linux-kernel - [PATCH v2 08/10] mm/page_alloc: drop stale pageblock comment in memmap_init

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Date:   Wed, 19 Aug 2020 19:59:55 +0200
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-mm@...ck.org, David Hildenbrand <david@...hat.com>,
        Michal Hocko <mhocko@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Wei Yang <richard.weiyang@...ux.alibaba.com>,
        Baoquan He <bhe@...hat.com>,
        Pankaj Gupta <pankaj.gupta.linux@...il.com>,
        Oscar Salvador <osalvador@...e.de>,
        Mel Gorman <mgorman@...e.de>
Subject: [PATCH v2 08/10] mm/page_alloc: drop stale pageblock comment in memmap_init_zone*()

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.

Acked-by: Michal Hocko <mhocko@...e.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Wei Yang <richard.weiyang@...ux.alibaba.com>
Cc: Baoquan He <bhe@...hat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@...il.com>
Cc: Oscar Salvador <osalvador@...e.de>
Cc: Mel Gorman <mgorman@...e.de>
Signed-off-by: David Hildenbrand <david@...hat.com>
---
 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