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Message-ID: <CAJuCfpGYgOVG7hpZJ7MED_ALXZfKgUuRcPN3YYjx6k_t-dGXhg@mail.gmail.com>
Date: Fri, 26 Sep 2025 16:28:43 -0700
From: Suren Baghdasaryan <surenb@...gle.com>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: "Liam R. Howlett" <Liam.Howlett@...cle.com>, Christoph Lameter <cl@...two.org>,
David Rientjes <rientjes@...gle.com>, Roman Gushchin <roman.gushchin@...ux.dev>,
Harry Yoo <harry.yoo@...cle.com>, Uladzislau Rezki <urezki@...il.com>,
Sidhartha Kumar <sidhartha.kumar@...cle.com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, rcu@...r.kernel.org,
maple-tree@...ts.infradead.org
Subject: Re: [PATCH v8 13/23] tools/testing: Add support for changes to slab
for sheaves
On Wed, Sep 10, 2025 at 1:01 AM Vlastimil Babka <vbabka@...e.cz> wrote:
>
> From: "Liam R. Howlett" <Liam.Howlett@...cle.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@...cle.com>
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
Reviewed-by: Suren Baghdasaryan <surenb@...gle.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
>
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