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authorRoman Gushchin <[email protected]>2019-07-11 20:56:24 -0700
committerLinus Torvalds <[email protected]>2019-07-12 11:05:44 -0700
commit63b02ef7dc4ec239df45c018ac0adbd02ba30a0c (patch)
tree8dba00a499a11f78abf6a12f963a26b9c57397d1
parent570332978ea7fdbec86a07086a584d796a87da2c (diff)
mm: memcg/slab: synchronize access to kmem_cache dying flag using a spinlock
Currently the memcg_params.dying flag and the corresponding workqueue used for the asynchronous deactivation of kmem_caches is synchronized using the slab_mutex. It makes impossible to check this flag from the irq context, which will be required in order to implement asynchronous release of kmem_caches. So let's switch over to the irq-save flavor of the spinlock-based synchronization. Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Roman Gushchin <[email protected]> Acked-by: Vladimir Davydov <[email protected]> Reviewed-by: Shakeel Butt <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Johannes Weiner <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Waiman Long <[email protected]> Cc: David Rientjes <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: Pekka Enberg <[email protected]> Cc: Andrei Vagin <[email protected]> Cc: Qian Cai <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
-rw-r--r--mm/slab_common.c15
1 files changed, 12 insertions, 3 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c
index afdd73553b88..a15557776d7d 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -130,6 +130,7 @@ 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 DEFINE_SPINLOCK(memcg_kmem_wq_lock);
void slab_init_memcg_params(struct kmem_cache *s)
{
@@ -734,14 +735,22 @@ static void kmemcg_cache_deactivate(struct kmem_cache *s)
__kmemcg_cache_deactivate(s);
+ /*
+ * memcg_kmem_wq_lock is used to synchronize memcg_params.dying
+ * flag and make sure that no new kmem_cache deactivation tasks
+ * are queued (see flush_memcg_workqueue() ).
+ */
+ spin_lock_irq(&memcg_kmem_wq_lock);
if (s->memcg_params.root_cache->memcg_params.dying)
- return;
+ goto unlock;
/* pin memcg so that @s doesn't get destroyed in the middle */
css_get(&s->memcg_params.memcg->css);
s->memcg_params.work_fn = __kmemcg_cache_deactivate_after_rcu;
call_rcu(&s->memcg_params.rcu_head, kmemcg_rcufn);
+unlock:
+ spin_unlock_irq(&memcg_kmem_wq_lock);
}
void memcg_deactivate_kmem_caches(struct mem_cgroup *memcg)
@@ -851,9 +860,9 @@ static int shutdown_memcg_caches(struct kmem_cache *s)
static void flush_memcg_workqueue(struct kmem_cache *s)
{
- mutex_lock(&slab_mutex);
+ spin_lock_irq(&memcg_kmem_wq_lock);
s->memcg_params.dying = true;
- mutex_unlock(&slab_mutex);
+ spin_unlock_irq(&memcg_kmem_wq_lock);
/*
* SLAB and SLUB deactivate the kmem_caches through call_rcu. Make