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mm: memcontrol/slab: Use helpers to access slab page's memcg_data

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To gather all direct accesses to struct page's memcg_data field in one
place, let's introduce 3 new helpers to use in the slab accounting code:

  struct obj_cgroup **page_objcgs(struct page *page);
  struct obj_cgroup **page_objcgs_check(struct page *page);
  bool set_page_objcgs(struct page *page, struct obj_cgroup **objcgs);

They are similar to the corresponding API for generic pages, except that
the setter can return false, indicating that the value has been already
set from a different thread.

Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lkml.kernel.org/r/20201027001657.3398190-3-guro@fb.com
Link: https://lore.kernel.org/bpf/20201201215900.3569844-3-guro@fb.com
This commit is contained in:
Roman Gushchin 2020-12-01 13:58:28 -08:00 • committed by Alexei Starovoitov
parent bcfe06bf26
commit 270c6a7146
3 changed files with 75 additions and 30 deletions
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64
include/linux/memcontrol.h
View file

@ -416,6 +416,70 @@ static inline struct mem_cgroup *page_memcg_check(struct page *page)
return (struct mem_cgroup *)memcg_data;
}
#ifdef CONFIG_MEMCG_KMEM
/*
* page_objcgs - get the object cgroups vector associated with a page
* @page: a pointer to the page struct
*
* Returns a pointer to the object cgroups vector associated with the page,
* or NULL. This function assumes that the page is known to have an
* associated object cgroups vector. It's not safe to call this function
* against pages, which might have an associated memory cgroup: e.g.
* kernel stack pages.
*/
static inline struct obj_cgroup **page_objcgs(struct page *page)
{
return (struct obj_cgroup **)(READ_ONCE(page->memcg_data) & ~0x1UL);
}
/*
* page_objcgs_check - get the object cgroups vector associated with a page
* @page: a pointer to the page struct
*
* Returns a pointer to the object cgroups vector associated with the page,
* or NULL. This function is safe to use if the page can be directly associated
* with a memory cgroup.
*/
static inline struct obj_cgroup **page_objcgs_check(struct page *page)
{
unsigned long memcg_data = READ_ONCE(page->memcg_data);
if (memcg_data && (memcg_data & 0x1UL))
return (struct obj_cgroup **)(memcg_data & ~0x1UL);
return NULL;
}
/*
* set_page_objcgs - associate a page with a object cgroups vector
* @page: a pointer to the page struct
* @objcgs: a pointer to the object cgroups vector
*
* Atomically associates a page with a vector of object cgroups.
*/
static inline bool set_page_objcgs(struct page *page,
struct obj_cgroup **objcgs)
{
return !cmpxchg(&page->memcg_data, 0, (unsigned long)objcgs | 0x1UL);
}
#else
static inline struct obj_cgroup **page_objcgs(struct page *page)
{
return NULL;
}
static inline struct obj_cgroup **page_objcgs_check(struct page *page)
{
return NULL;
}
static inline bool set_page_objcgs(struct page *page,
struct obj_cgroup **objcgs)
{
return true;
}
#endif
static __always_inline bool memcg_stat_item_in_bytes(int idx)
{
if (idx == MEMCG_PERCPU_B)