[PATCH 18/23] slub: charge allocation to a memcg

[Glauber Costa <glommer@parallels.com>]

This patch charges allocation of a slab object to a particular
memcg.

The cache is selected with mem_cgroup_get_kmem_cache(),
which is the biggest overhead we pay here, because
it happens at all allocations. However, other than forcing
a function call, this function is not very expensive, and
try to return as soon as we realize we are not a memcg cache.

The charge/uncharge functions are heavier, but are only called
for new page allocations.

The kmalloc_no_account variant is patched so the base
function is used and we don't even try to do cache
selection.

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <suleiman@google.com>
---
 include/linux/slub_def.h |   32 ++++++++++--
 mm/slub.c                |  124 +++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 138 insertions(+), 18 deletions(-)

diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 9a8000a..e75efcb 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -13,6 +13,7 @@
 #include <linux/kobject.h>
 
 #include <linux/kmemleak.h>
+#include <linux/memcontrol.h>
 
 enum stat_item {
 	ALLOC_FASTPATH,		/* Allocation from cpu slab */
@@ -210,14 +211,21 @@ static __always_inline int kmalloc_index(size_t size)
  * This ought to end up with a global pointer to the right cache
  * in kmalloc_caches.
  */
-static __always_inline struct kmem_cache *kmalloc_slab(size_t size)
+static __always_inline struct kmem_cache *kmalloc_slab(gfp_t flags, size_t size)
 {
+	struct kmem_cache *s;
 	int index = kmalloc_index(size);
 
 	if (index == 0)
 		return NULL;
 
-	return kmalloc_caches[index];
+	s = kmalloc_caches[index];
+
+	rcu_read_lock();
+	s = mem_cgroup_get_kmem_cache(s, flags);
+	rcu_read_unlock();
+
+	return s;
 }
 
 void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
@@ -225,13 +233,27 @@ void *kmalloc_no_account(size_t size, gfp_t);
 void *__kmalloc(size_t size, gfp_t flags);
 
 static __always_inline void *
-kmalloc_order(size_t size, gfp_t flags, unsigned int order)
+kmalloc_order_base(size_t size, gfp_t flags, unsigned int order)
 {
 	void *ret = (void *) __get_free_pages(flags | __GFP_COMP, order);
 	kmemleak_alloc(ret, size, 1, flags);
 	return ret;
 }
 
+static __always_inline void *
+kmalloc_order(size_t size, gfp_t flags, unsigned int order)
+{
+	void *ret = NULL;
+
+	if (!mem_cgroup_charge_kmem(flags, size))
+		return NULL;
+
+	ret = kmalloc_order_base(size, flags, order);
+	if (!ret)
+		mem_cgroup_uncharge_kmem((1 << order) << PAGE_SHIFT);
+	return ret;
+}
+
 /**
  * Calling this on allocated memory will check that the memory
  * is expected to be in use, and print warnings if not.
@@ -276,7 +298,7 @@ static __always_inline void *kmalloc(size_t size, gfp_t flags)
 			return kmalloc_large(size, flags);
 
 		if (!(flags & SLUB_DMA)) {
-			struct kmem_cache *s = kmalloc_slab(size);
+			struct kmem_cache *s = kmalloc_slab(flags, size);
 
 			if (!s)
 				return ZERO_SIZE_PTR;
@@ -309,7 +331,7 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
 {
 	if (__builtin_constant_p(size) &&
 		size <= SLUB_MAX_SIZE && !(flags & SLUB_DMA)) {
-			struct kmem_cache *s = kmalloc_slab(size);
+			struct kmem_cache *s = kmalloc_slab(flags, size);
 
 		if (!s)
 			return ZERO_SIZE_PTR;
diff --git a/mm/slub.c b/mm/slub.c
index d754b06..9b22139 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1283,11 +1283,17 @@ static inline struct page *alloc_slab_page(gfp_t flags, int node,
 		return alloc_pages_exact_node(node, flags, order);
 }
 
+static inline unsigned long size_in_bytes(unsigned int order)
+{
+	return (1 << order) << PAGE_SHIFT;
+}
+
 static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 {
-	struct page *page;
+	struct page *page = NULL;
 	struct kmem_cache_order_objects oo = s->oo;
 	gfp_t alloc_gfp;
+	unsigned int memcg_allowed = oo_order(oo);
 
 	flags &= gfp_allowed_mask;
 
@@ -1296,13 +1302,29 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 
 	flags |= s->allocflags;
 
-	/*
-	 * Let the initial higher-order allocation fail under memory pressure
-	 * so we fall-back to the minimum order allocation.
-	 */
-	alloc_gfp = (flags | __GFP_NOWARN | __GFP_NORETRY) & ~__GFP_NOFAIL;
+	memcg_allowed = oo_order(oo);
+	if (!mem_cgroup_charge_slab(s, flags, size_in_bytes(memcg_allowed))) {
+
+		memcg_allowed = oo_order(s->min);
+		if (!mem_cgroup_charge_slab(s, flags,
+					    size_in_bytes(memcg_allowed))) {
+			if (flags & __GFP_WAIT)
+				local_irq_disable();
+			return NULL;
+		}
+	}
+
+	if (memcg_allowed == oo_order(oo)) {
+		/*
+		 * Let the initial higher-order allocation fail under memory
+		 * pressure so we fall-back to the minimum order allocation.
+		 */
+		alloc_gfp = (flags | __GFP_NOWARN | __GFP_NORETRY) &
+			     ~__GFP_NOFAIL;
+
+		page = alloc_slab_page(alloc_gfp, node, oo);
+	}
 
-	page = alloc_slab_page(alloc_gfp, node, oo);
 	if (unlikely(!page)) {
 		oo = s->min;
 		/*
@@ -1313,13 +1335,23 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 
 		if (page)
 			stat(s, ORDER_FALLBACK);
+		/*
+		 * We reserved more than we used, time to give it back
+		 */
+		if (page && memcg_allowed != oo_order(oo)) {
+			unsigned long delta;
+			delta = memcg_allowed - oo_order(oo);
+			mem_cgroup_uncharge_slab(s, size_in_bytes(delta));
+		}
 	}
 
 	if (flags & __GFP_WAIT)
 		local_irq_disable();
 
-	if (!page)
+	if (!page) {
+		mem_cgroup_uncharge_slab(s, size_in_bytes(memcg_allowed));
 		return NULL;
+	}
 
 	if (kmemcheck_enabled
 		&& !(s->flags & (SLAB_NOTRACK | DEBUG_DEFAULT_FLAGS))) {
@@ -1393,6 +1425,24 @@ out:
 	return page;
 }
 
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+static unsigned long slab_nr_pages(struct kmem_cache *s)
+{
+	int node;
+	unsigned long nr_slabs = 0;
+
+	for_each_online_node(node) {
+		struct kmem_cache_node *n = get_node(s, node);
+
+		if (!n)
+			continue;
+		nr_slabs += atomic_long_read(&n->nr_slabs);
+	}
+
+	return nr_slabs << oo_order(s->oo);
+}
+#endif
+
 static void __free_slab(struct kmem_cache *s, struct page *page)
 {
 	int order = compound_order(page);
@@ -1419,6 +1469,12 @@ static void __free_slab(struct kmem_cache *s, struct page *page)
 	if (current->reclaim_state)
 		current->reclaim_state->reclaimed_slab += pages;
 	__free_pages(page, order);
+
+	mem_cgroup_uncharge_slab(s, (1 << order) << PAGE_SHIFT);
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+	if (s->memcg_params.memcg && (slab_nr_pages(s) == 0))
+		mem_cgroup_destroy_cache(s);
+#endif
 }
 
 #define need_reserve_slab_rcu						\
@@ -2300,8 +2356,9 @@ new_slab:
  *
  * Otherwise we can simply pick the next object from the lockless free list.
  */
-static __always_inline void *slab_alloc(struct kmem_cache *s,
-		gfp_t gfpflags, int node, unsigned long addr)
+static __always_inline void *slab_alloc_base(struct kmem_cache *s,
+					     gfp_t gfpflags, int node,
+					     unsigned long addr)
 {
 	void **object;
 	struct kmem_cache_cpu *c;
@@ -2369,6 +2426,24 @@ redo:
 	return object;
 }
 
+static __always_inline void *slab_alloc(struct kmem_cache *s,
+		gfp_t gfpflags, int node, unsigned long addr)
+{
+
+	if (slab_pre_alloc_hook(s, gfpflags))
+		return NULL;
+
+	if (in_interrupt() || (current == NULL) || (gfpflags & __GFP_NOFAIL))
+		goto kernel_alloc;
+
+	rcu_read_lock();
+	s = mem_cgroup_get_kmem_cache(s, gfpflags);
+	rcu_read_unlock();
+
+kernel_alloc:
+	return slab_alloc_base(s, gfpflags, node, addr);
+}
+
 void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags)
 {
 	void *ret = slab_alloc(s, gfpflags, NUMA_NO_NODE, _RET_IP_);
@@ -3194,6 +3269,13 @@ void kmem_cache_destroy(struct kmem_cache *s)
 	s->refcount--;
 	if (!s->refcount) {
 		list_del(&s->list);
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+		/* Not a memcg cache */
+		if (s->memcg_params.id != -1) {
+			mem_cgroup_release_cache(s);
+			mem_cgroup_flush_cache_create_queue();
+		}
+#endif
 		up_write(&slub_lock);
 		if (kmem_cache_close(s)) {
 			printk(KERN_ERR "SLUB %s: %s called for cache that "
@@ -3273,6 +3355,7 @@ static struct kmem_cache *__init create_kmalloc_cache(const char *name,
 		goto panic;
 
 	list_add(&s->list, &slab_caches);
+	mem_cgroup_register_cache(NULL, s);
 	return s;
 
 panic:
@@ -3364,15 +3447,21 @@ void *kmalloc_no_account(size_t size, gfp_t flags)
 	struct kmem_cache *s;
 	void *ret;
 
-	if (unlikely(size > SLUB_MAX_SIZE))
-		return kmalloc_large(size, flags);
+	if (unlikely(size > SLUB_MAX_SIZE)) {
+		unsigned int order = get_order(size);
+		ret = kmalloc_order_base(size, flags, order);
+#ifdef CONFIG_TRACING
+		trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags);
+#endif
+		return ret;
+	}
 
 	s = get_slab(size, flags);
 
 	if (unlikely(ZERO_OR_NULL_PTR(s)))
 		return s;
 
-	ret = slab_alloc(s, flags, NUMA_NO_NODE, _RET_IP_);
+	ret = slab_alloc_base(s, flags, NUMA_NO_NODE, _RET_IP_);
 
 	trace_kmalloc(_RET_IP_, ret, size, s->size, flags);
 
@@ -3387,10 +3476,17 @@ static void *kmalloc_large_node(size_t size, gfp_t flags, int node)
 	void *ptr = NULL;
 
 	flags |= __GFP_COMP | __GFP_NOTRACK;
+
+	if (!mem_cgroup_charge_kmem(flags, size))
+		goto out;
+
 	page = alloc_pages_node(node, flags, get_order(size));
 	if (page)
 		ptr = page_address(page);
+	else
+		mem_cgroup_uncharge_kmem(size);
 
+out:
 	kmemleak_alloc(ptr, size, 1, flags);
 	return ptr;
 }
@@ -3938,8 +4034,10 @@ static struct kmem_cache *find_mergeable(struct mem_cgroup *memcg, size_t size,
 		if (s->size - size >= sizeof(void *))
 			continue;
 
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
 		if (memcg && s->memcg_params.memcg != memcg)
 			continue;
+#endif
 
 		return s;
 	}
-- 
1.7.7.6

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