Re: [PATCH v2] mm/sparse: Remove sparse buffer pre-allocation mechanism

[Mike Rapoport <rppt@kernel.org>]

On Mon, Apr 13, 2026 at 09:02:43PM +0200, David Hildenbrand (Arm) wrote:
> > -
> > -void * __meminit sparse_buffer_alloc(unsigned long size)
> > -{
> > -	void *ptr = NULL;
> > -
> > -	if (sparsemap_buf) {
> > -		ptr = (void *) roundup((unsigned long)sparsemap_buf, size);
> > -		if (ptr + size > sparsemap_buf_end)
> > -			ptr = NULL;
> > -		else {
> > -			/* Free redundant aligned space */
> > -			if ((unsigned long)(ptr - sparsemap_buf) > 0)
> > -				sparse_buffer_free((unsigned long)(ptr - sparsemap_buf));
> > -			sparsemap_buf = ptr + size;
> 
> This code implied, that we would usually get contiguous memory sections
> (on the same node) to have contiguous PFNs in the SPARSE !VMEMMAP case.
> That will no longer be the case (reliably).
> 
> The code must be prepared to handle that, so I guess that is fine. And
> we don't care that much about SPARSE !VMEMMAP.

I've started to hunt them down ;-P 

https://lore.kernel.org/all/20260413104649.852228-1-rppt@kernel.org/
 
> Acked-by: David Hildenbrand (Arm) <david@kernel.org>
> 
> -- 
> Cheers,
> 
> David

-- 
Sincerely yours,
Mike.