SLUB

Linux 6.18.37 LTS: mm/slub.c
Linux 6.18.37 LTS: mm/slab_common.c
Linux 6.18.37 LTS: include/linux/slab.h

		memset((void *)((char *)kasan_reset_tag(obj) + s->offset),
			0, sizeof(void *));
}

/*
 * Inlined fastpath so that allocation functions (kmalloc, kmem_cache_alloc)
 * have the fastpath folded into their functions. So no function call
 * overhead for requests that can be satisfied on the fastpath.
 *
 * The fastpath works by first checking if the lockless freelist can be used.
 * If not then __slab_alloc is called for slow processing.
 *
 * Otherwise we can simply pick the next object from the lockless free list.
 */
static __fastpath_inline void *slab_alloc_node(struct kmem_cache *s, struct list_lru *lru,
		gfp_t gfpflags, int node, unsigned long addr, size_t orig_size)
{
	void *object;
	struct obj_cgroup *objcg = NULL;
	bool init = false;

	s = slab_pre_alloc_hook(s, lru, &objcg, 1, gfpflags);
	if (!s)
		return NULL;

	object = kfence_alloc(s, orig_size, gfpflags);
	if (unlikely(object))
		goto out;

	object = __slab_alloc_node(s, gfpflags, node, addr, orig_size);

	maybe_wipe_obj_freeptr(s, object);
	init = slab_want_init_on_alloc(gfpflags, s);

out:
	/*
	 * When init equals 'true', like for kzalloc() family, only
	 * @orig_size bytes might be zeroed instead of s->object_size
	 */
	slab_post_alloc_hook(s, objcg, gfpflags, 1, &object, init, orig_size);

 *   an in-progress slow path operations. In this case the local lock is always
 *   taken but it still utilizes the freelist for the common operations.
 *
 *   lockless fastpaths
 *
 *   The fast path allocation (slab_alloc_node()) and freeing (do_slab_free())
 *   are fully lockless when satisfied from the percpu slab (and when
 *   cmpxchg_double is possible to use, otherwise slab_lock is taken).
 *   They also don't disable preemption or migration or irqs. They rely on
 *   the transaction id (tid) field to detect being preempted or moved to
 *   another cpu.
 *
 *   irq, preemption, migration considerations
 *
 *   Interrupts are disabled as part of list_lock or local_lock operations, or
 *   around the slab_lock operation, in order to make the slab allocator safe
 *   to use in the context of an irq.
 *
 *   In addition, preemption (or migration on PREEMPT_RT) is disabled in the
 *   allocation slowpath, bulk allocation, and put_cpu_partial(), so that the
 *   local cpu doesn't change in the process and e.g. the kmem_cache_cpu pointer
 *   doesn't have to be revalidated in each section protected by the local lock.
 *
 * SLUB assigns one slab for allocation to each processor.
 * Allocations only occur from these slabs called cpu slabs.
 *
 * Slabs with free elements are kept on a partial list and during regular
 * operations no list for full slabs is used. If an object in a full slab is
 * freed then the slab will show up again on the partial lists.
 * We track full slabs for debugging purposes though because otherwise we
 * cannot scan all objects.
 *
 * Slabs are freed when they become empty. Teardown and setup is
 * minimal so we rely on the page allocators per cpu caches for
 * fast frees and allocs.
 *
 * slab->frozen		The slab is frozen and exempt from list processing.
 * 			This means that the slab is dedicated to a purpose
 * 			such as satisfying allocations for a specific
 * 			processor. Objects may be freed in the slab while