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Commit 79cc304f authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Dave Airlie
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drm: make sure page protections are updated after changing vm_flags 



Some architectures compute ->vm_page_prot depending on ->vm_flags, so we
need to update the protections after adjusting the flags.

AFAIK this only affects running X under Xen; without this patch you get
lots of coloured blobs on the screen, or maybe a complete lockup.  Or
anything really.

But that still depends on lots of out-of-tree stuff, so I don't think
there are any consequences for anyone else.  But it is wrong in principle.

Reported-by: default avatarJan Beulich <JBeulich@novell.com>
Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent f82f5f3a

drivers/gpu/drm/drm_gem.c

+1 −1
Original line number Diff line number Diff line
@@ -552,7 +552,7 @@ int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma) 
	vma->vm_flags |= VM_RESERVED | VM_IO | VM_PFNMAP | VM_DONTEXPAND;

	vma->vm_ops = obj->dev->driver->gem_vm_ops;

	vma->vm_private_data = map->handle;

	vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);

	vma->vm_page_prot =  pgprot_writecombine(vm_get_page_prot(vma->vm_flags));



	/* Take a ref for this mapping of the object, so that the fault

	 * handler can dereference the mmap offset's pointer to the object.