diff mbox series

[v2,17/28] mm: memcg/slab: save obj_cgroup for non-root slab objects

Message ID 20200127173453.2089565-18-guro@fb.com (mailing list archive)
State New, archived
Headers show
Series The new cgroup slab memory controller | expand

Commit Message

Roman Gushchin Jan. 27, 2020, 5:34 p.m. UTC 
Store the obj_cgroup pointer in the corresponding place of
page->obj_cgroups for each allocated non-root slab object.
Make sure that each allocated object holds a reference to obj_cgroup.

Objcg pointer is obtained from the memcg->objcg dereferencing
in memcg_kmem_get_cache() and passed from pre_alloc_hook to
post_alloc_hook. Then in case of successful allocation(s) it's
getting stored in the page->obj_cgroups vector.

The objcg obtaining part look a bit bulky now, but it will be simplified
by next commits in the series.

Signed-off-by: Roman Gushchin <guro@fb.com>
---
 include/linux/memcontrol.h |  3 +-
 mm/memcontrol.c            | 14 +++++++--
 mm/slab.c                  | 18 +++++++-----
 mm/slab.h                  | 60 ++++++++++++++++++++++++++++++++++----
 mm/slub.c                  | 14 +++++----
 5 files changed, 88 insertions(+), 21 deletions(-)

Comments

Johannes Weiner Feb. 3, 2020, 7:53 p.m. UTC | #1 
On Mon, Jan 27, 2020 at 09:34:42AM -0800, Roman Gushchin wrote:
> Store the obj_cgroup pointer in the corresponding place of
> page->obj_cgroups for each allocated non-root slab object.
> Make sure that each allocated object holds a reference to obj_cgroup.
> 
> Objcg pointer is obtained from the memcg->objcg dereferencing
> in memcg_kmem_get_cache() and passed from pre_alloc_hook to
> post_alloc_hook. Then in case of successful allocation(s) it's
> getting stored in the page->obj_cgroups vector.
> 
> The objcg obtaining part look a bit bulky now, but it will be simplified
> by next commits in the series.
> 
> Signed-off-by: Roman Gushchin <guro@fb.com>
> ---
>  include/linux/memcontrol.h |  3 +-
>  mm/memcontrol.c            | 14 +++++++--
>  mm/slab.c                  | 18 +++++++-----
>  mm/slab.h                  | 60 ++++++++++++++++++++++++++++++++++----
>  mm/slub.c                  | 14 +++++----
>  5 files changed, 88 insertions(+), 21 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 30bbea3f85e2..54bfb26b5016 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -1431,7 +1431,8 @@ static inline void memcg_set_shrinker_bit(struct mem_cgroup *memcg,
>  }
>  #endif
>  
> -struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep);
> +struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep,
> +					struct obj_cgroup **objcgp);
>  void memcg_kmem_put_cache(struct kmem_cache *cachep);
>  
>  #ifdef CONFIG_MEMCG_KMEM
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 94337ab1ebe9..0e9fe272e688 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2896,7 +2896,8 @@ static inline bool memcg_kmem_bypass(void)
>   * done with it, memcg_kmem_put_cache() must be called to release the
>   * reference.
>   */
> -struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep)
> +struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep,
> +					struct obj_cgroup **objcgp)
>  {
>  	struct mem_cgroup *memcg;
>  	struct kmem_cache *memcg_cachep;
> @@ -2952,8 +2953,17 @@ struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep)
>  	 */
>  	if (unlikely(!memcg_cachep))
>  		memcg_schedule_kmem_cache_create(memcg, cachep);
> -	else if (percpu_ref_tryget(&memcg_cachep->memcg_params.refcnt))
> +	else if (percpu_ref_tryget(&memcg_cachep->memcg_params.refcnt)) {
> +		struct obj_cgroup *objcg = rcu_dereference(memcg->objcg);
> +
> +		if (!objcg || !obj_cgroup_tryget(objcg)) {
> +			percpu_ref_put(&memcg_cachep->memcg_params.refcnt);
> +			goto out_unlock;
> +		}

As per the reply to the previous patch: I don't understand why the
objcg requires a pulse check here. As long as the memcg is alive and
can be charged with memory, how can the objcg disappear?
diff mbox series

Patch

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 30bbea3f85e2..54bfb26b5016 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1431,7 +1431,8 @@  static inline void memcg_set_shrinker_bit(struct mem_cgroup *memcg,
 }
 #endif
 
-struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep);
+struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep,
+					struct obj_cgroup **objcgp);
 void memcg_kmem_put_cache(struct kmem_cache *cachep);
 
 #ifdef CONFIG_MEMCG_KMEM
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 94337ab1ebe9..0e9fe272e688 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2896,7 +2896,8 @@  static inline bool memcg_kmem_bypass(void)
  * done with it, memcg_kmem_put_cache() must be called to release the
  * reference.
  */
-struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep)
+struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep,
+					struct obj_cgroup **objcgp)
 {
 	struct mem_cgroup *memcg;
 	struct kmem_cache *memcg_cachep;
@@ -2952,8 +2953,17 @@  struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep)
 	 */
 	if (unlikely(!memcg_cachep))
 		memcg_schedule_kmem_cache_create(memcg, cachep);
-	else if (percpu_ref_tryget(&memcg_cachep->memcg_params.refcnt))
+	else if (percpu_ref_tryget(&memcg_cachep->memcg_params.refcnt)) {
+		struct obj_cgroup *objcg = rcu_dereference(memcg->objcg);
+
+		if (!objcg || !obj_cgroup_tryget(objcg)) {
+			percpu_ref_put(&memcg_cachep->memcg_params.refcnt);
+			goto out_unlock;
+		}
+
+		*objcgp = objcg;
 		cachep = memcg_cachep;
+	}
 out_unlock:
 	rcu_read_unlock();
 	return cachep;
diff --git a/mm/slab.c b/mm/slab.c
index 22e161b57367..f16e896d5a3d 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3223,9 +3223,10 @@  slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
 	unsigned long save_flags;
 	void *ptr;
 	int slab_node = numa_mem_id();
+	struct obj_cgroup *objcg = NULL;
 
 	flags &= gfp_allowed_mask;
-	cachep = slab_pre_alloc_hook(cachep, flags);
+	cachep = slab_pre_alloc_hook(cachep, &objcg, 1, flags);
 	if (unlikely(!cachep))
 		return NULL;
 
@@ -3261,7 +3262,7 @@  slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
 	if (unlikely(slab_want_init_on_alloc(flags, cachep)) && ptr)
 		memset(ptr, 0, cachep->object_size);
 
-	slab_post_alloc_hook(cachep, flags, 1, &ptr);
+	slab_post_alloc_hook(cachep, objcg, flags, 1, &ptr);
 	return ptr;
 }
 
@@ -3302,9 +3303,10 @@  slab_alloc(struct kmem_cache *cachep, gfp_t flags, unsigned long caller)
 {
 	unsigned long save_flags;
 	void *objp;
+	struct obj_cgroup *objcg = NULL;
 
 	flags &= gfp_allowed_mask;
-	cachep = slab_pre_alloc_hook(cachep, flags);
+	cachep = slab_pre_alloc_hook(cachep, &objcg, 1, flags);
 	if (unlikely(!cachep))
 		return NULL;
 
@@ -3318,7 +3320,7 @@  slab_alloc(struct kmem_cache *cachep, gfp_t flags, unsigned long caller)
 	if (unlikely(slab_want_init_on_alloc(flags, cachep)) && objp)
 		memset(objp, 0, cachep->object_size);
 
-	slab_post_alloc_hook(cachep, flags, 1, &objp);
+	slab_post_alloc_hook(cachep, objcg, flags, 1, &objp);
 	return objp;
 }
 
@@ -3440,6 +3442,7 @@  void ___cache_free(struct kmem_cache *cachep, void *objp,
 		memset(objp, 0, cachep->object_size);
 	kmemleak_free_recursive(objp, cachep->flags);
 	objp = cache_free_debugcheck(cachep, objp, caller);
+	memcg_slab_free_hook(cachep, virt_to_head_page(objp), objp);
 
 	/*
 	 * Skip calling cache_free_alien() when the platform is not numa.
@@ -3505,8 +3508,9 @@  int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
 			  void **p)
 {
 	size_t i;
+	struct obj_cgroup *objcg = NULL;
 
-	s = slab_pre_alloc_hook(s, flags);
+	s = slab_pre_alloc_hook(s, &objcg, size, flags);
 	if (!s)
 		return 0;
 
@@ -3529,13 +3533,13 @@  int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
 		for (i = 0; i < size; i++)
 			memset(p[i], 0, s->object_size);
 
-	slab_post_alloc_hook(s, flags, size, p);
+	slab_post_alloc_hook(s, objcg, flags, size, p);
 	/* FIXME: Trace call missing. Christoph would like a bulk variant */
 	return size;
 error:
 	local_irq_enable();
 	cache_alloc_debugcheck_after_bulk(s, flags, i, p, _RET_IP_);
-	slab_post_alloc_hook(s, flags, i, p);
+	slab_post_alloc_hook(s, objcg, flags, i, p);
 	__kmem_cache_free_bulk(s, i, p);
 	return 0;
 }
diff --git a/mm/slab.h b/mm/slab.h
index 8ee8c3a250ac..0fdbeaf4aa8c 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -437,6 +437,41 @@  static inline void memcg_free_page_obj_cgroups(struct page *page)
 	page->obj_cgroups = NULL;
 }
 
+static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s,
+					      struct obj_cgroup *objcg,
+					      size_t size, void **p)
+{
+	struct page *page;
+	unsigned long off;
+	size_t i;
+
+	for (i = 0; i < size; i++) {
+		if (likely(p[i])) {
+			page = virt_to_head_page(p[i]);
+			off = obj_to_index(s, page, p[i]);
+			obj_cgroup_get(objcg);
+			page_obj_cgroups(page)[off] = objcg;
+		}
+	}
+	obj_cgroup_put(objcg);
+	memcg_kmem_put_cache(s);
+}
+
+static inline void memcg_slab_free_hook(struct kmem_cache *s, struct page *page,
+					void *p)
+{
+	struct obj_cgroup *objcg;
+	unsigned int off;
+
+	if (!memcg_kmem_enabled() || is_root_cache(s))
+		return;
+
+	off = obj_to_index(s, page, p);
+	objcg = page_obj_cgroups(page)[off];
+	page_obj_cgroups(page)[off] = NULL;
+	obj_cgroup_put(objcg);
+}
+
 extern void slab_init_memcg_params(struct kmem_cache *);
 extern void memcg_link_cache(struct kmem_cache *s, struct mem_cgroup *memcg);
 
@@ -496,6 +531,17 @@  static inline void memcg_free_page_obj_cgroups(struct page *page)
 {
 }
 
+static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s,
+					      struct obj_cgroup *objcg,
+					      size_t size, void **p)
+{
+}
+
+static inline void memcg_slab_free_hook(struct kmem_cache *s, struct page *page,
+					void *p)
+{
+}
+
 static inline void slab_init_memcg_params(struct kmem_cache *s)
 {
 }
@@ -605,7 +651,8 @@  static inline size_t slab_ksize(const struct kmem_cache *s)
 }
 
 static inline struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s,
-						     gfp_t flags)
+						     struct obj_cgroup **objcgp,
+						     size_t size, gfp_t flags)
 {
 	flags &= gfp_allowed_mask;
 
@@ -619,13 +666,14 @@  static inline struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s,
 
 	if (memcg_kmem_enabled() &&
 	    ((flags & __GFP_ACCOUNT) || (s->flags & SLAB_ACCOUNT)))
-		return memcg_kmem_get_cache(s);
+		return memcg_kmem_get_cache(s, objcgp);
 
 	return s;
 }
 
-static inline void slab_post_alloc_hook(struct kmem_cache *s, gfp_t flags,
-					size_t size, void **p)
+static inline void slab_post_alloc_hook(struct kmem_cache *s,
+					struct obj_cgroup *objcg,
+					gfp_t flags, size_t size, void **p)
 {
 	size_t i;
 
@@ -637,8 +685,8 @@  static inline void slab_post_alloc_hook(struct kmem_cache *s, gfp_t flags,
 					 s->flags, flags);
 	}
 
-	if (memcg_kmem_enabled())
-		memcg_kmem_put_cache(s);
+	if (!is_root_cache(s))
+		memcg_slab_post_alloc_hook(s, objcg, size, p);
 }
 
 #ifndef CONFIG_SLOB
diff --git a/mm/slub.c b/mm/slub.c
index 165e43076c8b..6365e89cd503 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2698,8 +2698,9 @@  static __always_inline void *slab_alloc_node(struct kmem_cache *s,
 	struct kmem_cache_cpu *c;
 	struct page *page;
 	unsigned long tid;
+	struct obj_cgroup *objcg = NULL;
 
-	s = slab_pre_alloc_hook(s, gfpflags);
+	s = slab_pre_alloc_hook(s, &objcg, 1, gfpflags);
 	if (!s)
 		return NULL;
 redo:
@@ -2775,7 +2776,7 @@  static __always_inline void *slab_alloc_node(struct kmem_cache *s,
 	if (unlikely(slab_want_init_on_alloc(gfpflags, s)) && object)
 		memset(object, 0, s->object_size);
 
-	slab_post_alloc_hook(s, gfpflags, 1, &object);
+	slab_post_alloc_hook(s, objcg, gfpflags, 1, &object);
 
 	return object;
 }
@@ -2980,6 +2981,8 @@  static __always_inline void do_slab_free(struct kmem_cache *s,
 	void *tail_obj = tail ? : head;
 	struct kmem_cache_cpu *c;
 	unsigned long tid;
+
+	memcg_slab_free_hook(s, page, head);
 redo:
 	/*
 	 * Determine the currently cpus per cpu slab.
@@ -3157,9 +3160,10 @@  int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
 {
 	struct kmem_cache_cpu *c;
 	int i;
+	struct obj_cgroup *objcg = NULL;
 
 	/* memcg and kmem_cache debug support */
-	s = slab_pre_alloc_hook(s, flags);
+	s = slab_pre_alloc_hook(s, &objcg, size, flags);
 	if (unlikely(!s))
 		return false;
 	/*
@@ -3204,11 +3208,11 @@  int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
 	}
 
 	/* memcg and kmem_cache debug support */
-	slab_post_alloc_hook(s, flags, size, p);
+	slab_post_alloc_hook(s, objcg, flags, size, p);
 	return i;
 error:
 	local_irq_enable();
-	slab_post_alloc_hook(s, flags, i, p);
+	slab_post_alloc_hook(s, objcg, flags, i, p);
 	__kmem_cache_free_bulk(s, i, p);
 	return 0;
 }