On 11/16/2016 06:19 AM, Jason Liu wrote:
> If the cma reserve region goes through the device-tree method,
> also need ensure the cma reserved region not cross the low/high
> mem boundary. This patch did the similar fix as commit:16195dd
> ("mm: cma: Ensure that reservations never cross the low/high mem boundary")
>
> Signed-off-by: Jason Liu <jason.hui....@nxp.com>
> Cc: Marek Szyprowski <m.szyprow...@samsung.com>
> Cc: Joonsoo Kim <iamjoonsoo....@lge.com>
> Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
> ---
> drivers/base/dma-contiguous.c | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c
> index e167a1e1..2bc093c 100644
> --- a/drivers/base/dma-contiguous.c
> +++ b/drivers/base/dma-contiguous.c
> @@ -244,6 +244,7 @@ static int __init rmem_cma_setup(struct reserved_mem
> *rmem)
> {
> phys_addr_t align = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
> phys_addr_t mask = align - 1;
> + phys_addr_t highmem_start;
> unsigned long node = rmem->fdt_node;
> struct cma *cma;
> int err;
> @@ -256,6 +257,32 @@ static int __init rmem_cma_setup(struct reserved_mem
> *rmem)
> pr_err("Reserved memory: incorrect alignment of CMA region\n");
> return -EINVAL;
> }
> +#ifdef CONFIG_X86
> + /*
> + * high_memory isn't direct mapped memory so retrieving its physical
> + * address isn't appropriate. But it would be useful to check the
> + * physical address of the highmem boundary so it's justfiable to get
> + * the physical address from it. On x86 there is a validation check for
> + * this case, so the following workaround is needed to avoid it.
> + */
> + highmem_start = __pa_nodebug(high_memory);
> +#else
> + highmem_start = __pa(high_memory);
> +#endif
The inline #ifdef is not great style, we shouldn't be spreading it around.
> +
> + /*
> + * All pages in the reserved area must come from the same zone.
> + * If the reserved region crosses the low/high memory boundary,
> + * try to fix it up and then fall back to allocate from the low mem
> + */
> + if (rmem->base < highmem_start &&
> + (rmem->base + rmem->size) > highmem_start) {
> + memblock_free(rmem->base, rmem->size);
> + rmem->base = memblock_alloc_range(rmem->size, align, 0,
> + highmem_start, MEMBLOCK_NONE);
> + if (!rmem->base)
> + return -ENOMEM;
> + }
Given the alloc happened in the of code, it seems bad form to be
bringing the free and re-alloc here. Perhaps we should be doing the
limiting and checking in the reserved mem code?
If there is no other solution, at the least this deserves a pr_warn
so users know why a reason specified may not be getting requested.
>
> err = cma_init_reserved_mem(rmem->base, rmem->size, 0, &cma);
> if (err) {
>
Thanks,
Laura
