On Tue, May 31, 2022 at 02:39:08AM +0800, Zorro Lang wrote:

On Mon, May 30, 2022 at 04:06:16PM +0800, Zorro Lang wrote:

quoted

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.

It's not a regression *recently* at least, I still can reproduce this bug on
linux v5.16.

But I found it's related with someone kernel configuration (sorry I haven't
figured out which one config is). I've upload two kernel config files, one[1]
can build a kernel which reproduce this bug, the other[2] can't. Hope that
helps.

Thanks,
Zorro

[1]
https://bugzilla.kernel.org/attachment.cgi?id=301076

[2]
https://bugzilla.kernel.org/attachment.cgi?id=301077

Rather than make anyone looking at this download multiple files and
run diff, perhaps you could just post the output of 'diff -u
config.good config.bad'?

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com