On Thu, Aug 21 2014, Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote:
> Automatically allocated regions should not cross low/high memory boundary,
> because such regions cannot be later correctly initialized due to spanning
> across two memory zones. This patch adds a check for this case and a simple
> code for moving region to low memory if automatically selected address might
> not fit completely into high memory.
>
> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx>
> ---
> mm/cma.c | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/mm/cma.c b/mm/cma.c
> index c17751c0dcaf..4acc6aa4a086 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -32,6 +32,7 @@
> #include <linux/slab.h>
> #include <linux/log2.h>
> #include <linux/cma.h>
> +#include <linux/highmem.h>
>
> struct cma {
> unsigned long base_pfn;
> @@ -163,6 +164,8 @@ int __init cma_declare_contiguous(phys_addr_t base,
> bool fixed, struct cma **res_cma)
> {
> struct cma *cma;
> + phys_addr_t memblock_end = memblock_end_of_DRAM();
> + phys_addr_t highmem_start = __pa(high_memory);
> int ret = 0;
>
> pr_debug("%s(size %lx, base %08lx, limit %08lx alignment %08lx)\n",
> @@ -196,6 +199,24 @@ int __init cma_declare_contiguous(phys_addr_t base,
> if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit))
> return -EINVAL;
>
> + /*
> + * adjust limit to avoid crossing low/high memory boundary for
> + * automatically allocated regions
> + */
> + if (((limit == 0 || limit > memblock_end) &&
> + (memblock_end - size < highmem_start &&
> + memblock_end > highmem_start)) ||
> + (!fixed && limit > highmem_start && limit - size < highmem_start)) {
> + limit = highmem_start;
> + }
> +
> + if (fixed && base < highmem_start && base+size > highmem_start) {
> + ret = -EINVAL;
> + pr_err("Region at %08lx defined on low/high memory boundary (%08lx)\n",
> + (unsigned long)base, (unsigned long)highmem_start);
> + goto err;
> + }
> +
> /* Reserve memory */
> if (base && fixed) {
> if (memblock_is_region_reserved(base, size) ||
> --
> 1.9.2
>
--
Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, Michał “mina86” Nazarewicz (o o)
ooo +--<mpn@xxxxxxxxxx>--<xmpp:mina86@xxxxxxxxxx>--ooO--(_)--Ooo--
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