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Date:   Fri, 25 Jan 2019 08:25:58 +0100
From:   Michal Hocko <mhocko@kernel.org>
To:     Chris Down <chris@chrisdown.name>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Tejun Heo <tj@kernel.org>, Roman Gushchin <guro@fb.com>,
        linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
        linux-mm@kvack.org, kernel-team@fb.com
Subject: Re: [PATCH 1/2] mm: Create mem_cgroup_from_seq
Message-ID: <20190125072558.GB3560@dhcp22.suse.cz>
References: <20190124194050.GA31341@chrisdown.name>
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On Thu 24-01-19 14:40:50, Chris Down wrote:
> This is the start of a series of patches similar to my earlier
> DEFINE_MEMCG_MAX_OR_VAL work, but with less Macro Magic(tm).
> 
> There are a bunch of places we go from seq_file to mem_cgroup, which
> currently requires manually getting the css, then getting the mem_cgroup
> from the css. It's in enough places now that having mem_cgroup_from_seq
> makes sense (and also makes the next patch a bit nicer).
> 
> Signed-off-by: Chris Down <chris@chrisdown.name>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Roman Gushchin <guro@fb.com>
> Cc: linux-kernel@vger.kernel.org
> Cc: cgroups@vger.kernel.org
> Cc: linux-mm@kvack.org
> Cc: kernel-team@fb.com

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

> ---
>  include/linux/memcontrol.h | 10 ++++++++++
>  mm/memcontrol.c            | 24 ++++++++++++------------
>  mm/slab_common.c           |  6 +++---
>  3 files changed, 25 insertions(+), 15 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index b0eb29ea0d9c..1f3d880b7ca1 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -429,6 +429,11 @@ static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg)
>  }
>  struct mem_cgroup *mem_cgroup_from_id(unsigned short id);
>  
> +static inline struct mem_cgroup *mem_cgroup_from_seq(struct seq_file *m)
> +{
> +	return mem_cgroup_from_css(seq_css(m));
> +}
> +
>  static inline struct mem_cgroup *lruvec_memcg(struct lruvec *lruvec)
>  {
>  	struct mem_cgroup_per_node *mz;
> @@ -937,6 +942,11 @@ static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
>  	return NULL;
>  }
>  
> +static inline struct mem_cgroup *mem_cgroup_from_seq(struct seq_file *m)
> +{
> +	return NULL;
> +}
> +
>  static inline struct mem_cgroup *lruvec_memcg(struct lruvec *lruvec)
>  {
>  	return NULL;
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 18f4aefbe0bf..98aad31f5226 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3359,7 +3359,7 @@ static int memcg_numa_stat_show(struct seq_file *m, void *v)
>  	const struct numa_stat *stat;
>  	int nid;
>  	unsigned long nr;
> -	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
>  
>  	for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
>  		nr = mem_cgroup_nr_lru_pages(memcg, stat->lru_mask);
> @@ -3410,7 +3410,7 @@ static const char *const memcg1_event_names[] = {
>  
>  static int memcg_stat_show(struct seq_file *m, void *v)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
>  	unsigned long memory, memsw;
>  	struct mem_cgroup *mi;
>  	unsigned int i;
> @@ -3842,7 +3842,7 @@ static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg,
>  
>  static int mem_cgroup_oom_control_read(struct seq_file *sf, void *v)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(sf));
> +	struct mem_cgroup *memcg = mem_cgroup_from_seq(sf);
>  
>  	seq_printf(sf, "oom_kill_disable %d\n", memcg->oom_kill_disable);
>  	seq_printf(sf, "under_oom %d\n", (bool)memcg->under_oom);
> @@ -5385,7 +5385,7 @@ static u64 memory_current_read(struct cgroup_subsys_state *css,
>  
>  static int memory_min_show(struct seq_file *m, void *v)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
>  	unsigned long min = READ_ONCE(memcg->memory.min);
>  
>  	if (min == PAGE_COUNTER_MAX)
> @@ -5415,7 +5415,7 @@ static ssize_t memory_min_write(struct kernfs_open_file *of,
>  
>  static int memory_low_show(struct seq_file *m, void *v)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
>  	unsigned long low = READ_ONCE(memcg->memory.low);
>  
>  	if (low == PAGE_COUNTER_MAX)
> @@ -5445,7 +5445,7 @@ static ssize_t memory_low_write(struct kernfs_open_file *of,
>  
>  static int memory_high_show(struct seq_file *m, void *v)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
>  	unsigned long high = READ_ONCE(memcg->high);
>  
>  	if (high == PAGE_COUNTER_MAX)
> @@ -5482,7 +5482,7 @@ static ssize_t memory_high_write(struct kernfs_open_file *of,
>  
>  static int memory_max_show(struct seq_file *m, void *v)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
>  	unsigned long max = READ_ONCE(memcg->memory.max);
>  
>  	if (max == PAGE_COUNTER_MAX)
> @@ -5544,7 +5544,7 @@ static ssize_t memory_max_write(struct kernfs_open_file *of,
>  
>  static int memory_events_show(struct seq_file *m, void *v)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
>  
>  	seq_printf(m, "low %lu\n",
>  		   atomic_long_read(&memcg->memory_events[MEMCG_LOW]));
> @@ -5562,7 +5562,7 @@ static int memory_events_show(struct seq_file *m, void *v)
>  
>  static int memory_stat_show(struct seq_file *m, void *v)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
>  	struct accumulated_stats acc;
>  	int i;
>  
> @@ -5639,7 +5639,7 @@ static int memory_stat_show(struct seq_file *m, void *v)
>  
>  static int memory_oom_group_show(struct seq_file *m, void *v)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
>  
>  	seq_printf(m, "%d\n", memcg->oom_group);
>  
> @@ -6622,7 +6622,7 @@ static u64 swap_current_read(struct cgroup_subsys_state *css,
>  
>  static int swap_max_show(struct seq_file *m, void *v)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
>  	unsigned long max = READ_ONCE(memcg->swap.max);
>  
>  	if (max == PAGE_COUNTER_MAX)
> @@ -6652,7 +6652,7 @@ static ssize_t swap_max_write(struct kernfs_open_file *of,
>  
>  static int swap_events_show(struct seq_file *m, void *v)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
>  
>  	seq_printf(m, "max %lu\n",
>  		   atomic_long_read(&memcg->memory_events[MEMCG_SWAP_MAX]));
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 81732d05e74a..3dfdbe49ce34 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -1424,7 +1424,7 @@ void dump_unreclaimable_slab(void)
>  #if defined(CONFIG_MEMCG)
>  void *memcg_slab_start(struct seq_file *m, loff_t *pos)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
>  
>  	mutex_lock(&slab_mutex);
>  	return seq_list_start(&memcg->kmem_caches, *pos);
> @@ -1432,7 +1432,7 @@ void *memcg_slab_start(struct seq_file *m, loff_t *pos)
>  
>  void *memcg_slab_next(struct seq_file *m, void *p, loff_t *pos)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
>  
>  	return seq_list_next(p, &memcg->kmem_caches, pos);
>  }
> @@ -1446,7 +1446,7 @@ int memcg_slab_show(struct seq_file *m, void *p)
>  {
>  	struct kmem_cache *s = list_entry(p, struct kmem_cache,
>  					  memcg_params.kmem_caches_node);
> -	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
>  
>  	if (p == memcg->kmem_caches.next)
>  		print_slabinfo_header(m);
> -- 
> 2.20.1

-- 
Michal Hocko
SUSE Labs