Allocate and release memory to store obj_cgroup pointers for each
non-root slab page. Reuse page->mem_cgroup pointer to store a pointer
to the allocated space.
To distinguish between obj_cgroups and memcg pointers in case
when it's not obvious which one is used (as in page_cgroup_ino()),
let's always set the lowest bit in the obj_cgroup case.
Signed-off-by: Roman Gushchin <guro@xxxxxx>
---
include/linux/mm.h | 25 ++++++++++++++++++--
include/linux/mm_types.h | 5 +++-
mm/memcontrol.c | 5 ++--
mm/slab.c | 3 ++-
mm/slab.h | 51 +++++++++++++++++++++++++++++++++++++++-
mm/slub.c | 2 +-
6 files changed, 83 insertions(+), 8 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 080f8ac8bfb7..65224becc4ca 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1264,12 +1264,33 @@ static inline void set_page_links(struct page *page, enum zone_type zone,
#ifdef CONFIG_MEMCG
static inline struct mem_cgroup *page_memcg(struct page *page)
{
- return page->mem_cgroup;
+ struct mem_cgroup *memcg = page->mem_cgroup;
+
+ /*
+ * The lowest bit set means that memcg isn't a valid memcg pointer,
+ * but a obj_cgroups pointer. In this case the page is shared and
+ * isn't charged to any specific memory cgroup. Return NULL.
+ */
+ if ((unsigned long) memcg & 0x1UL)
+ memcg = NULL;
+
+ return memcg;
}
static inline struct mem_cgroup *page_memcg_rcu(struct page *page)
{
+ struct mem_cgroup *memcg = READ_ONCE(page->mem_cgroup);
+
WARN_ON_ONCE(!rcu_read_lock_held());
- return READ_ONCE(page->mem_cgroup);
+
+ /*
+ * The lowest bit set means that memcg isn't a valid memcg pointer,
+ * but a obj_cgroups pointer. In this case the page is shared and
+ * isn't charged to any specific memory cgroup. Return NULL.
+ */
+ if ((unsigned long) memcg & 0x1UL)
+ memcg = NULL;
+
+ return memcg;
}
#else
static inline struct mem_cgroup *page_memcg(struct page *page)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 270aa8fd2800..5102f00f3336 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -198,7 +198,10 @@ struct page {
atomic_t _refcount;
#ifdef CONFIG_MEMCG
- struct mem_cgroup *mem_cgroup;
+ union {
+ struct mem_cgroup *mem_cgroup;
+ struct obj_cgroup **obj_cgroups;
+ };
#endif
/*
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9aa37bc61db5..94337ab1ebe9 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -545,7 +545,8 @@ ino_t page_cgroup_ino(struct page *page)
if (PageSlab(page) && !PageTail(page))
memcg = memcg_from_slab_page(page);
else
- memcg = READ_ONCE(page->mem_cgroup);
+ memcg = page_memcg_rcu(page);
+
while (memcg && !(memcg->css.flags & CSS_ONLINE))
memcg = parent_mem_cgroup(memcg);
if (memcg)
@@ -2783,7 +2784,7 @@ struct mem_cgroup *mem_cgroup_from_obj(void *p)
return memcg_from_slab_page(page);
/* All other pages use page->mem_cgroup */
- return page->mem_cgroup;
+ return page_memcg(page);
}
static int memcg_alloc_cache_id(void)
diff --git a/mm/slab.c b/mm/slab.c
index a89633603b2d..22e161b57367 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1370,7 +1370,8 @@ static struct page *kmem_getpages(struct kmem_cache *cachep, gfp_t flags,
return NULL;
}
- if (charge_slab_page(page, flags, cachep->gfporder, cachep)) {
+ if (charge_slab_page(page, flags, cachep->gfporder, cachep,
+ cachep->num)) {
__free_pages(page, cachep->gfporder);
return NULL;
}
diff --git a/mm/slab.h b/mm/slab.h
index 7925f7005161..8ee8c3a250ac 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -319,6 +319,18 @@ static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s)
return s->memcg_params.root_cache;
}
+static inline struct obj_cgroup **page_obj_cgroups(struct page *page)
+{
+ /*
+ * page->mem_cgroup and page->obj_cgroups are sharing the same
+ * space. To distinguish between them in case we don't know for sure
+ * that the page is a slab page (e.g. page_cgroup_ino()), let's
+ * always set the lowest bit of obj_cgroups.
+ */
+ return (struct obj_cgroup **)
+ ((unsigned long)page->obj_cgroups & ~0x1UL);
+}
+
/*
* Expects a pointer to a slab page. Please note, that PageSlab() check
* isn't sufficient, as it returns true also for tail compound slab pages,
@@ -406,6 +418,25 @@ static __always_inline void memcg_uncharge_slab(struct page *page, int order,
percpu_ref_put_many(&s->memcg_params.refcnt, nr_pages);
}
+static inline int memcg_alloc_page_obj_cgroups(struct page *page, gfp_t gfp,
+ unsigned int objects)
+{
+ void *vec;
+
+ vec = kcalloc(objects, sizeof(struct obj_cgroup *), gfp);
+ if (!vec)
+ return -ENOMEM;
+
+ page->obj_cgroups = (struct obj_cgroup **) ((unsigned long)vec | 0x1UL);
+ return 0;
+}
+
+static inline void memcg_free_page_obj_cgroups(struct page *page)
+{
+ kfree(page_obj_cgroups(page));
+ page->obj_cgroups = NULL;
+}
+
extern void slab_init_memcg_params(struct kmem_cache *);
extern void memcg_link_cache(struct kmem_cache *s, struct mem_cgroup *memcg);
@@ -455,6 +486,16 @@ static inline void memcg_uncharge_slab(struct page *page, int order,
{
}
+static inline int memcg_alloc_page_obj_cgroups(struct page *page, gfp_t gfp,
+ unsigned int objects)
+{
+ return 0;
+}
+
+static inline void memcg_free_page_obj_cgroups(struct page *page)
+{
+}
+
static inline void slab_init_memcg_params(struct kmem_cache *s)
{
}
@@ -479,14 +520,21 @@ static inline struct kmem_cache *virt_to_cache(const void *obj)
static __always_inline int charge_slab_page(struct page *page,
gfp_t gfp, int order,
- struct kmem_cache *s)
+ struct kmem_cache *s,
+ unsigned int objects)
{
+ int ret;
+
if (is_root_cache(s)) {
mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s),
PAGE_SIZE << order);
return 0;
}
+ ret = memcg_alloc_page_obj_cgroups(page, gfp, objects);
+ if (ret)
+ return ret;
+
return memcg_charge_slab(page, gfp, order, s);
}
@@ -499,6 +547,7 @@ static __always_inline void uncharge_slab_page(struct page *page, int order,
return;
}
+ memcg_free_page_obj_cgroups(page);
memcg_uncharge_slab(page, order, s);
}
diff --git a/mm/slub.c b/mm/slub.c
index ed6aea234400..165e43076c8b 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1516,7 +1516,7 @@ static inline struct page *alloc_slab_page(struct kmem_cache *s,
else
page = __alloc_pages_node(node, flags, order);
- if (page && charge_slab_page(page, flags, order, s)) {
+ if (page && charge_slab_page(page, flags, order, s, oo_objects(oo))) {
__free_pages(page, order);
page = NULL;
}
--
2.24.1
