slab: infrastructure for bulk object allocation and freeing

Add the basic infrastructure for alloc/free operations on pointer arrays.
It includes a generic function in the common slab code that is used in
this infrastructure patch to create the unoptimized functionality for slab
bulk operations.

Allocators can then provide optimized allocation functions for situations
in which large numbers of objects are needed.  These optimization may
avoid taking locks repeatedly and bypass metadata creation if all objects
in slab pages can be used to provide the objects required.

Allocators can extend the skeletons provided and add their own code to the
bulk alloc and free functions.  They can keep the generic allocation and
freeing and just fall back to those if optimizations would not work (like
for example when debugging is on).

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

6 files changed, 82 insertions, 0 deletions

diff --git a/include/linux/slab.h b/include/linux/slab.h
index a99f0e5243e1..7e37d448ed91 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -290,6 +290,16 @@ void *__kmalloc(size_t size, gfp_t flags);
 void *kmem_cache_alloc(struct kmem_cache *, gfp_t flags);
 void kmem_cache_free(struct kmem_cache *, void *);
 
+/*
+ * Bulk allocation and freeing operations. These are accellerated in an
+ * allocator specific way to avoid taking locks repeatedly or building
+ * metadata structures unnecessarily.
+ *
+ * Note that interrupts must be enabled when calling these functions.
+ */
+void kmem_cache_free_bulk(struct kmem_cache *, size_t, void **);
+bool kmem_cache_alloc_bulk(struct kmem_cache *, gfp_t, size_t, void **);
+
 #ifdef CONFIG_NUMA
 void *__kmalloc_node(size_t size, gfp_t flags, int node);
 void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node);
diff --git a/mm/slab.c b/mm/slab.c
index bbd0b47dc6a9..60c936938b84 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3416,6 +3416,19 @@ void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
 }
 EXPORT_SYMBOL(kmem_cache_alloc);
 
+void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p)
+{
+	__kmem_cache_free_bulk(s, size, p);
+}
+EXPORT_SYMBOL(kmem_cache_free_bulk);
+
+bool kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
+								void **p)
+{
+	return __kmem_cache_alloc_bulk(s, flags, size, p);
+}
+EXPORT_SYMBOL(kmem_cache_alloc_bulk);
+
 #ifdef CONFIG_TRACING
 void *
 kmem_cache_alloc_trace(struct kmem_cache *cachep, gfp_t flags, size_t size)
diff --git a/mm/slab.h b/mm/slab.h
index 8da63e4e470f..88b55497738c 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -163,6 +163,15 @@ void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s);
 ssize_t slabinfo_write(struct file *file, const char __user *buffer,
 		       size_t count, loff_t *ppos);
 
+/*
+ * Generic implementation of bulk operations
+ * These are useful for situations in which the allocator cannot
+ * perform optimizations. In that case segments of the objecct listed
+ * may be allocated or freed using these operations.
+ */
+void __kmem_cache_free_bulk(struct kmem_cache *, size_t, void **);
+bool __kmem_cache_alloc_bulk(struct kmem_cache *, gfp_t, size_t, void **);
+
 #ifdef CONFIG_MEMCG_KMEM
 /*
  * Iterate over all memcg caches of the given root cache. The caller must hold
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 86831105a09f..c26829fe4e37 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -104,6 +104,29 @@ static inline int kmem_cache_sanity_check(const char *name, size_t size)
 }
 #endif
 
+void __kmem_cache_free_bulk(struct kmem_cache *s, size_t nr, void **p)
+{
+	size_t i;
+
+	for (i = 0; i < nr; i++)
+		kmem_cache_free(s, p[i]);
+}
+
+bool __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr,
+								void **p)
+{
+	size_t i;
+
+	for (i = 0; i < nr; i++) {
+		void *x = p[i] = kmem_cache_alloc(s, flags);
+		if (!x) {
+			__kmem_cache_free_bulk(s, i, p);
+			return false;
+		}
+	}
+	return true;
+}
+
 #ifdef CONFIG_MEMCG_KMEM
 void slab_init_memcg_params(struct kmem_cache *s)
 {
diff --git a/mm/slob.c b/mm/slob.c
index 4765f65019c7..165bbd3cd606 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -611,6 +611,19 @@ void kmem_cache_free(struct kmem_cache *c, void *b)
 }
 EXPORT_SYMBOL(kmem_cache_free);
 
+void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p)
+{
+	__kmem_cache_free_bulk(s, size, p);
+}
+EXPORT_SYMBOL(kmem_cache_free_bulk);
+
+bool kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
+								void **p)
+{
+	return __kmem_cache_alloc_bulk(s, flags, size, p);
+}
+EXPORT_SYMBOL(kmem_cache_alloc_bulk);
+
 int __kmem_cache_shutdown(struct kmem_cache *c)
 {
 	/* No way to check for remaining objects */
diff --git a/mm/slub.c b/mm/slub.c
index defd76f98648..3ca89ef9b7b0 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2750,6 +2750,20 @@ void kmem_cache_free(struct kmem_cache *s, void *x)
 }
 EXPORT_SYMBOL(kmem_cache_free);
 
+void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p)
+{
+	__kmem_cache_free_bulk(s, size, p);
+}
+EXPORT_SYMBOL(kmem_cache_free_bulk);
+
+bool kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
+								void **p)
+{
+	return __kmem_cache_alloc_bulk(s, flags, size, p);
+}
+EXPORT_SYMBOL(kmem_cache_alloc_bulk);
+
+
 /*
  * Object placement in a slab is made very easy because we always start at
  * offset 0. If we tune the size of the object to the alignment then we can