From: Roman Gushchin roman.gushchin@linux.dev
mainline inclusion from mainline-v6.7-rc1 commit 675d6c9b59e313ca2573c93e8fd87011a99bb8ce category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8YU7J
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
--------------------------------
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 Signed-off-by: Liu Shixin liushixin2@huawei.com --- include/linux/memcontrol.h | 8 +++++++- mm/memcontrol.c | 5 +++++ 2 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 649fbb5c1adc..370d02ebc3cc 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -317,7 +317,13 @@ struct mem_cgroup { #endif #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 19a9bc9f2f11..abeb80a192dc 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3939,6 +3939,8 @@ 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);
@@ -6393,6 +6395,9 @@ 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);