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

Heiko Carstens
2017-05-08T11:36:24Z

On Fri, May 05, 2017 at 01:03:16PM -0400, Pavel Tatashin wrote:
> If we are using deferred struct page initialization feature, most of
> "struct page"es are getting initialized after other CPUs are started, and
> hence we are benefiting from doing this job in parallel. However, we are
> still zeroing all the memory that is allocated for "struct pages" using the
> boot CPU. This patch solves this problem, by deferring zeroing "struct
> pages" to only when they are initialized on s390 platforms.
>
> Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
> Reviewed-by: Shannon Nelson <shannon.nelson@oracle.com>
> ---
> arch/s390/mm/vmem.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
> index 9c75214..ffe9ba1 100644
> --- a/arch/s390/mm/vmem.c
> +++ b/arch/s390/mm/vmem.c
> @@ -252,7 +252,7 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
> void *new_page;
>
> new_page = vmemmap_alloc_block(PMD_SIZE, node,
> - true);
> + VMEMMAP_ZERO);
> if (!new_page)
> goto out;
> pmd_val(*pm_dir) = __pa(new_page) | sgt_prot;

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;