Re: [PATCH v3 3/7] mm: introduce __memcg_kmem_uncharge_memcg()

Shakeel Butt
2019-05-11T00:33:24Z

Date: Wed, May 8, 2019 at 1:30 PM
To: Andrew Morton, Shakeel Butt
Cc: <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
<kernel-team@fb.com>, Johannes Weiner, Michal Hocko, Rik van Riel,
Christoph Lameter, Vladimir Davydov, <cgroups@vger.kernel.org>, Roman
Gushchin

> Let's separate the page counter modification code out of
> __memcg_kmem_uncharge() in a way similar to what
> __memcg_kmem_charge() and __memcg_kmem_charge_memcg() work.
>
> This will allow to reuse this code later using a new
> memcg_kmem_uncharge_memcg() wrapper, which calls
> __memcg_kmem_unchare_memcg() if memcg_kmem_enabled()

__memcg_kmem_uncharge_memcg()

> check is passed.
>
> Signed-off-by: Roman Gushchin <guro@fb.com>

Reviewed-by: Shakeel Butt <shakeelb@google.com>

> ---
> include/linux/memcontrol.h | 10 ++++++++++
> mm/memcontrol.c | 25 +++++++++++++++++--------
> 2 files changed, 27 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 36bdfe8e5965..deb209510902 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -1298,6 +1298,8 @@ int __memcg_kmem_charge(struct page *page, gfp_t gfp, int order);
> void __memcg_kmem_uncharge(struct page *page, int order);
> int __memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order,
> struct mem_cgroup *memcg);
> +void __memcg_kmem_uncharge_memcg(struct mem_cgroup *memcg,
> + unsigned int nr_pages);
>
> extern struct static_key_false memcg_kmem_enabled_key;
> extern struct workqueue_struct *memcg_kmem_cache_wq;
> @@ -1339,6 +1341,14 @@ static inline int memcg_kmem_charge_memcg(struct page *page, gfp_t gfp,
> return __memcg_kmem_charge_memcg(page, gfp, order, memcg);
> return 0;
> }
> +
> +static inline void memcg_kmem_uncharge_memcg(struct page *page, int order,
> + struct mem_cgroup *memcg)
> +{
> + if (memcg_kmem_enabled())
> + __memcg_kmem_uncharge_memcg(memcg, 1 << order);
> +}
> +
> /*
> * helper for accessing a memcg's index. It will be used as an index in the
> * child cache array in kmem_cache, and also to derive its name. This function
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 48a8f1c35176..b2c39f187cbb 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2750,6 +2750,22 @@ int __memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
> css_put(&memcg->css);
> return ret;
> }
> +
> +/**
> + * __memcg_kmem_uncharge_memcg: uncharge a kmem page
> + * @memcg: memcg to uncharge
> + * @nr_pages: number of pages to uncharge
> + */
> +void __memcg_kmem_uncharge_memcg(struct mem_cgroup *memcg,
> + unsigned int nr_pages)
> +{
> + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
> + page_counter_uncharge(&memcg->kmem, nr_pages);
> +
> + page_counter_uncharge(&memcg->memory, nr_pages);
> + if (do_memsw_account())
> + page_counter_uncharge(&memcg->memsw, nr_pages);
> +}
> /**
> * __memcg_kmem_uncharge: uncharge a kmem page
> * @page: page to uncharge
> @@ -2764,14 +2780,7 @@ void __memcg_kmem_uncharge(struct page *page, int order)
> return;
>
> VM_BUG_ON_PAGE(mem_cgroup_is_root(memcg), page);
> -
> - if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
> - page_counter_uncharge(&memcg->kmem, nr_pages);
> -
> - page_counter_uncharge(&memcg->memory, nr_pages);
> - if (do_memsw_account())
> - page_counter_uncharge(&memcg->memsw, nr_pages);
> -
> + __memcg_kmem_uncharge_memcg(memcg, nr_pages);
> page->mem_cgroup = NULL;
>
> /* slab pages do not have PageKmemcg flag set */
> --
> 2.20.1
>