[PATCH] drm/vma-manager: Don't unmap COW'd pages when zapping bo ptes

[Daniel Vetter]

On Wed, Nov 20, 2013 at 01:55:49AM -0800, Thomas Hellstrom wrote:
> Not sure if there are any user-space users of private bo mappings, but
> if there are, or will be, zapping the COW'd pages when, for example,
> moving a bo would confuse the user immensely since the net effect for the
> user would be that pages written to would lose their contents.
> 
> Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>

Presuming I'm not horribly confused about that all the vm slang in the
kerneldoc means this changes is

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

Now I still hold that userspace creating anynomous bo mappings is rather
crazy, but meh ;-) I guess the real question is whether we have anyone
relying on this out there (or planing to), in which case we either need to
funnel this through stable kernels or whack a drm feature flag onto
drivers/kernels with this fixed. But I seriously hope the answer is no.

Cheers, Daniel
> ---
>  include/drm/drm_vma_manager.h |    6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/include/drm/drm_vma_manager.h b/include/drm/drm_vma_manager.h
> index c18a593..347077d 100644
> --- a/include/drm/drm_vma_manager.h
> +++ b/include/drm/drm_vma_manager.h
> @@ -231,9 +231,9 @@ static inline void drm_vma_node_unmap(struct drm_vma_offset_node *node,
>  				      struct address_space *file_mapping)
>  {
>  	if (file_mapping && drm_vma_node_has_offset(node))
> -		unmap_mapping_range(file_mapping,
> -				    drm_vma_node_offset_addr(node),
> -				    drm_vma_node_size(node) << PAGE_SHIFT, 1);
> +		unmap_shared_mapping_range
> +			(file_mapping, drm_vma_node_offset_addr(node),
> +			 drm_vma_node_size(node) << PAGE_SHIFT);
>  }
>  
>  /**
> -- 
> 1.7.10.4
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch