Commit 3e38e0aa authored Aug 11, 2020 by Roman Gushchin Committed by Linus Torvalds Aug 12, 2020

mm: memcg: charge memcg percpu memory to the parent cgroup

Memory cgroups are using large chunks of percpu memory to store vmstat
data.  Yet this memory is not accounted at all, so in the case when there
are many (dying) cgroups, it's not exactly clear where all the memory is.

Because the size of memory cgroup internal structures can dramatically
exceed the size of object or page which is pinning it in the memory, it's
not a good idea to simply ignore it.  It actually breaks the isolation
between cgroups.

Let's account the consumed percpu memory to the parent cgroup.

[guro@fb.com: add WARN_ON_ONCE()s, per Johannes]
  Link: http://lkml.kernel.org/r/20200811170611.GB1507044@carbon.DHCP.thefacebook.com



Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Dennis Zhou <dennis@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Tobin C. Harding <tobin@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Waiman Long <longman@redhat.com>
Cc: Bixuan Cui <cuibixuan@huawei.com>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: http://lkml.kernel.org/r/20200623184515.4132564-5-guro@fb.com


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 772616b0

mm/memcontrol.c

+16 −4

Original line number	Diff line number	Diff line
		@@ -5131,13 +5131,18 @@ static int alloc_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
		if (!pn)
		return 1;

		pn->lruvec_stat_local = alloc_percpu(struct lruvec_stat);
		/* We charge the parent cgroup, never the current task */
		WARN_ON_ONCE(!current->active_memcg);

		pn->lruvec_stat_local = alloc_percpu_gfp(struct lruvec_stat,
		GFP_KERNEL_ACCOUNT);
		if (!pn->lruvec_stat_local) {
		kfree(pn);
		return 1;
		}

		pn->lruvec_stat_cpu = alloc_percpu(struct lruvec_stat);
		pn->lruvec_stat_cpu = alloc_percpu_gfp(struct lruvec_stat,
		GFP_KERNEL_ACCOUNT);
		if (!pn->lruvec_stat_cpu) {
		free_percpu(pn->lruvec_stat_local);
		kfree(pn);
		@@ -5211,11 +5216,16 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
		goto fail;
		}

		memcg->vmstats_local = alloc_percpu(struct memcg_vmstats_percpu);
		/* We charge the parent cgroup, never the current task */
		WARN_ON_ONCE(!current->active_memcg);

		memcg->vmstats_local = alloc_percpu_gfp(struct memcg_vmstats_percpu,
		GFP_KERNEL_ACCOUNT);
		if (!memcg->vmstats_local)
		goto fail;

		memcg->vmstats_percpu = alloc_percpu(struct memcg_vmstats_percpu);
		memcg->vmstats_percpu = alloc_percpu_gfp(struct memcg_vmstats_percpu,
		GFP_KERNEL_ACCOUNT);
		if (!memcg->vmstats_percpu)
		goto fail;

		@@ -5264,7 +5274,9 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
		struct mem_cgroup *memcg;
		long error = -ENOMEM;

		memalloc_use_memcg(parent);
		memcg = mem_cgroup_alloc();
		memalloc_unuse_memcg();
		if (IS_ERR(memcg))
		return ERR_CAST(memcg);

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