[patch 06/24] lmb: add lmb_alloc_nid()

[Paul Mackerras]

akpm at linux-foundation.org writes:

> From: David Miller <davem at davemloft.net>
> 
> A variant of lmb_alloc() that tries to allocate memory on a specified NUMA
> node 'nid' but falls back to normal lmb_alloc() if that fails.

...

> +static u64 __init lmb_alloc_nid_unreserved(u64 start, u64 end,
> +					   u64 size, u64 align)
> +{
> +	u64 base;
> +	long j;
> +
> +	base = lmb_align_down((end - size), align);
> +	while (start <= base &&
> +	       ((j = lmb_overlaps_region(&lmb.reserved, base, size)) >= 0))
> +		base = lmb_align_down(lmb.reserved.region[j].base - size,
> +				      align);

How do we know that lmb.reserved.region[j].base is >= size at this
point?  If it isn't, then base could end up as some extremely large
unsigned value, which would be a Bad Thing.

Paul.