This patch provides kmem_cache_dup(), that duplicates
a cache for a memcg, preserving its creation properties.
Object size, alignment and flags are all respected.
When a duplicate cache is created, the parent cache cannot
be destructed during the child lifetime. To assure this,
its reference count is increased if the cache creation
succeeds.
Signed-off-by: Glauber Costa <glommer@xxxxxxxxxxxxx>
CC: Christoph Lameter <cl@xxxxxxxxx>
CC: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
CC: Michal Hocko <mhocko@xxxxxxx>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
CC: Johannes Weiner <hannes@xxxxxxxxxxx>
CC: Suleiman Souhlal <suleiman@xxxxxxxxxx>
---
include/linux/memcontrol.h | 3 +++
include/linux/slab.h | 3 +++
mm/memcontrol.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
mm/slub.c | 37 +++++++++++++++++++++++++++++++++++++
4 files changed, 87 insertions(+), 0 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 99e14b9..493ecdd 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -445,6 +445,9 @@ int memcg_css_id(struct mem_cgroup *memcg);
void mem_cgroup_register_cache(struct mem_cgroup *memcg,
struct kmem_cache *s);
void mem_cgroup_release_cache(struct kmem_cache *cachep);
+extern char *mem_cgroup_cache_name(struct mem_cgroup *memcg,
+ struct kmem_cache *cachep);
+
#else
static inline void mem_cgroup_register_cache(struct mem_cgroup *memcg,
struct kmem_cache *s)
diff --git a/include/linux/slab.h b/include/linux/slab.h
index c7a7e05..909b508 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -323,6 +323,9 @@ extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
#define MAX_KMEM_CACHE_TYPES 400
+extern struct kmem_cache *kmem_cache_dup(struct mem_cgroup *memcg,
+ struct kmem_cache *cachep);
+void kmem_cache_drop_ref(struct kmem_cache *cachep);
#else
#define MAX_KMEM_CACHE_TYPES 0
#endif /* CONFIG_CGROUP_MEM_RES_CTLR_KMEM */
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0015ed0..e881d83 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -467,6 +467,50 @@ struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg)
EXPORT_SYMBOL(tcp_proto_cgroup);
#endif /* CONFIG_INET */
+/*
+ * This is to prevent races againt the kmalloc cache creations.
+ * Should never be used outside the core memcg code. Therefore,
+ * copy it here, instead of letting it in lib/
+ */
+static char *kasprintf_no_account(gfp_t gfp, const char *fmt, ...)
+{
+ unsigned int len;
+ char *p = NULL;
+ va_list ap, aq;
+
+ va_start(ap, fmt);
+ va_copy(aq, ap);
+ len = vsnprintf(NULL, 0, fmt, aq);
+ va_end(aq);
+
+ p = kmalloc_no_account(len+1, gfp);
+ if (!p)
+ goto out;
+
+ vsnprintf(p, len+1, fmt, ap);
+
+out:
+ va_end(ap);
+ return p;
+}
+
+char *mem_cgroup_cache_name(struct mem_cgroup *memcg, struct kmem_cache *cachep)
+{
+ char *name;
+ struct dentry *dentry = memcg->css.cgroup->dentry;
+
+ BUG_ON(dentry == NULL);
+
+ /* Preallocate the space for "dead" at the end */
+ name = kasprintf_no_account(GFP_KERNEL, "%s(%d:%s)dead",
+ cachep->name, css_id(&memcg->css), dentry->d_name.name);
+
+ if (name)
+ /* Remove "dead" */
+ name[strlen(name) - 4] = '\0';
+ return name;
+}
+
/* Bitmap used for allocating the cache id numbers. */
static DECLARE_BITMAP(cache_types, MAX_KMEM_CACHE_TYPES);
diff --git a/mm/slub.c b/mm/slub.c
index 86e40cc..2285a96 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3993,6 +3993,43 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size,
}
EXPORT_SYMBOL(kmem_cache_create);
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+struct kmem_cache *kmem_cache_dup(struct mem_cgroup *memcg,
+ struct kmem_cache *s)
+{
+ char *name;
+ struct kmem_cache *new;
+
+ name = mem_cgroup_cache_name(memcg, s);
+ if (!name)
+ return NULL;
+
+ new = kmem_cache_create_memcg(memcg, name, s->objsize, s->align,
+ s->allocflags, s->ctor);
+
+ /*
+ * We increase the reference counter in the parent cache, to
+ * prevent it from being deleted. If kmem_cache_destroy() is
+ * called for the root cache before we call it for a child cache,
+ * it will be queued for destruction when we finally drop the
+ * reference on the child cache.
+ */
+ if (new) {
+ down_write(&slub_lock);
+ s->refcount++;
+ up_write(&slub_lock);
+ }
+
+ return new;
+}
+
+void kmem_cache_drop_ref(struct kmem_cache *s)
+{
+ BUG_ON(s->memcg_params.id != -1);
+ kmem_cache_destroy(s);
+}
+#endif
+
#ifdef CONFIG_SMP
/*
* Use the cpu notifier to insure that the cpu slabs are flushed when
--
1.7.7.6
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