mm/memory_hotplug: allow arch_remove_memory() without CONFIG_MEMORY_HOTREMOVE

We want to improve error handling while adding memory by allowing to use
arch_remove_memory() and __remove_pages() even if
CONFIG_MEMORY_HOTREMOVE is not set to e.g., implement something like:

	arch_add_memory()
	rc = do_something();
	if (rc) {
		arch_remove_memory();
	}

We won't get rid of CONFIG_MEMORY_HOTREMOVE for now, as it will require
quite some dependencies for memory offlining.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Reviewed-by: Pavel Tatashin <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Yoshinori Sato <[email protected]>
Cc: Rich Felker <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Alex Deucher <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: "[email protected]" <[email protected]>
Cc: Andrew Banman <[email protected]>
Cc: Arun KS <[email protected]>
Cc: Qian Cai <[email protected]>
Cc: Mathieu Malaterre <[email protected]>
Cc: Baoquan He <[email protected]>
Cc: Logan Gunthorpe <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Chintan Pandya <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jonathan Cameron <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Jun Yao <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Robin Murphy <[email protected]>
Cc: Wei Yang <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Yu Zhao <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

drivers/base/memory.c

@@ -723,7 +723,6 @@ out:
 	return ret;
 }
 
-#ifdef CONFIG_MEMORY_HOTREMOVE
 static void
 unregister_memory(struct memory_block *memory)
 {
@@ -762,7 +761,6 @@ void unregister_memory_section(struct mem_section *section)
 out_unlock:
 	mutex_unlock(&mem_sysfs_mutex);
 }
-#endif /* CONFIG_MEMORY_HOTREMOVE */
 
 /* return true if the memory block is offlined, otherwise, return false */
 bool is_memblock_offlined(struct memory_block *mem)