memremap: remove to_vmem_altmap

All callers are gone now.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

include/linux/memremap.h

@@ -26,15 +26,6 @@ struct vmem_altmap {
 	unsigned long alloc;
 };
 
-#ifdef CONFIG_ZONE_DEVICE
-struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start);
-#else
-static inline struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
-{
-	return NULL;
-}
-#endif
-
 /*
  * Specialize ZONE_DEVICE memory into multiple types each having differents
  * usage.

kernel/memremap.c

@@ -476,32 +476,6 @@ void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
 	altmap->alloc -= nr_pfns;
 }
 
-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_SPARSEMEM_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;
-
-	/*
-	 * Unconditionally 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;
-}
-
 /**
  * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
  * @pfn: page frame number to lookup page_map