Re: [GIT PULL] XArray for 4.19

[Dan Williams]

On Wed, Aug 22, 2018 at 10:43 AM Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> On Wed, Aug 22, 2018 at 10:40 AM Christopher Lameter <cl@xxxxxxxxx> wrote:
> >
> > Is this going in this cycle? I have a bunch of stuff on top of this to
> > enable slab object migration.
>
> No.
>
> It was based on a buggy branch that isn't getting pulled

To be clear, I don't think the problem you identified can be triggered
in practice. We are under the equivalent of the page lock for dax in
that path, and if ->mapping is NULL we would bail before finding that
the mapping-size helper returns zero.

> so when I
> started looking at it, the pull request was rejected before I got much
> further.

For the record I think skipping the entirety of the libnvdimm pull
request for this cycle due to that misuse of ilog2() is overkill, but
it's not my kernel.

Andrew, I think this means we need to lean on you to merge
dax-memory-failure and Xarray for 4.20 rather than try to coordinate
our own git branches for these specific topics.

At a minimum for 4.19 I think we should disable MADV_HWPOISON for dax
mappings this cycle to at least close that trivial method to crash the
kernel when using dax.

Dave, I recommend dropping dax-memory-failure and sending the other
libnvdimm topics for 4.19 that have been soaking in -next.