Commit cc61eb85 authored by Vlastimil Babka's avatar Vlastimil Babka
Browse files

mm, slab: use an enum to define SLAB_ cache creation flags 



The values of SLAB_ cache creation flags are defined by hand, which is
tedious and error-prone. Use an enum to assign the bit number and a
__SLAB_FLAG_BIT() macro to #define the final flags.

This renumbers the flag values, which is OK as they are only used
internally.

Also define a __SLAB_FLAG_UNUSED macro to assign value to flags disabled
by their respective config options in a unified and sparse-friendly way.

Reviewed-and-tested-by: default avatarXiongwei Song <xiongwei.song@windriver.com>
Reviewed-by: default avatarChengming Zhou <chengming.zhou@linux.dev>
Reviewed-by: default avatarRoman Gushchin <roman.gushchin@linux.dev>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
parent cdeeaaba

include/linux/slab.h

+67 −27
Original line number Diff line number Diff line
@@ -21,29 +21,69 @@ 
#include <linux/cleanup.h>

#include <linux/hash.h>



enum _slab_flag_bits {

	_SLAB_CONSISTENCY_CHECKS,

	_SLAB_RED_ZONE,

	_SLAB_POISON,

	_SLAB_KMALLOC,

	_SLAB_HWCACHE_ALIGN,

	_SLAB_CACHE_DMA,

	_SLAB_CACHE_DMA32,

	_SLAB_STORE_USER,

	_SLAB_PANIC,

	_SLAB_TYPESAFE_BY_RCU,

	_SLAB_TRACE,

#ifdef CONFIG_DEBUG_OBJECTS

	_SLAB_DEBUG_OBJECTS,

#endif

	_SLAB_NOLEAKTRACE,

	_SLAB_NO_MERGE,

#ifdef CONFIG_FAILSLAB

	_SLAB_FAILSLAB,

#endif

#ifdef CONFIG_MEMCG_KMEM

	_SLAB_ACCOUNT,

#endif

#ifdef CONFIG_KASAN_GENERIC

	_SLAB_KASAN,

#endif

	_SLAB_NO_USER_FLAGS,

#ifdef CONFIG_KFENCE

	_SLAB_SKIP_KFENCE,

#endif

#ifndef CONFIG_SLUB_TINY

	_SLAB_RECLAIM_ACCOUNT,

#endif

	_SLAB_OBJECT_POISON,

	_SLAB_CMPXCHG_DOUBLE,

	_SLAB_FLAGS_LAST_BIT

};



#define __SLAB_FLAG_BIT(nr)	((slab_flags_t __force)(1U << (nr)))

#define __SLAB_FLAG_UNUSED	((slab_flags_t __force)(0U))



/*

 * Flags to pass to kmem_cache_create().

 * 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)

#define SLAB_CONSISTENCY_CHECKS	__SLAB_FLAG_BIT(_SLAB_CONSISTENCY_CHECKS)

/* DEBUG: Red zone objs in a cache */

#define SLAB_RED_ZONE		((slab_flags_t __force)0x00000400U)

#define SLAB_RED_ZONE		__SLAB_FLAG_BIT(_SLAB_RED_ZONE)

/* DEBUG: Poison objects */

#define SLAB_POISON		((slab_flags_t __force)0x00000800U)

#define SLAB_POISON		__SLAB_FLAG_BIT(_SLAB_POISON)

/* Indicate a kmalloc slab */

#define SLAB_KMALLOC		((slab_flags_t __force)0x00001000U)

#define SLAB_KMALLOC		__SLAB_FLAG_BIT(_SLAB_KMALLOC)

/* Align objs on cache lines */

#define SLAB_HWCACHE_ALIGN	((slab_flags_t __force)0x00002000U)

#define SLAB_HWCACHE_ALIGN	__SLAB_FLAG_BIT(_SLAB_HWCACHE_ALIGN)

/* Use GFP_DMA memory */

#define SLAB_CACHE_DMA		((slab_flags_t __force)0x00004000U)

#define SLAB_CACHE_DMA		__SLAB_FLAG_BIT(_SLAB_CACHE_DMA)

/* Use GFP_DMA32 memory */

#define SLAB_CACHE_DMA32	((slab_flags_t __force)0x00008000U)

#define SLAB_CACHE_DMA32	__SLAB_FLAG_BIT(_SLAB_CACHE_DMA32)

/* DEBUG: Store the last owner for bug hunting */

#define SLAB_STORE_USER		((slab_flags_t __force)0x00010000U)

#define SLAB_STORE_USER		__SLAB_FLAG_BIT(_SLAB_STORE_USER)

/* Panic if kmem_cache_create() fails */

#define SLAB_PANIC		((slab_flags_t __force)0x00040000U)

#define SLAB_PANIC		__SLAB_FLAG_BIT(_SLAB_PANIC)

/*

 * SLAB_TYPESAFE_BY_RCU - **WARNING** READ THIS!

 *
@@ -95,19 +135,19 @@ 
 * Note that SLAB_TYPESAFE_BY_RCU was originally named SLAB_DESTROY_BY_RCU.

 */

/* Defer freeing slabs to RCU */

#define SLAB_TYPESAFE_BY_RCU	((slab_flags_t __force)0x00080000U)

#define SLAB_TYPESAFE_BY_RCU	__SLAB_FLAG_BIT(_SLAB_TYPESAFE_BY_RCU)

/* Trace allocations and frees */

#define SLAB_TRACE		((slab_flags_t __force)0x00200000U)

#define SLAB_TRACE		__SLAB_FLAG_BIT(_SLAB_TRACE)



/* Flag to prevent checks on free */

#ifdef CONFIG_DEBUG_OBJECTS

# define SLAB_DEBUG_OBJECTS	((slab_flags_t __force)0x00400000U)

# define SLAB_DEBUG_OBJECTS	__SLAB_FLAG_BIT(_SLAB_DEBUG_OBJECTS)

#else

# define SLAB_DEBUG_OBJECTS	0

# define SLAB_DEBUG_OBJECTS	__SLAB_FLAG_UNUSED

#endif



/* Avoid kmemleak tracing */

#define SLAB_NOLEAKTRACE	((slab_flags_t __force)0x00800000U)

#define SLAB_NOLEAKTRACE	__SLAB_FLAG_BIT(_SLAB_NOLEAKTRACE)



/*

 * Prevent merging with compatible kmem caches. This flag should be used
@@ -119,25 +159,25 @@ 
 * - performance critical caches, should be very rare and consulted with slab

 *   maintainers, and not used together with CONFIG_SLUB_TINY

 */

#define SLAB_NO_MERGE		((slab_flags_t __force)0x01000000U)

#define SLAB_NO_MERGE		__SLAB_FLAG_BIT(_SLAB_NO_MERGE)



/* Fault injection mark */

#ifdef CONFIG_FAILSLAB

# define SLAB_FAILSLAB		((slab_flags_t __force)0x02000000U)

# define SLAB_FAILSLAB		__SLAB_FLAG_BIT(_SLAB_FAILSLAB)

#else

# define SLAB_FAILSLAB		0

# define SLAB_FAILSLAB		__SLAB_FLAG_UNUSED

#endif

/* Account to memcg */

#ifdef CONFIG_MEMCG_KMEM

# define SLAB_ACCOUNT		((slab_flags_t __force)0x04000000U)

# define SLAB_ACCOUNT		__SLAB_FLAG_BIT(_SLAB_ACCOUNT)

#else

# define SLAB_ACCOUNT		0

# define SLAB_ACCOUNT		__SLAB_FLAG_UNUSED

#endif



#ifdef CONFIG_KASAN_GENERIC

#define SLAB_KASAN		((slab_flags_t __force)0x08000000U)

#define SLAB_KASAN		__SLAB_FLAG_BIT(_SLAB_KASAN)

#else

#define SLAB_KASAN		0

#define SLAB_KASAN		__SLAB_FLAG_UNUSED

#endif



/*
@@ -145,25 +185,25 @@ 
 * Intended for caches created for self-tests so they have only flags

 * specified in the code and other flags are ignored.

 */

#define SLAB_NO_USER_FLAGS	((slab_flags_t __force)0x10000000U)

#define SLAB_NO_USER_FLAGS	__SLAB_FLAG_BIT(_SLAB_NO_USER_FLAGS)



#ifdef CONFIG_KFENCE

#define SLAB_SKIP_KFENCE	((slab_flags_t __force)0x20000000U)

#define SLAB_SKIP_KFENCE	__SLAB_FLAG_BIT(_SLAB_SKIP_KFENCE)

#else

#define SLAB_SKIP_KFENCE	0

#define SLAB_SKIP_KFENCE	__SLAB_FLAG_UNUSED

#endif



/* The following flags affect the page allocator grouping pages by mobility */

/* Objects are reclaimable */

#ifndef CONFIG_SLUB_TINY

#define SLAB_RECLAIM_ACCOUNT	((slab_flags_t __force)0x00020000U)

#define SLAB_RECLAIM_ACCOUNT	__SLAB_FLAG_BIT(_SLAB_RECLAIM_ACCOUNT)

#else

#define SLAB_RECLAIM_ACCOUNT	((slab_flags_t __force)0)

#define SLAB_RECLAIM_ACCOUNT	__SLAB_FLAG_UNUSED

#endif

#define SLAB_TEMPORARY		SLAB_RECLAIM_ACCOUNT	/* Objects are short-lived */



/* Obsolete unused flag, to be removed */

#define SLAB_MEM_SPREAD		((slab_flags_t __force)0U)

#define SLAB_MEM_SPREAD		__SLAB_FLAG_UNUSED



/*

 * ZERO_SIZE_PTR will be returned for zero sized kmalloc requests.

mm/slub.c

+3 −3
Original line number Diff line number Diff line
@@ -306,13 +306,13 @@ static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s) 


/* Internal SLUB flags */

/* Poison object */

#define __OBJECT_POISON		((slab_flags_t __force)0x80000000U)

#define __OBJECT_POISON		__SLAB_FLAG_BIT(_SLAB_OBJECT_POISON)

/* Use cmpxchg_double */



#ifdef system_has_freelist_aba

#define __CMPXCHG_DOUBLE	((slab_flags_t __force)0x40000000U)

#define __CMPXCHG_DOUBLE	__SLAB_FLAG_BIT(_SLAB_CMPXCHG_DOUBLE)

#else

#define __CMPXCHG_DOUBLE	((slab_flags_t __force)0U)

#define __CMPXCHG_DOUBLE	__SLAB_FLAG_UNUSED

#endif



/*