linux-kernel - [PATCH] mm/slub: remove dead code for debug caches on deactivate

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Message-Id: <20221014114322.97512-1-42.hyeyoo@gmail.com>
Date:   Fri, 14 Oct 2022 20:43:22 +0900
From:   Hyeonggon Yoo <42.hyeyoo@...il.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>,
        Vlastimil Babka <vbabka@...e.cz>,
        Roman Gushchin <roman.gushchin@...ux.dev>
Cc:     Hyeonggon Yoo <42.hyeyoo@...il.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] mm/slub: remove dead code for debug caches on deactivate_slab()

After commit c7323a5ad0786 ("mm/slub: restrict sysfs validation to debug
caches and make it safe"), SLUB does not take a slab from partial list for
debug caches. As deactivation isn't needed anymore, remove dead code.

Signed-off-by: Hyeonggon Yoo <42.hyeyoo@...il.com>
---
 mm/slub.c | 16 ++--------------
 1 file changed, 2 insertions(+), 14 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 96dd392d7f99..e2215240954d 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2411,7 +2411,7 @@ static void init_kmem_cache_cpus(struct kmem_cache *s)
 static void deactivate_slab(struct kmem_cache *s, struct slab *slab,
 			    void *freelist)
 {
-	enum slab_modes { M_NONE, M_PARTIAL, M_FULL, M_FREE, M_FULL_NOLIST };
+	enum slab_modes { M_NONE, M_PARTIAL, M_FREE, M_FULL_NOLIST };
 	struct kmem_cache_node *n = get_node(s, slab_nid(slab));
 	int free_delta = 0;
 	enum slab_modes mode = M_NONE;
@@ -2487,14 +2487,6 @@ static void deactivate_slab(struct kmem_cache *s, struct slab *slab,
 		 * acquire_slab() will see a slab that is frozen
 		 */
 		spin_lock_irqsave(&n->list_lock, flags);
-	} else if (kmem_cache_debug_flags(s, SLAB_STORE_USER)) {
-		mode = M_FULL;
-		/*
-		 * This also ensures that the scanning of full
-		 * slabs from diagnostic functions will not see
-		 * any frozen slabs.
-		 */
-		spin_lock_irqsave(&n->list_lock, flags);
 	} else {
 		mode = M_FULL_NOLIST;
 	}
@@ -2504,7 +2496,7 @@ static void deactivate_slab(struct kmem_cache *s, struct slab *slab,
 				old.freelist, old.counters,
 				new.freelist, new.counters,
 				"unfreezing slab")) {
-		if (mode == M_PARTIAL || mode == M_FULL)
+		if (mode == M_PARTIAL)
 			spin_unlock_irqrestore(&n->list_lock, flags);
 		goto redo;
 	}
@@ -2518,10 +2510,6 @@ static void deactivate_slab(struct kmem_cache *s, struct slab *slab,
 		stat(s, DEACTIVATE_EMPTY);
 		discard_slab(s, slab);
 		stat(s, FREE_SLAB);
-	} else if (mode == M_FULL) {
-		add_full(s, n, slab);
-		spin_unlock_irqrestore(&n->list_lock, flags);
-		stat(s, DEACTIVATE_FULL);
 	} else if (mode == M_FULL_NOLIST) {
 		stat(s, DEACTIVATE_FULL);
 	}
-- 
2.32.0