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Date:	Tue, 14 Oct 2014 17:56:47 +0200
From:	Michal Hocko <mhocko@...e.cz>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Vladimir Davydov <vdavydov@...allels.com>,
	cgroups@...r.kernel.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [patch 1/3] mm: memcontrol: lockless page counters

On Mon 13-10-14 21:46:01, Johannes Weiner wrote:
> Memory is internally accounted in bytes, using spinlock-protected
> 64-bit counters, even though the smallest accounting delta is a page.
> The counter interface is also convoluted and does too many things.
> 
> Introduce a new lockless word-sized page counter API, then change all
> memory accounting over to it.  The translation from and to bytes then
> only happens when interfacing with userspace.
> 
> The removed locking overhead is noticable when scaling beyond the
> per-cpu charge caches - on a 4-socket machine with 144-threads, the
> following test shows the performance differences of 288 memcgs
> concurrently running a page fault benchmark:

I assume you had root.use_hierarchy = 1, right? Processes wouldn't bounce
on the same lock otherwise.

> vanilla:
> 
>    18631648.500498      task-clock (msec)         #  140.643 CPUs utilized            ( +-  0.33% )
>          1,380,638      context-switches          #    0.074 K/sec                    ( +-  0.75% )
>             24,390      cpu-migrations            #    0.001 K/sec                    ( +-  8.44% )
>      1,843,305,768      page-faults               #    0.099 M/sec                    ( +-  0.00% )
> 50,134,994,088,218      cycles                    #    2.691 GHz                      ( +-  0.33% )
>    <not supported>      stalled-cycles-frontend
>    <not supported>      stalled-cycles-backend
>  8,049,712,224,651      instructions              #    0.16  insns per cycle          ( +-  0.04% )
>  1,586,970,584,979      branches                  #   85.176 M/sec                    ( +-  0.05% )
>      1,724,989,949      branch-misses             #    0.11% of all branches          ( +-  0.48% )
> 
>      132.474343877 seconds time elapsed                                          ( +-  0.21% )
> 
> lockless:
> 
>    12195979.037525      task-clock (msec)         #  133.480 CPUs utilized            ( +-  0.18% )
>            832,850      context-switches          #    0.068 K/sec                    ( +-  0.54% )
>             15,624      cpu-migrations            #    0.001 K/sec                    ( +- 10.17% )
>      1,843,304,774      page-faults               #    0.151 M/sec                    ( +-  0.00% )
> 32,811,216,801,141      cycles                    #    2.690 GHz                      ( +-  0.18% )
>    <not supported>      stalled-cycles-frontend
>    <not supported>      stalled-cycles-backend
>  9,999,265,091,727      instructions              #    0.30  insns per cycle          ( +-  0.10% )
>  2,076,759,325,203      branches                  #  170.282 M/sec                    ( +-  0.12% )
>      1,656,917,214      branch-misses             #    0.08% of all branches          ( +-  0.55% )
> 
>       91.369330729 seconds time elapsed                                          ( +-  0.45% )

So this is ~30% improvement which is more than I expected. Nice!
It is true that this test case is never hitting any limit so this is
always a hot-path but once we hit the limit the res_counter is the last
thing we care about.

> On top of improved scalability, this also gets rid of the icky long
> long types in the very heart of memcg, which is great for 32 bit and
> also makes the code a lot more readable.
> 
> Notable differences between the old and new API:
> 
> - res_counter_charge() and res_counter_charge_nofail() become
>   page_counter_try_charge() and page_counter_charge() resp. to match
>   the more common kernel naming scheme of try_do()/do()
> 
> - res_counter_uncharge_until() is only ever used to cancel a local
>   counter and never to uncharge bigger segments of a hierarchy, so
>   it's replaced by the simpler page_counter_cancel()
> 
> - res_counter_set_limit() is replaced by page_counter_limit(), which
>   expects its callers to serialize against themselves
> 
> - res_counter_memparse_write_strategy() is replaced by
>   page_counter_limit(), which rounds down to the nearest page size -
>   rather than up.  This is more reasonable for explicitely requested
>   hard upper limits.
> 
> - to keep charging light-weight, page_counter_try_charge() charges
>   speculatively, only to roll back if the result exceeds the limit.
>   Because of this, a failing bigger charge can temporarily lock out
>   smaller charges that would otherwise succeed.  The error is bounded
>   to the difference between the smallest and the biggest possible
>   charge size, so for memcg, this means that a failing THP charge can
>   send base page charges into reclaim upto 2MB (4MB) before the limit
>   would have been reached.  This should be acceptable.

Thanks!.

> Signed-off-by: Johannes Weiner <hannes@...xchg.org>

You have only missed MAINTAINERS...

Acked-by: Michal Hocko <mhocko@...e.cz>

> ---
>  Documentation/cgroups/memory.txt |   4 +-
>  include/linux/memcontrol.h       |   5 +-
>  include/linux/page_counter.h     |  49 +++
>  include/net/sock.h               |  26 +-
>  init/Kconfig                     |   5 +-
>  mm/Makefile                      |   1 +
>  mm/memcontrol.c                  | 633 ++++++++++++++++++---------------------
>  mm/page_counter.c                | 203 +++++++++++++
>  net/ipv4/tcp_memcontrol.c        |  87 +++---
>  9 files changed, 609 insertions(+), 404 deletions(-)
>  create mode 100644 include/linux/page_counter.h
>  create mode 100644 mm/page_counter.c
> 
> diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
> index 02ab997a1ed2..f624727ab404 100644
> --- a/Documentation/cgroups/memory.txt
> +++ b/Documentation/cgroups/memory.txt
> @@ -52,9 +52,9 @@ Brief summary of control files.
>   tasks				 # attach a task(thread) and show list of threads
>   cgroup.procs			 # show list of processes
>   cgroup.event_control		 # an interface for event_fd()
> - memory.usage_in_bytes		 # show current res_counter usage for memory
> + memory.usage_in_bytes		 # show current usage for memory
>  				 (See 5.5 for details)
> - memory.memsw.usage_in_bytes	 # show current res_counter usage for memory+Swap
> + memory.memsw.usage_in_bytes	 # show current usage for memory+Swap
>  				 (See 5.5 for details)
>   memory.limit_in_bytes		 # set/show limit of memory usage
>   memory.memsw.limit_in_bytes	 # set/show limit of memory+Swap usage
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 19df5d857411..0daf383f8f1c 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -471,9 +471,8 @@ memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **memcg, int order)
>  	/*
>  	 * __GFP_NOFAIL allocations will move on even if charging is not
>  	 * possible. Therefore we don't even try, and have this allocation
> -	 * unaccounted. We could in theory charge it with
> -	 * res_counter_charge_nofail, but we hope those allocations are rare,
> -	 * and won't be worth the trouble.
> +	 * unaccounted. We could in theory charge it forcibly, but we hope
> +	 * those allocations are rare, and won't be worth the trouble.
>  	 */
>  	if (gfp & __GFP_NOFAIL)
>  		return true;
> diff --git a/include/linux/page_counter.h b/include/linux/page_counter.h
> new file mode 100644
> index 000000000000..d92d18949474
> --- /dev/null
> +++ b/include/linux/page_counter.h
> @@ -0,0 +1,49 @@
> +#ifndef _LINUX_PAGE_COUNTER_H
> +#define _LINUX_PAGE_COUNTER_H
> +
> +#include <linux/atomic.h>
> +
> +struct page_counter {
> +	atomic_long_t count;
> +	unsigned long limit;
> +	struct page_counter *parent;
> +
> +	/* legacy */
> +	unsigned long watermark;
> +	unsigned long failcnt;
> +};
> +
> +#if BITS_PER_LONG == 32
> +#define PAGE_COUNTER_MAX LONG_MAX
> +#else
> +#define PAGE_COUNTER_MAX (LONG_MAX / PAGE_SIZE)
> +#endif
> +
> +static inline void page_counter_init(struct page_counter *counter,
> +				     struct page_counter *parent)
> +{
> +	atomic_long_set(&counter->count, 0);
> +	counter->limit = PAGE_COUNTER_MAX;
> +	counter->parent = parent;
> +}
> +
> +static inline unsigned long page_counter_read(struct page_counter *counter)
> +{
> +	return atomic_long_read(&counter->count);
> +}
> +
> +int page_counter_cancel(struct page_counter *counter, unsigned long nr_pages);
> +void page_counter_charge(struct page_counter *counter, unsigned long nr_pages);
> +int page_counter_try_charge(struct page_counter *counter,
> +			    unsigned long nr_pages,
> +			    struct page_counter **fail);
> +int page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages);
> +int page_counter_limit(struct page_counter *counter, unsigned long limit);
> +int page_counter_memparse(const char *buf, unsigned long *nr_pages);
> +
> +static inline void page_counter_reset_watermark(struct page_counter *counter)
> +{
> +	counter->watermark = page_counter_read(counter);
> +}
> +
> +#endif /* _LINUX_PAGE_COUNTER_H */
> diff --git a/include/net/sock.h b/include/net/sock.h
> index 7db3db112baa..0fa8cf908b65 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -54,8 +54,8 @@
>  #include <linux/security.h>
>  #include <linux/slab.h>
>  #include <linux/uaccess.h>
> +#include <linux/page_counter.h>
>  #include <linux/memcontrol.h>
> -#include <linux/res_counter.h>
>  #include <linux/static_key.h>
>  #include <linux/aio.h>
>  #include <linux/sched.h>
> @@ -1061,7 +1061,7 @@ enum cg_proto_flags {
>  };
>  
>  struct cg_proto {
> -	struct res_counter	memory_allocated;	/* Current allocated memory. */
> +	struct page_counter	memory_allocated;	/* Current allocated memory. */
>  	struct percpu_counter	sockets_allocated;	/* Current number of sockets. */
>  	int			memory_pressure;
>  	long			sysctl_mem[3];
> @@ -1213,34 +1213,26 @@ static inline void memcg_memory_allocated_add(struct cg_proto *prot,
>  					      unsigned long amt,
>  					      int *parent_status)
>  {
> -	struct res_counter *fail;
> -	int ret;
> +	page_counter_charge(&prot->memory_allocated, amt);
>  
> -	ret = res_counter_charge_nofail(&prot->memory_allocated,
> -					amt << PAGE_SHIFT, &fail);
> -	if (ret < 0)
> +	if (page_counter_read(&prot->memory_allocated) >
> +	    prot->memory_allocated.limit)
>  		*parent_status = OVER_LIMIT;
>  }
>  
>  static inline void memcg_memory_allocated_sub(struct cg_proto *prot,
>  					      unsigned long amt)
>  {
> -	res_counter_uncharge(&prot->memory_allocated, amt << PAGE_SHIFT);
> -}
> -
> -static inline u64 memcg_memory_allocated_read(struct cg_proto *prot)
> -{
> -	u64 ret;
> -	ret = res_counter_read_u64(&prot->memory_allocated, RES_USAGE);
> -	return ret >> PAGE_SHIFT;
> +	page_counter_uncharge(&prot->memory_allocated, amt);
>  }
>  
>  static inline long
>  sk_memory_allocated(const struct sock *sk)
>  {
>  	struct proto *prot = sk->sk_prot;
> +
>  	if (mem_cgroup_sockets_enabled && sk->sk_cgrp)
> -		return memcg_memory_allocated_read(sk->sk_cgrp);
> +		return page_counter_read(&sk->sk_cgrp->memory_allocated);
>  
>  	return atomic_long_read(prot->memory_allocated);
>  }
> @@ -1254,7 +1246,7 @@ sk_memory_allocated_add(struct sock *sk, int amt, int *parent_status)
>  		memcg_memory_allocated_add(sk->sk_cgrp, amt, parent_status);
>  		/* update the root cgroup regardless */
>  		atomic_long_add_return(amt, prot->memory_allocated);
> -		return memcg_memory_allocated_read(sk->sk_cgrp);
> +		return page_counter_read(&sk->sk_cgrp->memory_allocated);
>  	}
>  
>  	return atomic_long_add_return(amt, prot->memory_allocated);
> diff --git a/init/Kconfig b/init/Kconfig
> index b454b162d2df..3fc577e9de75 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -985,9 +985,12 @@ config RESOURCE_COUNTERS
>  	  This option enables controller independent resource accounting
>  	  infrastructure that works with cgroups.
>  
> +config PAGE_COUNTER
> +       bool
> +
>  config MEMCG
>  	bool "Memory Resource Controller for Control Groups"
> -	depends on RESOURCE_COUNTERS
> +	select PAGE_COUNTER
>  	select EVENTFD
>  	help
>  	  Provides a memory resource controller that manages both anonymous
> diff --git a/mm/Makefile b/mm/Makefile
> index ba3ec4e1a66e..27ddb80403a9 100644
> --- a/mm/Makefile
> +++ b/mm/Makefile
> @@ -55,6 +55,7 @@ obj-$(CONFIG_FS_XIP) += filemap_xip.o
>  obj-$(CONFIG_MIGRATION) += migrate.o
>  obj-$(CONFIG_QUICKLIST) += quicklist.o
>  obj-$(CONFIG_TRANSPARENT_HUGEPAGE) += huge_memory.o
> +obj-$(CONFIG_PAGE_COUNTER) += page_counter.o
>  obj-$(CONFIG_MEMCG) += memcontrol.o page_cgroup.o vmpressure.o
>  obj-$(CONFIG_CGROUP_HUGETLB) += hugetlb_cgroup.o
>  obj-$(CONFIG_MEMORY_FAILURE) += memory-failure.o
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 23976fd885fd..b62972c80055 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -25,7 +25,7 @@
>   * GNU General Public License for more details.
>   */
>  
> -#include <linux/res_counter.h>
> +#include <linux/page_counter.h>
>  #include <linux/memcontrol.h>
>  #include <linux/cgroup.h>
>  #include <linux/mm.h>
> @@ -165,7 +165,7 @@ struct mem_cgroup_per_zone {
>  	struct mem_cgroup_reclaim_iter reclaim_iter[DEF_PRIORITY + 1];
>  
>  	struct rb_node		tree_node;	/* RB tree node */
> -	unsigned long long	usage_in_excess;/* Set to the value by which */
> +	unsigned long		usage_in_excess;/* Set to the value by which */
>  						/* the soft limit is exceeded*/
>  	bool			on_tree;
>  	struct mem_cgroup	*memcg;		/* Back pointer, we cannot */
> @@ -198,7 +198,7 @@ static struct mem_cgroup_tree soft_limit_tree __read_mostly;
>  
>  struct mem_cgroup_threshold {
>  	struct eventfd_ctx *eventfd;
> -	u64 threshold;
> +	unsigned long threshold;
>  };
>  
>  /* For threshold */
> @@ -284,10 +284,13 @@ static void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
>   */
>  struct mem_cgroup {
>  	struct cgroup_subsys_state css;
> -	/*
> -	 * the counter to account for memory usage
> -	 */
> -	struct res_counter res;
> +
> +	/* Accounted resources */
> +	struct page_counter memory;
> +	struct page_counter memsw;
> +	struct page_counter kmem;
> +
> +	unsigned long soft_limit;
>  
>  	/* vmpressure notifications */
>  	struct vmpressure vmpressure;
> @@ -296,15 +299,6 @@ struct mem_cgroup {
>  	int initialized;
>  
>  	/*
> -	 * the counter to account for mem+swap usage.
> -	 */
> -	struct res_counter memsw;
> -
> -	/*
> -	 * the counter to account for kernel memory usage.
> -	 */
> -	struct res_counter kmem;
> -	/*
>  	 * Should the accounting and control be hierarchical, per subtree?
>  	 */
>  	bool use_hierarchy;
> @@ -650,7 +644,7 @@ static void disarm_kmem_keys(struct mem_cgroup *memcg)
>  	 * This check can't live in kmem destruction function,
>  	 * since the charges will outlive the cgroup
>  	 */
> -	WARN_ON(res_counter_read_u64(&memcg->kmem, RES_USAGE) != 0);
> +	WARN_ON(page_counter_read(&memcg->kmem));
>  }
>  #else
>  static void disarm_kmem_keys(struct mem_cgroup *memcg)
> @@ -706,7 +700,7 @@ soft_limit_tree_from_page(struct page *page)
>  
>  static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_zone *mz,
>  					 struct mem_cgroup_tree_per_zone *mctz,
> -					 unsigned long long new_usage_in_excess)
> +					 unsigned long new_usage_in_excess)
>  {
>  	struct rb_node **p = &mctz->rb_root.rb_node;
>  	struct rb_node *parent = NULL;
> @@ -755,10 +749,21 @@ static void mem_cgroup_remove_exceeded(struct mem_cgroup_per_zone *mz,
>  	spin_unlock_irqrestore(&mctz->lock, flags);
>  }
>  
> +static unsigned long soft_limit_excess(struct mem_cgroup *memcg)
> +{
> +	unsigned long nr_pages = page_counter_read(&memcg->memory);
> +	unsigned long soft_limit = ACCESS_ONCE(memcg->soft_limit);
> +	unsigned long excess = 0;
> +
> +	if (nr_pages > soft_limit)
> +		excess = nr_pages - soft_limit;
> +
> +	return excess;
> +}
>  
>  static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page)
>  {
> -	unsigned long long excess;
> +	unsigned long excess;
>  	struct mem_cgroup_per_zone *mz;
>  	struct mem_cgroup_tree_per_zone *mctz;
>  
> @@ -769,7 +774,7 @@ static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page)
>  	 */
>  	for (; memcg; memcg = parent_mem_cgroup(memcg)) {
>  		mz = mem_cgroup_page_zoneinfo(memcg, page);
> -		excess = res_counter_soft_limit_excess(&memcg->res);
> +		excess = soft_limit_excess(memcg);
>  		/*
>  		 * We have to update the tree if mz is on RB-tree or
>  		 * mem is over its softlimit.
> @@ -825,7 +830,7 @@ retry:
>  	 * position in the tree.
>  	 */
>  	__mem_cgroup_remove_exceeded(mz, mctz);
> -	if (!res_counter_soft_limit_excess(&mz->memcg->res) ||
> +	if (!soft_limit_excess(mz->memcg) ||
>  	    !css_tryget_online(&mz->memcg->css))
>  		goto retry;
>  done:
> @@ -1492,7 +1497,7 @@ int mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec)
>  	return inactive * inactive_ratio < active;
>  }
>  
> -#define mem_cgroup_from_res_counter(counter, member)	\
> +#define mem_cgroup_from_counter(counter, member)	\
>  	container_of(counter, struct mem_cgroup, member)
>  
>  /**
> @@ -1504,12 +1509,23 @@ int mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec)
>   */
>  static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg)
>  {
> -	unsigned long long margin;
> +	unsigned long margin = 0;
> +	unsigned long count;
> +	unsigned long limit;
>  
> -	margin = res_counter_margin(&memcg->res);
> -	if (do_swap_account)
> -		margin = min(margin, res_counter_margin(&memcg->memsw));
> -	return margin >> PAGE_SHIFT;
> +	count = page_counter_read(&memcg->memory);
> +	limit = ACCESS_ONCE(memcg->memory.limit);
> +	if (count < limit)
> +		margin = limit - count;
> +
> +	if (do_swap_account) {
> +		count = page_counter_read(&memcg->memsw);
> +		limit = ACCESS_ONCE(memcg->memsw.limit);
> +		if (count <= limit)
> +			margin = min(margin, limit - count);
> +	}
> +
> +	return margin;
>  }
>  
>  int mem_cgroup_swappiness(struct mem_cgroup *memcg)
> @@ -1650,18 +1666,15 @@ void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
>  
>  	rcu_read_unlock();
>  
> -	pr_info("memory: usage %llukB, limit %llukB, failcnt %llu\n",
> -		res_counter_read_u64(&memcg->res, RES_USAGE) >> 10,
> -		res_counter_read_u64(&memcg->res, RES_LIMIT) >> 10,
> -		res_counter_read_u64(&memcg->res, RES_FAILCNT));
> -	pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %llu\n",
> -		res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10,
> -		res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10,
> -		res_counter_read_u64(&memcg->memsw, RES_FAILCNT));
> -	pr_info("kmem: usage %llukB, limit %llukB, failcnt %llu\n",
> -		res_counter_read_u64(&memcg->kmem, RES_USAGE) >> 10,
> -		res_counter_read_u64(&memcg->kmem, RES_LIMIT) >> 10,
> -		res_counter_read_u64(&memcg->kmem, RES_FAILCNT));
> +	pr_info("memory: usage %llukB, limit %llukB, failcnt %lu\n",
> +		K((u64)page_counter_read(&memcg->memory)),
> +		K((u64)memcg->memory.limit), memcg->memory.failcnt);
> +	pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %lu\n",
> +		K((u64)page_counter_read(&memcg->memsw)),
> +		K((u64)memcg->memsw.limit), memcg->memsw.failcnt);
> +	pr_info("kmem: usage %llukB, limit %llukB, failcnt %lu\n",
> +		K((u64)page_counter_read(&memcg->kmem)),
> +		K((u64)memcg->kmem.limit), memcg->kmem.failcnt);
>  
>  	for_each_mem_cgroup_tree(iter, memcg) {
>  		pr_info("Memory cgroup stats for ");
> @@ -1701,28 +1714,17 @@ static int mem_cgroup_count_children(struct mem_cgroup *memcg)
>  /*
>   * Return the memory (and swap, if configured) limit for a memcg.
>   */
> -static u64 mem_cgroup_get_limit(struct mem_cgroup *memcg)
> +static unsigned long mem_cgroup_get_limit(struct mem_cgroup *memcg)
>  {
> -	u64 limit;
> +	unsigned long limit;
>  
> -	limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
> -
> -	/*
> -	 * Do not consider swap space if we cannot swap due to swappiness
> -	 */
> +	limit = memcg->memory.limit;
>  	if (mem_cgroup_swappiness(memcg)) {
> -		u64 memsw;
> +		unsigned long memsw_limit;
>  
> -		limit += total_swap_pages << PAGE_SHIFT;
> -		memsw = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
> -
> -		/*
> -		 * If memsw is finite and limits the amount of swap space
> -		 * available to this memcg, return that limit.
> -		 */
> -		limit = min(limit, memsw);
> +		memsw_limit = memcg->memsw.limit;
> +		limit = min(limit + total_swap_pages, memsw_limit);
>  	}
> -
>  	return limit;
>  }
>  
> @@ -1746,7 +1748,7 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
>  	}
>  
>  	check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, order, NULL);
> -	totalpages = mem_cgroup_get_limit(memcg) >> PAGE_SHIFT ? : 1;
> +	totalpages = mem_cgroup_get_limit(memcg) ? : 1;
>  	for_each_mem_cgroup_tree(iter, memcg) {
>  		struct css_task_iter it;
>  		struct task_struct *task;
> @@ -1949,7 +1951,7 @@ static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
>  		.priority = 0,
>  	};
>  
> -	excess = res_counter_soft_limit_excess(&root_memcg->res) >> PAGE_SHIFT;
> +	excess = soft_limit_excess(root_memcg);
>  
>  	while (1) {
>  		victim = mem_cgroup_iter(root_memcg, victim, &reclaim);
> @@ -1980,7 +1982,7 @@ static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
>  		total += mem_cgroup_shrink_node_zone(victim, gfp_mask, false,
>  						     zone, &nr_scanned);
>  		*total_scanned += nr_scanned;
> -		if (!res_counter_soft_limit_excess(&root_memcg->res))
> +		if (!soft_limit_excess(root_memcg))
>  			break;
>  	}
>  	mem_cgroup_iter_break(root_memcg, victim);
> @@ -2307,33 +2309,31 @@ static DEFINE_MUTEX(percpu_charge_mutex);
>  static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
>  {
>  	struct memcg_stock_pcp *stock;
> -	bool ret = true;
> +	bool ret = false;
>  
>  	if (nr_pages > CHARGE_BATCH)
> -		return false;
> +		return ret;
>  
>  	stock = &get_cpu_var(memcg_stock);
> -	if (memcg == stock->cached && stock->nr_pages >= nr_pages)
> +	if (memcg == stock->cached && stock->nr_pages >= nr_pages) {
>  		stock->nr_pages -= nr_pages;
> -	else /* need to call res_counter_charge */
> -		ret = false;
> +		ret = true;
> +	}
>  	put_cpu_var(memcg_stock);
>  	return ret;
>  }
>  
>  /*
> - * Returns stocks cached in percpu to res_counter and reset cached information.
> + * Returns stocks cached in percpu and reset cached information.
>   */
>  static void drain_stock(struct memcg_stock_pcp *stock)
>  {
>  	struct mem_cgroup *old = stock->cached;
>  
>  	if (stock->nr_pages) {
> -		unsigned long bytes = stock->nr_pages * PAGE_SIZE;
> -
> -		res_counter_uncharge(&old->res, bytes);
> +		page_counter_uncharge(&old->memory, stock->nr_pages);
>  		if (do_swap_account)
> -			res_counter_uncharge(&old->memsw, bytes);
> +			page_counter_uncharge(&old->memsw, stock->nr_pages);
>  		stock->nr_pages = 0;
>  	}
>  	stock->cached = NULL;
> @@ -2362,7 +2362,7 @@ static void __init memcg_stock_init(void)
>  }
>  
>  /*
> - * Cache charges(val) which is from res_counter, to local per_cpu area.
> + * Cache charges(val) to local per_cpu area.
>   * This will be consumed by consume_stock() function, later.
>   */
>  static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
> @@ -2422,8 +2422,7 @@ out:
>  /*
>   * Tries to drain stocked charges in other cpus. This function is asynchronous
>   * and just put a work per cpu for draining localy on each cpu. Caller can
> - * expects some charges will be back to res_counter later but cannot wait for
> - * it.
> + * expects some charges will be back later but cannot wait for it.
>   */
>  static void drain_all_stock_async(struct mem_cgroup *root_memcg)
>  {
> @@ -2497,9 +2496,8 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
>  	unsigned int batch = max(CHARGE_BATCH, nr_pages);
>  	int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
>  	struct mem_cgroup *mem_over_limit;
> -	struct res_counter *fail_res;
> +	struct page_counter *counter;
>  	unsigned long nr_reclaimed;
> -	unsigned long long size;
>  	bool may_swap = true;
>  	bool drained = false;
>  	int ret = 0;
> @@ -2510,16 +2508,15 @@ retry:
>  	if (consume_stock(memcg, nr_pages))
>  		goto done;
>  
> -	size = batch * PAGE_SIZE;
>  	if (!do_swap_account ||
> -	    !res_counter_charge(&memcg->memsw, size, &fail_res)) {
> -		if (!res_counter_charge(&memcg->res, size, &fail_res))
> +	    !page_counter_try_charge(&memcg->memsw, batch, &counter)) {
> +		if (!page_counter_try_charge(&memcg->memory, batch, &counter))
>  			goto done_restock;
>  		if (do_swap_account)
> -			res_counter_uncharge(&memcg->memsw, size);
> -		mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
> +			page_counter_uncharge(&memcg->memsw, batch);
> +		mem_over_limit = mem_cgroup_from_counter(counter, memory);
>  	} else {
> -		mem_over_limit = mem_cgroup_from_res_counter(fail_res, memsw);
> +		mem_over_limit = mem_cgroup_from_counter(counter, memsw);
>  		may_swap = false;
>  	}
>  
> @@ -2602,32 +2599,12 @@ done:
>  
>  static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
>  {
> -	unsigned long bytes = nr_pages * PAGE_SIZE;
> -
>  	if (mem_cgroup_is_root(memcg))
>  		return;
>  
> -	res_counter_uncharge(&memcg->res, bytes);
> +	page_counter_uncharge(&memcg->memory, nr_pages);
>  	if (do_swap_account)
> -		res_counter_uncharge(&memcg->memsw, bytes);
> -}
> -
> -/*
> - * Cancel chrages in this cgroup....doesn't propagate to parent cgroup.
> - * This is useful when moving usage to parent cgroup.
> - */
> -static void __mem_cgroup_cancel_local_charge(struct mem_cgroup *memcg,
> -					unsigned int nr_pages)
> -{
> -	unsigned long bytes = nr_pages * PAGE_SIZE;
> -
> -	if (mem_cgroup_is_root(memcg))
> -		return;
> -
> -	res_counter_uncharge_until(&memcg->res, memcg->res.parent, bytes);
> -	if (do_swap_account)
> -		res_counter_uncharge_until(&memcg->memsw,
> -						memcg->memsw.parent, bytes);
> +		page_counter_uncharge(&memcg->memsw, nr_pages);
>  }
>  
>  /*
> @@ -2751,8 +2728,6 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg,
>  		unlock_page_lru(page, isolated);
>  }
>  
> -static DEFINE_MUTEX(set_limit_mutex);
> -
>  #ifdef CONFIG_MEMCG_KMEM
>  /*
>   * The memcg_slab_mutex is held whenever a per memcg kmem cache is created or
> @@ -2795,16 +2770,17 @@ static int mem_cgroup_slabinfo_read(struct seq_file *m, void *v)
>  }
>  #endif
>  
> -static int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size)
> +static int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp,
> +			     unsigned long nr_pages)
>  {
> -	struct res_counter *fail_res;
> +	struct page_counter *counter;
>  	int ret = 0;
>  
> -	ret = res_counter_charge(&memcg->kmem, size, &fail_res);
> -	if (ret)
> +	ret = page_counter_try_charge(&memcg->kmem, nr_pages, &counter);
> +	if (ret < 0)
>  		return ret;
>  
> -	ret = try_charge(memcg, gfp, size >> PAGE_SHIFT);
> +	ret = try_charge(memcg, gfp, nr_pages);
>  	if (ret == -EINTR)  {
>  		/*
>  		 * try_charge() chose to bypass to root due to OOM kill or
> @@ -2821,25 +2797,25 @@ static int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size)
>  		 * when the allocation triggers should have been already
>  		 * directed to the root cgroup in memcontrol.h
>  		 */
> -		res_counter_charge_nofail(&memcg->res, size, &fail_res);
> +		page_counter_charge(&memcg->memory, nr_pages);
>  		if (do_swap_account)
> -			res_counter_charge_nofail(&memcg->memsw, size,
> -						  &fail_res);
> +			page_counter_charge(&memcg->memsw, nr_pages);
>  		ret = 0;
>  	} else if (ret)
> -		res_counter_uncharge(&memcg->kmem, size);
> +		page_counter_uncharge(&memcg->kmem, nr_pages);
>  
>  	return ret;
>  }
>  
> -static void memcg_uncharge_kmem(struct mem_cgroup *memcg, u64 size)
> +static void memcg_uncharge_kmem(struct mem_cgroup *memcg,
> +				unsigned long nr_pages)
>  {
> -	res_counter_uncharge(&memcg->res, size);
> +	page_counter_uncharge(&memcg->memory, nr_pages);
>  	if (do_swap_account)
> -		res_counter_uncharge(&memcg->memsw, size);
> +		page_counter_uncharge(&memcg->memsw, nr_pages);
>  
>  	/* Not down to 0 */
> -	if (res_counter_uncharge(&memcg->kmem, size))
> +	if (page_counter_uncharge(&memcg->kmem, nr_pages))
>  		return;
>  
>  	/*
> @@ -3115,19 +3091,21 @@ static void memcg_schedule_register_cache(struct mem_cgroup *memcg,
>  
>  int __memcg_charge_slab(struct kmem_cache *cachep, gfp_t gfp, int order)
>  {
> +	unsigned int nr_pages = 1 << order;
>  	int res;
>  
> -	res = memcg_charge_kmem(cachep->memcg_params->memcg, gfp,
> -				PAGE_SIZE << order);
> +	res = memcg_charge_kmem(cachep->memcg_params->memcg, gfp, nr_pages);
>  	if (!res)
> -		atomic_add(1 << order, &cachep->memcg_params->nr_pages);
> +		atomic_add(nr_pages, &cachep->memcg_params->nr_pages);
>  	return res;
>  }
>  
>  void __memcg_uncharge_slab(struct kmem_cache *cachep, int order)
>  {
> -	memcg_uncharge_kmem(cachep->memcg_params->memcg, PAGE_SIZE << order);
> -	atomic_sub(1 << order, &cachep->memcg_params->nr_pages);
> +	unsigned int nr_pages = 1 << order;
> +
> +	memcg_uncharge_kmem(cachep->memcg_params->memcg, nr_pages);
> +	atomic_sub(nr_pages, &cachep->memcg_params->nr_pages);
>  }
>  
>  /*
> @@ -3248,7 +3226,7 @@ __memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **_memcg, int order)
>  		return true;
>  	}
>  
> -	ret = memcg_charge_kmem(memcg, gfp, PAGE_SIZE << order);
> +	ret = memcg_charge_kmem(memcg, gfp, 1 << order);
>  	if (!ret)
>  		*_memcg = memcg;
>  
> @@ -3265,7 +3243,7 @@ void __memcg_kmem_commit_charge(struct page *page, struct mem_cgroup *memcg,
>  
>  	/* The page allocation failed. Revert */
>  	if (!page) {
> -		memcg_uncharge_kmem(memcg, PAGE_SIZE << order);
> +		memcg_uncharge_kmem(memcg, 1 << order);
>  		return;
>  	}
>  	/*
> @@ -3298,7 +3276,7 @@ void __memcg_kmem_uncharge_pages(struct page *page, int order)
>  		return;
>  
>  	VM_BUG_ON_PAGE(mem_cgroup_is_root(memcg), page);
> -	memcg_uncharge_kmem(memcg, PAGE_SIZE << order);
> +	memcg_uncharge_kmem(memcg, 1 << order);
>  }
>  #else
>  static inline void memcg_unregister_all_caches(struct mem_cgroup *memcg)
> @@ -3476,8 +3454,12 @@ static int mem_cgroup_move_parent(struct page *page,
>  
>  	ret = mem_cgroup_move_account(page, nr_pages,
>  				pc, child, parent);
> -	if (!ret)
> -		__mem_cgroup_cancel_local_charge(child, nr_pages);
> +	if (!ret) {
> +		/* Take charge off the local counters */
> +		page_counter_cancel(&child->memory, nr_pages);
> +		if (do_swap_account)
> +			page_counter_cancel(&child->memsw, nr_pages);
> +	}
>  
>  	if (nr_pages > 1)
>  		compound_unlock_irqrestore(page, flags);
> @@ -3507,7 +3489,7 @@ static void mem_cgroup_swap_statistics(struct mem_cgroup *memcg,
>   *
>   * Returns 0 on success, -EINVAL on failure.
>   *
> - * The caller must have charged to @to, IOW, called res_counter_charge() about
> + * The caller must have charged to @to, IOW, called page_counter_charge() about
>   * both res and memsw, and called css_get().
>   */
>  static int mem_cgroup_move_swap_account(swp_entry_t entry,
> @@ -3523,7 +3505,7 @@ static int mem_cgroup_move_swap_account(swp_entry_t entry,
>  		mem_cgroup_swap_statistics(to, true);
>  		/*
>  		 * This function is only called from task migration context now.
> -		 * It postpones res_counter and refcount handling till the end
> +		 * It postpones page_counter and refcount handling till the end
>  		 * of task migration(mem_cgroup_clear_mc()) for performance
>  		 * improvement. But we cannot postpone css_get(to)  because if
>  		 * the process that has been moved to @to does swap-in, the
> @@ -3581,60 +3563,57 @@ void mem_cgroup_print_bad_page(struct page *page)
>  }
>  #endif
>  
> +static DEFINE_MUTEX(memcg_limit_mutex);
> +
>  static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
> -				unsigned long long val)
> +				   unsigned long limit)
>  {
> +	unsigned long curusage;
> +	unsigned long oldusage;
> +	bool enlarge = false;
>  	int retry_count;
> -	int ret = 0;
> -	int children = mem_cgroup_count_children(memcg);
> -	u64 curusage, oldusage;
> -	int enlarge;
> +	int ret;
>  
>  	/*
>  	 * For keeping hierarchical_reclaim simple, how long we should retry
>  	 * is depends on callers. We set our retry-count to be function
>  	 * of # of children which we should visit in this loop.
>  	 */
> -	retry_count = MEM_CGROUP_RECLAIM_RETRIES * children;
> +	retry_count = MEM_CGROUP_RECLAIM_RETRIES *
> +		      mem_cgroup_count_children(memcg);
>  
> -	oldusage = res_counter_read_u64(&memcg->res, RES_USAGE);
> +	oldusage = page_counter_read(&memcg->memory);
>  
> -	enlarge = 0;
> -	while (retry_count) {
> +	do {
>  		if (signal_pending(current)) {
>  			ret = -EINTR;
>  			break;
>  		}
> -		/*
> -		 * Rather than hide all in some function, I do this in
> -		 * open coded manner. You see what this really does.
> -		 * We have to guarantee memcg->res.limit <= memcg->memsw.limit.
> -		 */
> -		mutex_lock(&set_limit_mutex);
> -		if (res_counter_read_u64(&memcg->memsw, RES_LIMIT) < val) {
> +
> +		mutex_lock(&memcg_limit_mutex);
> +		if (limit > memcg->memsw.limit) {
> +			mutex_unlock(&memcg_limit_mutex);
>  			ret = -EINVAL;
> -			mutex_unlock(&set_limit_mutex);
>  			break;
>  		}
> -
> -		if (res_counter_read_u64(&memcg->res, RES_LIMIT) < val)
> -			enlarge = 1;
> -
> -		ret = res_counter_set_limit(&memcg->res, val);
> -		mutex_unlock(&set_limit_mutex);
> +		if (limit > memcg->memory.limit)
> +			enlarge = true;
> +		ret = page_counter_limit(&memcg->memory, limit);
> +		mutex_unlock(&memcg_limit_mutex);
>  
>  		if (!ret)
>  			break;
>  
>  		try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL, true);
>  
> -		curusage = res_counter_read_u64(&memcg->res, RES_USAGE);
> +		curusage = page_counter_read(&memcg->memory);
>  		/* Usage is reduced ? */
>  		if (curusage >= oldusage)
>  			retry_count--;
>  		else
>  			oldusage = curusage;
> -	}
> +	} while (retry_count);
> +
>  	if (!ret && enlarge)
>  		memcg_oom_recover(memcg);
>  
> @@ -3642,52 +3621,53 @@ static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
>  }
>  
>  static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
> -					unsigned long long val)
> +					 unsigned long limit)
>  {
> +	unsigned long curusage;
> +	unsigned long oldusage;
> +	bool enlarge = false;
>  	int retry_count;
> -	u64 oldusage, curusage;
> -	int children = mem_cgroup_count_children(memcg);
> -	int ret = -EBUSY;
> -	int enlarge = 0;
> +	int ret;
>  
>  	/* see mem_cgroup_resize_res_limit */
> -	retry_count = children * MEM_CGROUP_RECLAIM_RETRIES;
> -	oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
> -	while (retry_count) {
> +	retry_count = MEM_CGROUP_RECLAIM_RETRIES *
> +		      mem_cgroup_count_children(memcg);
> +
> +	oldusage = page_counter_read(&memcg->memsw);
> +
> +	do {
>  		if (signal_pending(current)) {
>  			ret = -EINTR;
>  			break;
>  		}
> -		/*
> -		 * Rather than hide all in some function, I do this in
> -		 * open coded manner. You see what this really does.
> -		 * We have to guarantee memcg->res.limit <= memcg->memsw.limit.
> -		 */
> -		mutex_lock(&set_limit_mutex);
> -		if (res_counter_read_u64(&memcg->res, RES_LIMIT) > val) {
> +
> +		mutex_lock(&memcg_limit_mutex);
> +		if (limit < memcg->memory.limit) {
> +			mutex_unlock(&memcg_limit_mutex);
>  			ret = -EINVAL;
> -			mutex_unlock(&set_limit_mutex);
>  			break;
>  		}
> -		if (res_counter_read_u64(&memcg->memsw, RES_LIMIT) < val)
> -			enlarge = 1;
> -		ret = res_counter_set_limit(&memcg->memsw, val);
> -		mutex_unlock(&set_limit_mutex);
> +		if (limit > memcg->memsw.limit)
> +			enlarge = true;
> +		ret = page_counter_limit(&memcg->memsw, limit);
> +		mutex_unlock(&memcg_limit_mutex);
>  
>  		if (!ret)
>  			break;
>  
>  		try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL, false);
>  
> -		curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
> +		curusage = page_counter_read(&memcg->memsw);
>  		/* Usage is reduced ? */
>  		if (curusage >= oldusage)
>  			retry_count--;
>  		else
>  			oldusage = curusage;
> -	}
> +	} while (retry_count);
> +
>  	if (!ret && enlarge)
>  		memcg_oom_recover(memcg);
> +
>  	return ret;
>  }
>  
> @@ -3700,7 +3680,7 @@ unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
>  	unsigned long reclaimed;
>  	int loop = 0;
>  	struct mem_cgroup_tree_per_zone *mctz;
> -	unsigned long long excess;
> +	unsigned long excess;
>  	unsigned long nr_scanned;
>  
>  	if (order > 0)
> @@ -3754,7 +3734,7 @@ unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
>  			} while (1);
>  		}
>  		__mem_cgroup_remove_exceeded(mz, mctz);
> -		excess = res_counter_soft_limit_excess(&mz->memcg->res);
> +		excess = soft_limit_excess(mz->memcg);
>  		/*
>  		 * One school of thought says that we should not add
>  		 * back the node to the tree if reclaim returns 0.
> @@ -3847,7 +3827,6 @@ static void mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
>  static void mem_cgroup_reparent_charges(struct mem_cgroup *memcg)
>  {
>  	int node, zid;
> -	u64 usage;
>  
>  	do {
>  		/* This is for making all *used* pages to be on LRU. */
> @@ -3879,9 +3858,8 @@ static void mem_cgroup_reparent_charges(struct mem_cgroup *memcg)
>  		 * right after the check. RES_USAGE should be safe as we always
>  		 * charge before adding to the LRU.
>  		 */
> -		usage = res_counter_read_u64(&memcg->res, RES_USAGE) -
> -			res_counter_read_u64(&memcg->kmem, RES_USAGE);
> -	} while (usage > 0);
> +	} while (page_counter_read(&memcg->memory) -
> +		 page_counter_read(&memcg->kmem) > 0);
>  }
>  
>  /*
> @@ -3921,7 +3899,7 @@ static int mem_cgroup_force_empty(struct mem_cgroup *memcg)
>  	/* we call try-to-free pages for make this cgroup empty */
>  	lru_add_drain_all();
>  	/* try to free all pages in this cgroup */
> -	while (nr_retries && res_counter_read_u64(&memcg->res, RES_USAGE) > 0) {
> +	while (nr_retries && page_counter_read(&memcg->memory)) {
>  		int progress;
>  
>  		if (signal_pending(current))
> @@ -3992,8 +3970,8 @@ out:
>  	return retval;
>  }
>  
> -static unsigned long mem_cgroup_recursive_stat(struct mem_cgroup *memcg,
> -					       enum mem_cgroup_stat_index idx)
> +static unsigned long tree_stat(struct mem_cgroup *memcg,
> +			       enum mem_cgroup_stat_index idx)
>  {
>  	struct mem_cgroup *iter;
>  	long val = 0;
> @@ -4011,55 +3989,72 @@ static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
>  {
>  	u64 val;
>  
> -	if (!mem_cgroup_is_root(memcg)) {
> +	if (mem_cgroup_is_root(memcg)) {
> +		val = tree_stat(memcg, MEM_CGROUP_STAT_CACHE);
> +		val += tree_stat(memcg, MEM_CGROUP_STAT_RSS);
> +		if (swap)
> +			val += tree_stat(memcg, MEM_CGROUP_STAT_SWAP);
> +	} else {
>  		if (!swap)
> -			return res_counter_read_u64(&memcg->res, RES_USAGE);
> +			val = page_counter_read(&memcg->memory);
>  		else
> -			return res_counter_read_u64(&memcg->memsw, RES_USAGE);
> +			val = page_counter_read(&memcg->memsw);
>  	}
> -
> -	/*
> -	 * Transparent hugepages are still accounted for in MEM_CGROUP_STAT_RSS
> -	 * as well as in MEM_CGROUP_STAT_RSS_HUGE.
> -	 */
> -	val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE);
> -	val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS);
> -
> -	if (swap)
> -		val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_SWAP);
> -
>  	return val << PAGE_SHIFT;
>  }
>  
> +enum {
> +	RES_USAGE,
> +	RES_LIMIT,
> +	RES_MAX_USAGE,
> +	RES_FAILCNT,
> +	RES_SOFT_LIMIT,
> +};
>  
>  static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
>  			       struct cftype *cft)
>  {
>  	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
> -	enum res_type type = MEMFILE_TYPE(cft->private);
> -	int name = MEMFILE_ATTR(cft->private);
> +	struct page_counter *counter;
>  
> -	switch (type) {
> +	switch (MEMFILE_TYPE(cft->private)) {
>  	case _MEM:
> -		if (name == RES_USAGE)
> -			return mem_cgroup_usage(memcg, false);
> -		return res_counter_read_u64(&memcg->res, name);
> +		counter = &memcg->memory;
> +		break;
>  	case _MEMSWAP:
> -		if (name == RES_USAGE)
> -			return mem_cgroup_usage(memcg, true);
> -		return res_counter_read_u64(&memcg->memsw, name);
> +		counter = &memcg->memsw;
> +		break;
>  	case _KMEM:
> -		return res_counter_read_u64(&memcg->kmem, name);
> +		counter = &memcg->kmem;
>  		break;
>  	default:
>  		BUG();
>  	}
> +
> +	switch (MEMFILE_ATTR(cft->private)) {
> +	case RES_USAGE:
> +		if (counter == &memcg->memory)
> +			return mem_cgroup_usage(memcg, false);
> +		if (counter == &memcg->memsw)
> +			return mem_cgroup_usage(memcg, true);
> +		return (u64)page_counter_read(counter) * PAGE_SIZE;
> +	case RES_LIMIT:
> +		return (u64)counter->limit * PAGE_SIZE;
> +	case RES_MAX_USAGE:
> +		return (u64)counter->watermark * PAGE_SIZE;
> +	case RES_FAILCNT:
> +		return counter->failcnt;
> +	case RES_SOFT_LIMIT:
> +		return (u64)memcg->soft_limit * PAGE_SIZE;
> +	default:
> +		BUG();
> +	}
>  }
>  
>  #ifdef CONFIG_MEMCG_KMEM
>  /* should be called with activate_kmem_mutex held */
>  static int __memcg_activate_kmem(struct mem_cgroup *memcg,
> -				 unsigned long long limit)
> +				 unsigned long nr_pages)
>  {
>  	int err = 0;
>  	int memcg_id;
> @@ -4106,7 +4101,7 @@ static int __memcg_activate_kmem(struct mem_cgroup *memcg,
>  	 * We couldn't have accounted to this cgroup, because it hasn't got the
>  	 * active bit set yet, so this should succeed.
>  	 */
> -	err = res_counter_set_limit(&memcg->kmem, limit);
> +	err = page_counter_limit(&memcg->kmem, nr_pages);
>  	VM_BUG_ON(err);
>  
>  	static_key_slow_inc(&memcg_kmem_enabled_key);
> @@ -4122,25 +4117,27 @@ out:
>  }
>  
>  static int memcg_activate_kmem(struct mem_cgroup *memcg,
> -			       unsigned long long limit)
> +			       unsigned long nr_pages)
>  {
>  	int ret;
>  
>  	mutex_lock(&activate_kmem_mutex);
> -	ret = __memcg_activate_kmem(memcg, limit);
> +	ret = __memcg_activate_kmem(memcg, nr_pages);
>  	mutex_unlock(&activate_kmem_mutex);
>  	return ret;
>  }
>  
>  static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
> -				   unsigned long long val)
> +				   unsigned long limit)
>  {
>  	int ret;
>  
> +	mutex_lock(&memcg_limit_mutex);
>  	if (!memcg_kmem_is_active(memcg))
> -		ret = memcg_activate_kmem(memcg, val);
> +		ret = memcg_activate_kmem(memcg, limit);
>  	else
> -		ret = res_counter_set_limit(&memcg->kmem, val);
> +		ret = page_counter_limit(&memcg->kmem, limit);
> +	mutex_unlock(&memcg_limit_mutex);
>  	return ret;
>  }
>  
> @@ -4158,13 +4155,13 @@ static int memcg_propagate_kmem(struct mem_cgroup *memcg)
>  	 * after this point, because it has at least one child already.
>  	 */
>  	if (memcg_kmem_is_active(parent))
> -		ret = __memcg_activate_kmem(memcg, RES_COUNTER_MAX);
> +		ret = __memcg_activate_kmem(memcg, PAGE_COUNTER_MAX);
>  	mutex_unlock(&activate_kmem_mutex);
>  	return ret;
>  }
>  #else
>  static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
> -				   unsigned long long val)
> +				   unsigned long limit)
>  {
>  	return -EINVAL;
>  }
> @@ -4178,110 +4175,69 @@ static ssize_t mem_cgroup_write(struct kernfs_open_file *of,
>  				char *buf, size_t nbytes, loff_t off)
>  {
>  	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
> -	enum res_type type;
> -	int name;
> -	unsigned long long val;
> +	unsigned long nr_pages;
>  	int ret;
>  
>  	buf = strstrip(buf);
> -	type = MEMFILE_TYPE(of_cft(of)->private);
> -	name = MEMFILE_ATTR(of_cft(of)->private);
> +	ret = page_counter_memparse(buf, &nr_pages);
> +	if (ret)
> +		return ret;
>  
> -	switch (name) {
> +	switch (MEMFILE_ATTR(of_cft(of)->private)) {
>  	case RES_LIMIT:
>  		if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
>  			ret = -EINVAL;
>  			break;
>  		}
> -		/* This function does all necessary parse...reuse it */
> -		ret = res_counter_memparse_write_strategy(buf, &val);
> -		if (ret)
> +		switch (MEMFILE_TYPE(of_cft(of)->private)) {
> +		case _MEM:
> +			ret = mem_cgroup_resize_limit(memcg, nr_pages);
>  			break;
> -		if (type == _MEM)
> -			ret = mem_cgroup_resize_limit(memcg, val);
> -		else if (type == _MEMSWAP)
> -			ret = mem_cgroup_resize_memsw_limit(memcg, val);
> -		else if (type == _KMEM)
> -			ret = memcg_update_kmem_limit(memcg, val);
> -		else
> -			return -EINVAL;
> -		break;
> -	case RES_SOFT_LIMIT:
> -		ret = res_counter_memparse_write_strategy(buf, &val);
> -		if (ret)
> +		case _MEMSWAP:
> +			ret = mem_cgroup_resize_memsw_limit(memcg, nr_pages);
>  			break;
> -		/*
> -		 * For memsw, soft limits are hard to implement in terms
> -		 * of semantics, for now, we support soft limits for
> -		 * control without swap
> -		 */
> -		if (type == _MEM)
> -			ret = res_counter_set_soft_limit(&memcg->res, val);
> -		else
> -			ret = -EINVAL;
> +		case _KMEM:
> +			ret = memcg_update_kmem_limit(memcg, nr_pages);
> +			break;
> +		}
>  		break;
> -	default:
> -		ret = -EINVAL; /* should be BUG() ? */
> +	case RES_SOFT_LIMIT:
> +		memcg->soft_limit = nr_pages;
> +		ret = 0;
>  		break;
>  	}
>  	return ret ?: nbytes;
>  }
>  
> -static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
> -		unsigned long long *mem_limit, unsigned long long *memsw_limit)
> -{
> -	unsigned long long min_limit, min_memsw_limit, tmp;
> -
> -	min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
> -	min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
> -	if (!memcg->use_hierarchy)
> -		goto out;
> -
> -	while (memcg->css.parent) {
> -		memcg = mem_cgroup_from_css(memcg->css.parent);
> -		if (!memcg->use_hierarchy)
> -			break;
> -		tmp = res_counter_read_u64(&memcg->res, RES_LIMIT);
> -		min_limit = min(min_limit, tmp);
> -		tmp = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
> -		min_memsw_limit = min(min_memsw_limit, tmp);
> -	}
> -out:
> -	*mem_limit = min_limit;
> -	*memsw_limit = min_memsw_limit;
> -}
> -
>  static ssize_t mem_cgroup_reset(struct kernfs_open_file *of, char *buf,
>  				size_t nbytes, loff_t off)
>  {
>  	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
> -	int name;
> -	enum res_type type;
> +	struct page_counter *counter;
>  
> -	type = MEMFILE_TYPE(of_cft(of)->private);
> -	name = MEMFILE_ATTR(of_cft(of)->private);
> +	switch (MEMFILE_TYPE(of_cft(of)->private)) {
> +	case _MEM:
> +		counter = &memcg->memory;
> +		break;
> +	case _MEMSWAP:
> +		counter = &memcg->memsw;
> +		break;
> +	case _KMEM:
> +		counter = &memcg->kmem;
> +		break;
> +	default:
> +		BUG();
> +	}
>  
> -	switch (name) {
> +	switch (MEMFILE_ATTR(of_cft(of)->private)) {
>  	case RES_MAX_USAGE:
> -		if (type == _MEM)
> -			res_counter_reset_max(&memcg->res);
> -		else if (type == _MEMSWAP)
> -			res_counter_reset_max(&memcg->memsw);
> -		else if (type == _KMEM)
> -			res_counter_reset_max(&memcg->kmem);
> -		else
> -			return -EINVAL;
> +		page_counter_reset_watermark(counter);
>  		break;
>  	case RES_FAILCNT:
> -		if (type == _MEM)
> -			res_counter_reset_failcnt(&memcg->res);
> -		else if (type == _MEMSWAP)
> -			res_counter_reset_failcnt(&memcg->memsw);
> -		else if (type == _KMEM)
> -			res_counter_reset_failcnt(&memcg->kmem);
> -		else
> -			return -EINVAL;
> +		counter->failcnt = 0;
>  		break;
> +	default:
> +		BUG();
>  	}
>  
>  	return nbytes;
> @@ -4378,6 +4334,7 @@ static inline void mem_cgroup_lru_names_not_uptodate(void)
>  static int memcg_stat_show(struct seq_file *m, void *v)
>  {
>  	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	unsigned long memory, memsw;
>  	struct mem_cgroup *mi;
>  	unsigned int i;
>  
> @@ -4397,14 +4354,16 @@ static int memcg_stat_show(struct seq_file *m, void *v)
>  			   mem_cgroup_nr_lru_pages(memcg, BIT(i)) * PAGE_SIZE);
>  
>  	/* Hierarchical information */
> -	{
> -		unsigned long long limit, memsw_limit;
> -		memcg_get_hierarchical_limit(memcg, &limit, &memsw_limit);
> -		seq_printf(m, "hierarchical_memory_limit %llu\n", limit);
> -		if (do_swap_account)
> -			seq_printf(m, "hierarchical_memsw_limit %llu\n",
> -				   memsw_limit);
> +	memory = memsw = PAGE_COUNTER_MAX;
> +	for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) {
> +		memory = min(memory, mi->memory.limit);
> +		memsw = min(memsw, mi->memsw.limit);
>  	}
> +	seq_printf(m, "hierarchical_memory_limit %llu\n",
> +		   (u64)memory * PAGE_SIZE);
> +	if (do_swap_account)
> +		seq_printf(m, "hierarchical_memsw_limit %llu\n",
> +			   (u64)memsw * PAGE_SIZE);
>  
>  	for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
>  		long long val = 0;
> @@ -4488,7 +4447,7 @@ static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
>  static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
>  {
>  	struct mem_cgroup_threshold_ary *t;
> -	u64 usage;
> +	unsigned long usage;
>  	int i;
>  
>  	rcu_read_lock();
> @@ -4587,10 +4546,11 @@ static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
>  {
>  	struct mem_cgroup_thresholds *thresholds;
>  	struct mem_cgroup_threshold_ary *new;
> -	u64 threshold, usage;
> +	unsigned long threshold;
> +	unsigned long usage;
>  	int i, size, ret;
>  
> -	ret = res_counter_memparse_write_strategy(args, &threshold);
> +	ret = page_counter_memparse(args, &threshold);
>  	if (ret)
>  		return ret;
>  
> @@ -4680,7 +4640,7 @@ static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
>  {
>  	struct mem_cgroup_thresholds *thresholds;
>  	struct mem_cgroup_threshold_ary *new;
> -	u64 usage;
> +	unsigned long usage;
>  	int i, j, size;
>  
>  	mutex_lock(&memcg->thresholds_lock);
> @@ -4874,7 +4834,7 @@ static void kmem_cgroup_css_offline(struct mem_cgroup *memcg)
>  
>  	memcg_kmem_mark_dead(memcg);
>  
> -	if (res_counter_read_u64(&memcg->kmem, RES_USAGE) != 0)
> +	if (page_counter_read(&memcg->kmem))
>  		return;
>  
>  	if (memcg_kmem_test_and_clear_dead(memcg))
> @@ -5354,9 +5314,9 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg)
>   */
>  struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg)
>  {
> -	if (!memcg->res.parent)
> +	if (!memcg->memory.parent)
>  		return NULL;
> -	return mem_cgroup_from_res_counter(memcg->res.parent, res);
> +	return mem_cgroup_from_counter(memcg->memory.parent, memory);
>  }
>  EXPORT_SYMBOL(parent_mem_cgroup);
>  
> @@ -5401,9 +5361,9 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
>  	/* root ? */
>  	if (parent_css == NULL) {
>  		root_mem_cgroup = memcg;
> -		res_counter_init(&memcg->res, NULL);
> -		res_counter_init(&memcg->memsw, NULL);
> -		res_counter_init(&memcg->kmem, NULL);
> +		page_counter_init(&memcg->memory, NULL);
> +		page_counter_init(&memcg->memsw, NULL);
> +		page_counter_init(&memcg->kmem, NULL);
>  	}
>  
>  	memcg->last_scanned_node = MAX_NUMNODES;
> @@ -5442,18 +5402,18 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css)
>  	memcg->swappiness = mem_cgroup_swappiness(parent);
>  
>  	if (parent->use_hierarchy) {
> -		res_counter_init(&memcg->res, &parent->res);
> -		res_counter_init(&memcg->memsw, &parent->memsw);
> -		res_counter_init(&memcg->kmem, &parent->kmem);
> +		page_counter_init(&memcg->memory, &parent->memory);
> +		page_counter_init(&memcg->memsw, &parent->memsw);
> +		page_counter_init(&memcg->kmem, &parent->kmem);
>  
>  		/*
>  		 * No need to take a reference to the parent because cgroup
>  		 * core guarantees its existence.
>  		 */
>  	} else {
> -		res_counter_init(&memcg->res, NULL);
> -		res_counter_init(&memcg->memsw, NULL);
> -		res_counter_init(&memcg->kmem, NULL);
> +		page_counter_init(&memcg->memory, NULL);
> +		page_counter_init(&memcg->memsw, NULL);
> +		page_counter_init(&memcg->kmem, NULL);
>  		/*
>  		 * Deeper hierachy with use_hierarchy == false doesn't make
>  		 * much sense so let cgroup subsystem know about this
> @@ -5535,7 +5495,7 @@ static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
>  	/*
>  	 * XXX: css_offline() would be where we should reparent all
>  	 * memory to prepare the cgroup for destruction.  However,
> -	 * memcg does not do css_tryget_online() and res_counter charging
> +	 * memcg does not do css_tryget_online() and page_counter charging
>  	 * under the same RCU lock region, which means that charging
>  	 * could race with offlining.  Offlining only happens to
>  	 * cgroups with no tasks in them but charges can show up
> @@ -5555,7 +5515,7 @@ static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
>  	 * call_rcu()
>  	 *   offline_css()
>  	 *     reparent_charges()
> -	 *                           res_counter_charge()
> +	 *                           page_counter_try_charge()
>  	 *                           css_put()
>  	 *                             css_free()
>  	 *                           pc->mem_cgroup = dead memcg
> @@ -5590,10 +5550,10 @@ static void mem_cgroup_css_reset(struct cgroup_subsys_state *css)
>  {
>  	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
>  
> -	mem_cgroup_resize_limit(memcg, ULLONG_MAX);
> -	mem_cgroup_resize_memsw_limit(memcg, ULLONG_MAX);
> -	memcg_update_kmem_limit(memcg, ULLONG_MAX);
> -	res_counter_set_soft_limit(&memcg->res, ULLONG_MAX);
> +	mem_cgroup_resize_limit(memcg, PAGE_COUNTER_MAX);
> +	mem_cgroup_resize_memsw_limit(memcg, PAGE_COUNTER_MAX);
> +	memcg_update_kmem_limit(memcg, PAGE_COUNTER_MAX);
> +	memcg->soft_limit = 0;
>  }
>  
>  #ifdef CONFIG_MMU
> @@ -5907,19 +5867,18 @@ static void __mem_cgroup_clear_mc(void)
>  	if (mc.moved_swap) {
>  		/* uncharge swap account from the old cgroup */
>  		if (!mem_cgroup_is_root(mc.from))
> -			res_counter_uncharge(&mc.from->memsw,
> -					     PAGE_SIZE * mc.moved_swap);
> -
> -		for (i = 0; i < mc.moved_swap; i++)
> -			css_put(&mc.from->css);
> +			page_counter_uncharge(&mc.from->memsw, mc.moved_swap);
>  
>  		/*
> -		 * we charged both to->res and to->memsw, so we should
> -		 * uncharge to->res.
> +		 * we charged both to->memory and to->memsw, so we
> +		 * should uncharge to->memory.
>  		 */
>  		if (!mem_cgroup_is_root(mc.to))
> -			res_counter_uncharge(&mc.to->res,
> -					     PAGE_SIZE * mc.moved_swap);
> +			page_counter_uncharge(&mc.to->memory, mc.moved_swap);
> +
> +		for (i = 0; i < mc.moved_swap; i++)
> +			css_put(&mc.from->css);
> +
>  		/* we've already done css_get(mc.to) */
>  		mc.moved_swap = 0;
>  	}
> @@ -6285,7 +6244,7 @@ void mem_cgroup_uncharge_swap(swp_entry_t entry)
>  	memcg = mem_cgroup_lookup(id);
>  	if (memcg) {
>  		if (!mem_cgroup_is_root(memcg))
> -			res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
> +			page_counter_uncharge(&memcg->memsw, 1);
>  		mem_cgroup_swap_statistics(memcg, false);
>  		css_put(&memcg->css);
>  	}
> @@ -6451,11 +6410,9 @@ static void uncharge_batch(struct mem_cgroup *memcg, unsigned long pgpgout,
>  
>  	if (!mem_cgroup_is_root(memcg)) {
>  		if (nr_mem)
> -			res_counter_uncharge(&memcg->res,
> -					     nr_mem * PAGE_SIZE);
> +			page_counter_uncharge(&memcg->memory, nr_mem);
>  		if (nr_memsw)
> -			res_counter_uncharge(&memcg->memsw,
> -					     nr_memsw * PAGE_SIZE);
> +			page_counter_uncharge(&memcg->memsw, nr_memsw);
>  		memcg_oom_recover(memcg);
>  	}
>  
> diff --git a/mm/page_counter.c b/mm/page_counter.c
> new file mode 100644
> index 000000000000..fc4990c6bb5b
> --- /dev/null
> +++ b/mm/page_counter.c
> @@ -0,0 +1,203 @@
> +/*
> + * Lockless hierarchical page accounting & limiting
> + *
> + * Copyright (C) 2014 Red Hat, Inc., Johannes Weiner
> + */
> +
> +#include <linux/page_counter.h>
> +#include <linux/atomic.h>
> +#include <linux/sched.h>
> +
> +/**
> + * page_counter_cancel - take pages out of the local counter
> + * @counter: counter
> + * @nr_pages: number of pages to cancel
> + *
> + * Returns whether there are remaining pages in the counter.
> + */
> +int page_counter_cancel(struct page_counter *counter, unsigned long nr_pages)
> +{
> +	long new;
> +
> +	new = atomic_long_sub_return(nr_pages, &counter->count);
> +
> +	/* More uncharges than charges? */
> +	WARN_ON_ONCE(new < 0);
> +
> +	return new > 0;
> +}
> +
> +/**
> + * page_counter_charge - hierarchically charge pages
> + * @counter: counter
> + * @nr_pages: number of pages to charge
> + *
> + * NOTE: This does not consider any configured counter limits.
> + */
> +void page_counter_charge(struct page_counter *counter, unsigned long nr_pages)
> +{
> +	struct page_counter *c;
> +
> +	for (c = counter; c; c = c->parent) {
> +		long new;
> +
> +		new = atomic_long_add_return(nr_pages, &c->count);
> +		/*
> +		 * This is indeed racy, but we can live with some
> +		 * inaccuracy in the watermark.
> +		 */
> +		if (new > c->watermark)
> +			c->watermark = new;
> +	}
> +}
> +
> +/**
> + * page_counter_try_charge - try to hierarchically charge pages
> + * @counter: counter
> + * @nr_pages: number of pages to charge
> + * @fail: points first counter to hit its limit, if any
> + *
> + * Returns 0 on success, or -ENOMEM and @fail if the counter or one of
> + * its ancestors has hit its configured limit.
> + */
> +int page_counter_try_charge(struct page_counter *counter,
> +			    unsigned long nr_pages,
> +			    struct page_counter **fail)
> +{
> +	struct page_counter *c;
> +
> +	for (c = counter; c; c = c->parent) {
> +		long new;
> +		/*
> +		 * Charge speculatively to avoid an expensive CAS.  If
> +		 * a bigger charge fails, it might falsely lock out a
> +		 * racing smaller charge and send it into reclaim
> +		 * early, but the error is limited to the difference
> +		 * between the two sizes, which is less than 2M/4M in
> +		 * case of a THP locking out a regular page charge.
> +		 *
> +		 * The atomic_long_add_return() implies a full memory
> +		 * barrier between incrementing the count and reading
> +		 * the limit.  When racing with page_counter_limit(),
> +		 * we either see the new limit or the setter sees the
> +		 * counter has changed and retries.
> +		 */
> +		new = atomic_long_add_return(nr_pages, &c->count);
> +		if (new > c->limit) {
> +			atomic_long_sub(nr_pages, &c->count);
> +			/*
> +			 * This is racy, but we can live with some
> +			 * inaccuracy in the failcnt.
> +			 */
> +			c->failcnt++;
> +			*fail = c;
> +			goto failed;
> +		}
> +		/*
> +		 * Just like with failcnt, we can live with some
> +		 * inaccuracy in the watermark.
> +		 */
> +		if (new > c->watermark)
> +			c->watermark = new;
> +	}
> +	return 0;
> +
> +failed:
> +	for (c = counter; c != *fail; c = c->parent)
> +		page_counter_cancel(c, nr_pages);
> +
> +	return -ENOMEM;
> +}
> +
> +/**
> + * page_counter_uncharge - hierarchically uncharge pages
> + * @counter: counter
> + * @nr_pages: number of pages to uncharge
> + *
> + * Returns whether there are remaining charges in @counter.
> + */
> +int page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages)
> +{
> +	struct page_counter *c;
> +	int ret = 1;
> +
> +	for (c = counter; c; c = c->parent) {
> +		int remainder;
> +
> +		remainder = page_counter_cancel(c, nr_pages);
> +		if (c == counter && !remainder)
> +			ret = 0;
> +	}
> +
> +	return ret;
> +}
> +
> +/**
> + * page_counter_limit - limit the number of pages allowed
> + * @counter: counter
> + * @limit: limit to set
> + *
> + * Returns 0 on success, -EBUSY if the current number of pages on the
> + * counter already exceeds the specified limit.
> + *
> + * The caller must serialize invocations on the same counter.
> + */
> +int page_counter_limit(struct page_counter *counter, unsigned long limit)
> +{
> +	for (;;) {
> +		unsigned long old;
> +		long count;
> +
> +		/*
> +		 * Update the limit while making sure that it's not
> +		 * below the concurrently-changing counter value.
> +		 *
> +		 * The xchg implies two full memory barriers before
> +		 * and after, so the read-swap-read is ordered and
> +		 * ensures coherency with page_counter_try_charge():
> +		 * that function modifies the count before checking
> +		 * the limit, so if it sees the old limit, we see the
> +		 * modified counter and retry.
> +		 */
> +		count = atomic_long_read(&counter->count);
> +
> +		if (count > limit)
> +			return -EBUSY;
> +
> +		old = xchg(&counter->limit, limit);
> +
> +		if (atomic_long_read(&counter->count) <= count)
> +			return 0;
> +
> +		counter->limit = old;
> +		cond_resched();
> +	}
> +}
> +
> +/**
> + * page_counter_memparse - memparse() for page counter limits
> + * @buf: string to parse
> + * @nr_pages: returns the result in number of pages
> + *
> + * Returns -EINVAL, or 0 and @nr_pages on success.  @nr_pages will be
> + * limited to %PAGE_COUNTER_MAX.
> + */
> +int page_counter_memparse(const char *buf, unsigned long *nr_pages)
> +{
> +	char unlimited[] = "-1";
> +	char *end;
> +	u64 bytes;
> +
> +	if (!strncmp(buf, unlimited, sizeof(unlimited))) {
> +		*nr_pages = PAGE_COUNTER_MAX;
> +		return 0;
> +	}
> +
> +	bytes = memparse(buf, &end);
> +	if (*end != '\0')
> +		return -EINVAL;
> +
> +	*nr_pages = min(bytes / PAGE_SIZE, (u64)PAGE_COUNTER_MAX);
> +
> +	return 0;
> +}
> diff --git a/net/ipv4/tcp_memcontrol.c b/net/ipv4/tcp_memcontrol.c
> index 1d191357bf88..272327134a1b 100644
> --- a/net/ipv4/tcp_memcontrol.c
> +++ b/net/ipv4/tcp_memcontrol.c
> @@ -9,13 +9,13 @@
>  int tcp_init_cgroup(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
>  {
>  	/*
> -	 * The root cgroup does not use res_counters, but rather,
> +	 * The root cgroup does not use page_counters, but rather,
>  	 * rely on the data already collected by the network
>  	 * subsystem
>  	 */
> -	struct res_counter *res_parent = NULL;
> -	struct cg_proto *cg_proto, *parent_cg;
>  	struct mem_cgroup *parent = parent_mem_cgroup(memcg);
> +	struct page_counter *counter_parent = NULL;
> +	struct cg_proto *cg_proto, *parent_cg;
>  
>  	cg_proto = tcp_prot.proto_cgroup(memcg);
>  	if (!cg_proto)
> @@ -29,9 +29,9 @@ int tcp_init_cgroup(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
>  
>  	parent_cg = tcp_prot.proto_cgroup(parent);
>  	if (parent_cg)
> -		res_parent = &parent_cg->memory_allocated;
> +		counter_parent = &parent_cg->memory_allocated;
>  
> -	res_counter_init(&cg_proto->memory_allocated, res_parent);
> +	page_counter_init(&cg_proto->memory_allocated, counter_parent);
>  	percpu_counter_init(&cg_proto->sockets_allocated, 0, GFP_KERNEL);
>  
>  	return 0;
> @@ -50,7 +50,7 @@ void tcp_destroy_cgroup(struct mem_cgroup *memcg)
>  }
>  EXPORT_SYMBOL(tcp_destroy_cgroup);
>  
> -static int tcp_update_limit(struct mem_cgroup *memcg, u64 val)
> +static int tcp_update_limit(struct mem_cgroup *memcg, unsigned long nr_pages)
>  {
>  	struct cg_proto *cg_proto;
>  	int i;
> @@ -60,20 +60,17 @@ static int tcp_update_limit(struct mem_cgroup *memcg, u64 val)
>  	if (!cg_proto)
>  		return -EINVAL;
>  
> -	if (val > RES_COUNTER_MAX)
> -		val = RES_COUNTER_MAX;
> -
> -	ret = res_counter_set_limit(&cg_proto->memory_allocated, val);
> +	ret = page_counter_limit(&cg_proto->memory_allocated, nr_pages);
>  	if (ret)
>  		return ret;
>  
>  	for (i = 0; i < 3; i++)
> -		cg_proto->sysctl_mem[i] = min_t(long, val >> PAGE_SHIFT,
> +		cg_proto->sysctl_mem[i] = min_t(long, nr_pages,
>  						sysctl_tcp_mem[i]);
>  
> -	if (val == RES_COUNTER_MAX)
> +	if (nr_pages == PAGE_COUNTER_MAX)
>  		clear_bit(MEMCG_SOCK_ACTIVE, &cg_proto->flags);
> -	else if (val != RES_COUNTER_MAX) {
> +	else {
>  		/*
>  		 * The active bit needs to be written after the static_key
>  		 * update. This is what guarantees that the socket activation
> @@ -102,11 +99,20 @@ static int tcp_update_limit(struct mem_cgroup *memcg, u64 val)
>  	return 0;
>  }
>  
> +enum {
> +	RES_USAGE,
> +	RES_LIMIT,
> +	RES_MAX_USAGE,
> +	RES_FAILCNT,
> +};
> +
> +static DEFINE_MUTEX(tcp_limit_mutex);
> +
>  static ssize_t tcp_cgroup_write(struct kernfs_open_file *of,
>  				char *buf, size_t nbytes, loff_t off)
>  {
>  	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
> -	unsigned long long val;
> +	unsigned long nr_pages;
>  	int ret = 0;
>  
>  	buf = strstrip(buf);
> @@ -114,10 +120,12 @@ static ssize_t tcp_cgroup_write(struct kernfs_open_file *of,
>  	switch (of_cft(of)->private) {
>  	case RES_LIMIT:
>  		/* see memcontrol.c */
> -		ret = res_counter_memparse_write_strategy(buf, &val);
> +		ret = page_counter_memparse(buf, &nr_pages);
>  		if (ret)
>  			break;
> -		ret = tcp_update_limit(memcg, val);
> +		mutex_lock(&tcp_limit_mutex);
> +		ret = tcp_update_limit(memcg, nr_pages);
> +		mutex_unlock(&tcp_limit_mutex);
>  		break;
>  	default:
>  		ret = -EINVAL;
> @@ -126,43 +134,36 @@ static ssize_t tcp_cgroup_write(struct kernfs_open_file *of,
>  	return ret ?: nbytes;
>  }
>  
> -static u64 tcp_read_stat(struct mem_cgroup *memcg, int type, u64 default_val)
> -{
> -	struct cg_proto *cg_proto;
> -
> -	cg_proto = tcp_prot.proto_cgroup(memcg);
> -	if (!cg_proto)
> -		return default_val;
> -
> -	return res_counter_read_u64(&cg_proto->memory_allocated, type);
> -}
> -
> -static u64 tcp_read_usage(struct mem_cgroup *memcg)
> -{
> -	struct cg_proto *cg_proto;
> -
> -	cg_proto = tcp_prot.proto_cgroup(memcg);
> -	if (!cg_proto)
> -		return atomic_long_read(&tcp_memory_allocated) << PAGE_SHIFT;
> -
> -	return res_counter_read_u64(&cg_proto->memory_allocated, RES_USAGE);
> -}
> -
>  static u64 tcp_cgroup_read(struct cgroup_subsys_state *css, struct cftype *cft)
>  {
>  	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
> +	struct cg_proto *cg_proto = tcp_prot.proto_cgroup(memcg);
>  	u64 val;
>  
>  	switch (cft->private) {
>  	case RES_LIMIT:
> -		val = tcp_read_stat(memcg, RES_LIMIT, RES_COUNTER_MAX);
> +		if (!cg_proto)
> +			return PAGE_COUNTER_MAX;
> +		val = cg_proto->memory_allocated.limit;
> +		val *= PAGE_SIZE;
>  		break;
>  	case RES_USAGE:
> -		val = tcp_read_usage(memcg);
> +		if (!cg_proto)
> +			val = atomic_long_read(&tcp_memory_allocated);
> +		else
> +			val = page_counter_read(&cg_proto->memory_allocated);
> +		val *= PAGE_SIZE;
>  		break;
>  	case RES_FAILCNT:
> +		if (!cg_proto)
> +			return 0;
> +		val = cg_proto->memory_allocated.failcnt;
> +		break;
>  	case RES_MAX_USAGE:
> -		val = tcp_read_stat(memcg, cft->private, 0);
> +		if (!cg_proto)
> +			return 0;
> +		val = cg_proto->memory_allocated.watermark;
> +		val *= PAGE_SIZE;
>  		break;
>  	default:
>  		BUG();
> @@ -183,10 +184,10 @@ static ssize_t tcp_cgroup_reset(struct kernfs_open_file *of,
>  
>  	switch (of_cft(of)->private) {
>  	case RES_MAX_USAGE:
> -		res_counter_reset_max(&cg_proto->memory_allocated);
> +		page_counter_reset_watermark(&cg_proto->memory_allocated);
>  		break;
>  	case RES_FAILCNT:
> -		res_counter_reset_failcnt(&cg_proto->memory_allocated);
> +		cg_proto->memory_allocated.failcnt = 0;
>  		break;
>  	}
>  
> -- 
> 2.1.2
> 

-- 
Michal Hocko
SUSE Labs
--
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