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authorVladimir Davydov <vdavydov@parallels.com>2014-06-04 16:07:20 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-04 16:53:59 -0700
commit03afc0e25f7fc03537014a770f4c54ebbe63a24c (patch)
tree520cdb32e6d35cd5b4e61fc5254a151fb03fc24a /mm/slab_common.c
parentbfc8c90139ebd049b9801a951db3b9a4a00bed9c (diff)
slab: get_online_mems for kmem_cache_{create,destroy,shrink}
When we create a sl[au]b cache, we allocate kmem_cache_node structures for each online NUMA node. To handle nodes taken online/offline, we register memory hotplug notifier and allocate/free kmem_cache_node corresponding to the node that changes its state for each kmem cache. To synchronize between the two paths we hold the slab_mutex during both the cache creationg/destruction path and while tuning per-node parts of kmem caches in memory hotplug handler, but that's not quite right, because it does not guarantee that a newly created cache will have all kmem_cache_nodes initialized in case it races with memory hotplug. For instance, in case of slub: CPU0 CPU1 ---- ---- kmem_cache_create: online_pages: __kmem_cache_create: slab_memory_callback: slab_mem_going_online_callback: lock slab_mutex for each slab_caches list entry allocate kmem_cache node unlock slab_mutex lock slab_mutex init_kmem_cache_nodes: for_each_node_state(node, N_NORMAL_MEMORY) allocate kmem_cache node add kmem_cache to slab_caches list unlock slab_mutex online_pages (continued): node_states_set_node As a result we'll get a kmem cache with not all kmem_cache_nodes allocated. To avoid issues like that we should hold get/put_online_mems() during the whole kmem cache creation/destruction/shrink paths, just like we deal with cpu hotplug. This patch does the trick. Note, that after it's applied, there is no need in taking the slab_mutex for kmem_cache_shrink any more, so it is removed from there. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Toshi Kani <toshi.kani@hp.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Cc: Jiang Liu <liuj97@gmail.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slab_common.c')
-rw-r--r--mm/slab_common.c35
1 files changed, 33 insertions, 2 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 2834bc2886fd..2dd920dc3776 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -205,6 +205,8 @@ kmem_cache_create(const char *name, size_t size, size_t align,
int err;
get_online_cpus();
+ get_online_mems();
+
mutex_lock(&slab_mutex);
err = kmem_cache_sanity_check(name, size);
@@ -239,6 +241,8 @@ kmem_cache_create(const char *name, size_t size, size_t align,
out_unlock:
mutex_unlock(&slab_mutex);
+
+ put_online_mems();
put_online_cpus();
if (err) {
@@ -272,6 +276,8 @@ void kmem_cache_create_memcg(struct mem_cgroup *memcg, struct kmem_cache *root_c
char *cache_name;
get_online_cpus();
+ get_online_mems();
+
mutex_lock(&slab_mutex);
/*
@@ -295,6 +301,8 @@ void kmem_cache_create_memcg(struct mem_cgroup *memcg, struct kmem_cache *root_c
out_unlock:
mutex_unlock(&slab_mutex);
+
+ put_online_mems();
put_online_cpus();
}
@@ -328,6 +336,8 @@ void slab_kmem_cache_release(struct kmem_cache *s)
void kmem_cache_destroy(struct kmem_cache *s)
{
get_online_cpus();
+ get_online_mems();
+
mutex_lock(&slab_mutex);
s->refcount--;
@@ -359,15 +369,36 @@ void kmem_cache_destroy(struct kmem_cache *s)
#else
slab_kmem_cache_release(s);
#endif
- goto out_put_cpus;
+ goto out;
out_unlock:
mutex_unlock(&slab_mutex);
-out_put_cpus:
+out:
+ put_online_mems();
put_online_cpus();
}
EXPORT_SYMBOL(kmem_cache_destroy);
+/**
+ * kmem_cache_shrink - Shrink a cache.
+ * @cachep: The cache to shrink.
+ *
+ * Releases as many slabs as possible for a cache.
+ * To help debugging, a zero exit status indicates all slabs were released.
+ */
+int kmem_cache_shrink(struct kmem_cache *cachep)
+{
+ int ret;
+
+ get_online_cpus();
+ get_online_mems();
+ ret = __kmem_cache_shrink(cachep);
+ put_online_mems();
+ put_online_cpus();
+ return ret;
+}
+EXPORT_SYMBOL(kmem_cache_shrink);
+
int slab_is_available(void)
{
return slab_state >= UP;