100, Andi Kleen <ak@xxxxxx> wrote:
> > You can't use get_user_pages in this case because the AGP aperture
> > can be above mem_map. If none of the callers take page_table_lock
> > already you would need to add that too. I guess from the context the lock
> > is not taken, but better double check.
> >
> > Perhaps we should add a get_user_phys() or somesuch for this.
>
> No where in DRM is page_table_lock being taken. Also, no other device
> driver takes page_table_lock either, so that probably implies that DRM
> shouldn't start doing it to.

No other device driver is also doing such lowlevel stuff with
page tables directly afaics. drivers/char/drm seem to be the only drivers
using [pgd|pmd|pte]_offset() routines.

Dave

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