mm/memory_hotplug: rename walk_memory_range() and pass start+size instead of pfns

walk_memory_range() was once used to iterate over sections.  Now, it
iterates over memory blocks.  Rename the function, fixup the
documentation.

Also, pass start+size instead of PFNs, which is what most callers
already have at hand.  (we'll rework link_mem_sections() most probably
soon)

Follow-up patches will rework, simplify, and move walk_memory_blocks()
to drivers/base/memory.c.

Note: walk_memory_blocks() only works correctly right now if the
start_pfn is aligned to a section start.  This is the case right now,
but we'll generalize the function in a follow up patch so the semantics
match the documentation.

[akpm@linux-foundation.org: remove unused variable]
Link: http://lkml.kernel.org/r/20190614100114.311-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Rashmica Gupta <rashmica.g@gmail.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memory_hotplug.c

@@ -1124,8 +1124,7 @@ int __ref add_memory_resource(int nid, struct resource *res)
 
 	/* online pages if requested */
 	if (memhp_auto_online)
-		walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1),
-				  NULL, online_memory_block);
+		walk_memory_blocks(start, size, NULL, online_memory_block);
 
 	return ret;
 error:
@@ -1663,20 +1662,24 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 
 /**
- * walk_memory_range - walks through all mem sections in [start_pfn, end_pfn)
- * @start_pfn: start pfn of the memory range
- * @end_pfn: end pfn of the memory range
- * @arg: argument passed to func
- * @func: callback for each memory section walked
+ * walk_memory_blocks - walk through all present memory blocks overlapped
+ *			by the range [start, start + size)
  *
- * This function walks through all present mem sections in range
- * [start_pfn, end_pfn) and call func on each mem section.
+ * @start: start address of the memory range
+ * @size: size of the memory range
+ * @arg: argument passed to func
+ * @func: callback for each memory block walked
+ *
+ * This function walks through all present memory blocks overlapped by the
+ * range [start, start + size), calling func on each memory block.
  *
  * Returns the return value of func.
  */
-int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
+int walk_memory_blocks(unsigned long start, unsigned long size,
 		void *arg, int (*func)(struct memory_block *, void *))
 {
+	const unsigned long start_pfn = PFN_DOWN(start);
+	const unsigned long end_pfn = PFN_UP(start + size - 1);
 	struct memory_block *mem = NULL;
 	struct mem_section *section;
 	unsigned long pfn, section_nr;
@@ -1822,8 +1825,7 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
 	 * whether all memory blocks in question are offline and return error
 	 * if this is not the case.
 	 */
-	rc = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1), NULL,
-			       check_memblock_offlined_cb);
+	rc = walk_memory_blocks(start, size, NULL, check_memblock_offlined_cb);
 	if (rc)
 		goto done;