[PATCH v2 4/6] slab: add SLAB_ACCOUNT flag

From: Vladimir Davydov <vdavydov@virtuozzo.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>, Tejun Heo <tj@kernel.org>,
	Greg Thelen <gthelen@google.com>,
	Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>, <linux-mm@kvack.org>,
	<cgroups@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: [PATCH v2 4/6] slab: add SLAB_ACCOUNT flag
Date: Tue, 10 Nov 2015 21:34:05 +0300	[thread overview]
Message-ID: <1ce23e932ea53f47a3376de90b21a9db8293bd6c.1447172835.git.vdavydov@virtuozzo.com> (raw)
In-Reply-To: <cover.1447172835.git.vdavydov@virtuozzo.com>

Currently, if we want to account all objects of a particular kmem cache,
we have to pass __GFP_ACCOUNT to each kmem_cache_alloc call, which is
inconvenient. This patch introduces SLAB_ACCOUNT flag which if passed to
kmem_cache_create will force accounting for every allocation from this
cache even if __GFP_ACCOUNT is not passed.

This patch does not make any of the existing caches use this flag - it
will be done later in the series.

Note, a cache with SLAB_ACCOUNT cannot be merged with a cache w/o
SLAB_ACCOUNT, i.e. using this flag will probably reduce the number of
merged slabs even if kmem accounting is not used (only compiled in).

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
---
 include/linux/memcontrol.h | 15 +++++++--------
 include/linux/slab.h       |  5 +++++
 mm/memcontrol.c            |  8 +++++++-
 mm/slab.h                  |  5 +++--
 mm/slab_common.c           |  3 ++-
 mm/slub.c                  |  2 ++
 6 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index c9d9a8e7b45f..5c97265c1c6e 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -766,15 +766,13 @@ static inline int memcg_cache_id(struct mem_cgroup *memcg)
 	return memcg ? memcg->kmemcg_id : -1;
 }
 
-struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep);
+struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp);
 void __memcg_kmem_put_cache(struct kmem_cache *cachep);
 
-static inline bool __memcg_kmem_bypass(gfp_t gfp)
+static inline bool __memcg_kmem_bypass(void)
 {
 	if (!memcg_kmem_enabled())
 		return true;
-	if (!(gfp & __GFP_ACCOUNT))
-		return true;
 	if (in_interrupt() || (!current->mm) || (current->flags & PF_KTHREAD))
 		return true;
 	return false;
@@ -791,7 +789,9 @@ static inline bool __memcg_kmem_bypass(gfp_t gfp)
 static __always_inline int memcg_kmem_charge(struct page *page,
 					     gfp_t gfp, int order)
 {
-	if (__memcg_kmem_bypass(gfp))
+	if (__memcg_kmem_bypass())
+		return 0;
+	if (!(gfp & __GFP_ACCOUNT))
 		return 0;
 	return __memcg_kmem_charge(page, gfp, order);
 }
@@ -810,16 +810,15 @@ static __always_inline void memcg_kmem_uncharge(struct page *page, int order)
 /**
  * memcg_kmem_get_cache: selects the correct per-memcg cache for allocation
  * @cachep: the original global kmem cache
- * @gfp: allocation flags.
  *
  * All memory allocated from a per-memcg cache is charged to the owner memcg.
  */
 static __always_inline struct kmem_cache *
 memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
 {
-	if (__memcg_kmem_bypass(gfp))
+	if (__memcg_kmem_bypass())
 		return cachep;
-	return __memcg_kmem_get_cache(cachep);
+	return __memcg_kmem_get_cache(cachep, gfp);
 }
 
 static __always_inline void memcg_kmem_put_cache(struct kmem_cache *cachep)
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 7c82e3b307a3..20168c6ffe89 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -86,6 +86,11 @@
 #else
 # define SLAB_FAILSLAB		0x00000000UL
 #endif
+#ifdef CONFIG_MEMCG_KMEM
+# define SLAB_ACCOUNT		0x04000000UL	/* Account to memcg */
+#else
+# define SLAB_ACCOUNT		0x00000000UL
+#endif
 
 /* The following flags affect the page allocator grouping pages by mobility */
 #define SLAB_RECLAIM_ACCOUNT	0x00020000UL		/* Objects are reclaimable */
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index bc502e590366..06e4f538e38e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2332,7 +2332,7 @@ static void memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg,
  * Can't be called in interrupt context or from kernel threads.
  * This function needs to be called with rcu_read_lock() held.
  */
-struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep)
+struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
 {
 	struct mem_cgroup *memcg;
 	struct kmem_cache *memcg_cachep;
@@ -2340,6 +2340,12 @@ struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep)
 
 	VM_BUG_ON(!is_root_cache(cachep));
 
+	if (cachep->flags & SLAB_ACCOUNT)
+		gfp |= __GFP_ACCOUNT;
+
+	if (!(gfp & __GFP_ACCOUNT))
+		return cachep;
+
 	if (current->memcg_kmem_skip_account)
 		return cachep;
 
diff --git a/mm/slab.h b/mm/slab.h
index 27492eb678f7..2778de8673bd 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -128,10 +128,11 @@ static inline unsigned long kmem_cache_flags(unsigned long object_size,
 
 #if defined(CONFIG_SLAB)
 #define SLAB_CACHE_FLAGS (SLAB_MEM_SPREAD | SLAB_NOLEAKTRACE | \
-			  SLAB_RECLAIM_ACCOUNT | SLAB_TEMPORARY | SLAB_NOTRACK)
+			  SLAB_RECLAIM_ACCOUNT | SLAB_TEMPORARY | \
+			  SLAB_NOTRACK | SLAB_ACCOUNT)
 #elif defined(CONFIG_SLUB)
 #define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE | SLAB_RECLAIM_ACCOUNT | \
-			  SLAB_TEMPORARY | SLAB_NOTRACK)
+			  SLAB_TEMPORARY | SLAB_NOTRACK | SLAB_ACCOUNT)
 #else
 #define SLAB_CACHE_FLAGS (0)
 #endif
diff --git a/mm/slab_common.c b/mm/slab_common.c
index d88e97c10a2e..698b2c97b22b 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -37,7 +37,8 @@ struct kmem_cache *kmem_cache;
 		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \
 		SLAB_FAILSLAB)
 
-#define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | SLAB_NOTRACK)
+#define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
+			 SLAB_NOTRACK | SLAB_ACCOUNT)
 
 /*
  * Merge control. If this is set then no merging of slab caches will occur.
diff --git a/mm/slub.c b/mm/slub.c
index 75a5fa92ac2a..b037cea9cfeb 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5247,6 +5247,8 @@ static char *create_unique_id(struct kmem_cache *s)
 		*p++ = 'F';
 	if (!(s->flags & SLAB_NOTRACK))
 		*p++ = 't';
+	if (s->flags & SLAB_ACCOUNT)
+		*p++ = 'A';
 	if (p != name + 1)
 		*p++ = '-';
 	p += sprintf(p, "%07d", s->size);
-- 
2.1.4

