[PATCH v2 3/4] mm: cma: Ensure that reservations never cross the low/high mem boundary

[Michal Nazarewicz]

On Fri, Oct 24 2014, Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com> wrote:
> Commit 95b0e655f914 ("ARM: mm: don't limit default CMA region only to
> low memory") extended CMA memory reservation to allow usage of high
> memory. It relied on commit f7426b983a6a ("mm: cma: adjust address limit
> to avoid hitting low/high memory boundary") to ensure that the reserved
> block never crossed the low/high memory boundary. While the
> implementation correctly lowered the limit, it failed to consider the
> case where the base..limit range crossed the low/high memory boundary
> with enough space on each side to reserve the requested size on either
> low or high memory.
>
> Rework the base and limit adjustment to fix the problem. The function
> now starts by rejecting the reservation altogether for fixed
> reservations that cross the boundary, tries to reserve from high memory
> first and then falls back to low memory.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com>

Acked-by: Michal Nazarewicz <mina86 at mina86.com>