[PATCH v5 15/25] mm: Allow arm64 mmap(PROT_MTE) on RAM-based files

[Andrew Morton]

On Wed, 24 Jun 2020 18:52:34 +0100 Catalin Marinas <catalin.marinas at arm.com> wrote:

> Since arm64 memory (allocation) tags can only be stored in RAM, mapping
> files with PROT_MTE is not allowed by default. RAM-based files like
> those in a tmpfs mount or memfd_create() can support memory tagging, so
> update the vm_flags accordingly in shmem_mmap().
> 
> ...
>
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -2206,6 +2206,9 @@ static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
>  			vma->vm_flags &= ~(VM_MAYWRITE);
>  	}
>  
> +	/* arm64 - allow memory tagging on RAM-based files */
> +	vma->vm_flags |= VM_MTE_ALLOWED;
> +
>  	file_accessed(file);
>  	vma->vm_ops = &shmem_vm_ops;
>  	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&

Acked-by: Andrew Morton <akpm at linux-foundation.org>