Re: [RFC PATCH v1 1/1] linux: mm_types: allow to modified the vm_flags in vm_area_struct

[Andrew Morton]

On Sun, 12 Mar 2023 23:42:50 +0100 Vincenzo Palazzo <vincenzopalazzodev@xxxxxxxxx> wrote:

> With 6.3-rc1 is not possible to build the following drivers

Well, let's cc Suren who actually wrote bc292ab00f6c ("mm: introduce
vma->vm_flags wrapper functions").

> - nvidia, that the compilation returns the following errors
> 
> - vboxhost/7.0.6_OSE where the build fails with the following errors
> 
> ...
>
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -497,7 +497,7 @@ struct vm_area_struct {
>  	 * To modify use vm_flags_{init|reset|set|clear|mod} functions.
>  	 */
>  	union {
> -		const vm_flags_t vm_flags;
> +		vm_flags_t vm_flags;
>  		vm_flags_t __private __vm_flags;
>  	};

These out-of-tree drivers should be converted to use the wrappers which
bc292ab00f6c added.  Their maintainers have a couple of months to do
this before bc292ab00f6c is released in 6.3.

It's unfortunate.  I guess it would be better if we were to find a way
to permit these drivers to compile OK but to generate warnings, as an
interim thing for six months or so.  Perhaps there's some clever way.