LKML Archive on lore.kernel.org
 help / color / Atom feed
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 13/19] mm: memcg/slab: simplify memcg cache creation
Date: Mon, 8 Jun 2020 16:06:48 -0700
Message-ID: <20200608230654.828134-14-guro@fb.com> (raw)
In-Reply-To: <20200608230654.828134-1-guro@fb.com>

Because the number of non-root kmem_caches doesn't depend on the
number of memory cgroups anymore and is generally not very big,
there is no more need for a dedicated workqueue.

Also, as there is no more need to pass any arguments to the
memcg_create_kmem_cache() except the root kmem_cache, it's
possible to just embed the work structure into the kmem_cache
and avoid the dynamic allocation of the work structure.

This will also simplify the synchronization: for each root kmem_cache
there is only one work. So there will be no more concurrent attempts
to create a non-root kmem_cache for a root kmem_cache: the second and
all following attempts to queue the work will fail.

On the kmem_cache destruction path there is no more need to call the
expensive flush_workqueue() and wait for all pending works to be
finished. Instead, cancel_work_sync() can be used to cancel/wait for
only one work.

Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
---
 include/linux/memcontrol.h |  1 -
 mm/memcontrol.c            | 48 +-------------------------------------
 mm/slab.h                  |  2 ++
 mm/slab_common.c           | 22 +++++++++--------
 4 files changed, 15 insertions(+), 58 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index e2c4d54aa1f6..ed0d2ac6a5d2 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1418,7 +1418,6 @@ int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size);
 void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size);
 
 extern struct static_key_false memcg_kmem_enabled_key;
-extern struct workqueue_struct *memcg_kmem_cache_wq;
 
 extern int memcg_nr_cache_ids;
 void memcg_get_cache_ids(void);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 995204f65217..2695cdc15baa 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -399,8 +399,6 @@ void memcg_put_cache_ids(void)
  */
 DEFINE_STATIC_KEY_FALSE(memcg_kmem_enabled_key);
 EXPORT_SYMBOL(memcg_kmem_enabled_key);
-
-struct workqueue_struct *memcg_kmem_cache_wq;
 #endif
 
 static int memcg_shrinker_map_size;
@@ -2902,39 +2900,6 @@ static void memcg_free_cache_id(int id)
 	ida_simple_remove(&memcg_cache_ida, id);
 }
 
-struct memcg_kmem_cache_create_work {
-	struct kmem_cache *cachep;
-	struct work_struct work;
-};
-
-static void memcg_kmem_cache_create_func(struct work_struct *w)
-{
-	struct memcg_kmem_cache_create_work *cw =
-		container_of(w, struct memcg_kmem_cache_create_work, work);
-	struct kmem_cache *cachep = cw->cachep;
-
-	memcg_create_kmem_cache(cachep);
-
-	kfree(cw);
-}
-
-/*
- * Enqueue the creation of a per-memcg kmem_cache.
- */
-static void memcg_schedule_kmem_cache_create(struct kmem_cache *cachep)
-{
-	struct memcg_kmem_cache_create_work *cw;
-
-	cw = kmalloc(sizeof(*cw), GFP_NOWAIT | __GFP_NOWARN);
-	if (!cw)
-		return;
-
-	cw->cachep = cachep;
-	INIT_WORK(&cw->work, memcg_kmem_cache_create_func);
-
-	queue_work(memcg_kmem_cache_wq, &cw->work);
-}
-
 /**
  * memcg_kmem_get_cache: select memcg or root cache for allocation
  * @cachep: the original global kmem cache
@@ -2951,7 +2916,7 @@ struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep)
 
 	memcg_cachep = READ_ONCE(cachep->memcg_params.memcg_cache);
 	if (unlikely(!memcg_cachep)) {
-		memcg_schedule_kmem_cache_create(cachep);
+		queue_work(system_wq, &cachep->memcg_params.work);
 		return cachep;
 	}
 
@@ -7062,17 +7027,6 @@ static int __init mem_cgroup_init(void)
 {
 	int cpu, node;
 
-#ifdef CONFIG_MEMCG_KMEM
-	/*
-	 * Kmem cache creation is mostly done with the slab_mutex held,
-	 * so use a workqueue with limited concurrency to avoid stalling
-	 * all worker threads in case lots of cgroups are created and
-	 * destroyed simultaneously.
-	 */
-	memcg_kmem_cache_wq = alloc_workqueue("memcg_kmem_cache", 0, 1);
-	BUG_ON(!memcg_kmem_cache_wq);
-#endif
-
 	cpuhp_setup_state_nocalls(CPUHP_MM_MEMCQ_DEAD, "mm/memctrl:dead", NULL,
 				  memcg_hotplug_cpu_dead);
 
diff --git a/mm/slab.h b/mm/slab.h
index 8f8552df5675..c6c7987dfd85 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -45,12 +45,14 @@ 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 */
 
diff --git a/mm/slab_common.c b/mm/slab_common.c
index e9deaafddbb6..10aa2acb84ca 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -132,10 +132,18 @@ int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr,
 
 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,
+						 memcg_params.work);
+	memcg_create_kmem_cache(cachep);
+}
+
 void slab_init_memcg_params(struct kmem_cache *s)
 {
 	s->memcg_params.root_cache = NULL;
 	s->memcg_params.memcg_cache = NULL;
+	INIT_WORK(&s->memcg_params.work, memcg_kmem_cache_create_func);
 }
 
 static void init_memcg_params(struct kmem_cache *s,
@@ -584,15 +592,9 @@ static int shutdown_memcg_caches(struct kmem_cache *s)
 	return 0;
 }
 
-static void flush_memcg_workqueue(struct kmem_cache *s)
+static void cancel_memcg_cache_creation(struct kmem_cache *s)
 {
-	/*
-	 * SLAB and SLUB create memcg kmem_caches through workqueue and SLUB
-	 * deactivates the memcg kmem_caches through workqueue. Make sure all
-	 * previous workitems on workqueue are processed.
-	 */
-	if (likely(memcg_kmem_cache_wq))
-		flush_workqueue(memcg_kmem_cache_wq);
+	cancel_work_sync(&s->memcg_params.work);
 }
 #else
 static inline int shutdown_memcg_caches(struct kmem_cache *s)
@@ -600,7 +602,7 @@ static inline int shutdown_memcg_caches(struct kmem_cache *s)
 	return 0;
 }
 
-static inline void flush_memcg_workqueue(struct kmem_cache *s)
+static inline void cancel_memcg_cache_creation(struct kmem_cache *s)
 {
 }
 #endif /* CONFIG_MEMCG_KMEM */
@@ -619,7 +621,7 @@ void kmem_cache_destroy(struct kmem_cache *s)
 	if (unlikely(!s))
 		return;
 
-	flush_memcg_workqueue(s);
+	cancel_memcg_cache_creation(s);
 
 	get_online_cpus();
 	get_online_mems();
-- 
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 ` Roman Gushchin [this message]
2020-06-22 17:29   ` [PATCH v6 13/19] mm: memcg/slab: simplify memcg cache creation 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 ` [PATCH v6 15/19] mm: memcg/slab: deprecate slab_root_caches Roman Gushchin
2020-06-22 17:36   ` 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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200608230654.828134-14-guro@fb.com \
    --to=guro@fb.com \
    --cc=akpm@linux-foundation.org \
    --cc=cl@linux.com \
    --cc=hannes@cmpxchg.org \
    --cc=kernel-team@fb.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mhocko@kernel.org \
    --cc=shakeelb@google.com \
    --cc=vbabka@suse.cz \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git
	git clone --mirror https://lore.kernel.org/lkml/9 lkml/git/9.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git