From: Roman Gushchin <[email protected]> commit 63b02ef7dc4ec239df45c018ac0adbd02ba30a0c upstream
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]> Signed-off-by: Zhang Xiao <[email protected]> --- mm/slab_common.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/mm/slab_common.c b/mm/slab_common.c index 0d247ef3057b..1815e9fe02b8 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) { @@ -752,14 +753,24 @@ void slab_deactivate_memcg_cache_rcu_sched(struct kmem_cache *s, WARN_ON_ONCE(s->memcg_params.deact_fn)) return; + /* + * 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.deact_fn = deact_fn; call_rcu(&s->memcg_params.deact_rcu_head, kmemcg_deactivate_rcufn); + +unlock: + spin_unlock_irq(&memcg_kmem_wq_lock); } void memcg_deactivate_kmem_caches(struct mem_cgroup *memcg) @@ -869,9 +880,9 @@ static int shutdown_memcg_caches(struct kmem_cache *s) static void memcg_set_kmem_cache_dying(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); } static void flush_memcg_workqueue(struct kmem_cache *s) -- 2.17.1
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