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mm: memcg/slab: use mem_cgroup_from_obj()

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Sometimes we need to get a memcg pointer from a charged kernel object.
The right way to get it depends on whether it's a proper slab object or
it's backed by raw pages (e.g.  it's a vmalloc alloction).  In the first
case the kmem_cache->memcg_params.memcg indirection should be used; in
other cases it's just page->mem_cgroup.

To simplify this task and hide the implementation details let's use the
mem_cgroup_from_obj() helper, which takes a pointer to any kernel object
and returns a valid memcg pointer or NULL.

Passing a kernel address rather than a pointer to a page will allow to use
this helper for per-object (rather than per-page) tracked objects in the
future.

The caller is still responsible to ensure that the returned memcg isn't
going away underneath: take the rcu read lock, cgroup mutex etc; depending
on the context.

mem_cgroup_from_kmem() defined in mm/list_lru.c is now obsolete and can be
removed.

Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Link: http://lkml.kernel.org/r/20200117203609.3146239-1-guro@fb.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Roman Gushchin 2020-04-01 21:06:36 -07:00 committed by Linus Torvalds
parent 86daf94efb
commit 4f103c6363
2 changed files with 3 additions and 14 deletions
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12
mm/list_lru.c
View File

@ -57,16 +57,6 @@ list_lru_from_memcg_idx(struct list_lru_node *nlru, int idx)
return &nlru->lru;
}
static __always_inline struct mem_cgroup *mem_cgroup_from_kmem(void *ptr)
{
struct page *page;
if (!memcg_kmem_enabled())
return NULL;
page = virt_to_head_page(ptr);
return memcg_from_slab_page(page);
}
static inline struct list_lru_one *
list_lru_from_kmem(struct list_lru_node *nlru, void *ptr,
struct mem_cgroup **memcg_ptr)
@ -77,7 +67,7 @@ list_lru_from_kmem(struct list_lru_node *nlru, void *ptr,
if (!nlru->memcg_lrus)
goto out;
memcg = mem_cgroup_from_kmem(ptr);
memcg = mem_cgroup_from_obj(ptr);
if (!memcg)
goto out;

5
mm/memcontrol.c
View File

@ -759,13 +759,12 @@ void __mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
void __mod_lruvec_slab_state(void *p, enum node_stat_item idx, int val)
{
struct page *page = virt_to_head_page(p);
pg_data_t *pgdat = page_pgdat(page);
pg_data_t *pgdat = page_pgdat(virt_to_page(p));
struct mem_cgroup *memcg;
struct lruvec *lruvec;
rcu_read_lock();
memcg = memcg_from_slab_page(page);
memcg = mem_cgroup_from_obj(p);
/* Untracked pages have no memcg, no lruvec. Update only the node */
if (!memcg || memcg == root_mem_cgroup) {