Re: [PATCH v8 13/23] tools/testing: Add support for changes to slab for sheaves

[Suren Baghdasaryan <surenb@google.com>]

On Wed, Sep 10, 2025 at 1:01 AM Vlastimil Babka <vbabka@suse.cz> wrote:
>
> From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>
>
> The slab changes for sheaves requires more effort in the testing code.
> Unite all the kmem_cache work into the tools/include slab header for
> both the vma and maple tree testing.
>
> The vma test code also requires importing more #defines to allow for
> seamless use of the shared kmem_cache code.
>
> This adds the pthread header to the slab header in the tools directory
> to allow for the pthread_mutex in linux.c.
>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Reviewed-by: Suren Baghdasaryan <surenb@google.com>

The patch does several things and could be split in 3 (code
refactoring, kmem_cache_create change, new definitions like
_slab_flag_bits) but I don't think it's worth a respin.

> ---
>  tools/include/linux/slab.h        | 137 ++++++++++++++++++++++++++++++++++++--
>  tools/testing/shared/linux.c      |  26 ++------
>  tools/testing/shared/maple-shim.c |   1 +
>  tools/testing/vma/vma_internal.h  |  92 +------------------------
>  4 files changed, 142 insertions(+), 114 deletions(-)
>
> diff --git a/tools/include/linux/slab.h b/tools/include/linux/slab.h
> index c87051e2b26f5a7fee0362697fae067076b8e84d..c5c5cc6db5668be2cc94c29065ccfa7ca7b4bb08 100644
> --- a/tools/include/linux/slab.h
> +++ b/tools/include/linux/slab.h
> @@ -4,11 +4,31 @@
>
>  #include <linux/types.h>
>  #include <linux/gfp.h>
> +#include <pthread.h>
>
> -#define SLAB_PANIC 2
>  #define SLAB_RECLAIM_ACCOUNT    0x00020000UL            /* Objects are reclaimable */
>
>  #define kzalloc_node(size, flags, node) kmalloc(size, flags)
> +enum _slab_flag_bits {
> +       _SLAB_KMALLOC,
> +       _SLAB_HWCACHE_ALIGN,
> +       _SLAB_PANIC,
> +       _SLAB_TYPESAFE_BY_RCU,
> +       _SLAB_ACCOUNT,
> +       _SLAB_FLAGS_LAST_BIT
> +};
> +
> +#define __SLAB_FLAG_BIT(nr)    ((unsigned int __force)(1U << (nr)))
> +#define __SLAB_FLAG_UNUSED     ((unsigned int __force)(0U))
> +
> +#define SLAB_HWCACHE_ALIGN     __SLAB_FLAG_BIT(_SLAB_HWCACHE_ALIGN)
> +#define SLAB_PANIC             __SLAB_FLAG_BIT(_SLAB_PANIC)
> +#define SLAB_TYPESAFE_BY_RCU   __SLAB_FLAG_BIT(_SLAB_TYPESAFE_BY_RCU)
> +#ifdef CONFIG_MEMCG
> +# define SLAB_ACCOUNT          __SLAB_FLAG_BIT(_SLAB_ACCOUNT)
> +#else
> +# define SLAB_ACCOUNT          __SLAB_FLAG_UNUSED
> +#endif
>
>  void *kmalloc(size_t size, gfp_t gfp);
>  void kfree(void *p);
> @@ -23,6 +43,86 @@ enum slab_state {
>         FULL
>  };
>
> +struct kmem_cache {
> +       pthread_mutex_t lock;
> +       unsigned int size;
> +       unsigned int align;
> +       unsigned int sheaf_capacity;
> +       int nr_objs;
> +       void *objs;
> +       void (*ctor)(void *);
> +       bool non_kernel_enabled;
> +       unsigned int non_kernel;
> +       unsigned long nr_allocated;
> +       unsigned long nr_tallocated;
> +       bool exec_callback;
> +       void (*callback)(void *);
> +       void *private;
> +};
> +
> +struct kmem_cache_args {
> +       /**
> +        * @align: The required alignment for the objects.
> +        *
> +        * %0 means no specific alignment is requested.
> +        */
> +       unsigned int align;
> +       /**
> +        * @sheaf_capacity: The maximum size of the sheaf.
> +        */
> +       unsigned int sheaf_capacity;
> +       /**
> +        * @useroffset: Usercopy region offset.
> +        *
> +        * %0 is a valid offset, when @usersize is non-%0
> +        */
> +       unsigned int useroffset;
> +       /**
> +        * @usersize: Usercopy region size.
> +        *
> +        * %0 means no usercopy region is specified.
> +        */
> +       unsigned int usersize;
> +       /**
> +        * @freeptr_offset: Custom offset for the free pointer
> +        * in &SLAB_TYPESAFE_BY_RCU caches
> +        *
> +        * By default &SLAB_TYPESAFE_BY_RCU caches place the free pointer
> +        * outside of the object. This might cause the object to grow in size.
> +        * Cache creators that have a reason to avoid this can specify a custom
> +        * free pointer offset in their struct where the free pointer will be
> +        * placed.
> +        *
> +        * Note that placing the free pointer inside the object requires the
> +        * caller to ensure that no fields are invalidated that are required to
> +        * guard against object recycling (See &SLAB_TYPESAFE_BY_RCU for
> +        * details).
> +        *
> +        * Using %0 as a value for @freeptr_offset is valid. If @freeptr_offset
> +        * is specified, %use_freeptr_offset must be set %true.
> +        *
> +        * Note that @ctor currently isn't supported with custom free pointers
> +        * as a @ctor requires an external free pointer.
> +        */
> +       unsigned int freeptr_offset;
> +       /**
> +        * @use_freeptr_offset: Whether a @freeptr_offset is used.
> +        */
> +       bool use_freeptr_offset;
> +       /**
> +        * @ctor: A constructor for the objects.
> +        *
> +        * The constructor is invoked for each object in a newly allocated slab
> +        * page. It is the cache user's responsibility to free object in the
> +        * same state as after calling the constructor, or deal appropriately
> +        * with any differences between a freshly constructed and a reallocated
> +        * object.
> +        *
> +        * %NULL means no constructor.
> +        */
> +       void (*ctor)(void *);
> +};
> +
>  static inline void *kzalloc(size_t size, gfp_t gfp)
>  {
>         return kmalloc(size, gfp | __GFP_ZERO);
> @@ -37,9 +137,38 @@ static inline void *kmem_cache_alloc(struct kmem_cache *cachep, int flags)
>  }
>  void kmem_cache_free(struct kmem_cache *cachep, void *objp);
>
> -struct kmem_cache *kmem_cache_create(const char *name, unsigned int size,
> -                       unsigned int align, unsigned int flags,
> -                       void (*ctor)(void *));
> +
> +struct kmem_cache *
> +__kmem_cache_create_args(const char *name, unsigned int size,
> +               struct kmem_cache_args *args, unsigned int flags);
> +
> +/* If NULL is passed for @args, use this variant with default arguments. */
> +static inline struct kmem_cache *
> +__kmem_cache_default_args(const char *name, unsigned int size,
> +               struct kmem_cache_args *args, unsigned int flags)
> +{
> +       struct kmem_cache_args kmem_default_args = {};
> +
> +       return __kmem_cache_create_args(name, size, &kmem_default_args, flags);
> +}
> +
> +static inline struct kmem_cache *
> +__kmem_cache_create(const char *name, unsigned int size, unsigned int align,
> +               unsigned int flags, void (*ctor)(void *))
> +{
> +       struct kmem_cache_args kmem_args = {
> +               .align  = align,
> +               .ctor   = ctor,
> +       };
> +
> +       return __kmem_cache_create_args(name, size, &kmem_args, flags);
> +}
> +
> +#define kmem_cache_create(__name, __object_size, __args, ...)           \
> +       _Generic((__args),                                              \
> +               struct kmem_cache_args *: __kmem_cache_create_args,     \
> +               void *: __kmem_cache_default_args,                      \
> +               default: __kmem_cache_create)(__name, __object_size, __args, __VA_ARGS__)
>
>  void kmem_cache_free_bulk(struct kmem_cache *cachep, size_t size, void **list);
>  int kmem_cache_alloc_bulk(struct kmem_cache *cachep, gfp_t gfp, size_t size,
> diff --git a/tools/testing/shared/linux.c b/tools/testing/shared/linux.c
> index 0f97fb0d19e19c327aa4843a35b45cc086f4f366..97b8412ccbb6d222604c7b397c53c65618d8d51b 100644
> --- a/tools/testing/shared/linux.c
> +++ b/tools/testing/shared/linux.c
> @@ -16,21 +16,6 @@ int nr_allocated;
>  int preempt_count;
>  int test_verbose;
>
> -struct kmem_cache {
> -       pthread_mutex_t lock;
> -       unsigned int size;
> -       unsigned int align;
> -       int nr_objs;
> -       void *objs;
> -       void (*ctor)(void *);
> -       unsigned int non_kernel;
> -       unsigned long nr_allocated;
> -       unsigned long nr_tallocated;
> -       bool exec_callback;
> -       void (*callback)(void *);
> -       void *private;
> -};
> -
>  void kmem_cache_set_callback(struct kmem_cache *cachep, void (*callback)(void *))
>  {
>         cachep->callback = callback;
> @@ -234,23 +219,26 @@ int kmem_cache_alloc_bulk(struct kmem_cache *cachep, gfp_t gfp, size_t size,
>  }
>
>  struct kmem_cache *
> -kmem_cache_create(const char *name, unsigned int size, unsigned int align,
> -               unsigned int flags, void (*ctor)(void *))
> +__kmem_cache_create_args(const char *name, unsigned int size,
> +                         struct kmem_cache_args *args,
> +                         unsigned int flags)
>  {
>         struct kmem_cache *ret = malloc(sizeof(*ret));
>
>         pthread_mutex_init(&ret->lock, NULL);
>         ret->size = size;
> -       ret->align = align;
> +       ret->align = args->align;
> +       ret->sheaf_capacity = args->sheaf_capacity;
>         ret->nr_objs = 0;
>         ret->nr_allocated = 0;
>         ret->nr_tallocated = 0;
>         ret->objs = NULL;
> -       ret->ctor = ctor;
> +       ret->ctor = args->ctor;
>         ret->non_kernel = 0;
>         ret->exec_callback = false;
>         ret->callback = NULL;
>         ret->private = NULL;
> +
>         return ret;
>  }
>
> diff --git a/tools/testing/shared/maple-shim.c b/tools/testing/shared/maple-shim.c
> index 640df76f483e09f3b6f85612786060dd273e2362..9d7b743415660305416e972fa75b56824211b0eb 100644
> --- a/tools/testing/shared/maple-shim.c
> +++ b/tools/testing/shared/maple-shim.c
> @@ -3,5 +3,6 @@
>  /* Very simple shim around the maple tree. */
>
>  #include "maple-shared.h"
> +#include <linux/slab.h>
>
>  #include "../../../lib/maple_tree.c"
> diff --git a/tools/testing/vma/vma_internal.h b/tools/testing/vma/vma_internal.h
> index 6b6e2b05918c9f95b537f26e20a943b34082825a..d5b87fa6a133f6d676488de2538c509e0f0e1d54 100644
> --- a/tools/testing/vma/vma_internal.h
> +++ b/tools/testing/vma/vma_internal.h
> @@ -26,6 +26,7 @@
>  #include <linux/mm.h>
>  #include <linux/rbtree.h>
>  #include <linux/refcount.h>
> +#include <linux/slab.h>
>
>  extern unsigned long stack_guard_gap;
>  #ifdef CONFIG_MMU
> @@ -509,65 +510,6 @@ struct pagetable_move_control {
>                 .len_in = len_,                                         \
>         }
>
> -struct kmem_cache_args {
> -       /**
> -        * @align: The required alignment for the objects.
> -        *
> -        * %0 means no specific alignment is requested.
> -        */
> -       unsigned int align;
> -       /**
> -        * @useroffset: Usercopy region offset.
> -        *
> -        * %0 is a valid offset, when @usersize is non-%0
> -        */
> -       unsigned int useroffset;
> -       /**
> -        * @usersize: Usercopy region size.
> -        *
> -        * %0 means no usercopy region is specified.
> -        */
> -       unsigned int usersize;
> -       /**
> -        * @freeptr_offset: Custom offset for the free pointer
> -        * in &SLAB_TYPESAFE_BY_RCU caches
> -        *
> -        * By default &SLAB_TYPESAFE_BY_RCU caches place the free pointer
> -        * outside of the object. This might cause the object to grow in size.
> -        * Cache creators that have a reason to avoid this can specify a custom
> -        * free pointer offset in their struct where the free pointer will be
> -        * placed.
> -        *
> -        * Note that placing the free pointer inside the object requires the
> -        * caller to ensure that no fields are invalidated that are required to
> -        * guard against object recycling (See &SLAB_TYPESAFE_BY_RCU for
> -        * details).
> -        *
> -        * Using %0 as a value for @freeptr_offset is valid. If @freeptr_offset
> -        * is specified, %use_freeptr_offset must be set %true.
> -        *
> -        * Note that @ctor currently isn't supported with custom free pointers
> -        * as a @ctor requires an external free pointer.
> -        */
> -       unsigned int freeptr_offset;
> -       /**
> -        * @use_freeptr_offset: Whether a @freeptr_offset is used.
> -        */
> -       bool use_freeptr_offset;
> -       /**
> -        * @ctor: A constructor for the objects.
> -        *
> -        * The constructor is invoked for each object in a newly allocated slab
> -        * page. It is the cache user's responsibility to free object in the
> -        * same state as after calling the constructor, or deal appropriately
> -        * with any differences between a freshly constructed and a reallocated
> -        * object.
> -        *
> -        * %NULL means no constructor.
> -        */
> -       void (*ctor)(void *);
> -};
> -
>  static inline void vma_iter_invalidate(struct vma_iterator *vmi)
>  {
>         mas_pause(&vmi->mas);
> @@ -652,38 +594,6 @@ static inline void vma_init(struct vm_area_struct *vma, struct mm_struct *mm)
>         vma->vm_lock_seq = UINT_MAX;
>  }
>
> -struct kmem_cache {
> -       const char *name;
> -       size_t object_size;
> -       struct kmem_cache_args *args;
> -};
> -
> -static inline struct kmem_cache *__kmem_cache_create(const char *name,
> -                                                    size_t object_size,
> -                                                    struct kmem_cache_args *args)
> -{
> -       struct kmem_cache *ret = malloc(sizeof(struct kmem_cache));
> -
> -       ret->name = name;
> -       ret->object_size = object_size;
> -       ret->args = args;
> -
> -       return ret;
> -}
> -
> -#define kmem_cache_create(__name, __object_size, __args, ...)           \
> -       __kmem_cache_create((__name), (__object_size), (__args))
> -
> -static inline void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags)
> -{
> -       return calloc(1, s->object_size);
> -}
> -
> -static inline void kmem_cache_free(struct kmem_cache *s, void *x)
> -{
> -       free(x);
> -}
> -
>  /*
>   * These are defined in vma.h, but sadly vm_stat_account() is referenced by
>   * kernel/fork.c, so we have to these broadly available there, and temporarily
>
> --
> 2.51.0
>