mm: clean up is_device_*_page() definitions

Refactor is_device_{public,private}_page() with is_pci_p2pdma_page() to
make them all consistent in depending on their respective config options
even when CONFIG_DEV_PAGEMAP_OPS is enabled for other reasons.  This
allows a little more compile-time optimisation as well as the conceptual
and cosmetic cleanup.

Link: http://lkml.kernel.org/r/187c2ab27dea70635d375a61b2f2076d26c032b0.1558547956.git.robin.murphy@arm.comSigned-off-by: Robin Murphy <robin.murphy@arm.com>
Suggested-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oliver O'Halloran <oohall@gmail.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mm.h

@@ -956,41 +956,28 @@ static inline bool put_devmap_managed_page(struct page *page)
 	return false;
 }
 
-static inline bool is_device_private_page(const struct page *page)
-{
-	return is_zone_device_page(page) &&
-		page->pgmap->type == MEMORY_DEVICE_PRIVATE;
-}
-
-#ifdef CONFIG_PCI_P2PDMA
-static inline bool is_pci_p2pdma_page(const struct page *page)
-{
-	return is_zone_device_page(page) &&
-		page->pgmap->type == MEMORY_DEVICE_PCI_P2PDMA;
-}
-#else /* CONFIG_PCI_P2PDMA */
-static inline bool is_pci_p2pdma_page(const struct page *page)
-{
-	return false;
-}
-#endif /* CONFIG_PCI_P2PDMA */
-
 #else /* CONFIG_DEV_PAGEMAP_OPS */
 static inline bool put_devmap_managed_page(struct page *page)
 {
 	return false;
 }
+#endif /* CONFIG_DEV_PAGEMAP_OPS */
 
 static inline bool is_device_private_page(const struct page *page)
 {
-	return false;
+	return IS_ENABLED(CONFIG_DEV_PAGEMAP_OPS) &&
+		IS_ENABLED(CONFIG_DEVICE_PRIVATE) &&
+		is_zone_device_page(page) &&
+		page->pgmap->type == MEMORY_DEVICE_PRIVATE;
 }
 
 static inline bool is_pci_p2pdma_page(const struct page *page)
 {
-	return false;
+	return IS_ENABLED(CONFIG_DEV_PAGEMAP_OPS) &&
+		IS_ENABLED(CONFIG_PCI_P2PDMA) &&
+		is_zone_device_page(page) &&
+		page->pgmap->type == MEMORY_DEVICE_PCI_P2PDMA;
 }
-#endif /* CONFIG_DEV_PAGEMAP_OPS */
 
 /* 127: arbitrary random number, small enough to assemble well */
 #define page_ref_zero_or_close_to_overflow(page) \