mm: memcontrol: use vmalloc fallback for large kmem memcg arrays (f80c7dab) · Commits · 戴 / test

For quick per-memcg indexing, slab caches and list_lru structures maintain linear arrays of descriptors. As the number of concurrent memory cgroups in the system goes up, this requires large contiguous allocations (8k cgroups = order-5, 16k cgroups = order-6 etc.) for every existing slab cache and list_lru, which can easily fail on loaded systems. E.g.: mkdir: page allocation failure: order:5, mode:0x14040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null) CPU: 1 PID: 6399 Comm: mkdir Not tainted 4.13.0-mm1-00065-g720bbe532b7c-dirty #481 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-20170228_101828-anatol 04/01/2014 Call Trace: ? __alloc_pages_direct_compact+0x4c/0x110 __alloc_pages_nodemask+0xf50/0x1430 alloc_pages_current+0x60/0xc0 kmalloc_order_trace+0x29/0x1b0 __kmalloc+0x1f4/0x320 memcg_update_all_list_lrus+0xca/0x2e0 mem_cgroup_css_alloc+0x612/0x670 cgroup_apply_control_enable+0x19e/0x360 cgroup_mkdir+0x322/0x490 kernfs_iop_mkdir+0x55/0x80 vfs_mkdir+0xd0/0x120 SyS_mkdirat+0x6c/0xe0 SyS_mkdir+0x14/0x20 entry_SYSCALL_64_fastpath+0x18/0xad Mem-Info: active_anon:2965 inactive_anon:19 isolated_anon:0 active_file:100270 inactive_file:98846 isolated_file:0 unevictable:0 dirty:0 writeback:0 unstable:0 slab_reclaimable:7328 slab_unreclaimable:16402 mapped:771 shmem:52 pagetables:278 bounce:0 free:13718 free_pcp:0 free_cma:0 This output is from an artificial reproducer, but we have repeatedly observed order-7 failures in production in the Facebook fleet. These systems become useless as they cannot run more jobs, even though there is plenty of memory to allocate 128 individual pages. Use kvmalloc and kvzalloc to fall back to vmalloc space if these arrays prove too large for allocating them physically contiguous. Link: http://lkml.kernel.org/r/20170918184919.20644-1-hannes@cmpxchg.org Signed-off-by:

Johannes Weiner <hannes@cmpxchg.org> Reviewed-by:

Josef Bacik <jbacik@fb.com> Acked-by:

Michal Hocko <mhocko@suse.com> Acked-by:

Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by:

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

Linus Torvalds <torvalds@linux-foundation.org>

mm/list_lru.c

+6 −6

Original line number	Diff line number	Diff line
		@@ -325,12 +325,12 @@ static int memcg_init_list_lru_node(struct list_lru_node *nlru)
		{
		int size = memcg_nr_cache_ids;

		nlru->memcg_lrus = kmalloc(size * sizeof(void *), GFP_KERNEL);
		nlru->memcg_lrus = kvmalloc(size * sizeof(void *), GFP_KERNEL);
		if (!nlru->memcg_lrus)
		return -ENOMEM;

		if (__memcg_init_list_lru_node(nlru->memcg_lrus, 0, size)) {
		kfree(nlru->memcg_lrus);
		kvfree(nlru->memcg_lrus);
		return -ENOMEM;
		}

		@@ -340,7 +340,7 @@ static int memcg_init_list_lru_node(struct list_lru_node *nlru)
		static void memcg_destroy_list_lru_node(struct list_lru_node *nlru)
		{
		__memcg_destroy_list_lru_node(nlru->memcg_lrus, 0, memcg_nr_cache_ids);
		kfree(nlru->memcg_lrus);
		kvfree(nlru->memcg_lrus);
		}

		static int memcg_update_list_lru_node(struct list_lru_node *nlru,
		@@ -351,12 +351,12 @@ static int memcg_update_list_lru_node(struct list_lru_node *nlru,
		BUG_ON(old_size > new_size);

		old = nlru->memcg_lrus;
		new = kmalloc(new_size * sizeof(void *), GFP_KERNEL);
		new = kvmalloc(new_size * sizeof(void *), GFP_KERNEL);
		if (!new)
		return -ENOMEM;

		if (__memcg_init_list_lru_node(new, old_size, new_size)) {
		kfree(new);
		kvfree(new);
		return -ENOMEM;
		}

		@@ -373,7 +373,7 @@ static int memcg_update_list_lru_node(struct list_lru_node *nlru,
		nlru->memcg_lrus = new;
		spin_unlock_irq(&nlru->lock);

		kfree(old);
		kvfree(old);
		return 0;
		}

mm/slab_common.c

+15 −7

Original line number	Diff line number	Diff line
		@@ -165,7 +165,7 @@ static int init_memcg_params(struct kmem_cache *s,
		if (!memcg_nr_cache_ids)
		return 0;

		arr = kzalloc(sizeof(struct memcg_cache_array) +
		arr = kvzalloc(sizeof(struct memcg_cache_array) +
		memcg_nr_cache_ids * sizeof(void *),
		GFP_KERNEL);
		if (!arr)
		@@ -178,14 +178,22 @@ static int init_memcg_params(struct kmem_cache *s,
		static void destroy_memcg_params(struct kmem_cache *s)
		{
		if (is_root_cache(s))
		kfree(rcu_access_pointer(s->memcg_params.memcg_caches));
		kvfree(rcu_access_pointer(s->memcg_params.memcg_caches));
		}

		static void free_memcg_params(struct rcu_head *rcu)
		{
		struct memcg_cache_array *old;

		old = container_of(rcu, struct memcg_cache_array, rcu);
		kvfree(old);
		}

		static int update_memcg_params(struct kmem_cache *s, int new_array_size)
		{
		struct memcg_cache_array old, new;

		new = kzalloc(sizeof(struct memcg_cache_array) +
		new = kvzalloc(sizeof(struct memcg_cache_array) +
		new_array_size * sizeof(void *), GFP_KERNEL);
		if (!new)
		return -ENOMEM;
		@@ -198,7 +206,7 @@ static int update_memcg_params(struct kmem_cache *s, int new_array_size)

		rcu_assign_pointer(s->memcg_params.memcg_caches, new);
		if (old)
		kfree_rcu(old, rcu);
		call_rcu(&old->rcu, free_memcg_params);
		return 0;
		}

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