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x86, mm: introduce vmem_altmap to augment vmemmap_populate()

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In support of providing struct page for large persistent memory
capacities, use struct vmem_altmap to change the default policy for
allocating memory for the memmap array.  The default vmemmap_populate()
allocates page table storage area from the page allocator.  Given
persistent memory capacities relative to DRAM it may not be feasible to
store the memmap in 'System Memory'.  Instead vmem_altmap represents
pre-allocated "device pages" to satisfy vmemmap_alloc_block_buf()
requests.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: kbuild test robot <lkp@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dan Williams 2016-01-15 16:56:22 -08:00 • committed by Linus Torvalds
parent 9476df7d80
commit 4b94ffdc41
10 changed files with 282 additions and 42 deletions
Download patch file Download diff file Expand all files Collapse all files

72
kernel/memremap.c
View file

@ -166,6 +166,7 @@ struct page_map {
struct resource res;
struct percpu_ref *ref;
struct dev_pagemap pgmap;
struct vmem_altmap altmap;
};
static void pgmap_radix_release(struct resource *res)
@ -183,6 +184,7 @@ static void devm_memremap_pages_release(struct device *dev, void *data)
struct page_map *page_map = data;
struct resource *res = &page_map->res;
resource_size_t align_start, align_size;
struct dev_pagemap *pgmap = &page_map->pgmap;
pgmap_radix_release(res);
@ -190,6 +192,8 @@ static void devm_memremap_pages_release(struct device *dev, void *data)
align_start = res->start & ~(SECTION_SIZE - 1);
align_size = ALIGN(resource_size(res), SECTION_SIZE);
arch_remove_memory(align_start, align_size);
dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc,
"%s: failed to free all reserved pages\n", __func__);
}
/* assumes rcu_read_lock() held at entry */
@ -203,11 +207,23 @@ struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
return page_map ? &page_map->pgmap : NULL;
}
void *devm_memremap_pages(struct device *dev, struct resource *res)
/**
* devm_memremap_pages - remap and provide memmap backing for the given resource
* @dev: hosting device for @res
* @res: "host memory" address range
* @altmap: optional descriptor for allocating the memmap from @res
*
* Note, the expectation is that @res is a host memory range that could
* feasibly be treated as a "System RAM" range, i.e. not a device mmio
* range, but this is not enforced.
*/
void *devm_memremap_pages(struct device *dev, struct resource *res,
struct vmem_altmap *altmap)
{
int is_ram = region_intersects(res->start, resource_size(res),
"System RAM");
resource_size_t key, align_start, align_size;
struct dev_pagemap *pgmap;
struct page_map *page_map;
int error, nid;
@ -220,14 +236,27 @@ void *devm_memremap_pages(struct device *dev, struct resource *res)
if (is_ram == REGION_INTERSECTS)
return __va(res->start);
if (altmap && !IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP)) {
dev_err(dev, "%s: altmap requires CONFIG_SPARSEMEM_VMEMMAP=y\n",
__func__);
return ERR_PTR(-ENXIO);
}
page_map = devres_alloc_node(devm_memremap_pages_release,
sizeof(*page_map), GFP_KERNEL, dev_to_node(dev));
if (!page_map)
return ERR_PTR(-ENOMEM);
pgmap = &page_map->pgmap;
memcpy(&page_map->res, res, sizeof(*res));
page_map->pgmap.dev = dev;
pgmap->dev = dev;
if (altmap) {
memcpy(&page_map->altmap, altmap, sizeof(*altmap));
pgmap->altmap = &page_map->altmap;
}
pgmap->res = &page_map->res;
mutex_lock(&pgmap_lock);
error = 0;
for (key = res->start; key <= res->end; key += SECTION_SIZE) {
@ -273,4 +302,43 @@ void *devm_memremap_pages(struct device *dev, struct resource *res)
return ERR_PTR(error);
}
EXPORT_SYMBOL(devm_memremap_pages);
unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
{
/* number of pfns from base where pfn_to_page() is valid */
return altmap->reserve + altmap->free;
}
void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
{
altmap->alloc -= nr_pfns;
}
#ifdef CONFIG_SPARSEMEM_VMEMMAP
struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
{
/*
* 'memmap_start' is the virtual address for the first "struct
* page" in this range of the vmemmap array. In the case of
* CONFIG_SPARSE_VMEMMAP a page_to_pfn conversion is simple
* pointer arithmetic, so we can perform this to_vmem_altmap()
* conversion without concern for the initialization state of
* the struct page fields.
*/
struct page *page = (struct page *) memmap_start;
struct dev_pagemap *pgmap;
/*
* Uncoditionally retrieve a dev_pagemap associated with the
* given physical address, this is only for use in the
* arch_{add|remove}_memory() for setting up and tearing down
* the memmap.
*/
rcu_read_lock();
pgmap = find_dev_pagemap(__pfn_to_phys(page_to_pfn(page)));
rcu_read_unlock();
return pgmap ? pgmap->altmap : NULL;
}
#endif /* CONFIG_SPARSEMEM_VMEMMAP */
#endif /* CONFIG_ZONE_DEVICE */