Hi mm folks:

I reported a regression bug on latest upstream linux:
https://bugzilla.kernel.org/show_bug.cgi?id=216047

It's about xfs/ext4 + DAX, panic at mm/page_table_check.c:51!

  static struct page_table_check *get_page_table_check(struct page_ext *page_ext)
  {
==>     BUG_ON(!page_ext);
        return (void *)(page_ext) + page_table_check_ops.offset;
  }

It's 100% reproducible for me, by running fstests generic/623:
  https://git.kernel.org/pub/scm/fs/xfs/xfstests-dev.git/tree/tests/generic/623
on xfs or ext4 with DAX enabled.

It doesn't look like a xfs or ext4 issue, so send to linux-mm to get more
reviewing. More details please refer to above bug link. I changed its Pruduct
to mm, but the Assignee isn't changed by default.

Thanks,
Zorro