[Devel] [PATCH rh7] memcg: allow to disable cleancache per memcg

[Konstantin Khorenko]

Kirill, please review.

--
Best regards,

Konstantin Khorenko,
Virtuozzo Linux Kernel Team

On 09/25/2015 04:10 PM, Vladimir Davydov wrote:
> Currently, it is only possible to disable tcache system-wide, but it
> might be useful to disable it for a particular container while leaving
> it enabled for others, e.g. in case the container is known to generate
> tons of used-once page cache (backup).
>
> This patch introduces memory.disable_cleancache per memcg knob. Writing
> 1 to it disables cleancache for the corresponding cgroup. Cleancache may
> be re-enabled by writing 0 to it.
>
> https://jira.sw.ru/browse/PSBM-34163
>
> Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>
> ---
>   include/linux/memcontrol.h |  6 +++++
>   mm/cleancache.c            | 10 ++++++--
>   mm/memcontrol.c            | 58 ++++++++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 72 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index ac3f16f0ee28..85a3b2182c9d 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -117,6 +117,7 @@ void mem_cgroup_iter_break(struct mem_cgroup *, struct mem_cgroup *);
>    */
>   int mem_cgroup_inactive_anon_is_low(struct lruvec *lruvec);
>   bool mem_cgroup_low(struct mem_cgroup *root, struct mem_cgroup *memcg);
> +bool mem_cgroup_cleancache_disabled(struct page *page);
>   int mem_cgroup_select_victim_node(struct mem_cgroup *memcg);
>   unsigned long mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list);
>   void mem_cgroup_update_lru_size(struct lruvec *, enum lru_list, int);
> @@ -333,6 +334,11 @@ static inline bool mem_cgroup_low(struct mem_cgroup *root,
>   	return false;
>   }
>
> +static inline bool mem_cgroup_cleancache_disabled(struct page *page)
> +{
> +	return false;
> +}
> +
>   static inline unsigned long
>   mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru)
>   {
> diff --git a/mm/cleancache.c b/mm/cleancache.c
> index a3308bcaa116..16fc1d7c90ae 100644
> --- a/mm/cleancache.c
> +++ b/mm/cleancache.c
> @@ -15,6 +15,7 @@
>   #include <linux/fs.h>
>   #include <linux/exportfs.h>
>   #include <linux/mm.h>
> +#include <linux/memcontrol.h>
>   #include <linux/debugfs.h>
>   #include <linux/cleancache.h>
>
> @@ -227,8 +228,13 @@ void __cleancache_put_page(struct page *page)
>   	pool_id = page->mapping->host->i_sb->cleancache_poolid;
>   	if (pool_id >= 0 &&
>   		cleancache_get_key(page->mapping->host, &key) >= 0) {
> -		cleancache_ops->put_page(pool_id, key, page->index, page);
> -		cleancache_puts++;
> +		if (!mem_cgroup_cleancache_disabled(page)) {
> +			cleancache_ops->put_page(pool_id, key,
> +						 page->index, page);
> +			cleancache_puts++;
> +		} else
> +			cleancache_ops->invalidate_page(pool_id, key,
> +							page->index);
>   	}
>   }
>   EXPORT_SYMBOL(__cleancache_put_page);
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 00cc66db5052..30782b37e2c2 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -326,6 +326,10 @@ struct mem_cgroup {
>   	/* For oom notifier event fd */
>   	struct list_head oom_notify;
>
> +#ifdef CONFIG_CLEANCACHE
> +	bool cleancache_disabled;
> +#endif
> +
>   	/*
>   	 * Should we move charges of a task when a task is moved into this
>   	 * mem_cgroup ? And what type of charges should we move ?
> @@ -1577,6 +1581,37 @@ bool mem_cgroup_low(struct mem_cgroup *root, struct mem_cgroup *memcg)
>   	return true;
>   }
>
> +#ifdef CONFIG_CLEANCACHE
> +bool mem_cgroup_cleancache_disabled(struct page *page)
> +{
> +	struct mem_cgroup *memcg = NULL;
> +	struct page_cgroup *pc;
> +	bool ret = false;
> +
> +	if (mem_cgroup_disabled())
> +		goto out;
> +
> +	pc = lookup_page_cgroup(page);
> +	if (!PageCgroupUsed(pc))
> +		goto out;
> +
> +	lock_page_cgroup(pc);
> +	if (!PageCgroupUsed(pc))
> +		goto out_unlock;
> +
> +	for (memcg = pc->mem_cgroup; memcg; memcg = parent_mem_cgroup(memcg)) {
> +		if (memcg->cleancache_disabled) {
> +			ret = true;
> +			break;
> +		}
> +	}
> +out_unlock:
> +	unlock_page_cgroup(pc);
> +out:
> +	return ret;
> +}
> +#endif
> +
>   static bool __mem_cgroup_below_oom_guarantee(struct mem_cgroup *root,
>   					     struct mem_cgroup *memcg)
>   {
> @@ -5292,6 +5327,21 @@ static int mem_cgroup_oom_guarantee_write(struct cgroup *cont,
>   	return 0;
>   }
>
> +#ifdef CONFIG_CLEANCACHE
> +static u64 mem_cgroup_disable_cleancache_read(struct cgroup *cgrp,
> +					      struct cftype *cft)
> +{
> +	return mem_cgroup_from_cont(cgrp)->cleancache_disabled;
> +}
> +
> +static int mem_cgroup_disable_cleancache_write(struct cgroup *cgrp,
> +					       struct cftype *cft, u64 val)
> +{
> +	mem_cgroup_from_cont(cgrp)->cleancache_disabled = !!val;
> +	return 0;
> +}
> +#endif
> +
>   static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
>   		unsigned long long *mem_limit, unsigned long long *memsw_limit)
>   {
> @@ -6226,6 +6276,14 @@ static struct cftype mem_cgroup_files[] = {
>   		.read_seq_string = memcg_numa_stat_show,
>   	},
>   #endif
> +#ifdef CONFIG_CLEANCACHE
> +	{
> +		.name = "disable_cleancache",
> +		.flags = CFTYPE_NOT_ON_ROOT,
> +		.read_u64 = mem_cgroup_disable_cleancache_read,
> +		.write_u64 = mem_cgroup_disable_cleancache_write,
> +	},
> +#endif
>   #ifdef CONFIG_MEMCG_KMEM
>   	{
>   		.name = "kmem.limit_in_bytes",
>