Subject: hmm pud-entry callback locking?

Hi, Jerome,

I was asked by Kirill to try to unify the pagewalk pud_entry and
pmd_entry callbacks. The only user of the pagewalk pud-entry is
currently hmm.

But the pagewalk code call pud_entry only for huge puds with the
page-table lock held, whereas the hmm callback appears to assume it gets
called unconditionally without the page-table lock held?

Could you shed some light into this?

Thanks,
Thomas



2019-10-07 14:22:33

by Jerome Glisse

[permalink] [raw]
Subject: Re: hmm pud-entry callback locking?

On Sat, Oct 05, 2019 at 02:29:40PM +0200, Thomas Hellstr?m (VMware) wrote:
> Hi, Jerome,
>
> I was asked by Kirill to try to unify the pagewalk pud_entry and pmd_entry
> callbacks. The only user of the pagewalk pud-entry is currently hmm.
>
> But the pagewalk code call pud_entry only for huge puds with the page-table
> lock held, whereas the hmm callback appears to assume it gets called
> unconditionally without the page-table lock held?
>
> Could you shed some light into this?

I think in my mind they were already unified :) I think easiest thing is
to remove the hmm pud walker, this is not a big deal this will break huge
pud for now, we can re-add this to hmm once you unified them.

Cheers,
J?r?me