[PATCH 1/4] mm/compaction: stop recording free page order in page->private

[Zi Yan]

Commit 733aea0b3a7bb ("mm/compaction: add support for >0 order folio
memory compaction.") stores isolated free pages in an array indexed by free
page orders, it is no longer needed to store the order in each page's
->private field. And there is no code using the stored order. Stop doing
that.

It also prepares for an upcoming change that ensures subpage->private is
zero at page free time and the removal of set_page_private(0) from
prep_compound_tail(). In alloc_contig_frozen_range_noprof(),
isolate_freepages_range() is used to grab free pages from buddy allocator
and it leaves the aforementioned page->private set until
either split_free_frozen_pages() or prep_new_page() is called. That
triggers the upcoming subpage->private nonzero check along once
set_page_private(0) is removed from prep_compound_tail(), which is called
via prep_new_page().

Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
---
 mm/compaction.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index b776f35ad020..349838cc6c19 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -644,7 +644,6 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
 		isolated = __isolate_free_page(page, order);
 		if (!isolated)
 			break;
-		set_page_private(page, order);
 
 		nr_scanned += isolated - 1;
 		total_isolated += isolated;
@@ -1617,7 +1616,6 @@ static void fast_isolate_freepages(struct compact_control *cc)
 		/* Isolate the page if available */
 		if (page) {
 			if (__isolate_free_page(page, order)) {
-				set_page_private(page, order);
 				nr_isolated = 1 << order;
 				nr_scanned += nr_isolated - 1;
 				total_isolated += nr_isolated;
@@ -1846,7 +1844,6 @@ static struct folio *compaction_alloc_noprof(struct folio *src, unsigned long da
 		size >>= 1;
 
 		list_add(&freepage[size].lru, &cc->freepages[start_order]);
-		set_page_private(&freepage[size], start_order);
 	}
 	dst = (struct folio *)freepage;
 

-- 
2.53.0