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authorRoman Gushchin <roman.gushchin@linux.dev>2023-10-19 15:53:43 -0700
committerAndrew Morton <akpm@linux-foundation.org>2023-10-25 16:47:11 -0700
commit675d6c9b59e313ca2573c93e8fd87011a99bb8ce (patch)
tree1699758fc9f4ffc43fb885516aa28a57fad72ce4
parent1aacbd354313f25c855e662e41c04e2abf71444a (diff)
mm: kmem: make memcg keep a reference to the original objcg
Keep a reference to the original objcg object for the entire life of a memcg structure. This allows to simplify the synchronization on the kernel memory allocation paths: pinning a (live) memcg will also pin the corresponding objcg. The memory overhead of this change is minimal because object cgroups usually outlive their corresponding memory cgroups even without this change, so it's only an additional pointer per memcg. Link: https://lkml.kernel.org/r/20231019225346.1822282-4-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin (Cruise) <roman.gushchin@linux.dev> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> Acked-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--include/linux/memcontrol.h8
-rw-r--r--mm/memcontrol.c5
2 files changed, 12 insertions, 1 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 6674c12725d5..cc110cc8fdfc 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -289,7 +289,13 @@ struct mem_cgroup {
#ifdef CONFIG_MEMCG_KMEM
int kmemcg_id;
- struct obj_cgroup __rcu *objcg;
+ /*
+ * memcg->objcg is wiped out as a part of the objcg repaprenting
+ * process. memcg->orig_objcg preserves a pointer (and a reference)
+ * to the original objcg until the end of live of memcg.
+ */
+ struct obj_cgroup __rcu *objcg;
+ struct obj_cgroup *orig_objcg;
/* list of inherited objcgs, protected by objcg_lock */
struct list_head objcg_list;
#endif
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 96f4c319f025..ff036d5d339d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3899,6 +3899,8 @@ static int memcg_online_kmem(struct mem_cgroup *memcg)
objcg->memcg = memcg;
rcu_assign_pointer(memcg->objcg, objcg);
+ obj_cgroup_get(objcg);
+ memcg->orig_objcg = objcg;
static_branch_enable(&memcg_kmem_online_key);
@@ -5406,6 +5408,9 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg)
{
int node;
+ if (memcg->orig_objcg)
+ obj_cgroup_put(memcg->orig_objcg);
+
for_each_node(node)
free_mem_cgroup_per_node_info(memcg, node);
kfree(memcg->vmstats);