[Cluster-devel] GFS2: Use kmalloc when possible for ->readdir() (try #2)

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 28 Jul 2010 17:56:23 +0100 Steven Whitehouse <swhiteho@redhat.com> wrote:

> +static void *gfs2_alloc_sort_buffer(unsigned size)
> +{
> +	void *ptr = NULL;
> +
> +	if (size < KMALLOC_MAX_SIZE)
> +		ptr = kmalloc(size, GFP_NOFS | __GFP_NOWARN);
> +	if (!ptr)
> +		ptr = __vmalloc(size, GFP_NOFS, PAGE_KERNEL);
> +	return ptr;
> +}
> +
> +static void gfs2_free_sort_buffer(void *ptr)
> +{
> +	if (is_vmalloc_addr(ptr))
> +		vfree(ptr);
> +	else
> +		kfree(ptr);
> +}

This got kicked around a bit in May (Subject: mm: generic adaptive
large memory allocation APIs).  That patch tried kmalloc(), then
alloc_pages(), then vmalloc().  Nothing got merged though.

I wasn't terribly excited about it because of vague fears that it would
just incite people to spend even less effort thinking about how large
their individual allocations are.

apparmor has a private kvfree/kvmalloc.  Probably there are other
versions floating around the tree as well.