Re: [PATCH] drm: make sure page protections are updated afterchanging vm_flags.

[Andrew Morton]

On Wed, 30 Sep 2009 15:55:39 -0700
Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:

> Some architectures compute ->vm_page_prot depending on ->vm_flags, so
> we need to update the protections after adjusting the flags.
> 
> Reported-by: Jan Beulich <JBeulich@xxxxxxxxxx>
> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
> 
> diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
> index 8104eca..9d3e39f 100644
> --- a/drivers/gpu/drm/drm_gem.c
> +++ b/drivers/gpu/drm/drm_gem.c
> @@ -537,7 +537,7 @@ int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
>  	vma->vm_ops = obj->dev->driver->gem_vm_ops;
>  	vma->vm_private_data = map->handle;
>  	/* FIXME: use pgprot_writecombine when available */
> -	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.

u fail changelogology.

What were the consequences of the bug which you just fixed?
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