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From: Roman Gushchin <guro@fb.com>
To: Andrew Morton <akpm@linux-foundation.org>,
	Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>,
	Shakeel Butt <shakeelb@google.com>, <linux-mm@kvack.org>,
	Vlastimil Babka <vbabka@suse.cz>, <kernel-team@fb.com>,
	<linux-kernel@vger.kernel.org>, Roman Gushchin <guro@fb.com>
Subject: [PATCH v6 15/19] mm: memcg/slab: deprecate slab_root_caches
Date: Mon, 8 Jun 2020 16:06:50 -0700
Message-ID: <20200608230654.828134-16-guro@fb.com> (raw)
In-Reply-To: <20200608230654.828134-1-guro@fb.com>

Currently there are two lists of kmem_caches:
1) slab_caches, which contains all kmem_caches,
2) slab_root_caches, which contains only root kmem_caches.

And there is some preprocessor magic to have a single list
if CONFIG_MEMCG_KMEM isn't enabled.

It was required earlier because the number of non-root kmem_caches
was proportional to the number of memory cgroups and could reach
really big values. Now, when it cannot exceed the number of root
kmem_caches, there is really no reason to maintain two lists.

We never iterate over the slab_root_caches list on any hot paths,
so it's perfectly fine to iterate over slab_caches and filter out
non-root kmem_caches.

It allows to remove a lot of config-dependent code and two pointers
from the kmem_cache structure.

Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
---
 mm/slab.c        |  1 -
 mm/slab.h        | 17 -----------------
 mm/slab_common.c | 37 ++++++++-----------------------------
 mm/slub.c        |  1 -
 4 files changed, 8 insertions(+), 48 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index 7e8d0f62f30b..18a782bacd1b 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1239,7 +1239,6 @@ void __init kmem_cache_init(void)
 				  nr_node_ids * sizeof(struct kmem_cache_node *),
 				  SLAB_HWCACHE_ALIGN, 0, 0);
 	list_add(&kmem_cache->list, &slab_caches);
-	memcg_link_cache(kmem_cache);
 	slab_state = PARTIAL;
 
 	/*
diff --git a/mm/slab.h b/mm/slab.h
index f4033298a776..c49a863adb63 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -44,14 +44,12 @@ struct kmem_cache {
  *
  * @memcg_cache: pointer to memcg kmem cache, used by all non-root memory
  *		cgroups.
- * @root_caches_node: list node for slab_root_caches list.
  * @work: work struct used to create the non-root cache.
  */
 struct memcg_cache_params {
 	struct kmem_cache *root_cache;
 
 	struct kmem_cache *memcg_cache;
-	struct list_head __root_caches_node;
 	struct work_struct work;
 };
 #endif /* CONFIG_SLOB */
@@ -235,11 +233,6 @@ static inline int cache_vmstat_idx(struct kmem_cache *s)
 }
 
 #ifdef CONFIG_MEMCG_KMEM
-
-/* List of all root caches. */
-extern struct list_head		slab_root_caches;
-#define root_caches_node	memcg_params.__root_caches_node
-
 static inline bool is_root_cache(struct kmem_cache *s)
 {
 	return !s->memcg_params.root_cache;
@@ -415,14 +408,8 @@ static inline void memcg_slab_free_hook(struct kmem_cache *s, struct page *page,
 }
 
 extern void slab_init_memcg_params(struct kmem_cache *);
-extern void memcg_link_cache(struct kmem_cache *s);
 
 #else /* CONFIG_MEMCG_KMEM */
-
-/* If !memcg, all caches are root. */
-#define slab_root_caches	slab_caches
-#define root_caches_node	list
-
 static inline bool is_root_cache(struct kmem_cache *s)
 {
 	return true;
@@ -491,10 +478,6 @@ static inline void slab_init_memcg_params(struct kmem_cache *s)
 {
 }
 
-static inline void memcg_link_cache(struct kmem_cache *s)
-{
-}
-
 #endif /* CONFIG_MEMCG_KMEM */
 
 static inline struct kmem_cache *virt_to_cache(const void *obj)
diff --git a/mm/slab_common.c b/mm/slab_common.c
index f8874a159637..c045afb9724e 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -129,9 +129,6 @@ int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr,
 }
 
 #ifdef CONFIG_MEMCG_KMEM
-
-LIST_HEAD(slab_root_caches);
-
 static void memcg_kmem_cache_create_func(struct work_struct *work)
 {
 	struct kmem_cache *cachep = container_of(work, struct kmem_cache,
@@ -154,27 +151,11 @@ static void init_memcg_params(struct kmem_cache *s,
 	else
 		slab_init_memcg_params(s);
 }
-
-void memcg_link_cache(struct kmem_cache *s)
-{
-	if (is_root_cache(s))
-		list_add(&s->root_caches_node, &slab_root_caches);
-}
-
-static void memcg_unlink_cache(struct kmem_cache *s)
-{
-	if (is_root_cache(s))
-		list_del(&s->root_caches_node);
-}
 #else
 static inline void init_memcg_params(struct kmem_cache *s,
 				     struct kmem_cache *root_cache)
 {
 }
-
-static inline void memcg_unlink_cache(struct kmem_cache *s)
-{
-}
 #endif /* CONFIG_MEMCG_KMEM */
 
 /*
@@ -251,7 +232,7 @@ struct kmem_cache *find_mergeable(unsigned int size, unsigned int align,
 	if (flags & SLAB_NEVER_MERGE)
 		return NULL;
 
-	list_for_each_entry_reverse(s, &slab_root_caches, root_caches_node) {
+	list_for_each_entry_reverse(s, &slab_caches, list) {
 		if (slab_unmergeable(s))
 			continue;
 
@@ -310,7 +291,6 @@ static struct kmem_cache *create_cache(const char *name,
 
 	s->refcount = 1;
 	list_add(&s->list, &slab_caches);
-	memcg_link_cache(s);
 out:
 	if (err)
 		return ERR_PTR(err);
@@ -505,7 +485,6 @@ static int shutdown_cache(struct kmem_cache *s)
 	if (__kmem_cache_shutdown(s) != 0)
 		return -EBUSY;
 
-	memcg_unlink_cache(s);
 	list_del(&s->list);
 
 	if (s->flags & SLAB_TYPESAFE_BY_RCU) {
@@ -749,7 +728,6 @@ struct kmem_cache *__init create_kmalloc_cache(const char *name,
 
 	create_boot_cache(s, name, size, flags, useroffset, usersize);
 	list_add(&s->list, &slab_caches);
-	memcg_link_cache(s);
 	s->refcount = 1;
 	return s;
 }
@@ -1090,12 +1068,12 @@ static void print_slabinfo_header(struct seq_file *m)
 void *slab_start(struct seq_file *m, loff_t *pos)
 {
 	mutex_lock(&slab_mutex);
-	return seq_list_start(&slab_root_caches, *pos);
+	return seq_list_start(&slab_caches, *pos);
 }
 
 void *slab_next(struct seq_file *m, void *p, loff_t *pos)
 {
-	return seq_list_next(p, &slab_root_caches, pos);
+	return seq_list_next(p, &slab_caches, pos);
 }
 
 void slab_stop(struct seq_file *m, void *p)
@@ -1148,11 +1126,12 @@ static void cache_show(struct kmem_cache *s, struct seq_file *m)
 
 static int slab_show(struct seq_file *m, void *p)
 {
-	struct kmem_cache *s = list_entry(p, struct kmem_cache, root_caches_node);
+	struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
 
-	if (p == slab_root_caches.next)
+	if (p == slab_caches.next)
 		print_slabinfo_header(m);
-	cache_show(s, m);
+	if (is_root_cache(s))
+		cache_show(s, m);
 	return 0;
 }
 
@@ -1254,7 +1233,7 @@ static int memcg_slabinfo_show(struct seq_file *m, void *unused)
 	mutex_lock(&slab_mutex);
 	seq_puts(m, "# <name> <css_id[:dead|deact]> <active_objs> <num_objs>");
 	seq_puts(m, " <active_slabs> <num_slabs>\n");
-	list_for_each_entry(s, &slab_root_caches, root_caches_node) {
+	list_for_each_entry(s, &slab_caches, list) {
 		/*
 		 * Skip kmem caches that don't have the memcg cache.
 		 */
diff --git a/mm/slub.c b/mm/slub.c
index 6761e40e2c2e..891ae2716df1 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4292,7 +4292,6 @@ static struct kmem_cache * __init bootstrap(struct kmem_cache *static_cache)
 	}
 	slab_init_memcg_params(s);
 	list_add(&s->list, &slab_caches);
-	memcg_link_cache(s);
 	return s;
 }
 
-- 
2.25.4


  parent reply index

Thread overview: 92+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-08 23:06 [PATCH v6 00/19] The new cgroup slab memory controller Roman Gushchin
2020-06-08 23:06 ` [PATCH v6 01/19] mm: memcg: factor out memcg- and lruvec-level changes out of __mod_lruvec_state() Roman Gushchin
2020-06-17  1:52   ` Shakeel Butt
2020-06-17  2:50     ` Roman Gushchin
2020-06-17  2:59       ` Shakeel Butt
2020-06-17  3:19         ` Roman Gushchin
2020-06-08 23:06 ` [PATCH v6 02/19] mm: memcg: prepare for byte-sized vmstat items Roman Gushchin
2020-06-17  2:57   ` Shakeel Butt
2020-06-17  3:19     ` Roman Gushchin
2020-06-17 15:55   ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 03/19] mm: memcg: convert vmstat slab counters to bytes Roman Gushchin
2020-06-17  3:03   ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 04/19] mm: slub: implement SLUB version of obj_to_index() Roman Gushchin
2020-06-17  3:08   ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 05/19] mm: memcontrol: decouple reference counting from page accounting Roman Gushchin
2020-06-18  0:47   ` Shakeel Butt
2020-06-18 14:55   ` Shakeel Butt
2020-06-18 19:51     ` Roman Gushchin
2020-06-19  1:08     ` Roman Gushchin
2020-06-19  1:18       ` Shakeel Butt
2020-06-19  1:31   ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 06/19] mm: memcg/slab: obj_cgroup API Roman Gushchin
2020-06-19 15:42   ` Shakeel Butt
2020-06-19 21:38     ` Roman Gushchin
2020-06-19 22:16       ` Shakeel Butt
2020-06-19 22:52         ` Roman Gushchin
2020-06-20 22:50       ` Andrew Morton
2020-06-08 23:06 ` [PATCH v6 07/19] mm: memcg/slab: allocate obj_cgroups for non-root slab pages Roman Gushchin
2020-06-19 16:36   ` Shakeel Butt
2020-06-20  0:25     ` Roman Gushchin
2020-06-20  0:31       ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 08/19] mm: memcg/slab: save obj_cgroup for non-root slab objects Roman Gushchin
2020-06-20  0:16   ` Shakeel Butt
2020-06-20  1:19     ` Roman Gushchin
2020-06-08 23:06 ` [PATCH v6 09/19] mm: memcg/slab: charge individual slab objects instead of pages Roman Gushchin
2020-06-20  0:54   ` Shakeel Butt
2020-06-20  1:29     ` Roman Gushchin
2020-06-08 23:06 ` [PATCH v6 10/19] mm: memcg/slab: deprecate memory.kmem.slabinfo Roman Gushchin
2020-06-22 17:12   ` Shakeel Butt
2020-06-22 18:01     ` Roman Gushchin
2020-06-22 18:09       ` Shakeel Butt
2020-06-22 18:25         ` Roman Gushchin
2020-06-22 18:38           ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 11/19] mm: memcg/slab: move memcg_kmem_bypass() to memcontrol.h Roman Gushchin
2020-06-20  1:19   ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 12/19] mm: memcg/slab: use a single set of kmem_caches for all accounted allocations Roman Gushchin
2020-06-22 16:56   ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 13/19] mm: memcg/slab: simplify memcg cache creation Roman Gushchin
2020-06-22 17:29   ` Shakeel Butt
2020-06-22 17:40     ` Roman Gushchin
2020-06-22 18:03       ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 14/19] mm: memcg/slab: remove memcg_kmem_get_cache() Roman Gushchin
2020-06-22 18:42   ` Shakeel Butt
2020-06-08 23:06 ` Roman Gushchin [this message]
2020-06-22 17:36   ` [PATCH v6 15/19] mm: memcg/slab: deprecate slab_root_caches Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 16/19] mm: memcg/slab: remove redundant check in memcg_accumulate_slabinfo() Roman Gushchin
2020-06-22 17:32   ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 17/19] mm: memcg/slab: use a single set of kmem_caches for all allocations Roman Gushchin
2020-06-17 23:35   ` Andrew Morton
2020-06-18  0:35     ` Roman Gushchin
2020-06-18  7:33       ` Vlastimil Babka
2020-06-18 19:54         ` Roman Gushchin
2020-06-22 19:21   ` Shakeel Butt
2020-06-22 20:37     ` Roman Gushchin
2020-06-22 21:04       ` Shakeel Butt
2020-06-22 21:13         ` Roman Gushchin
2020-06-22 21:28           ` Shakeel Butt
2020-06-22 21:58             ` Roman Gushchin
2020-06-22 22:05               ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 18/19] kselftests: cgroup: add kernel memory accounting tests Roman Gushchin
2020-06-17  1:46 ` [PATCH v6 00/19] The new cgroup slab memory controller Shakeel Butt
2020-06-17  2:41   ` Roman Gushchin
2020-06-17  3:05     ` Shakeel Butt
2020-06-17  3:32       ` Roman Gushchin
2020-06-17 11:24         ` Vlastimil Babka
2020-06-17 14:31           ` Mel Gorman
2020-06-20  0:57             ` Roman Gushchin
2020-06-18  1:29           ` Roman Gushchin
2020-06-18  8:43             ` Jesper Dangaard Brouer
2020-06-18  9:31               ` Jesper Dangaard Brouer
2020-06-19  1:30                 ` Roman Gushchin
2020-06-19  8:32                   ` Jesper Dangaard Brouer
2020-06-19  1:27               ` Roman Gushchin
2020-06-19  9:39                 ` Jesper Dangaard Brouer
2020-06-19 18:47                   ` Roman Gushchin
2020-06-18  1:18   ` Roman Gushchin
2020-06-18  9:27 ` Mike Rapoport
2020-06-18 20:43   ` Roman Gushchin
2020-06-21 22:57 ` Qian Cai
2020-06-21 23:34   ` Roman Gushchin
2020-06-21 23:53     ` Qian Cai
2020-06-22  3:07       ` Roman Gushchin

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