Re: [v3 9/9] s390: teach platforms not to zero struct pages memory

Heiko Carstens
2017-05-15T23:17:16Z

Hello Pasha,

> Thank you for looking at this patch. I am worried to make the proposed
> change, because, as I understand in this case we allocate memory not for
> "struct page"s but for table that hold them. So, we will change the behavior
> from the current one, where this table is allocated zeroed, but now it won't
> be zeroed.

The page table, if needed, is allocated and populated a couple of lines
above. See the vmem_pte_alloc() call. So my request to include the hunk
below is still valid ;)

> >If you add the hunk below then this is
> >
> >Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
> >
> >diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
> >index ffe9ba1aec8b..bf88a8b9c24d 100644
> >--- a/arch/s390/mm/vmem.c
> >+++ b/arch/s390/mm/vmem.c
> >@@ -272,7 +272,7 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
> > if (pte_none(*pt_dir)) {
> > void *new_page;
> >- new_page = vmemmap_alloc_block(PAGE_SIZE, node, true);
> >+ new_page = vmemmap_alloc_block(PAGE_SIZE, node, VMEMMAP_ZERO);
> > if (!new_page)
> > goto out;
> > pte_val(*pt_dir) = __pa(new_page) | pgt_prot;
> >