[PATCH v2 07/21] mm/slab: remove CONFIG_SLAB code from slab common code

Vlastimil Babka
2023-11-20T18:34:42Z

In slab_common.c and slab.h headers, we can now remove all code behind
CONFIG_SLAB and CONFIG_DEBUG_SLAB ifdefs, and remove all CONFIG_SLUB
ifdefs.

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
include/linux/slab.h | 14 ++---------
mm/slab.h | 69 ++++------------------------------------------------
mm/slab_common.c | 22 ++---------------
3 files changed, 9 insertions(+), 96 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 34e43cddc520..b2015d0e01ad 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -24,7 +24,7 @@

/*
* Flags to pass to kmem_cache_create().
- * The ones marked DEBUG are only valid if CONFIG_DEBUG_SLAB is set.
+ * The ones marked DEBUG need CONFIG_SLUB_DEBUG enabled, otherwise are no-op
*/
/* DEBUG: Perform (expensive) checks on alloc/free */
#define SLAB_CONSISTENCY_CHECKS ((slab_flags_t __force)0x00000100U)
@@ -302,25 +302,15 @@ static inline unsigned int arch_slab_minalign(void)
* Kmalloc array related definitions
*/

-#ifdef CONFIG_SLAB
/*
- * SLAB and SLUB directly allocates requests fitting in to an order-1 page
+ * SLUB directly allocates requests fitting in to an order-1 page
* (PAGE_SIZE*2). Larger requests are passed to the page allocator.
*/
#define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 1)
#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT)
#ifndef KMALLOC_SHIFT_LOW
-#define KMALLOC_SHIFT_LOW 5
-#endif
-#endif
-
-#ifdef CONFIG_SLUB
-#define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 1)
-#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT)
-#ifndef KMALLOC_SHIFT_LOW
#define KMALLOC_SHIFT_LOW 3
#endif
-#endif

/* Maximum allocatable size */
#define KMALLOC_MAX_SIZE (1UL << KMALLOC_SHIFT_MAX)
diff --git a/mm/slab.h b/mm/slab.h
index 3d07fb428393..014c36ea51fa 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -42,21 +42,6 @@ typedef union {
struct slab {
unsigned long __page_flags;

-#if defined(CONFIG_SLAB)
-
- struct kmem_cache *slab_cache;
- union {
- struct {
- struct list_head slab_list;
- void *freelist; /* array of free object indexes */
- void *s_mem; /* first object */
- };
- struct rcu_head rcu_head;
- };
- unsigned int active;
-
-#elif defined(CONFIG_SLUB)
-
struct kmem_cache *slab_cache;
union {
struct {
@@ -91,10 +76,6 @@ struct slab {
};
unsigned int __unused;

-#else
-#error "Unexpected slab allocator configured"
-#endif
-
atomic_t __page_refcount;
#ifdef CONFIG_MEMCG
unsigned long memcg_data;
@@ -111,7 +92,7 @@ SLAB_MATCH(memcg_data, memcg_data);
#endif
#undef SLAB_MATCH
static_assert(sizeof(struct slab) <= sizeof(struct page));
-#if defined(system_has_freelist_aba) && defined(CONFIG_SLUB)
+#if defined(system_has_freelist_aba)
static_assert(IS_ALIGNED(offsetof(struct slab, freelist), sizeof(freelist_aba_t)));
#endif

@@ -228,13 +209,7 @@ static inline size_t slab_size(const struct slab *slab)
return PAGE_SIZE << slab_order(slab);
}

-#ifdef CONFIG_SLAB
-#include <linux/slab_def.h>
-#endif
-
-#ifdef CONFIG_SLUB
#include <linux/slub_def.h>
-#endif

#include <linux/memcontrol.h>
#include <linux/fault-inject.h>
@@ -320,26 +295,16 @@ static inline bool is_kmalloc_cache(struct kmem_cache *s)
SLAB_CACHE_DMA32 | SLAB_PANIC | \
SLAB_TYPESAFE_BY_RCU | SLAB_DEBUG_OBJECTS )

-#if defined(CONFIG_DEBUG_SLAB)
-#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
-#elif defined(CONFIG_SLUB_DEBUG)
+#ifdef CONFIG_SLUB_DEBUG
#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
SLAB_TRACE | SLAB_CONSISTENCY_CHECKS)
#else
#define SLAB_DEBUG_FLAGS (0)
#endif

-#if defined(CONFIG_SLAB)
-#define SLAB_CACHE_FLAGS (SLAB_MEM_SPREAD | SLAB_NOLEAKTRACE | \
- SLAB_RECLAIM_ACCOUNT | SLAB_TEMPORARY | \
- SLAB_ACCOUNT | SLAB_NO_MERGE)
-#elif defined(CONFIG_SLUB)
#define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE | SLAB_RECLAIM_ACCOUNT | \
SLAB_TEMPORARY | SLAB_ACCOUNT | \
SLAB_NO_USER_FLAGS | SLAB_KMALLOC | SLAB_NO_MERGE)
-#else
-#define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE)
-#endif

/* Common flags available with current configuration */
#define CACHE_CREATE_MASK (SLAB_CORE_FLAGS | SLAB_DEBUG_FLAGS | SLAB_CACHE_FLAGS)
@@ -672,18 +637,14 @@ size_t __ksize(const void *objp);

static inline size_t slab_ksize(const struct kmem_cache *s)
{
-#ifndef CONFIG_SLUB
- return s->object_size;
-
-#else /* CONFIG_SLUB */
-# ifdef CONFIG_SLUB_DEBUG
+#ifdef CONFIG_SLUB_DEBUG
/*
* Debugging requires use of the padding between object
* and whatever may come after it.
*/
if (s->flags & (SLAB_RED_ZONE | SLAB_POISON))
return s->object_size;
-# endif
+#endif
if (s->flags & SLAB_KASAN)
return s->object_size;
/*
@@ -697,7 +658,6 @@ static inline size_t slab_ksize(const struct kmem_cache *s)
* Else we can use all the padding etc for the allocation
*/
return s->size;
-#endif
}

static inline struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s,
@@ -775,23 +735,6 @@ static inline void slab_post_alloc_hook(struct kmem_cache *s,
* The slab lists for all objects.
*/
struct kmem_cache_node {
-#ifdef CONFIG_SLAB
- raw_spinlock_t list_lock;
- struct list_head slabs_partial; /* partial list first, better asm code */
- struct list_head slabs_full;
- struct list_head slabs_free;
- unsigned long total_slabs; /* length of all slab lists */
- unsigned long free_slabs; /* length of free slab list only */
- unsigned long free_objects;
- unsigned int free_limit;
- unsigned int colour_next; /* Per-node cache coloring */
- struct array_cache *shared; /* shared per node */
- struct alien_cache **alien; /* on other nodes */
- unsigned long next_reap; /* updated without locking */
- int free_touched; /* updated without locking */
-#endif
-
-#ifdef CONFIG_SLUB
spinlock_t list_lock;
unsigned long nr_partial;
struct list_head partial;
@@ -800,8 +743,6 @@ struct kmem_cache_node {
atomic_long_t total_objects;
struct list_head full;
#endif
-#endif
-
};

static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
@@ -818,7 +759,7 @@ static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
if ((__n = get_node(__s, __node)))

-#if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)
+#ifdef CONFIG_SLUB_DEBUG
void dump_unreclaimable_slab(void);
#else
static inline void dump_unreclaimable_slab(void)
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 8d431193c273..63b8411db7ce 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -71,10 +71,8 @@ static int __init setup_slab_merge(char *str)
return 1;
}

-#ifdef CONFIG_SLUB
__setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0);
__setup_param("slub_merge", slub_merge, setup_slab_merge, 0);
-#endif

__setup("slab_nomerge", setup_slab_nomerge);
__setup("slab_merge", setup_slab_merge);
@@ -197,10 +195,6 @@ struct kmem_cache *find_mergeable(unsigned int size, unsigned int align,
if (s->size - size >= sizeof(void *))
continue;

- if (IS_ENABLED(CONFIG_SLAB) && align &&
- (align > s->align || s->align % align))
- continue;
-
return s;
}
return NULL;
@@ -1222,12 +1216,8 @@ void cache_random_seq_destroy(struct kmem_cache *cachep)
}
#endif /* CONFIG_SLAB_FREELIST_RANDOM */

-#if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)
-#ifdef CONFIG_SLAB
-#define SLABINFO_RIGHTS (0600)
-#else
+#ifdef CONFIG_SLUB_DEBUG
#define SLABINFO_RIGHTS (0400)
-#endif

static void print_slabinfo_header(struct seq_file *m)
{
@@ -1235,18 +1225,10 @@ static void print_slabinfo_header(struct seq_file *m)
* Output format version, so at least we can change it
* without _too_ many complaints.
*/
-#ifdef CONFIG_DEBUG_SLAB
- seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
-#else
seq_puts(m, "slabinfo - version: 2.1\n");
-#endif
seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
-#ifdef CONFIG_DEBUG_SLAB
- seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
- seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
-#endif
seq_putc(m, '\n');
}

@@ -1370,7 +1352,7 @@ static int __init slab_proc_init(void)
}
module_init(slab_proc_init);

-#endif /* CONFIG_SLAB || CONFIG_SLUB_DEBUG */
+#endif /* CONFIG_SLUB_DEBUG */

static __always_inline __realloc_size(2) void *
__do_krealloc(const void *p, size_t new_size, gfp_t flags)

--
2.42.1