[v2,1/2] mm/zbud: reuse unbuddied[0] as buddied in zbud_pool

Commit Message

Miaohe Lin June 8, 2021, 11:45 a.m. UTC

Since commit 9d8c5b5284e4 ("mm: zbud: fix condition check on allocation
size"), zbud_pool.unbuddied[0] is always unused. We can reuse it as buddied
field to save some possible memory.

Signed-off-by: Miaohe Lin <[e-mail]>
---
 mm/zbud.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Patch

diff --git a/mm/zbud.c b/mm/zbud.c
index a200121da400..78e80ca58869 100644
--- a/mm/zbud.c
+++ b/mm/zbud.c
@@ -95,8 +95,14 @@ 
  */
 struct zbud_pool {
 	spinlock_t lock;
-	struct list_head unbuddied[NCHUNKS];
-	struct list_head buddied;
+	union {
+		/*
+		 * Reuse unbuddied[0] as buddied on the ground that
+		 * unbuddied[0] is unused.
+		 */
+		struct list_head buddied;
+		struct list_head unbuddied[NCHUNKS];
+	};
 	struct list_head lru;
 	u64 pages_nr;
 	const struct zbud_ops *ops;