Commit 615d66c3 authored by Vladimir Davydov's avatar Vladimir Davydov Committed by Linus Torvalds
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mm: memcontrol: fix memcg id ref counter on swap charge move 

Since commit 73f576c0 ("mm: memcontrol: fix cgroup creation failure
after many small jobs") swap entries do not pin memcg->css.refcnt
directly.  Instead, they pin memcg->id.ref.  So we should adjust the
reference counters accordingly when moving swap charges between cgroups.

Fixes: 73f576c0 ("mm: memcontrol: fix cgroup creation failure after many small jobs")
Link: http://lkml.kernel.org/r/9ce297c64954a42dc90b543bc76106c4a94f07e8.1470219853.git.vdavydov@virtuozzo.com


Signed-off-by: default avatarVladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>	[3.19+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1f47b61f

mm/memcontrol.c

+18 −6
Original line number Diff line number Diff line
@@ -4077,9 +4077,9 @@ static struct cftype mem_cgroup_legacy_files[] = { 


static DEFINE_IDR(mem_cgroup_idr);



static void mem_cgroup_id_get(struct mem_cgroup *memcg)

static void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n)

{

	atomic_inc(&memcg->id.ref);

	atomic_add(n, &memcg->id.ref);

}



static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg)
@@ -4100,9 +4100,9 @@ static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg) 
	return memcg;

}



static void mem_cgroup_id_put(struct mem_cgroup *memcg)

static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n)

{

	if (atomic_dec_and_test(&memcg->id.ref)) {

	if (atomic_sub_and_test(n, &memcg->id.ref)) {

		idr_remove(&mem_cgroup_idr, memcg->id.id);

		memcg->id.id = 0;
@@ -4111,6 +4111,16 @@ static void mem_cgroup_id_put(struct mem_cgroup *memcg) 
	}

}



static inline void mem_cgroup_id_get(struct mem_cgroup *memcg)

{

	mem_cgroup_id_get_many(memcg, 1);

}



static inline void mem_cgroup_id_put(struct mem_cgroup *memcg)

{

	mem_cgroup_id_put_many(memcg, 1);

}



/**

 * mem_cgroup_from_id - look up a memcg from a memcg id

 * @id: the memcg id to look up
@@ -4745,6 +4755,8 @@ static void __mem_cgroup_clear_mc(void) 
		if (!mem_cgroup_is_root(mc.from))

			page_counter_uncharge(&mc.from->memsw, mc.moved_swap);



		mem_cgroup_id_put_many(mc.from, mc.moved_swap);



		/*

		 * we charged both to->memory and to->memsw, so we

		 * should uncharge to->memory.
@@ -4752,9 +4764,9 @@ static void __mem_cgroup_clear_mc(void) 
		if (!mem_cgroup_is_root(mc.to))

			page_counter_uncharge(&mc.to->memory, mc.moved_swap);



		css_put_many(&mc.from->css, mc.moved_swap);

		mem_cgroup_id_get_many(mc.to, mc.moved_swap);

		css_put_many(&mc.to->css, mc.moved_swap);



		/* we've already done css_get(mc.to) */

		mc.moved_swap = 0;

	}

	memcg_oom_recover(from);

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