Re: [PATCH 1/2] mm: reuse pageblock_start/end_pfn() macro

Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> · Fri, 2 Sep 2022 16:48:35 +0800

On 2022/9/2 16:20, David Hildenbrand wrote:
On 02.09.22 08:47, Kefeng Wang wrote:
Move pageblock_start_pfn/pageblock_end_pfn() into pageblock-flags.h,
then they could be used somewhere else, not only in compaction.

Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
---
  include/linux/pageblock-flags.h |  2 ++
  mm/compaction.c                 |  2 --
  mm/memblock.c                   |  2 +-
  mm/page_alloc.c                 | 13 ++++++-------
  mm/page_isolation.c             |  2 +-
  mm/page_owner.c                 |  4 ++--
  6 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
index 83c7248053a1..ef2e17e312ae 100644
--- a/include/linux/pageblock-flags.h
+++ b/include/linux/pageblock-flags.h
@@ -53,6 +53,8 @@ extern unsigned int pageblock_order;
  #endif /* CONFIG_HUGETLB_PAGE */
  
  #define pageblock_nr_pages	(1UL << pageblock_order)
+#define pageblock_start_pfn(pfn)	round_down(pfn, pageblock_nr_pages)
+#define pageblock_end_pfn(pfn)		ALIGN((pfn + 1), pageblock_nr_pages)
  
I'd naturally have paired ALIGN with ALIGN_DOWN -- or round_up with round_down.
(You're replacing one instance where ALIGN_DOWN was used at least.)

I think they are same for pageblock usage，but the original macro 
introduced from Vlastimil

(06b6640a3902 mm, compaction: wrap calculating first and last pfn of 
pageblock), let's

wait for Vlastimil to see if there are some background.


But maybe there is an obvious reason that I am missing :)

  /* Forward declaration */
  struct page;
diff --git a/mm/compaction.c b/mm/compaction.c
index f72907c7cfef..65bef5f78897 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -52,8 +52,6 @@ static inline void count_compact_events(enum vm_event_item item, long delta)
  
  #define block_start_pfn(pfn, order)	round_down(pfn, 1UL << (order))
  #define block_end_pfn(pfn, order)	ALIGN((pfn) + 1, 1UL << (order))
-#define pageblock_start_pfn(pfn)	block_start_pfn(pfn, pageblock_order)
-#define pageblock_end_pfn(pfn)		block_end_pfn(pfn, pageblock_order)
  
  /*
   * Page order with-respect-to which proactive compaction
diff --git a/mm/memblock.c b/mm/memblock.c
index b5d3026979fc..46fe7575f03c 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -2000,7 +2000,7 @@ static void __init free_unused_memmap(void)
  		 * presume that there are no holes in the memory map inside
  		 * a pageblock
  		 */
-		start = round_down(start, pageblock_nr_pages);
+		start = pageblock_start_pfn(start);
  
  		/*
  		 * If we had a previous bank, and there is a space
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 36b20215a3be..93339cc61f92 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -544,7 +544,7 @@ static inline int pfn_to_bitidx(const struct page *page, unsigned long pfn)
  #ifdef CONFIG_SPARSEMEM
  	pfn &= (PAGES_PER_SECTION-1);
  #else
-	pfn = pfn - round_down(page_zone(page)->zone_start_pfn, pageblock_nr_pages);
+	pfn = pfn - pageblock_start_pfn(page_zone(page)->zone_start_pfn);
  #endif /* CONFIG_SPARSEMEM */
  	return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
  }
@@ -1857,7 +1857,7 @@ void set_zone_contiguous(struct zone *zone)
  	unsigned long block_start_pfn = zone->zone_start_pfn;
  	unsigned long block_end_pfn;
  
-	block_end_pfn = ALIGN(block_start_pfn + 1, pageblock_nr_pages);
+	block_end_pfn = pageblock_end_pfn(block_start_pfn);
  	for (; block_start_pfn < zone_end_pfn(zone);
  			block_start_pfn = block_end_pfn,
  			 block_end_pfn += pageblock_nr_pages) {
@@ -2653,8 +2653,8 @@ int move_freepages_block(struct zone *zone, struct page *page,
  		*num_movable = 0;
  
  	pfn = page_to_pfn(page);
-	start_pfn = pfn & ~(pageblock_nr_pages - 1);
-	end_pfn = start_pfn + pageblock_nr_pages - 1;
+	start_pfn = pageblock_start_pfn(pfn);
+	end_pfn = pageblock_end_pfn(pfn) - 1;
  
  	/* Do not cross zone boundaries */
  	if (!zone_spans_pfn(zone, start_pfn))
@@ -6939,9 +6939,8 @@ static void __init init_unavailable_range(unsigned long spfn,
  	u64 pgcnt = 0;
  
  	for (pfn = spfn; pfn < epfn; pfn++) {
-		if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) {
-			pfn = ALIGN_DOWN(pfn, pageblock_nr_pages)
-				+ pageblock_nr_pages - 1;
+		if (!pfn_valid(pageblock_start_pfn(pfn))) {
+			pfn = pageblock_end_pfn(pfn) - 1;
  			continue;
  		}
  		__init_single_page(pfn_to_page(pfn), pfn, zone, node);
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 9d73dc38e3d7..f2df4ad53cd6 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -172,7 +172,7 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_
  	 * to avoid redundant checks.
  	 */
  	check_unmovable_start = max(page_to_pfn(page), start_pfn);
-	check_unmovable_end = min(ALIGN(page_to_pfn(page) + 1, pageblock_nr_pages),
+	check_unmovable_end = min(pageblock_end_pfn(page_to_pfn(page)),
  				  end_pfn);
  

There are some more cases that might need care as well:


mm/memblock.c:          prev_end = ALIGN(end, pageblock_nr_pages);
mm/memblock.c:          prev_end = ALIGN(end, pageblock_nr_pages);
mm/page_isolation.c:    VM_BUG_ON(ALIGN_DOWN(start_pfn, pageblock_nr_pages) !=
mm/page_isolation.c:              ALIGN_DOWN(end_pfn - 1, pageblock_nr_pages));
mm/page_isolation.c:    unsigned long isolate_start = ALIGN_DOWN(start_pfn, pageblock_nr_pages);
mm/page_isolation.c:    unsigned long isolate_end = ALIGN(end_pfn, pageblock_nr_pages);
mm/page_isolation.c:    unsigned long isolate_start = ALIGN_DOWN(start_pfn, pageblock_nr_pages);
mm/page_isolation.c:    unsigned long isolate_end = ALIGN(end_pfn, pageblock_nr_pages);

ok, will update.











