[PATCH 5/7] mm/slab: remove CONFIG_SLOB code from slab common code

Vlastimil Babka
2023-03-10T10:32:23Z

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 <vbabka@suse.cz>
---
include/linux/slab.h | 39 ----------------------------
mm/slab.h | 61 --------------------------------------------
mm/slab_common.c | 2 --
3 files changed, 102 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 45af70315a94..7f645a4c1298 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -298,19 +298,6 @@ static inline unsigned int arch_slab_minalign(void)
#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 */
@@ -366,7 +353,6 @@ enum kmalloc_cache_type {
NR_KMALLOC_TYPES
};

-#ifndef CONFIG_SLOB
extern struct kmem_cache *
kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1];

@@ -458,7 +444,6 @@ static __always_inline unsigned int __kmalloc_index(size_t size,
}
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);

@@ -487,10 +472,6 @@ void kmem_cache_free(struct kmem_cache *s, void *objp);
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);
@@ -567,7 +548,6 @@ void *kmalloc_large_node(size_t size, gfp_t flags, int node) __assume_page_align
* 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) {
@@ -583,17 +563,7 @@ static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
}
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) {
@@ -609,15 +579,6 @@ static __always_inline __alloc_size(1) void *kmalloc_node(size_t size, gfp_t fla
}
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.
diff --git a/mm/slab.h b/mm/slab.h
index 43966aa5fadf..399966b3ce52 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -51,14 +51,6 @@ struct slab {
};
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
@@ -72,11 +64,7 @@ struct slab {
#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);
@@ -200,31 +188,6 @@ static inline size_t slab_size(const struct slab *slab)
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
@@ -274,7 +237,6 @@ extern const struct kmalloc_info_struct {
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);
@@ -286,7 +248,6 @@ void *__kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags,
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);

@@ -303,33 +264,16 @@ extern void create_boot_cache(struct kmem_cache *, const char *name,
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 */
@@ -634,7 +578,6 @@ static inline void memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab,
}
#endif /* CONFIG_MEMCG_KMEM */

-#ifndef CONFIG_SLOB
static inline struct kmem_cache *virt_to_cache(const void *obj)
{
struct slab *slab;
@@ -684,8 +627,6 @@ static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)

void free_large_kmalloc(struct folio *folio, void *object);

-#endif /* CONFIG_SLOB */
-
size_t __ksize(const void *objp);

static inline size_t slab_ksize(const struct kmem_cache *s)
@@ -777,7 +718,6 @@ static inline void slab_post_alloc_hook(struct kmem_cache *s,
memcg_slab_post_alloc_hook(s, objcg, flags, size, p);
}

-#ifndef CONFIG_SLOB
/*
* The slab lists for all objects.
*/
@@ -824,7 +764,6 @@ static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
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);
diff --git a/mm/slab_common.c b/mm/slab_common.c
index bf4e777cfe90..1522693295f5 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -625,7 +625,6 @@ void kmem_dump_obj(void *object)
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,
@@ -1079,7 +1078,6 @@ void *kmalloc_node_trace(struct kmem_cache *s, gfp_t gfpflags,
return ret;
}
EXPORT_SYMBOL(kmalloc_node_trace);
-#endif /* !CONFIG_SLOB */

gfp_t kmalloc_fix_flags(gfp_t flags)
{
--
2.39.2