hugetlb: update vma flag check for hugetlb vma lock

The check for whether a hugetlb vma lock exists partially depends on the
vma's flags.  Currently, it checks for either VM_MAYSHARE or VM_SHARED. 
The reason both flags are used is because VM_MAYSHARE was previously
cleared in hugetlb vmas as they are tore down.  This is no longer the
case, and only the VM_MAYSHARE check is required.

Link: https://lkml.kernel.org/r/20221212235042.178355-2-mike.kravetz@oracle.comSigned-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb.c

@@ -262,8 +262,7 @@ static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma)
  */
 static bool __vma_shareable_lock(struct vm_area_struct *vma)
 {
-	return vma->vm_flags & (VM_MAYSHARE | VM_SHARED) &&
-		vma->vm_private_data;
+	return vma->vm_flags & VM_MAYSHARE && vma->vm_private_data;
 }
 
 void hugetlb_vma_lock_read(struct vm_area_struct *vma)