On Tue, Nov 10, 2020 at 11:50:52AM +0100, Alexander Gordeev wrote:
> > > static void __vmemmap_use_sub_pmd(unsigned long start, unsigned long end)
> > > {
> > >+ unsigned long size = min(end - start, sizeof(struct page));
> > >+
> > > /*
> > > * As we expect to add in the same granularity as we remove, it's
> > > * sufficient to mark only some piece used to block the memmap page from
> > > * getting removed (just in case the memmap never gets initialized,
> > > * e.g., because the memory block never gets onlined).
> > > */
> > >- memset(__va(start), 0, sizeof(struct page));
> > >+ memset(__va(start), 0, size);
> > > }
> > > static void vmemmap_use_sub_pmd(unsigned long start, unsigned long end)
> > >
> >
> > I don't really see a need for that. Can you spell out one possible
> > configuration that would trigger that in the future? It's sounds
> > very unlikely and I have the feeling there might be more to change
> > at other points.
>
> No configuration in mind. But dependency on struct page is the only
> obstacle that prevents the whole thing to become generic (unless I
> am missing something). Moreover, the memset() would not be needed
> also - just a single non-PAGE_UNUSED word within [start..end) should
> be enough.
Well, I agree with David here - so not applying.
