linux-kernel - [PATCH RFC v2 08/27] mm: page_alloc: Partially revert "mm: page

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Date:   Sun, 19 Nov 2023 16:57:02 +0000
From:   Alexandru Elisei <alexandru.elisei@....com>
To:     catalin.marinas@....com, will@...nel.org, oliver.upton@...ux.dev,
        maz@...nel.org, james.morse@....com, suzuki.poulose@....com,
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Subject: [PATCH RFC v2 08/27] mm: page_alloc: Partially revert "mm: page_alloc: remove stale CMA guard code"

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 <alexandru.elisei@....com>
---
 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