[PATCH 10/22] mm/khugepaged: restrict collapse to common memory

[Gregory Price (Meta)]

Collapse is an opportunistic MM service and should operate only on
common memory. The anonymous scan and isolation paths already filter
zone device for the same reason.

Replace the zone_device check with page_is_common_memory().

collapse_scan_file() gains a folio_is_common_memory() check. Page-cache
folios are never ZONE_DEVICE, so there it only filters memory outside
N_MEMORY_COMMON.

All memory is common at this point, so behavior is unchanged.

Signed-off-by: Gregory Price (Meta) <gourry@xxxxxxxxxx>
---
 mm/khugepaged.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 4bbe319ef86fa..b4bd29f25c145 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -628,7 +628,7 @@ static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma,
 			goto out;
 		}
 		page = vm_normal_page(vma, addr, pteval);
-		if (unlikely(!page) || unlikely(is_zone_device_page(page))) {
+		if (unlikely(!page) || unlikely(!page_is_common_memory(page))) {
 			result = SCAN_PAGE_NULL;
 			goto out;
 		}
@@ -1673,7 +1673,7 @@ static enum scan_result collapse_scan_anon(struct vm_area_struct *vma,
 		}
 
 		page = vm_normal_page(vma, addr, pteval);
-		if (unlikely(!page) || unlikely(is_zone_device_page(page))) {
+		if (unlikely(!page) || unlikely(!page_is_common_memory(page))) {
 			result = SCAN_PAGE_NULL;
 			goto out_unmap;
 		}
@@ -2741,6 +2741,12 @@ static enum scan_result collapse_scan_file(struct mm_struct *mm,
 			break;
 		}
 
+		if (unlikely(!folio_is_common_memory(folio))) {
+			result = SCAN_PAGE_NULL;
+			failed_pfn = folio_pfn(folio);
+			folio_put(folio);
+			break;
+		}
 		node = folio_nid(folio);
 		if (collapse_scan_abort(node, cc)) {
 			result = SCAN_SCAN_ABORT;
-- 
2.53.1-Meta