mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_wp

commit 1cb9dc4 ("mm: hwpoison: support recovery from HugePage
copy-on-write faults") added support to use the mc variants when coping
hugetlb pages on CoW faults.

Add the missing VM_FAULT_SET_HINDEX, so the right si_addr_lsb will be
passed to userspace to report the extension of the faulty area.

Link: https://lkml.kernel.org/r/20240509100148.22384-3-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: osalvadorvilardaga

mm/hugetlb.c

@@ -6067,7 +6067,7 @@ static vm_fault_t hugetlb_wp(struct folio *pagecache_folio,
 		goto out_release_all;
 
 	if (copy_user_large_folio(new_folio, old_folio, vmf->real_address, vma)) {
-		ret = VM_FAULT_HWPOISON_LARGE;
+		ret = VM_FAULT_HWPOISON_LARGE | VM_FAULT_SET_HINDEX(hstate_index(h));
 		goto out_release_all;
 	}
 	__folio_mark_uptodate(new_folio);