[PATCH] hugetlbfs: add MTE support

[Yang Shi]

On Wed, Jun 26, 2024 at 1:40 PM Andrew Morton <akpm at linux-foundation.org> wrote:
>
> On Tue, 25 Jun 2024 16:37:17 -0700 Yang Shi <yang at os.amperecomputing.com> wrote:
>
> > MTE can be supported on ram based filesystem. It is supported on tmpfs.
> > There is use case to use MTE on hugetlbfs as well, adding MTE support.
> >
> > --- a/fs/hugetlbfs/inode.c
> > +++ b/fs/hugetlbfs/inode.c
> > @@ -110,7 +110,7 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
> >        * way when do_mmap unwinds (may be important on powerpc
> >        * and ia64).
> >        */
> > -     vm_flags_set(vma, VM_HUGETLB | VM_DONTEXPAND);
> > +     vm_flags_set(vma, VM_HUGETLB | VM_DONTEXPAND | VM_MTE_ALLOWED);
> >       vma->vm_ops = &hugetlb_vm_ops;
> >
> >       ret = seal_check_write(info->seals, vma);
>
> How thoroughly has this been tested?
>
> Can we expect normal linux-next testing to exercise this, or must
> testers make special arangements to get the coverage?

It requires special arrangements. This needs hardware support and
custom-patched QEMU. We did in-house test on AmpereOne platform with
patched QEMU 8.1.

>