Re: scheduling while atomic in z3fold

[Mike Galbraith]

On Mon, 2020-11-30 at 17:32 +0100, Sebastian Andrzej Siewior wrote:
> On 2020-11-30 17:27:17 [+0100], Mike Galbraith wrote:
> > > This just passed. It however killed my git-gc task which wasn't done.
> > > Let me try tomorrow with your config.
> >
> > FYI, I tried 5.9-rt (after fixing 5.9.11), it exploded in the same way,
> > so (as expected) it's not some devel tree oopsie.
>
> v5.9 has the same missing local-lock init due to merged local-lock
> upstream. I don't remember when this get_cpu_ptr() came it.

Looks like get_cpu_ptr() arrived in 4.14.

I patched up zswap/z3fold in my old 5.1-rt tree (old forward port of
4.19-rt), turned them on with a script, and it all worked fine, so the
RT zswap allergy lies somewhere upstream of there it seems.

If I were to start merging zswap and friends forward, I'd likely
eventually meet whatever RT is allergic to.  I might try that, but
won't be the least surprised if it turns into a god awful mess of
dependencies.

Hopping forward in rt branches first and patching them up will bracket
the little bugger a lot quicker.

	-Mike