On Tue 18-09-12 18:04:07, Glauber Costa wrote:
[...]
> include/linux/memcontrol.h | 4 +++-
> mm/memcontrol.c | 26 ++++++++++++++++++++++++--
> 2 files changed, 27 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 82ede9a..4ec9fd5 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -22,6 +22,7 @@
> #include <linux/cgroup.h>
> #include <linux/vm_event_item.h>
> #include <linux/hardirq.h>
> +#include <linux/jump_label.h>
>
> struct mem_cgroup;
> struct page_cgroup;
> @@ -401,9 +402,10 @@ struct sock;
> void sock_update_memcg(struct sock *sk);
> void sock_release_memcg(struct sock *sk);
>
> +extern struct static_key memcg_kmem_enabled_key;
> static inline bool memcg_kmem_enabled(void)
> {
> - return true;
> + return static_key_false(&memcg_kmem_enabled_key);
> }
>
> extern bool __memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **memcg,
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 720e4bb..aada601 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -467,6 +467,8 @@ struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *s)
> #include <net/sock.h>
> #include <net/ip.h>
>
> +struct static_key memcg_kmem_enabled_key;
> +
> static bool mem_cgroup_is_root(struct mem_cgroup *memcg);
> static int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size);
> static void memcg_uncharge_kmem(struct mem_cgroup *memcg, u64 size);
> @@ -624,6 +626,16 @@ void __memcg_kmem_uncharge_page(struct page *page, int order)
> WARN_ON(mem_cgroup_is_root(memcg));
> memcg_uncharge_kmem(memcg, PAGE_SIZE << order);
> }
> +
> +static void disarm_kmem_keys(struct mem_cgroup *memcg)
> +{
> + if (memcg_kmem_is_accounted(memcg))
> + static_key_slow_dec(&memcg_kmem_enabled_key);
> +}
> +#else
> +static void disarm_kmem_keys(struct mem_cgroup *memcg)
> +{
> +}
> #endif /* CONFIG_MEMCG_KMEM */
>
> #if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM)
> @@ -639,6 +651,12 @@ static void disarm_sock_keys(struct mem_cgroup *memcg)
> }
> #endif
>
> +static void disarm_static_keys(struct mem_cgroup *memcg)
> +{
> + disarm_sock_keys(memcg);
> + disarm_kmem_keys(memcg);
> +}
> +
> static void drain_all_stock_async(struct mem_cgroup *memcg);
>
> static struct mem_cgroup_per_zone *
> @@ -4131,7 +4149,11 @@ static void memcg_update_kmem_limit(struct mem_cgroup *memcg, u64 val)
> */
> mutex_lock(&set_limit_mutex);
> if ((val != RESOURCE_MAX) && memcg_kmem_set_active(memcg)) {
> -
> + /*
> + * Once the static branch is enabled it will only be
> + * disabled when the last reference to memcg is gone.
> + */
> + static_key_slow_inc(&memcg_kmem_enabled_key);
I guess the reason why we do not need to inc also for children is that
we do not inherit kmem_accounted, right?
> mem_cgroup_get(memcg);
>
> for_each_mem_cgroup_tree(iter, memcg) {
> @@ -5066,7 +5088,7 @@ static void free_work(struct work_struct *work)
> * to move this code around, and make sure it is outside
> * the cgroup_lock.
> */
> - disarm_sock_keys(memcg);
> + disarm_static_keys(memcg);
> if (size < PAGE_SIZE)
> kfree(memcg);
> else
> --
> 1.7.11.4
>
> --
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--
Michal Hocko
SUSE Labs
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