[PATCH] mm/list_lru: make the case where mlru is NULL as unlikely

[Jingxiang Zeng <jingxiangzeng.cas@gmail.com>]

From: Zeng Jingxiang <linuszeng@tencent.com>

In the following memcg_list_lru_alloc() function, mlru here is almost
always NULL, so in most cases this should save a function call, mark
mlru as unlikely to optimize the code.
        do {
                xas_lock_irqsave(&xas, flags);
                if (!xas_load(&xas) && !css_is_dying(&pos->css)) {
                        xas_store(&xas, mlru);
                        if (!xas_error(&xas))
                                mlru = NULL;
                }
                xas_unlock_irqrestore(&xas, flags);
        } while (xas_nomem(&xas, GFP_KERNEL));
>       if (mlru)
                kfree(mlru);

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202412290924.UTP7GH2Z-lkp@intel.com/
Signed-off-by: Zeng Jingxiang <linuszeng@tencent.com>
---
 mm/list_lru.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/list_lru.c b/mm/list_lru.c
index 064d2018e265..e7e13513ff8e 100644
--- a/mm/list_lru.c
+++ b/mm/list_lru.c
@@ -552,7 +552,7 @@ static int memcg_list_lru_alloc(struct mem_cgroup *memcg, struct list_lru *lru)
 			}
 			xas_unlock_irqrestore(&xas, flags);
 		} while (xas_nomem(&xas, GFP_KERNEL));
-		if (mlru)
+		if (unlikely(mlru))
 			kfree(mlru);
 		set_active_memcg(cur);
 	} while (pos != memcg && !css_is_dying(&pos->css));
-- 
2.43.5