On Wed 19-08-20 12:11:55, David Hildenbrand wrote:
> Commit ac5d2539b238 ("mm: meminit: reduce number of times pageblocks are
> set during struct page init") moved the actual zone range check, leaving
> only the alignment check for pageblocks.
>
> Let's drop the stale comment and make the pageblock check easier to read.
I do agree athat IS_ALIGNED is easier to read in this case.
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx>
> Cc: Baoquan He <bhe@xxxxxxxxxx>
> Cc: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx>
> Cc: Oscar Salvador <osalvador@xxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> mm/page_alloc.c | 14 ++------------
> 1 file changed, 2 insertions(+), 12 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 848664352dfe2..5db0b35f95e20 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -6022,13 +6022,8 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
> * to reserve their blocks rather than leaking throughout
> * the address space during boot when many long-lived
> * kernel allocations are made.
> - *
> - * bitmap is created for zone's valid pfn range. but memmap
> - * can be created for invalid pages (for alignment)
> - * check here not to call set_pageblock_migratetype() against
> - * pfn out of zone.
> */
> - if (!(pfn & (pageblock_nr_pages - 1))) {
> + if (IS_ALIGNED(pfn, pageblock_nr_pages)) {
> set_pageblock_migratetype(page, MIGRATE_MOVABLE);
> cond_resched();
> }
> @@ -6091,15 +6086,10 @@ void __ref memmap_init_zone_device(struct zone *zone,
> * the address space during boot when many long-lived
> * kernel allocations are made.
> *
> - * bitmap is created for zone's valid pfn range. but memmap
> - * can be created for invalid pages (for alignment)
> - * check here not to call set_pageblock_migratetype() against
> - * pfn out of zone.
> - *
> * Please note that MEMMAP_HOTPLUG path doesn't clear memmap
> * because this is done early in section_activate()
> */
> - if (!(pfn & (pageblock_nr_pages - 1))) {
> + if (IS_ALIGNED(pfn, pageblock_nr_pages)) {
> set_pageblock_migratetype(page, MIGRATE_MOVABLE);
> cond_resched();
> }
> --
> 2.26.2
>
--
Michal Hocko
SUSE Labs
