linux-kernel - [PATCH] mm/slub: make add_full() condition more explicit

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Date:   Tue, 11 Aug 2020 10:02:36 +0800
From:   <wuyun.wu@...wei.com>
To:     Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        "David Rientjes" <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        "Andrew Morton" <akpm@...ux-foundation.org>
CC:     <liu.xiang6@....com.cn>, Abel Wu <wuyun.wu@...wei.com>,
        "open list:SLAB ALLOCATOR" <linux-mm@...ck.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: [PATCH] mm/slub: make add_full() condition more explicit

From: Abel Wu <wuyun.wu@...wei.com>

The commit below is incomplete, as it didn't handle the add_full() part.
commit a4d3f8916c65 ("slub: remove useless kmem_cache_debug() before remove_full()")

This patch checks for SLAB_STORE_USER instead of kmem_cache_debug(),
since that should be the only context in which we need the list_lock for
add_full().

Signed-off-by: Abel Wu <wuyun.wu@...wei.com>
---
 mm/slub.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/slub.c b/mm/slub.c
index f226d66408ee..df93a5a0e9a4 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2182,7 +2182,8 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page,
 		}
 	} else {
 		m = M_FULL;
-		if (kmem_cache_debug(s) && !lock) {
+#ifdef CONFIG_SLUB_DEBUG
+		if ((s->flags & SLAB_STORE_USER) && !lock) {
 			lock = 1;
 			/*
 			 * This also ensures that the scanning of full
@@ -2191,6 +2192,7 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page,
 			 */
 			spin_lock(&n->list_lock);
 		}
+#endif
 	}
 
 	if (l != m) {
-- 
2.28.0.windows.1