Re: Bulk kmalloc

[Jesper Dangaard Brouer <brouer@redhat.com>]

On Thu, 09 May 2019 16:28:58 +0100 David Howells <dhowells@redhat.com> wrote:

> Is it possible to use kmem_cache_alloc_bulk() with kmalloc slabs to
> effect a bulk kmalloc?

Well, we have kfree_bulk() which is a simple wrapper around
kmem_cache_free_bulk() (as Christoph make me handle that case).

We/I didn't code the kmalloc_bulk() variant.

What is you use case?

(p.s. fixed the MM-email address)
-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer


static __always_inline void kfree_bulk(size_t size, void **p)
{
	kmem_cache_free_bulk(NULL, size, p);
}


Handling code for kfree_bulk case:

	page = virt_to_head_page(object);
	if (!s) {
		/* Handle kalloc'ed objects */
		if (unlikely(!PageSlab(page))) {
			BUG_ON(!PageCompound(page));
			kfree_hook(object);
			__free_pages(page, compound_order(page));
			p[size] = NULL; /* mark object processed */
			return size;
		}
		/* Derive kmem_cache from object */
		df->s = page->slab_cache;
	} else {
		df->s = cache_from_obj(s, object); /* Support for memcg */
	}