The patch titled
Subject: mm: memcg/slab: introduce mem_cgroup_from_obj()
has been added to the -mm tree. Its filename is
mm-memcg-slab-introduce-mem_cgroup_from_obj.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memcg-slab-introduce-mem_cgroup_from_obj.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memcg-slab-introduce-mem_cgroup_from_obj.patch
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------------------------------------------------------
From: Roman Gushchin <guro@xxxxxx>
Subject: mm: memcg/slab: introduce mem_cgroup_from_obj()
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 introduce
a 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.
Link: http://lkml.kernel.org/r/20200117203609.3146239-1-guro@xxxxxx
Signed-off-by: Roman Gushchin <guro@xxxxxx>
Acked-by: Yafang Shao <laoar.shao@xxxxxxxxx>
Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/memcontrol.h | 7 +++++++
mm/list_lru.c | 12 +-----------
mm/memcontrol.c | 32 +++++++++++++++++++++++++++++---
3 files changed, 37 insertions(+), 14 deletions(-)
--- a/include/linux/memcontrol.h~mm-memcg-slab-introduce-mem_cgroup_from_obj
+++ a/include/linux/memcontrol.h
@@ -420,6 +420,8 @@ struct lruvec *mem_cgroup_page_lruvec(st
struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
+struct mem_cgroup *mem_cgroup_from_obj(void *p);
+
struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm);
struct mem_cgroup *get_mem_cgroup_from_page(struct page *page);
@@ -912,6 +914,11 @@ static inline bool mm_match_cgroup(struc
return true;
}
+static inline struct mem_cgroup *mem_cgroup_from_obj(void *p)
+{
+ return NULL;
+}
+
static inline struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
{
return NULL;
--- a/mm/list_lru.c~mm-memcg-slab-introduce-mem_cgroup_from_obj
+++ a/mm/list_lru.c
@@ -57,16 +57,6 @@ list_lru_from_memcg_idx(struct list_lru_
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
if (!nlru->memcg_lrus)
goto out;
- memcg = mem_cgroup_from_kmem(ptr);
+ memcg = mem_cgroup_from_obj(ptr);
if (!memcg)
goto out;
--- a/mm/memcontrol.c~mm-memcg-slab-introduce-mem_cgroup_from_obj
+++ a/mm/memcontrol.c
@@ -759,13 +759,12 @@ void __mod_lruvec_state(struct lruvec *l
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) {
@@ -2637,6 +2636,33 @@ static void commit_charge(struct page *p
unlock_page_lru(page, isolated);
}
+/*
+ * Returns a pointer to the memory cgroup to which the kernel object is charged.
+ *
+ * The caller must ensure the memcg lifetime, e.g. by taking rcu_read_lock(),
+ * cgroup_mutex, etc.
+ */
+struct mem_cgroup *mem_cgroup_from_obj(void *p)
+{
+ struct page *page;
+
+ if (mem_cgroup_disabled())
+ return NULL;
+
+ page = virt_to_head_page(p);
+
+ /*
+ * Slab pages don't have page->mem_cgroup set because corresponding
+ * kmem caches can be reparented during the lifetime. That's why
+ * memcg_from_slab_page() should be used instead.
+ */
+ if (PageSlab(page))
+ return memcg_from_slab_page(page);
+
+ /* All other pages use page->mem_cgroup */
+ return page->mem_cgroup;
+}
+
#ifdef CONFIG_MEMCG_KMEM
static int memcg_alloc_cache_id(void)
{
_
Patches currently in -mm which might be from guro@xxxxxx are
mm-memcg-slab-introduce-mem_cgroup_from_obj.patch
