[2/3] mm, slab: use an enum to define SLAB_ cache creation flags

Message ID 20240220-slab-cleanup-flags-v1-2-e657e373944a@suse.cz
State New
Headers
Series cleanup of SLAB_ flags |

Commit Message

Vlastimil Babka Feb. 20, 2024, 4:58 p.m. UTC
  The values of SLAB_ cache creation flagsare defined by hand, which is
tedious and error-prone. Use an enum to assign the bit number and a
__SF_BIT() macro to #define the final flags.

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

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
 include/linux/slab.h | 81 ++++++++++++++++++++++++++++++++++++++--------------
 mm/slub.c            |  6 ++--
 2 files changed, 63 insertions(+), 24 deletions(-)
  

Comments

Xiongwei Song Feb. 21, 2024, 2:23 a.m. UTC | #1
> The values of SLAB_ cache creation flagsare defined by hand, which is

A blank space missed between flags and are.

> tedious and error-prone. Use an enum to assign the bit number and a
> __SF_BIT() macro to #define the final flags.
> 
> This renumbers the flag values, which is OK as they are only used
> internally.
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Ran a rough test with build and bootup with the related debug configs enabled,
feel free to add

Tested-by: Xiongwei Song <xiongwei.song@windriver.com>
Reviewed-by: Xiongwei Song <xiongwei.song@windriver.com>

Thanks,
Xiognwei
> ---
>  include/linux/slab.h | 81 ++++++++++++++++++++++++++++++++++++++--------------
>  mm/slub.c            |  6 ++--
>  2 files changed, 63 insertions(+), 24 deletions(-)
> 
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 6252f44115c2..f893a132dd5a 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -21,29 +21,68 @@
>  #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 __SF_BIT(nr)   ((slab_flags_t __force)(1U << (nr)))
> 
>  /*
>   * 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        __SF_BIT(_SLAB_CONSISTENCY_CHECKS)
>  /* DEBUG: Red zone objs in a cache */
> -#define SLAB_RED_ZONE          ((slab_flags_t __force)0x00000400U)
> +#define SLAB_RED_ZONE          __SF_BIT(_SLAB_RED_ZONE)
>  /* DEBUG: Poison objects */
> -#define SLAB_POISON            ((slab_flags_t __force)0x00000800U)
> +#define SLAB_POISON            __SF_BIT(_SLAB_POISON)
>  /* Indicate a kmalloc slab */
> -#define SLAB_KMALLOC           ((slab_flags_t __force)0x00001000U)
> +#define SLAB_KMALLOC           __SF_BIT(_SLAB_KMALLOC)
>  /* Align objs on cache lines */
> -#define SLAB_HWCACHE_ALIGN     ((slab_flags_t __force)0x00002000U)
> +#define SLAB_HWCACHE_ALIGN     __SF_BIT(_SLAB_HWCACHE_ALIGN)
>  /* Use GFP_DMA memory */
> -#define SLAB_CACHE_DMA         ((slab_flags_t __force)0x00004000U)
> +#define SLAB_CACHE_DMA         __SF_BIT(_SLAB_CACHE_DMA)
>  /* Use GFP_DMA32 memory */
> -#define SLAB_CACHE_DMA32       ((slab_flags_t __force)0x00008000U)
> +#define SLAB_CACHE_DMA32       __SF_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                __SF_BIT(_SLAB_STORE_USER)
>  /* Panic if kmem_cache_create() fails */
> -#define SLAB_PANIC             ((slab_flags_t __force)0x00040000U)
> +#define SLAB_PANIC             __SF_BIT(_SLAB_PANIC)
>  /*
>   * SLAB_TYPESAFE_BY_RCU - **WARNING** READ THIS!
>   *
> @@ -95,19 +134,19 @@
>   * 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   __SF_BIT(_SLAB_TYPESAFE_BY_RCU)
>  /* Trace allocations and frees */
> -#define SLAB_TRACE             ((slab_flags_t __force)0x00200000U)
> +#define SLAB_TRACE             __SF_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    __SF_BIT(_SLAB_DEBUG_OBJECTS)
>  #else
>  # define SLAB_DEBUG_OBJECTS    0
>  #endif
> 
>  /* Avoid kmemleak tracing */
> -#define SLAB_NOLEAKTRACE       ((slab_flags_t __force)0x00800000U)
> +#define SLAB_NOLEAKTRACE       __SF_BIT(_SLAB_NOLEAKTRACE)
> 
>  /*
>   * Prevent merging with compatible kmem caches. This flag should be used
> @@ -119,23 +158,23 @@
>   * - 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          __SF_BIT(_SLAB_NO_MERGE)
> 
>  /* Fault injection mark */
>  #ifdef CONFIG_FAILSLAB
> -# define SLAB_FAILSLAB         ((slab_flags_t __force)0x02000000U)
> +# define SLAB_FAILSLAB         __SF_BIT(_SLAB_FAILSLAB)
>  #else
>  # define SLAB_FAILSLAB         0
>  #endif
>  /* Account to memcg */
>  #ifdef CONFIG_MEMCG_KMEM
> -# define SLAB_ACCOUNT          ((slab_flags_t __force)0x04000000U)
> +# define SLAB_ACCOUNT          __SF_BIT(_SLAB_ACCOUNT)
>  #else
>  # define SLAB_ACCOUNT          0
>  #endif
> 
>  #ifdef CONFIG_KASAN_GENERIC
> -#define SLAB_KASAN             ((slab_flags_t __force)0x08000000U)
> +#define SLAB_KASAN             __SF_BIT(_SLAB_KASAN)
>  #else
>  #define SLAB_KASAN             0
>  #endif
> @@ -145,10 +184,10 @@
>   * 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     __SF_BIT(_SLAB_NO_USER_FLAGS)
> 
>  #ifdef CONFIG_KFENCE
> -#define SLAB_SKIP_KFENCE       ((slab_flags_t __force)0x20000000U)
> +#define SLAB_SKIP_KFENCE       __SF_BIT(_SLAB_SKIP_KFENCE)
>  #else
>  #define SLAB_SKIP_KFENCE       0
>  #endif
> @@ -156,9 +195,9 @@
>  /* 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   __SF_BIT(_SLAB_RECLAIM_ACCOUNT)
>  #else
> -#define SLAB_RECLAIM_ACCOUNT   ((slab_flags_t __force)0)
> +#define SLAB_RECLAIM_ACCOUNT   0
>  #endif
>  #define SLAB_TEMPORARY         SLAB_RECLAIM_ACCOUNT    /* Objects are short-lived */
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index 2ef88bbf56a3..a93c5a17cbbb 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -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                __SF_BIT(_SLAB_OBJECT_POISON)
>  /* Use cmpxchg_double */
> 
>  #ifdef system_has_freelist_aba
> -#define __CMPXCHG_DOUBLE       ((slab_flags_t __force)0x40000000U)
> +#define __CMPXCHG_DOUBLE       __SF_BIT(_SLAB_CMPXCHG_DOUBLE)
>  #else
> -#define __CMPXCHG_DOUBLE       ((slab_flags_t __force)0U)
> +#define __CMPXCHG_DOUBLE       0
>  #endif
> 
>  /*
> 
> --
> 2.43.1
  
Chengming Zhou Feb. 21, 2024, 7:13 a.m. UTC | #2
On 2024/2/21 00:58, Vlastimil Babka wrote:
> The values of SLAB_ cache creation flagsare defined by hand, which is
> tedious and error-prone. Use an enum to assign the bit number and a
> __SF_BIT() macro to #define the final flags.
> 
> This renumbers the flag values, which is OK as they are only used
> internally.
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>

Thanks!

> ---
>  include/linux/slab.h | 81 ++++++++++++++++++++++++++++++++++++++--------------
>  mm/slub.c            |  6 ++--
>  2 files changed, 63 insertions(+), 24 deletions(-)
> 
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 6252f44115c2..f893a132dd5a 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -21,29 +21,68 @@
>  #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 __SF_BIT(nr)	((slab_flags_t __force)(1U << (nr)))
>  
>  /*
>   * 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	__SF_BIT(_SLAB_CONSISTENCY_CHECKS)
>  /* DEBUG: Red zone objs in a cache */
> -#define SLAB_RED_ZONE		((slab_flags_t __force)0x00000400U)
> +#define SLAB_RED_ZONE		__SF_BIT(_SLAB_RED_ZONE)
>  /* DEBUG: Poison objects */
> -#define SLAB_POISON		((slab_flags_t __force)0x00000800U)
> +#define SLAB_POISON		__SF_BIT(_SLAB_POISON)
>  /* Indicate a kmalloc slab */
> -#define SLAB_KMALLOC		((slab_flags_t __force)0x00001000U)
> +#define SLAB_KMALLOC		__SF_BIT(_SLAB_KMALLOC)
>  /* Align objs on cache lines */
> -#define SLAB_HWCACHE_ALIGN	((slab_flags_t __force)0x00002000U)
> +#define SLAB_HWCACHE_ALIGN	__SF_BIT(_SLAB_HWCACHE_ALIGN)
>  /* Use GFP_DMA memory */
> -#define SLAB_CACHE_DMA		((slab_flags_t __force)0x00004000U)
> +#define SLAB_CACHE_DMA		__SF_BIT(_SLAB_CACHE_DMA)
>  /* Use GFP_DMA32 memory */
> -#define SLAB_CACHE_DMA32	((slab_flags_t __force)0x00008000U)
> +#define SLAB_CACHE_DMA32	__SF_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		__SF_BIT(_SLAB_STORE_USER)
>  /* Panic if kmem_cache_create() fails */
> -#define SLAB_PANIC		((slab_flags_t __force)0x00040000U)
> +#define SLAB_PANIC		__SF_BIT(_SLAB_PANIC)
>  /*
>   * SLAB_TYPESAFE_BY_RCU - **WARNING** READ THIS!
>   *
> @@ -95,19 +134,19 @@
>   * 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	__SF_BIT(_SLAB_TYPESAFE_BY_RCU)
>  /* Trace allocations and frees */
> -#define SLAB_TRACE		((slab_flags_t __force)0x00200000U)
> +#define SLAB_TRACE		__SF_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	__SF_BIT(_SLAB_DEBUG_OBJECTS)
>  #else
>  # define SLAB_DEBUG_OBJECTS	0
>  #endif
>  
>  /* Avoid kmemleak tracing */
> -#define SLAB_NOLEAKTRACE	((slab_flags_t __force)0x00800000U)
> +#define SLAB_NOLEAKTRACE	__SF_BIT(_SLAB_NOLEAKTRACE)
>  
>  /*
>   * Prevent merging with compatible kmem caches. This flag should be used
> @@ -119,23 +158,23 @@
>   * - 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		__SF_BIT(_SLAB_NO_MERGE)
>  
>  /* Fault injection mark */
>  #ifdef CONFIG_FAILSLAB
> -# define SLAB_FAILSLAB		((slab_flags_t __force)0x02000000U)
> +# define SLAB_FAILSLAB		__SF_BIT(_SLAB_FAILSLAB)
>  #else
>  # define SLAB_FAILSLAB		0
>  #endif
>  /* Account to memcg */
>  #ifdef CONFIG_MEMCG_KMEM
> -# define SLAB_ACCOUNT		((slab_flags_t __force)0x04000000U)
> +# define SLAB_ACCOUNT		__SF_BIT(_SLAB_ACCOUNT)
>  #else
>  # define SLAB_ACCOUNT		0
>  #endif
>  
>  #ifdef CONFIG_KASAN_GENERIC
> -#define SLAB_KASAN		((slab_flags_t __force)0x08000000U)
> +#define SLAB_KASAN		__SF_BIT(_SLAB_KASAN)
>  #else
>  #define SLAB_KASAN		0
>  #endif
> @@ -145,10 +184,10 @@
>   * 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	__SF_BIT(_SLAB_NO_USER_FLAGS)
>  
>  #ifdef CONFIG_KFENCE
> -#define SLAB_SKIP_KFENCE	((slab_flags_t __force)0x20000000U)
> +#define SLAB_SKIP_KFENCE	__SF_BIT(_SLAB_SKIP_KFENCE)
>  #else
>  #define SLAB_SKIP_KFENCE	0
>  #endif
> @@ -156,9 +195,9 @@
>  /* 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	__SF_BIT(_SLAB_RECLAIM_ACCOUNT)
>  #else
> -#define SLAB_RECLAIM_ACCOUNT	((slab_flags_t __force)0)
> +#define SLAB_RECLAIM_ACCOUNT	0
>  #endif
>  #define SLAB_TEMPORARY		SLAB_RECLAIM_ACCOUNT	/* Objects are short-lived */
>  
> diff --git a/mm/slub.c b/mm/slub.c
> index 2ef88bbf56a3..a93c5a17cbbb 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -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		__SF_BIT(_SLAB_OBJECT_POISON)
>  /* Use cmpxchg_double */
>  
>  #ifdef system_has_freelist_aba
> -#define __CMPXCHG_DOUBLE	((slab_flags_t __force)0x40000000U)
> +#define __CMPXCHG_DOUBLE	__SF_BIT(_SLAB_CMPXCHG_DOUBLE)
>  #else
> -#define __CMPXCHG_DOUBLE	((slab_flags_t __force)0U)
> +#define __CMPXCHG_DOUBLE	0
>  #endif
>  
>  /*
>
  
Roman Gushchin Feb. 21, 2024, 6:33 p.m. UTC | #3
On Tue, Feb 20, 2024 at 05:58:26PM +0100, Vlastimil Babka wrote:
> The values of SLAB_ cache creation flagsare defined by hand, which is
> tedious and error-prone. Use an enum to assign the bit number and a
> __SF_BIT() macro to #define the final flags.
> 
> This renumbers the flag values, which is OK as they are only used
> internally.
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> ---
>  include/linux/slab.h | 81 ++++++++++++++++++++++++++++++++++++++--------------
>  mm/slub.c            |  6 ++--
>  2 files changed, 63 insertions(+), 24 deletions(-)
> 
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 6252f44115c2..f893a132dd5a 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -21,29 +21,68 @@
>  #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 __SF_BIT(nr)	((slab_flags_t __force)(1U << (nr)))

I'd rename it to (__)SLAB_FLAG_BIT(), as SF is a bit cryptic, but not a strong
preference. Otherwise looks really good to me, nice cleanup.

Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>

Thanks!
  
Vlastimil Babka Feb. 21, 2024, 10:19 p.m. UTC | #4
On 2/20/24 17:58, Vlastimil Babka wrote:
> @@ -156,9 +195,9 @@
>  /* 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 __SF_BIT(_SLAB_RECLAIM_ACCOUNT)
>  #else
> -#define SLAB_RECLAIM_ACCOUNT ((slab_flags_t __force)0)
> +#define SLAB_RECLAIM_ACCOUNT 0

lkp/sparse tells me this was the wrong way to unify all noop-due-to-config
flags [1,2]

so in v2 I'll unify all those to
((slab_flags_t __force)0U)

also the deprecated SLAB_MEM_SPREAD in patch 1

[1] https://lore.kernel.org/all/202402212310.KPtSDrRy-lkp@intel.com/
[2] https://lore.kernel.org/all/202402211803.Lmf1ANXx-lkp@intel.com/


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

Patch

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 6252f44115c2..f893a132dd5a 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -21,29 +21,68 @@ 
 #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 __SF_BIT(nr)	((slab_flags_t __force)(1U << (nr)))
 
 /*
  * 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	__SF_BIT(_SLAB_CONSISTENCY_CHECKS)
 /* DEBUG: Red zone objs in a cache */
-#define SLAB_RED_ZONE		((slab_flags_t __force)0x00000400U)
+#define SLAB_RED_ZONE		__SF_BIT(_SLAB_RED_ZONE)
 /* DEBUG: Poison objects */
-#define SLAB_POISON		((slab_flags_t __force)0x00000800U)
+#define SLAB_POISON		__SF_BIT(_SLAB_POISON)
 /* Indicate a kmalloc slab */
-#define SLAB_KMALLOC		((slab_flags_t __force)0x00001000U)
+#define SLAB_KMALLOC		__SF_BIT(_SLAB_KMALLOC)
 /* Align objs on cache lines */
-#define SLAB_HWCACHE_ALIGN	((slab_flags_t __force)0x00002000U)
+#define SLAB_HWCACHE_ALIGN	__SF_BIT(_SLAB_HWCACHE_ALIGN)
 /* Use GFP_DMA memory */
-#define SLAB_CACHE_DMA		((slab_flags_t __force)0x00004000U)
+#define SLAB_CACHE_DMA		__SF_BIT(_SLAB_CACHE_DMA)
 /* Use GFP_DMA32 memory */
-#define SLAB_CACHE_DMA32	((slab_flags_t __force)0x00008000U)
+#define SLAB_CACHE_DMA32	__SF_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		__SF_BIT(_SLAB_STORE_USER)
 /* Panic if kmem_cache_create() fails */
-#define SLAB_PANIC		((slab_flags_t __force)0x00040000U)
+#define SLAB_PANIC		__SF_BIT(_SLAB_PANIC)
 /*
  * SLAB_TYPESAFE_BY_RCU - **WARNING** READ THIS!
  *
@@ -95,19 +134,19 @@ 
  * 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	__SF_BIT(_SLAB_TYPESAFE_BY_RCU)
 /* Trace allocations and frees */
-#define SLAB_TRACE		((slab_flags_t __force)0x00200000U)
+#define SLAB_TRACE		__SF_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	__SF_BIT(_SLAB_DEBUG_OBJECTS)
 #else
 # define SLAB_DEBUG_OBJECTS	0
 #endif
 
 /* Avoid kmemleak tracing */
-#define SLAB_NOLEAKTRACE	((slab_flags_t __force)0x00800000U)
+#define SLAB_NOLEAKTRACE	__SF_BIT(_SLAB_NOLEAKTRACE)
 
 /*
  * Prevent merging with compatible kmem caches. This flag should be used
@@ -119,23 +158,23 @@ 
  * - 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		__SF_BIT(_SLAB_NO_MERGE)
 
 /* Fault injection mark */
 #ifdef CONFIG_FAILSLAB
-# define SLAB_FAILSLAB		((slab_flags_t __force)0x02000000U)
+# define SLAB_FAILSLAB		__SF_BIT(_SLAB_FAILSLAB)
 #else
 # define SLAB_FAILSLAB		0
 #endif
 /* Account to memcg */
 #ifdef CONFIG_MEMCG_KMEM
-# define SLAB_ACCOUNT		((slab_flags_t __force)0x04000000U)
+# define SLAB_ACCOUNT		__SF_BIT(_SLAB_ACCOUNT)
 #else
 # define SLAB_ACCOUNT		0
 #endif
 
 #ifdef CONFIG_KASAN_GENERIC
-#define SLAB_KASAN		((slab_flags_t __force)0x08000000U)
+#define SLAB_KASAN		__SF_BIT(_SLAB_KASAN)
 #else
 #define SLAB_KASAN		0
 #endif
@@ -145,10 +184,10 @@ 
  * 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	__SF_BIT(_SLAB_NO_USER_FLAGS)
 
 #ifdef CONFIG_KFENCE
-#define SLAB_SKIP_KFENCE	((slab_flags_t __force)0x20000000U)
+#define SLAB_SKIP_KFENCE	__SF_BIT(_SLAB_SKIP_KFENCE)
 #else
 #define SLAB_SKIP_KFENCE	0
 #endif
@@ -156,9 +195,9 @@ 
 /* 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	__SF_BIT(_SLAB_RECLAIM_ACCOUNT)
 #else
-#define SLAB_RECLAIM_ACCOUNT	((slab_flags_t __force)0)
+#define SLAB_RECLAIM_ACCOUNT	0
 #endif
 #define SLAB_TEMPORARY		SLAB_RECLAIM_ACCOUNT	/* Objects are short-lived */
 
diff --git a/mm/slub.c b/mm/slub.c
index 2ef88bbf56a3..a93c5a17cbbb 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -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		__SF_BIT(_SLAB_OBJECT_POISON)
 /* Use cmpxchg_double */
 
 #ifdef system_has_freelist_aba
-#define __CMPXCHG_DOUBLE	((slab_flags_t __force)0x40000000U)
+#define __CMPXCHG_DOUBLE	__SF_BIT(_SLAB_CMPXCHG_DOUBLE)
 #else
-#define __CMPXCHG_DOUBLE	((slab_flags_t __force)0U)
+#define __CMPXCHG_DOUBLE	0
 #endif
 
 /*