The patch titled
Subject: mm: memcg/slab: synchronize access to kmem_cache dying flag using a spinlock
has been added to the -mm tree. Its filename is
mm-synchronize-access-to-kmem_cache-dying-flag-using-a-spinlock.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-synchronize-access-to-kmem_cache-dying-flag-using-a-spinlock.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-synchronize-access-to-kmem_cache-dying-flag-using-a-spinlock.patch
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------------------------------------------------------
From: Roman Gushchin <guro@xxxxxx>
Subject: 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/20190611231813.3148843-8-guro@xxxxxx
Signed-off-by: Roman Gushchin <guro@xxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: Waiman Long <longman@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slab_common.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
--- a/mm/slab_common.c~mm-synchronize-access-to-kmem_cache-dying-flag-using-a-spinlock
+++ a/mm/slab_common.c
@@ -130,6 +130,7 @@ int __kmem_cache_alloc_bulk(struct kmem_
#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(stru
__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
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
_
Patches currently in -mm which might be from guro@xxxxxx are
mm-postpone-kmem_cache-memcg-pointer-initialization-to-memcg_link_cache.patch
mm-rename-slab-delayed-deactivation-functions-and-fields.patch
mm-generalize-postponed-non-root-kmem_cache-deactivation.patch
mm-introduce-__memcg_kmem_uncharge_memcg.patch
mm-unify-slab-and-slub-page-accounting.patch
mm-dont-check-the-dying-flag-on-kmem_cache-creation.patch
mm-synchronize-access-to-kmem_cache-dying-flag-using-a-spinlock.patch
mm-rework-non-root-kmem_cache-lifecycle-management.patch
mm-stop-setting-page-mem_cgroup-pointer-for-slab-pages.patch
mm-reparent-memcg-kmem_caches-on-cgroup-removal.patch
