Commit 0cc9a7e2 authored by Roman Gushchin's avatar Roman Gushchin Committed by Liu Shixin
Browse files

mm: kmem: make memcg keep a reference to the original objcg 

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/?id=675d6c9b59e313ca2573c93e8fd87011a99bb8ce

--------------------------------

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: default avatarRoman Gushchin (Cruise) <roman.gushchin@linux.dev>
Tested-by: default avatarNaresh Kamboju <naresh.kamboju@linaro.org>
Acked-by: default avatarShakeel Butt <shakeelb@google.com>
Reviewed-by: default avatarVlastimil 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLiu Shixin <liushixin2@huawei.com>
parent da0c01d5

include/linux/memcontrol.h

+7 −1
Original line number Diff line number Diff line
@@ -317,7 +317,13 @@ struct mem_cgroup { 
#endif

#ifdef CONFIG_MEMCG_KMEM

	int kmemcg_id;

	/*

	 * 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

mm/memcontrol.c

+5 −0
Original line number Diff line number Diff line
@@ -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);
@@ -6392,6 +6394,9 @@ 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);