On Fri, 19 Jul 2019, Joerg Roedel wrote:
> On Thu, Jul 18, 2019 at 11:04:57AM +0200, Thomas Gleixner wrote:
> > Joerg,
> >
> > On Thu, 18 Jul 2019, Joerg Roedel wrote:
> > > On Wed, Jul 17, 2019 at 11:43:43PM +0200, Thomas Gleixner wrote:
> > > > On Wed, 17 Jul 2019, Joerg Roedel wrote:
> > > > > +
> > > > > + if (!pmd_present(*pmd_k))
> > > > > + return NULL;
> > > > > else
> > > > > BUG_ON(pmd_pfn(*pmd) != pmd_pfn(*pmd_k));
> > > >
> > > > So in case of unmap, this updates only the first entry in the pgd_list
> > > > because vmalloc_sync_all() will break out of the iteration over pgd_list
> > > > when NULL is returned from vmalloc_sync_one().
> > > >
> > > > I'm surely missing something, but how is that supposed to sync _all_
> > > > page
> > > > tables on unmap as the changelog claims?
> > >
> > > No, you are right, I missed that. It is a bug in this patch, the code
> > > that breaks out of the loop in vmalloc_sync_all() needs to be removed as
> > > well. Will do that in the next version.
> >
> > I assume that p4d/pud do not need the pmd treatment, but a comment
> > explaining why would be appreciated.
>
> Actually there is already a comment in this function explaining why p4d
> and pud don't need any treatment:
>
> /*
> * set_pgd(pgd, *pgd_k); here would be useless on PAE
> * and redundant with the set_pmd() on non-PAE. As would
> * set_p4d/set_pud.
> */
Indeed. Why did I think there was none?
> I couldn't say it with less words :)
It's perfectly fine.
Thanks,
tglx
