[RFC PATCH 10/12] mm: add the buddy system interface

[Xishi Qiu <qiuxishi@huawei.com>]

Add the buddy system interface for address range mirroring feature.
Allocate mirrored pages in MIGRATE_MIRROR list. If there is no mirrored pages
left, use other types pages.

Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
---
 mm/page_alloc.c | 40 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d4d2066..0fb55288 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -599,6 +599,26 @@ static inline bool is_mirror_pfn(unsigned long pfn)
 
 	return false;
 }
+
+static inline bool change_to_mirror(gfp_t gfp_flags, int high_zoneidx)
+{
+	/*
+	 * Do not alloc mirrored memory below 4G, because 0-4G is
+	 * all mirrored by default, and the list is always empty.
+	 */
+	if (high_zoneidx < ZONE_NORMAL)
+		return false;
+
+	/* Alloc mirrored memory for only kernel */
+	if (gfp_flags & __GFP_MIRROR)
+		return true;
+
+	/* Alloc mirrored memory for both user and kernel */
+	if (sysctl_mirrorable)
+		return true;
+
+	return false;
+}
 #endif
 
 /*
@@ -1796,7 +1816,10 @@ struct page *buffered_rmqueue(struct zone *preferred_zone,
 			WARN_ON_ONCE(order > 1);
 		}
 		spin_lock_irqsave(&zone->lock, flags);
-		page = __rmqueue(zone, order, migratetype);
+		if (is_migrate_mirror(migratetype))
+			page = __rmqueue_smallest(zone, order, migratetype);
+		else
+			page = __rmqueue(zone, order, migratetype);
 		spin_unlock(&zone->lock);
 		if (!page)
 			goto failed;
@@ -2928,6 +2951,11 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
 	if (IS_ENABLED(CONFIG_CMA) && ac.migratetype == MIGRATE_MOVABLE)
 		alloc_flags |= ALLOC_CMA;
 
+#ifdef CONFIG_MEMORY_MIRROR
+	if (change_to_mirror(gfp_mask, ac.high_zoneidx))
+		ac.migratetype = MIGRATE_MIRROR;
+#endif
+
 retry_cpuset:
 	cpuset_mems_cookie = read_mems_allowed_begin();
 
@@ -2943,9 +2971,19 @@ retry_cpuset:
 
 	/* First allocation attempt */
 	alloc_mask = gfp_mask|__GFP_HARDWALL;
+retry:
 	page = get_page_from_freelist(alloc_mask, order, alloc_flags, &ac);
 	if (unlikely(!page)) {
 		/*
+		 * If there is no mirrored memory, we will alloc other
+		 * types memory.
+		 */
+		if (is_migrate_mirror(ac.migratetype)) {
+			ac.migratetype = gfpflags_to_migratetype(gfp_mask);
+			goto retry;
+		}
+
+		/*
 		 * Runtime PM, block IO and its error handling path
 		 * can deadlock because I/O on the device might not
 		 * complete.
-- 
2.0.0


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