On Tue, May 23, 2017 at 2:05 PM, Oliver O'Halloran <oohall@xxxxxxxxx> wrote:
> Adds support to powerpc for the altmap feature of ZONE_DEVICE memory. An
> altmap is a driver provided region that is used to provide the backing
> storage for the struct pages of ZONE_DEVICE memory. In situations where
> large amount of ZONE_DEVICE memory is being added to the system the
> altmap reduces pressure on main system memory by allowing the mm/
> metadata to be stored on the device itself rather in main memory.
>
> Signed-off-by: Oliver O'Halloran <oohall@xxxxxxxxx>
> ---
> arch/powerpc/mm/init_64.c | 15 +++++++++++++--
> arch/powerpc/mm/mem.c | 16 +++++++++++++---
> 2 files changed, 26 insertions(+), 5 deletions(-)
>
> diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
> index 8851e4f5dbab..225fbb8034e6 100644
> --- a/arch/powerpc/mm/init_64.c
> +++ b/arch/powerpc/mm/init_64.c
> @@ -44,6 +44,7 @@
> #include <linux/slab.h>
> #include <linux/of_fdt.h>
> #include <linux/libfdt.h>
> +#include <linux/memremap.h>
>
> #include <asm/pgalloc.h>
> #include <asm/page.h>
> @@ -171,13 +172,17 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
> pr_debug("vmemmap_populate %lx..%lx, node %d\n", start, end, node);
>
> for (; start < end; start += page_size) {
> + struct vmem_altmap *altmap;
> void *p;
> int rc;
>
> if (vmemmap_populated(start, page_size))
> continue;
>
> - p = vmemmap_alloc_block(page_size, node);
> + /* altmap lookups only work at section boundaries */
> + altmap = to_vmem_altmap(SECTION_ALIGN_DOWN(start));
> +
> + p = __vmemmap_alloc_block_buf(page_size, node, altmap);
> if (!p)
> return -ENOMEM;
>
> @@ -242,6 +247,8 @@ void __ref vmemmap_free(unsigned long start, unsigned long end)
>
> for (; start < end; start += page_size) {
> unsigned long nr_pages, addr;
> + struct vmem_altmap *altmap;
> + struct page *section_base;
> struct page *page;
>
> /*
> @@ -257,9 +264,13 @@ void __ref vmemmap_free(unsigned long start, unsigned long end)
> continue;
>
> page = pfn_to_page(addr >> PAGE_SHIFT);
> + section_base = pfn_to_page(vmemmap_section_start(start));
> nr_pages = 1 << page_order;
>
> - if (PageReserved(page)) {
> + altmap = to_vmem_altmap((unsigned long) section_base);
> + if (altmap) {
> + vmem_altmap_free(altmap, nr_pages);
> + } else if (PageReserved(page)) {
> /* allocated from bootmem */
> if (page_size < PAGE_SIZE) {
> /*
> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
> index 9ee536ec0739..2c0c16f11eee 100644
> --- a/arch/powerpc/mm/mem.c
> +++ b/arch/powerpc/mm/mem.c
> @@ -36,6 +36,7 @@
> #include <linux/hugetlb.h>
> #include <linux/slab.h>
> #include <linux/vmalloc.h>
> +#include <linux/memremap.h>
>
> #include <asm/pgalloc.h>
> #include <asm/prom.h>
> @@ -159,11 +160,20 @@ int arch_remove_memory(u64 start, u64 size)
> {
> unsigned long start_pfn = start >> PAGE_SHIFT;
> unsigned long nr_pages = size >> PAGE_SHIFT;
> - struct zone *zone;
> + struct vmem_altmap *altmap;
> + struct page *page;
> int ret;
>
> - zone = page_zone(pfn_to_page(start_pfn));
> - ret = __remove_pages(zone, start_pfn, nr_pages);
> + /*
> + * If we have an altmap then we need to skip over any reserved PFNs
> + * when querying the zone.
> + */
> + page = pfn_to_page(start_pfn);
> + altmap = to_vmem_altmap((unsigned long) page);
> + if (altmap)
> + page += vmem_altmap_offset(altmap);
> +
> + ret = __remove_pages(page_zone(page), start_pfn, nr_pages);
> if (ret)
> return ret;
Reviewed-by: Balbir Singh <bsingharora@xxxxxxxxx>
Balbir
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