mm/slab: remove CONFIG_SLOB code from slab common code

CONFIG_SLOB has been removed from Kconfig. Remove code and #ifdef's
specific to SLOB in the slab headers and common code.

Signed-off-by: Vlastimil Babka <[e-mail]>
Reviewed-by: Hyeonggon Yoo <[e-mail]>
Acked-by: Lorenzo Stoakes <[e-mail]>
Acked-by: Mike Rapoport (IBM) <[e-mail]>

include/linux/slab.h

···
 #endif
 #endif
 
-#ifdef CONFIG_SLOB
-/*
- * SLOB passes all requests larger than one page to the page allocator.
- * No kmalloc array is necessary since objects of different sizes can
- * be allocated from the same page.
- */
-#define KMALLOC_SHIFT_HIGH	PAGE_SHIFT
-#define KMALLOC_SHIFT_MAX	(MAX_ORDER + PAGE_SHIFT - 1)
-#ifndef KMALLOC_SHIFT_LOW
-#define KMALLOC_SHIFT_LOW	3
-#endif
-#endif
-
 /* Maximum allocatable size */
 #define KMALLOC_MAX_SIZE	(1UL << KMALLOC_SHIFT_MAX)
 /* Maximum size for which we actually use a slab cache */
···
 	NR_KMALLOC_TYPES
 };
 
-#ifndef CONFIG_SLOB
 extern struct kmem_cache *
 kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1];
 
···
 }
 static_assert(PAGE_SHIFT <= 20);
 #define kmalloc_index(s) __kmalloc_index(s, true)
-#endif /* !CONFIG_SLOB */
 
 void *__kmalloc(size_t size, gfp_t flags) __assume_kmalloc_alignment __alloc_size(1);
 
···
 void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p);
 int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, void **p);
 
-/*
- * Caller must not use kfree_bulk() on memory not originally allocated
- * by kmalloc(), because the SLOB allocator cannot handle this.
- */
 static __always_inline void kfree_bulk(size_t size, void **p)
 {
 	kmem_cache_free_bulk(NULL, size, p);
···
  *	Try really hard to succeed the allocation but fail
  *	eventually.
  */
-#ifndef CONFIG_SLOB
 static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
 {
 	if (__builtin_constant_p(size) && size) {
···
 	}
 	return __kmalloc(size, flags);
 }
-#else
-static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
-{
-	if (__builtin_constant_p(size) && size > KMALLOC_MAX_CACHE_SIZE)
-		return kmalloc_large(size, flags);
 
-	return __kmalloc(size, flags);
-}
-#endif
-
-#ifndef CONFIG_SLOB
 static __always_inline __alloc_size(1) void *kmalloc_node(size_t size, gfp_t flags, int node)
 {
 	if (__builtin_constant_p(size) && size) {
···
 	}
 	return __kmalloc_node(size, flags, node);
 }
-#else
-static __always_inline __alloc_size(1) void *kmalloc_node(size_t size, gfp_t flags, int node)
-{
-	if (__builtin_constant_p(size) && size > KMALLOC_MAX_CACHE_SIZE)
-		return kmalloc_large_node(size, flags, node);
-
-	return __kmalloc_node(size, flags, node);
-}
-#endif
 
 /**
  * kmalloc_array - allocate memory for an array.

mm/slab.h

···
 	};
 	unsigned int __unused;
 
-#elif defined(CONFIG_SLOB)
-
-	struct list_head slab_list;
-	void *__unused_1;
-	void *freelist;		/* first free block */
-	long units;
-	unsigned int __unused_2;
-
 #else
 #error "Unexpected slab allocator configured"
 #endif
···
 #define SLAB_MATCH(pg, sl)						\
 	static_assert(offsetof(struct page, pg) == offsetof(struct slab, sl))
 SLAB_MATCH(flags, __page_flags);
-#ifndef CONFIG_SLOB
 SLAB_MATCH(compound_head, slab_cache);	/* Ensure bit 0 is clear */
-#else
-SLAB_MATCH(compound_head, slab_list);	/* Ensure bit 0 is clear */
-#endif
 SLAB_MATCH(_refcount, __page_refcount);
 #ifdef CONFIG_MEMCG
 SLAB_MATCH(memcg_data, memcg_data);
···
 	return PAGE_SIZE << slab_order(slab);
 }
 
-#ifdef CONFIG_SLOB
-/*
- * Common fields provided in kmem_cache by all slab allocators
- * This struct is either used directly by the allocator (SLOB)
- * or the allocator must include definitions for all fields
- * provided in kmem_cache_common in their definition of kmem_cache.
- *
- * Once we can do anonymous structs (C11 standard) we could put a
- * anonymous struct definition in these allocators so that the
- * separate allocations in the kmem_cache structure of SLAB and
- * SLUB is no longer needed.
- */
-struct kmem_cache {
-	unsigned int object_size;/* The original size of the object */
-	unsigned int size;	/* The aligned/padded/added on size  */
-	unsigned int align;	/* Alignment as calculated */
-	slab_flags_t flags;	/* Active flags on the slab */
-	const char *name;	/* Slab name for sysfs */
-	int refcount;		/* Use counter */
-	void (*ctor)(void *);	/* Called on object slot creation */
-	struct list_head list;	/* List of all slab caches on the system */
-};
-
-#endif /* CONFIG_SLOB */
-
 #ifdef CONFIG_SLAB
 #include <linux/slab_def.h>
 #endif
···
 	unsigned int size;
 } kmalloc_info[];
 
-#ifndef CONFIG_SLOB
 /* Kmalloc array related functions */
 void setup_kmalloc_cache_index_table(void);
 void create_kmalloc_caches(slab_flags_t);
···
 			      int node, size_t orig_size,
 			      unsigned long caller);
 void __kmem_cache_free(struct kmem_cache *s, void *x, unsigned long caller);
-#endif
 
 gfp_t kmalloc_fix_flags(gfp_t flags);
 
···
 int slab_unmergeable(struct kmem_cache *s);
 struct kmem_cache *find_mergeable(unsigned size, unsigned align,
 		slab_flags_t flags, const char *name, void (*ctor)(void *));
-#ifndef CONFIG_SLOB
 struct kmem_cache *
 __kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
 		   slab_flags_t flags, void (*ctor)(void *));
 
 slab_flags_t kmem_cache_flags(unsigned int object_size,
 	slab_flags_t flags, const char *name);
-#else
-static inline struct kmem_cache *
-__kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
-		   slab_flags_t flags, void (*ctor)(void *))
-{ return NULL; }
-
-static inline slab_flags_t kmem_cache_flags(unsigned int object_size,
-	slab_flags_t flags, const char *name)
-{
-	return flags;
-}
-#endif
 
 static inline bool is_kmalloc_cache(struct kmem_cache *s)
 {
-#ifndef CONFIG_SLOB
 	return (s->flags & SLAB_KMALLOC);
-#else
-	return false;
-#endif
 }
 
 /* Legal flag mask for kmem_cache_create(), for various configurations */
···
 }
 #endif /* CONFIG_MEMCG_KMEM */
 
-#ifndef CONFIG_SLOB
 static inline struct kmem_cache *virt_to_cache(const void *obj)
 {
 	struct slab *slab;
···
 }
 
 void free_large_kmalloc(struct folio *folio, void *object);
-
-#endif /* CONFIG_SLOB */
 
 size_t __ksize(const void *objp);
 
···
 	memcg_slab_post_alloc_hook(s, objcg, flags, size, p);
 }
 
-#ifndef CONFIG_SLOB
 /*
  * The slab lists for all objects.
  */
···
 	for (__node = 0; __node < nr_node_ids; __node++) \
 		 if ((__n = get_node(__s, __node)))
 
-#endif
 
 #if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)
 void dump_unreclaimable_slab(void);

mm/slab_common.c

···
 EXPORT_SYMBOL_GPL(kmem_dump_obj);
 #endif
 
-#ifndef CONFIG_SLOB
 /* Create a cache during boot when no slab services are available yet */
 void __init create_boot_cache(struct kmem_cache *s, const char *name,
 		unsigned int size, slab_flags_t flags,
···
 	return ret;
 }
 EXPORT_SYMBOL(kmalloc_node_trace);
-#endif /* !CONFIG_SLOB */
 
 gfp_t kmalloc_fix_flags(gfp_t flags)
 {