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Message-ID: <20190108150317.GA31793@dhcp22.suse.cz>
Date: Tue, 8 Jan 2019 16:03:17 +0100
From: Michal Hocko <mhocko@...nel.org>
To: Shakeel Butt <shakeelb@...gle.com>
Cc: Johannes Weiner <hannes@...xchg.org>,
Vladimir Davydov <vdavydov.dev@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Roman Gushchin <guro@...com>, linux-mm@...ck.org,
cgroups@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] memcg: localize memcg_kmem_enabled() check
On Thu 03-01-19 08:12:03, Shakeel Butt wrote:
> Move the memcg_kmem_enabled() checks into memcg kmem charge/uncharge
> functions, so, the users don't have to explicitly check that condition.
> This is purely code cleanup patch without any functional change. Only
> the order of checks in memcg_charge_slab() can potentially be changed
> but the functionally it will be same. This should not matter as
> memcg_charge_slab() is not in the hot path.
Looks good to me
>
> Signed-off-by: Shakeel Butt <shakeelb@...gle.com>
Acked-by: Michal Hocko <mhocko@...e.com>
> ---
> Changelog since v1:
> - Fixed the build when CONFIG_MEMCG is not set
>
> fs/pipe.c | 3 +--
> include/linux/memcontrol.h | 37 +++++++++++++++++++++++++++++++++----
> mm/memcontrol.c | 16 ++++++++--------
> mm/page_alloc.c | 4 ++--
> mm/slab.h | 4 ----
> 5 files changed, 44 insertions(+), 20 deletions(-)
>
> diff --git a/fs/pipe.c b/fs/pipe.c
> index bdc5d3c0977d..51d5fd8840ab 100644
> --- a/fs/pipe.c
> +++ b/fs/pipe.c
> @@ -140,8 +140,7 @@ static int anon_pipe_buf_steal(struct pipe_inode_info *pipe,
> struct page *page = buf->page;
>
> if (page_count(page) == 1) {
> - if (memcg_kmem_enabled())
> - memcg_kmem_uncharge(page, 0);
> + memcg_kmem_uncharge(page, 0);
> __SetPageLocked(page);
> return 0;
> }
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 83ae11cbd12c..b0eb29ea0d9c 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -1273,12 +1273,12 @@ static inline bool mem_cgroup_under_socket_pressure(struct mem_cgroup *memcg)
>
> struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep);
> void memcg_kmem_put_cache(struct kmem_cache *cachep);
> -int memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order,
> - struct mem_cgroup *memcg);
>
> #ifdef CONFIG_MEMCG_KMEM
> -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(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);
>
> extern struct static_key_false memcg_kmem_enabled_key;
> extern struct workqueue_struct *memcg_kmem_cache_wq;
> @@ -1300,6 +1300,26 @@ static inline bool memcg_kmem_enabled(void)
> return static_branch_unlikely(&memcg_kmem_enabled_key);
> }
>
> +static inline int memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
> +{
> + if (memcg_kmem_enabled())
> + return __memcg_kmem_charge(page, gfp, order);
> + return 0;
> +}
> +
> +static inline void memcg_kmem_uncharge(struct page *page, int order)
> +{
> + if (memcg_kmem_enabled())
> + __memcg_kmem_uncharge(page, order);
> +}
> +
> +static inline int memcg_kmem_charge_memcg(struct page *page, gfp_t gfp,
> + int order, struct mem_cgroup *memcg)
> +{
> + if (memcg_kmem_enabled())
> + return __memcg_kmem_charge_memcg(page, gfp, order, memcg);
> + return 0;
> +}
> /*
> * 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
> @@ -1325,6 +1345,15 @@ static inline void memcg_kmem_uncharge(struct page *page, int order)
> {
> }
>
> +static inline int __memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
> +{
> + return 0;
> +}
> +
> +static inline void __memcg_kmem_uncharge(struct page *page, int order)
> +{
> +}
> +
> #define for_each_memcg_cache_index(_idx) \
> for (; NULL; )
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 4afd5971f2d4..e8ca09920d71 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2557,7 +2557,7 @@ void memcg_kmem_put_cache(struct kmem_cache *cachep)
> }
>
> /**
> - * memcg_kmem_charge_memcg: charge a kmem page
> + * __memcg_kmem_charge_memcg: charge a kmem page
> * @page: page to charge
> * @gfp: reclaim mode
> * @order: allocation order
> @@ -2565,7 +2565,7 @@ void memcg_kmem_put_cache(struct kmem_cache *cachep)
> *
> * Returns 0 on success, an error code on failure.
> */
> -int memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order,
> +int __memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order,
> struct mem_cgroup *memcg)
> {
> unsigned int nr_pages = 1 << order;
> @@ -2588,24 +2588,24 @@ int memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order,
> }
>
> /**
> - * memcg_kmem_charge: charge a kmem page to the current memory cgroup
> + * __memcg_kmem_charge: charge a kmem page to the current memory cgroup
> * @page: page to charge
> * @gfp: reclaim mode
> * @order: allocation order
> *
> * Returns 0 on success, an error code on failure.
> */
> -int memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
> +int __memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
> {
> struct mem_cgroup *memcg;
> int ret = 0;
>
> - if (mem_cgroup_disabled() || memcg_kmem_bypass())
> + if (memcg_kmem_bypass())
> return 0;
>
> memcg = get_mem_cgroup_from_current();
> if (!mem_cgroup_is_root(memcg)) {
> - ret = memcg_kmem_charge_memcg(page, gfp, order, memcg);
> + ret = __memcg_kmem_charge_memcg(page, gfp, order, memcg);
> if (!ret)
> __SetPageKmemcg(page);
> }
> @@ -2613,11 +2613,11 @@ int memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
> return ret;
> }
> /**
> - * memcg_kmem_uncharge: uncharge a kmem page
> + * __memcg_kmem_uncharge: uncharge a kmem page
> * @page: page to uncharge
> * @order: allocation order
> */
> -void memcg_kmem_uncharge(struct page *page, int order)
> +void __memcg_kmem_uncharge(struct page *page, int order)
> {
> struct mem_cgroup *memcg = page->mem_cgroup;
> unsigned int nr_pages = 1 << order;
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 0634fbdef078..d65c337d2257 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1053,7 +1053,7 @@ static __always_inline bool free_pages_prepare(struct page *page,
> if (PageMappingFlags(page))
> page->mapping = NULL;
> if (memcg_kmem_enabled() && PageKmemcg(page))
> - memcg_kmem_uncharge(page, order);
> + __memcg_kmem_uncharge(page, order);
> if (check_free)
> bad += free_pages_check(page);
> if (bad)
> @@ -4667,7 +4667,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
>
> out:
> if (memcg_kmem_enabled() && (gfp_mask & __GFP_ACCOUNT) && page &&
> - unlikely(memcg_kmem_charge(page, gfp_mask, order) != 0)) {
> + unlikely(__memcg_kmem_charge(page, gfp_mask, order) != 0)) {
> __free_pages(page, order);
> page = NULL;
> }
> diff --git a/mm/slab.h b/mm/slab.h
> index 4190c24ef0e9..cde51d7f631f 100644
> --- a/mm/slab.h
> +++ b/mm/slab.h
> @@ -276,8 +276,6 @@ static __always_inline int memcg_charge_slab(struct page *page,
> gfp_t gfp, int order,
> struct kmem_cache *s)
> {
> - if (!memcg_kmem_enabled())
> - return 0;
> if (is_root_cache(s))
> return 0;
> return memcg_kmem_charge_memcg(page, gfp, order, s->memcg_params.memcg);
> @@ -286,8 +284,6 @@ static __always_inline int memcg_charge_slab(struct page *page,
> static __always_inline void memcg_uncharge_slab(struct page *page, int order,
> struct kmem_cache *s)
> {
> - if (!memcg_kmem_enabled())
> - return;
> memcg_kmem_uncharge(page, order);
> }
>
> --
> 2.20.1.415.g653613c723-goog
--
Michal Hocko
SUSE Labs
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