mm/hugetlb: fix potential missing huge page size info

The huge page size is encoded for VM_FAULT_HWPOISON errors only.  So if
we return VM_FAULT_HWPOISON, huge page size would just be ignored.

Link: https://lkml.kernel.org/r/20210107123449.38481-1-linmiaohe@huawei.com


Fixes: aa50d3a7 ("Encode huge page size for VM_FAULT_HWPOISON errors")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>