Re: [patch 1/2] mm: page_counter: pull "-1" handling out of page_counter_memparse()

[Michal Hocko]

On Tue 20-01-15 10:31:54, Johannes Weiner wrote:
> The unified hierarchy interface for memory cgroups will no longer use
> "-1" to mean maximum possible resource value.  In preparation for
> this, make the string an argument and let the caller supply it.
> 
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>

Acked-by: Michal Hocko <mhocko@xxxxxxx>

Thanks!

> ---
>  include/linux/page_counter.h | 3 ++-
>  mm/hugetlb_cgroup.c          | 2 +-
>  mm/memcontrol.c              | 4 ++--
>  mm/page_counter.c            | 7 ++++---
>  net/ipv4/tcp_memcontrol.c    | 2 +-
>  5 files changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/page_counter.h b/include/linux/page_counter.h
> index 955421575d16..17fa4f8de3a6 100644
> --- a/include/linux/page_counter.h
> +++ b/include/linux/page_counter.h
> @@ -41,7 +41,8 @@ int page_counter_try_charge(struct page_counter *counter,
>  			    struct page_counter **fail);
>  void 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);
> +int page_counter_memparse(const char *buf, const char *max,
> +			  unsigned long *nr_pages);
>  
>  static inline void page_counter_reset_watermark(struct page_counter *counter)
>  {
> diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
> index 037e1c00a5b7..6e0057439a46 100644
> --- a/mm/hugetlb_cgroup.c
> +++ b/mm/hugetlb_cgroup.c
> @@ -279,7 +279,7 @@ static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of,
>  		return -EINVAL;
>  
>  	buf = strstrip(buf);
> -	ret = page_counter_memparse(buf, &nr_pages);
> +	ret = page_counter_memparse(buf, "-1", &nr_pages);
>  	if (ret)
>  		return ret;
>  
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 05ad91cda22c..a3592a756ad9 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3442,7 +3442,7 @@ static ssize_t mem_cgroup_write(struct kernfs_open_file *of,
>  	int ret;
>  
>  	buf = strstrip(buf);
> -	ret = page_counter_memparse(buf, &nr_pages);
> +	ret = page_counter_memparse(buf, "-1", &nr_pages);
>  	if (ret)
>  		return ret;
>  
> @@ -3814,7 +3814,7 @@ static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
>  	unsigned long usage;
>  	int i, size, ret;
>  
> -	ret = page_counter_memparse(args, &threshold);
> +	ret = page_counter_memparse(args, "-1", &threshold);
>  	if (ret)
>  		return ret;
>  
> diff --git a/mm/page_counter.c b/mm/page_counter.c
> index a009574fbba9..11b4beda14ba 100644
> --- a/mm/page_counter.c
> +++ b/mm/page_counter.c
> @@ -166,18 +166,19 @@ int page_counter_limit(struct page_counter *counter, unsigned long limit)
>  /**
>   * page_counter_memparse - memparse() for page counter limits
>   * @buf: string to parse
> + * @max: string meaning maximum possible value
>   * @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)
> +int page_counter_memparse(const char *buf, const char *max,
> +			  unsigned long *nr_pages)
>  {
> -	char unlimited[] = "-1";
>  	char *end;
>  	u64 bytes;
>  
> -	if (!strncmp(buf, unlimited, sizeof(unlimited))) {
> +	if (!strcmp(buf, max)) {
>  		*nr_pages = PAGE_COUNTER_MAX;
>  		return 0;
>  	}
> diff --git a/net/ipv4/tcp_memcontrol.c b/net/ipv4/tcp_memcontrol.c
> index 272327134a1b..c2a75c6957a1 100644
> --- a/net/ipv4/tcp_memcontrol.c
> +++ b/net/ipv4/tcp_memcontrol.c
> @@ -120,7 +120,7 @@ static ssize_t tcp_cgroup_write(struct kernfs_open_file *of,
>  	switch (of_cft(of)->private) {
>  	case RES_LIMIT:
>  		/* see memcontrol.c */
> -		ret = page_counter_memparse(buf, &nr_pages);
> +		ret = page_counter_memparse(buf, "-1", &nr_pages);
>  		if (ret)
>  			break;
>  		mutex_lock(&tcp_limit_mutex);
> -- 
> 2.2.0
> 

-- 
Michal Hocko
SUSE Labs
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