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Message-ID: 
 <PH0PR11MB51929679F8256CDE50F46F87EC572@PH0PR11MB5192.namprd11.prod.outlook.com>
Date: Wed, 21 Feb 2024 02:23:30 +0000
From: "Song, Xiongwei" <Xiongwei.Song@...driver.com>
To: Vlastimil Babka <vbabka@...e.cz>, Christoph Lameter <cl@...ux.com>,
        Pekka
 Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo
 Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Hyeonggon Yoo
	<42.hyeyoo@...il.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Alexander
 Potapenko <glider@...gle.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Vincenzo Frascino
	<vincenzo.frascino@....com>
CC: Zheng Yejian <zhengyejian1@...wei.com>,
        Chengming Zhou
	<chengming.zhou@...ux.dev>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kasan-dev@...glegroups.com" <kasan-dev@...glegroups.com>
Subject: RE: [PATCH 2/3] mm, slab: use an enum to define SLAB_ cache creation
 flags


> 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@...e.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@...driver.com>
Reviewed-by: Xiongwei Song <xiongwei.song@...driver.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

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