Re: [PATCH 3/6] powerpc/vmemmap: Add altmap support

[Balbir Singh]

On Tue, May 23, 2017 at 2:05 PM, Oliver O'Halloran  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 
> ---
>  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 
>  #include 
>  #include 
> +#include 
>
>  #include 
>  #include 
> @@ -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 
>  #include 
>  #include 
> +#include 
>
>  #include 
>  #include 
> @@ -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 

Balbir

[PATCH 3/6] powerpc/vmemmap: Add altmap support

[Oliver O'Halloran]

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 
---
 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 
 #include 
 #include 
+#include 
 
 #include 
 #include 
@@ -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 
 #include 
 #include 
+#include 
 
 #include 
 #include 
@@ -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;
 
-- 
2.9.3