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It is supported on tmpfs. >>> There is use case to use MTE on hugetlbfs as well, adding MTE support. >>> >>> Signed-off-by: Yang Shi >>> --- >>>   fs/hugetlbfs/inode.c | 2 +- >>>   1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c >>> index ecad73a4f713..c34faef62daf 100644 >>> --- 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; >> >> Last time I checked, about a year ago, this was not sufficient. One >> issue is that there's no arch_clear_hugetlb_flags() implemented by your >> patch, leaving PG_arch_{2,3} set on a page. The other issue was that I >> initially tried to do this only on the head page but this did not go >> well with the folio_copy() -> copy_highpage() which expects the >> PG_arch_* flags on each individual page. The alternative was for >> arch_clear_hugetlb_flags() to iterate over all the pages in a folio. > > This would likely also add a blocker for > ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP on arm64 (no idea if there are now > ways to move forward with that now, or if we are still not sure if we > can actually add support), correct? IIUC, it is not. We just need to guarantee each subpage has PG_mte_tagged flag and allocated tags. The HVO just maps the 7 vmemmap pages for sub pages to the first page, they still see the flag and the space for tag is not impacted, right? Did I miss something? > >