[Intel-gfx] [PATCH 2/2] drm/i915: Disable page-faults around the fast pwrite/pread paths

[Chris Wilson]

On Sat, 09 Jul 2011 07:41:57 -0700, Eric Anholt <eric at anholt.net> wrote:
> On Sat,  9 Jul 2011 09:38:51 +0100, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > --- a/drivers/gpu/drm/i915/i915_gem.c
> > +++ b/drivers/gpu/drm/i915/i915_gem.c
> 
> > -		vaddr = kmap_atomic(page, KM_USER0);
> > +		vaddr = kmap_atomic(page);
> > +		/* We have to disable faulting here in case the user address
> > +		 * is really a GTT mapping and so we can not enter
> > +		 * i915_gem_fault() whilst already holding struct_mutex.
> > +		 */
> > +		pagefault_disable();
> >  		ret = __copy_from_user_inatomic(vaddr + page_offset,
> >  						user_data,
> >  						page_length);
> > -		kunmap_atomic(vaddr, KM_USER0);
> > +		pagefault_enable();
> > +		kunmap_atomic(vaddr);
> 
> does this even compile?  Looks like you dropped an arg.

That parameter was removed several months ago and although a pass was made
through the kernel to update all callsites, this one inexplicably remained.

commit t 3e4d3af501cccdc8a8cca41bdbe57d54ad7e7e73
Author: Peter Zijlstra <a.p.zijlstra at chello.nl>
Date:   Tue Oct 26 14:21:51 2010 -0700

    mm: stack based kmap_atomic()

-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre