Thread (98 messages) 98 messages, 6 authors, 2023-12-18

[PATCH RFC v2 08/27] mm: page_alloc: Partially revert "mm: page_alloc: remove stale CMA guard code"

From: Alexandru Elisei <hidden>
Date: 2023-11-19 16:58:21
Also in: kvmarm, linux-arch, linux-arm-kernel, linux-fsdevel, linux-mm, lkml
Subsystem: memory management, memory management - page allocator, the rest · Maintainers: Andrew Morton, Vlastimil Babka, Linus Torvalds

The patch f945116e4e19 ("mm: page_alloc: remove stale CMA guard code")
removed the CMA filter when allocating from the MIGRATE_MOVABLE pcp list
because CMA is always allowed when __GFP_MOVABLE is set.

With the introduction of the arch_alloc_cma() function, the above is not
true anymore, so bring back the filter.

This is a partially revert because the stale comment remains removed.

Signed-off-by: Alexandru Elisei <redacted>
---
 mm/page_alloc.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0f508070c404..135f9283a863 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2907,10 +2907,17 @@ struct page *rmqueue(struct zone *preferred_zone,
 	WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1));
 
 	if (likely(pcp_allowed_order(order))) {
-		page = rmqueue_pcplist(preferred_zone, zone, order,
-				       migratetype, alloc_flags);
-		if (likely(page))
-			goto out;
+		/*
+		 * MIGRATE_MOVABLE pcplist could have the pages on CMA area and
+		 * we need to skip it when CMA area isn't allowed.
+		 */
+		if (!IS_ENABLED(CONFIG_CMA) || alloc_flags & ALLOC_CMA ||
+				migratetype != MIGRATE_MOVABLE) {
+			page = rmqueue_pcplist(preferred_zone, zone, order,
+					migratetype, alloc_flags);
+			if (likely(page))
+				goto out;
+		}
 	}
 
 	page = rmqueue_buddy(preferred_zone, zone, order, alloc_flags,
-- 
2.42.1
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