Date:	Tue, 15 Dec 2015 20:50:40 +0100
From:	Michal Hocko <mhocko@...nel.org>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	netdev@...r.kernel.org, cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 12/14] mm: memcontrol: account socket memory in unified
 hierarchy memory controller

On Tue 08-12-15 10:30:22, Johannes Weiner wrote:
> Socket memory can be a significant share of overall memory consumed by
> common workloads. In order to provide reasonable resource isolation in
> the unified hierarchy, this type of memory needs to be included in the
> tracking/accounting of a cgroup under active memory resource control.
> 
> Overhead is only incurred when a non-root control group is created AND
> the memory controller is instructed to track and account the memory
> footprint of that group. cgroup.memory=nosocket can be specified on
> the boot commandline to override any runtime configuration and
> forcibly exclude socket memory from active memory resource control.
> 
> Signed-off-by: Johannes Weiner <hannes@...xchg.org>
> Acked-by: David S. Miller <davem@...emloft.net>
> Reviewed-by: Vladimir Davydov <vdavydov@...tuozzo.com>

Sorry I forgot about this
Acked-by: Michal Hocko <mhocko@...e.com>

> ---
>  Documentation/kernel-parameters.txt |   4 ++
>  include/linux/memcontrol.h          |   9 ++-
>  mm/memcontrol.c                     | 122 +++++++++++++++++++++++++++++-------
>  3 files changed, 110 insertions(+), 25 deletions(-)
> 
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 742f69d..7868f1b 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -599,6 +599,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>  			cut the overhead, others just disable the usage. So
>  			only cgroup_disable=memory is actually worthy}
>  
> +	cgroup.memory=	[KNL] Pass options to the cgroup memory controller.
> +			Format: <string>
> +			nosocket -- Disable socket memory accounting.
> +
>  	checkreqprot	[SELINUX] Set initial checkreqprot flag value.
>  			Format: { "0" | "1" }
>  			See security/selinux/Kconfig help text.
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 654c2fb..863ae8d 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -170,6 +170,9 @@ struct mem_cgroup {
>  	unsigned long low;
>  	unsigned long high;
>  
> +	/* Range enforcement for interrupt charges */
> +	struct work_struct high_work;
> +
>  	unsigned long soft_limit;
>  
>  	/* vmpressure notifications */
> @@ -684,12 +687,16 @@ void sock_update_memcg(struct sock *sk);
>  void sock_release_memcg(struct sock *sk);
>  bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages);
>  void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages);
> -#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_INET)
> +#if defined(CONFIG_MEMCG) && defined(CONFIG_INET)
>  extern struct static_key memcg_sockets_enabled_key;
>  #define mem_cgroup_sockets_enabled static_key_false(&memcg_sockets_enabled_key)
>  static inline bool mem_cgroup_under_socket_pressure(struct mem_cgroup *memcg)
>  {
> +#ifdef CONFIG_MEMCG_KMEM
>  	return memcg->tcp_mem.memory_pressure;
> +#else
> +	return false;
> +#endif
>  }
>  #else
>  #define mem_cgroup_sockets_enabled 0
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index ed030b5..59555b0 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -80,6 +80,9 @@ struct mem_cgroup *root_mem_cgroup __read_mostly;
>  
>  #define MEM_CGROUP_RECLAIM_RETRIES	5
>  
> +/* Socket memory accounting disabled? */
> +static bool cgroup_memory_nosocket;
> +
>  /* Whether the swap controller is active */
>  #ifdef CONFIG_MEMCG_SWAP
>  int do_swap_account __read_mostly;
> @@ -1923,6 +1926,26 @@ static int memcg_cpu_hotplug_callback(struct notifier_block *nb,
>  	return NOTIFY_OK;
>  }
>  
> +static void reclaim_high(struct mem_cgroup *memcg,
> +			 unsigned int nr_pages,
> +			 gfp_t gfp_mask)
> +{
> +	do {
> +		if (page_counter_read(&memcg->memory) <= memcg->high)
> +			continue;
> +		mem_cgroup_events(memcg, MEMCG_HIGH, 1);
> +		try_to_free_mem_cgroup_pages(memcg, nr_pages, gfp_mask, true);
> +	} while ((memcg = parent_mem_cgroup(memcg)));
> +}
> +
> +static void high_work_func(struct work_struct *work)
> +{
> +	struct mem_cgroup *memcg;
> +
> +	memcg = container_of(work, struct mem_cgroup, high_work);
> +	reclaim_high(memcg, CHARGE_BATCH, GFP_KERNEL);
> +}
> +
>  /*
>   * Scheduled by try_charge() to be executed from the userland return path
>   * and reclaims memory over the high limit.
> @@ -1930,20 +1953,13 @@ static int memcg_cpu_hotplug_callback(struct notifier_block *nb,
>  void mem_cgroup_handle_over_high(void)
>  {
>  	unsigned int nr_pages = current->memcg_nr_pages_over_high;
> -	struct mem_cgroup *memcg, *pos;
> +	struct mem_cgroup *memcg;
>  
>  	if (likely(!nr_pages))
>  		return;
>  
> -	pos = memcg = get_mem_cgroup_from_mm(current->mm);
> -
> -	do {
> -		if (page_counter_read(&pos->memory) <= pos->high)
> -			continue;
> -		mem_cgroup_events(pos, MEMCG_HIGH, 1);
> -		try_to_free_mem_cgroup_pages(pos, nr_pages, GFP_KERNEL, true);
> -	} while ((pos = parent_mem_cgroup(pos)));
> -
> +	memcg = get_mem_cgroup_from_mm(current->mm);
> +	reclaim_high(memcg, nr_pages, GFP_KERNEL);
>  	css_put(&memcg->css);
>  	current->memcg_nr_pages_over_high = 0;
>  }
> @@ -2078,6 +2094,11 @@ done_restock:
>  	 */
>  	do {
>  		if (page_counter_read(&memcg->memory) > memcg->high) {
> +			/* Don't bother a random interrupted task */
> +			if (in_interrupt()) {
> +				schedule_work(&memcg->high_work);
> +				break;
> +			}
>  			current->memcg_nr_pages_over_high += batch;
>  			set_notify_resume(current);
>  			break;
> @@ -4126,6 +4147,8 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg)
>  {
>  	int node;
>  
> +	cancel_work_sync(&memcg->high_work);
> +
>  	mem_cgroup_remove_from_trees(memcg);
>  
>  	for_each_node(node)
> @@ -4172,6 +4195,7 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
>  		page_counter_init(&memcg->kmem, NULL);
>  	}
>  
> +	INIT_WORK(&memcg->high_work, high_work_func);
>  	memcg->last_scanned_node = MAX_NUMNODES;
>  	INIT_LIST_HEAD(&memcg->oom_notify);
>  	memcg->move_charge_at_immigrate = 0;
> @@ -4243,6 +4267,11 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css)
>  	if (ret)
>  		return ret;
>  
> +#ifdef CONFIG_INET
> +	if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket)
> +		static_key_slow_inc(&memcg_sockets_enabled_key);
> +#endif
> +
>  	/*
>  	 * Make sure the memcg is initialized: mem_cgroup_iter()
>  	 * orders reading memcg->initialized against its callers
> @@ -4282,6 +4311,10 @@ static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
>  	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
>  
>  	memcg_destroy_kmem(memcg);
> +#ifdef CONFIG_INET
> +	if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket)
> +		static_key_slow_dec(&memcg_sockets_enabled_key);
> +#endif
>  	__mem_cgroup_free(memcg);
>  }
>  
> @@ -5470,8 +5503,7 @@ void mem_cgroup_replace_page(struct page *oldpage, struct page *newpage)
>  	commit_charge(newpage, memcg, true);
>  }
>  
> -/* Writing them here to avoid exposing memcg's inner layout */
> -#if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM)
> +#ifdef CONFIG_INET
>  
>  struct static_key memcg_sockets_enabled_key;
>  EXPORT_SYMBOL(memcg_sockets_enabled_key);
> @@ -5496,10 +5528,15 @@ void sock_update_memcg(struct sock *sk)
>  
>  	rcu_read_lock();
>  	memcg = mem_cgroup_from_task(current);
> -	if (memcg != root_mem_cgroup &&
> -	    memcg->tcp_mem.active &&
> -	    css_tryget_online(&memcg->css))
> +	if (memcg == root_mem_cgroup)
> +		goto out;
> +#ifdef CONFIG_MEMCG_KMEM
> +	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && !memcg->tcp_mem.active)
> +		goto out;
> +#endif
> +	if (css_tryget_online(&memcg->css))
>  		sk->sk_memcg = memcg;
> +out:
>  	rcu_read_unlock();
>  }
>  EXPORT_SYMBOL(sock_update_memcg);
> @@ -5520,15 +5557,30 @@ void sock_release_memcg(struct sock *sk)
>   */
>  bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
>  {
> -	struct page_counter *counter;
> +	gfp_t gfp_mask = GFP_KERNEL;
>  
> -	if (page_counter_try_charge(&memcg->tcp_mem.memory_allocated,
> -				    nr_pages, &counter)) {
> -		memcg->tcp_mem.memory_pressure = 0;
> -		return true;
> +#ifdef CONFIG_MEMCG_KMEM
> +	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
> +		struct page_counter *counter;
> +
> +		if (page_counter_try_charge(&memcg->tcp_mem.memory_allocated,
> +					    nr_pages, &counter)) {
> +			memcg->tcp_mem.memory_pressure = 0;
> +			return true;
> +		}
> +		page_counter_charge(&memcg->tcp_mem.memory_allocated, nr_pages);
> +		memcg->tcp_mem.memory_pressure = 1;
> +		return false;
>  	}
> -	page_counter_charge(&memcg->tcp_mem.memory_allocated, nr_pages);
> -	memcg->tcp_mem.memory_pressure = 1;
> +#endif
> +	/* Don't block in the packet receive path */
> +	if (in_softirq())
> +		gfp_mask = GFP_NOWAIT;
> +
> +	if (try_charge(memcg, gfp_mask, nr_pages) == 0)
> +		return true;
> +
> +	try_charge(memcg, gfp_mask|__GFP_NOFAIL, nr_pages);
>  	return false;
>  }
>  
> @@ -5539,10 +5591,32 @@ bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
>   */
>  void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
>  {
> -	page_counter_uncharge(&memcg->tcp_mem.memory_allocated, nr_pages);
> +#ifdef CONFIG_MEMCG_KMEM
> +	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
> +		page_counter_uncharge(&memcg->tcp_mem.memory_allocated,
> +				      nr_pages);
> +		return;
> +	}
> +#endif
> +	page_counter_uncharge(&memcg->memory, nr_pages);
> +	css_put_many(&memcg->css, nr_pages);
>  }
>  
> -#endif
> +#endif /* CONFIG_INET */
> +
> +static int __init cgroup_memory(char *s)
> +{
> +	char *token;
> +
> +	while ((token = strsep(&s, ",")) != NULL) {
> +		if (!*token)
> +			continue;
> +		if (!strcmp(token, "nosocket"))
> +			cgroup_memory_nosocket = true;
> +	}
> +	return 0;
> +}
> +__setup("cgroup.memory=", cgroup_memory);
>  
>  /*
>   * subsys_initcall() for memory controller.
> -- 
> 2.6.3
> 
> --
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-- 
Michal Hocko
SUSE Labs
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