mm/slab: simplify create_kmalloc_cache() args and make it static

In the slab variant of kmem_cache_init(), call new_kmalloc_cache() instead
of initialising the kmalloc_caches array directly.  With this,
create_kmalloc_cache() is now only called from new_kmalloc_cache() in the
same file, so make it static.  In addition, the useroffset argument is
always 0 while usersize is the same as size.  Remove them.

Link: https://lkml.kernel.org/r/20230612153201.554742-4-catalin.marinas@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Isaac J. Manjarres <isaacmanjarres@google.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jerry Snitselaar <jsnitsel@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Mike Snitzer <snitzer@kernel.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/slab.c

@@ -1240,11 +1240,7 @@ void __init kmem_cache_init(void)
 	 * Initialize the caches that provide memory for the  kmem_cache_node
 	 * structures first.  Without this, further allocations will bug.
 	 */
-	kmalloc_caches[KMALLOC_NORMAL][INDEX_NODE] = create_kmalloc_cache(
-				kmalloc_info[INDEX_NODE].name[KMALLOC_NORMAL],
-				kmalloc_info[INDEX_NODE].size,
-				ARCH_KMALLOC_FLAGS, 0,
-				kmalloc_info[INDEX_NODE].size);
+	new_kmalloc_cache(INDEX_NODE, KMALLOC_NORMAL, ARCH_KMALLOC_FLAGS);
 	slab_state = PARTIAL_NODE;
 	setup_kmalloc_cache_index_table();
 

mm/slab.h

@@ -255,9 +255,8 @@ gfp_t kmalloc_fix_flags(gfp_t flags);
 /* Functions provided by the slab allocators */
 int __kmem_cache_create(struct kmem_cache *, slab_flags_t flags);
 
-struct kmem_cache *create_kmalloc_cache(const char *name, unsigned int size,
-			slab_flags_t flags, unsigned int useroffset,
-			unsigned int usersize);
+void __init new_kmalloc_cache(int idx, enum kmalloc_cache_type type,
+			      slab_flags_t flags);
 extern void create_boot_cache(struct kmem_cache *, const char *name,
 			unsigned int size, slab_flags_t flags,
 			unsigned int useroffset, unsigned int usersize);

mm/slab_common.c

@@ -658,17 +658,16 @@ void __init create_boot_cache(struct kmem_cache *s, const char *name,
 	s->refcount = -1;	/* Exempt from merging for now */
 }
 
-struct kmem_cache *__init create_kmalloc_cache(const char *name,
-		unsigned int size, slab_flags_t flags,
-		unsigned int useroffset, unsigned int usersize)
+static struct kmem_cache *__init create_kmalloc_cache(const char *name,
+						      unsigned int size,
+						      slab_flags_t flags)
 {
 	struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
 
 	if (!s)
 		panic("Out of memory when creating slab %s\n", name);
 
-	create_boot_cache(s, name, size, flags | SLAB_KMALLOC, useroffset,
-								usersize);
+	create_boot_cache(s, name, size, flags | SLAB_KMALLOC, 0, size);
 	list_add(&s->list, &slab_caches);
 	s->refcount = 1;
 	return s;
@@ -863,7 +862,7 @@ void __init setup_kmalloc_cache_index_table(void)
 	}
 }
 
-static void __init
+void __init
 new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags)
 {
 	if ((KMALLOC_RECLAIM != KMALLOC_NORMAL) && (type == KMALLOC_RECLAIM)) {
@@ -880,8 +879,7 @@ new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags)
 
 	kmalloc_caches[type][idx] = create_kmalloc_cache(
 					kmalloc_info[idx].name[type],
-					kmalloc_info[idx].size, flags, 0,
-					kmalloc_info[idx].size);
+					kmalloc_info[idx].size, flags);
 
 	/*
 	 * If CONFIG_MEMCG_KMEM is enabled, disable cache merging for