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

Michal Hocko
2015-01-20T16:04:43Z

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-druUgvl0LCNAfugRpC6u6w@public.gmane.org>

Acked-by: Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>

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