Hi Hillf, On Thu, Nov 10, 2016 at 05:08:07PM +0800, Hillf Danton wrote: > On Tuesday, November 08, 2016 7:32 AM Naoya Horiguchi wrote: > > > > @@ -1013,6 +1027,9 @@ int do_huge_pmd_wp_page(struct fault_env *fe, pmd_t > > orig_pmd) > > if (unlikely(!pmd_same(*fe->pmd, orig_pmd))) > > goto out_unlock; > > > > + if (unlikely(!pmd_present(orig_pmd))) > > + goto out_unlock; > > + > > Can we encounter a migration entry after acquiring ptl ?
I think we can. thp migration code releases ptl after converting pmd into migration entry, so other code can see it even within ptl. Thanks, Naoya Horiguchi
