mm/memcontrol.c: convert mem_cgroup_id::ref to refcount_t type (1c2d479a) · Commits · 戴 / test

This will allow to use generic refcount_t interfaces to check counters overflow instead of currently existing VM_BUG_ON(). The only difference after the patch is VM_BUG_ON() may cause BUG(), while refcount_t fires with WARN(). But this seems not to be significant here, since such the problems are usually caught by syzbot with panic-on-warn enabled. Link: http://lkml.kernel.org/r/153910718919.7006.13400779039257185427.stgit@localhost.localdomain Signed-off-by:

Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by:

Andrew Morton <akpm@linux-foundation.org> Acked-by:

Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Andrea Parri <andrea.parri@amarulasolutions.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

include/linux/memcontrol.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -78,7 +78,7 @@ struct mem_cgroup_reclaim_cookie {

		struct mem_cgroup_id {
		int id;
		atomic_t ref;
		refcount_t ref;
		};

		/*

mm/memcontrol.c

+4 −6

Original line number	Diff line number	Diff line
		@@ -4299,14 +4299,12 @@ static void mem_cgroup_id_remove(struct mem_cgroup *memcg)

		static void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n)
		{
		VM_BUG_ON(atomic_read(&memcg->id.ref) <= 0);
		atomic_add(n, &memcg->id.ref);
		refcount_add(n, &memcg->id.ref);
		}

		static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n)
		{
		VM_BUG_ON(atomic_read(&memcg->id.ref) < n);
		if (atomic_sub_and_test(n, &memcg->id.ref)) {
		if (refcount_sub_and_test(n, &memcg->id.ref)) {
		mem_cgroup_id_remove(memcg);

		/* Memcg ID pins CSS */
		@@ -4523,7 +4521,7 @@ static int mem_cgroup_css_online(struct cgroup_subsys_state *css)
		}

		/* Online state pins memcg ID, memcg ID pins CSS */
		atomic_set(&memcg->id.ref, 1);
		refcount_set(&memcg->id.ref, 1);
		css_get(css);
		return 0;
		}
		@@ -6357,7 +6355,7 @@ subsys_initcall(mem_cgroup_init);
		#ifdef CONFIG_MEMCG_SWAP
		static struct mem_cgroup mem_cgroup_id_get_online(struct mem_cgroup memcg)
		{
		while (!atomic_inc_not_zero(&memcg->id.ref)) {
		while (!refcount_inc_not_zero(&memcg->id.ref)) {
		/*
		* The root cgroup cannot be destroyed, so it's refcount must
		* always be >= 1.

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