Let's move the split comment regarding bootmem allocations and memory
holes, especially in the context of ZONE_MOVABLE, to the PageReserved()
check.
Reviewed-by: Baoquan He <bhe@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
mm/page_alloc.c | 22 ++++++----------------
1 file changed, 6 insertions(+), 16 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e028b87ce2942..042ba09d70c5d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8207,14 +8207,6 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page,
unsigned long iter = 0;
unsigned long pfn = page_to_pfn(page);
- /*
- * TODO we could make this much more efficient by not checking every
- * page in the range if we know all of them are in MOVABLE_ZONE and
- * that the movable zone guarantees that pages are migratable but
- * the later is not the case right now unfortunatelly. E.g. movablecore
- * can still lead to having bootmem allocations in zone_movable.
- */
-
if (is_migrate_cma_page(page)) {
/*
* CMA allocations (alloc_contig_range) really need to mark
@@ -8233,6 +8225,12 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page,
page = pfn_to_page(pfn + iter);
+ /*
+ * Both, bootmem allocations and memory holes are marked
+ * PG_reserved and are unmovable. We can even have unmovable
+ * allocations inside ZONE_MOVABLE, for example when
+ * specifying "movablecore".
+ */
if (PageReserved(page))
return page;
@@ -8306,14 +8304,6 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page,
* it. But now, memory offline itself doesn't call
* shrink_node_slabs() and it still to be fixed.
*/
- /*
- * If the page is not RAM, page_count()should be 0.
- * we don't need more check. This is an _used_ not-movable page.
- *
- * The problematic thing here is PG_reserved pages. PG_reserved
- * is set to both of a memory hole page and a _used_ kernel
- * page at boot.
- */
return page;
}
return NULL;
--
2.26.2
