mm/memory_hotplug: remove memory block devices before arch_remove_memory()

Let's factor out removing of memory block devices, which is only
necessary for memory added via add_memory() and friends that created
memory block devices.  Remove the devices before calling
arch_remove_memory().

This finishes factoring out memory block device handling from
arch_add_memory() and arch_remove_memory().

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

Author: davidhildenbrand

drivers/base/memory.c

@@ -759,32 +759,31 @@ int create_memory_block_devices(unsigned long start, unsigned long size)
 	return ret;
 }
 
-void unregister_memory_section(struct mem_section *section)
+/*
+ * Remove memory block devices for the given memory area. Start and size
+ * have to be aligned to memory block granularity. Memory block devices
+ * have to be offline.
+ */
+void remove_memory_block_devices(unsigned long start, unsigned long size)
 {
+	const int start_block_id = pfn_to_block_id(PFN_DOWN(start));
+	const int end_block_id = pfn_to_block_id(PFN_DOWN(start + size));
 	struct memory_block *mem;
+	int block_id;
 
-	if (WARN_ON_ONCE(!present_section(section)))
+	if (WARN_ON_ONCE(!IS_ALIGNED(start, memory_block_size_bytes()) ||
+			 !IS_ALIGNED(size, memory_block_size_bytes())))
 		return;
 
 	mutex_lock(&mem_sysfs_mutex);
-
-	/*
-	 * Some users of the memory hotplug do not want/need memblock to
-	 * track all sections. Skip over those.
-	 */
-	mem = find_memory_block(section);
-	if (!mem)
-		goto out_unlock;
-
-	unregister_mem_sect_under_nodes(mem, __section_nr(section));
-
-	mem->section_count--;
-	if (mem->section_count == 0)
+	for (block_id = start_block_id; block_id != end_block_id; block_id++) {
+		mem = find_memory_block_by_id(block_id, NULL);
+		if (WARN_ON_ONCE(!mem))
+			continue;
+		mem->section_count = 0;
+		unregister_memory_block_under_nodes(mem);
 		unregister_memory(mem);
-	else
-		put_device(&mem->dev);
-
-out_unlock:
+	}
 	mutex_unlock(&mem_sysfs_mutex);
 }
 

drivers/base/node.c

@@ -802,9 +802,10 @@ int register_mem_sect_under_node(struct memory_block *mem_blk, void *arg)
 	return 0;
 }
 
-/* unregister memory section under all nodes that it spans */
-int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
-				    unsigned long phys_index)
+/*
+ * Unregister memory block device under all nodes that it spans.
+ */
+int unregister_memory_block_under_nodes(struct memory_block *mem_blk)
 {
 	NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL);
 	unsigned long pfn, sect_start_pfn, sect_end_pfn;
@@ -817,8 +818,8 @@ int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
 		return -ENOMEM;
 	nodes_clear(*unlinked_nodes);
 
-	sect_start_pfn = section_nr_to_pfn(phys_index);
-	sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
+	sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr);
+	sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr);
 	for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
 		int nid;
 

include/linux/memory.h

@@ -112,7 +112,7 @@ extern void unregister_memory_notifier(struct notifier_block *nb);
 extern int register_memory_isolate_notifier(struct notifier_block *nb);
 extern void unregister_memory_isolate_notifier(struct notifier_block *nb);
 int create_memory_block_devices(unsigned long start, unsigned long size);
-extern void unregister_memory_section(struct mem_section *);
+void remove_memory_block_devices(unsigned long start, unsigned long size);
 extern int memory_dev_init(void);
 extern int memory_notify(unsigned long val, void *v);
 extern int memory_isolate_notify(unsigned long val, void *v);

include/linux/node.h

@@ -139,8 +139,7 @@ extern int register_cpu_under_node(unsigned int cpu, unsigned int nid);
 extern int unregister_cpu_under_node(unsigned int cpu, unsigned int nid);
 extern int register_mem_sect_under_node(struct memory_block *mem_blk,
 						void *arg);
-extern int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
-					   unsigned long phys_index);
+extern int unregister_memory_block_under_nodes(struct memory_block *mem_blk);
 
 extern int register_memory_node_under_compute_node(unsigned int mem_nid,
 						   unsigned int cpu_nid,
@@ -176,8 +175,7 @@ static inline int register_mem_sect_under_node(struct memory_block *mem_blk,
 {
 	return 0;
 }
-static inline int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
-						  unsigned long phys_index)
+static inline int unregister_memory_block_under_nodes(struct memory_block *mem_blk)
 {
 	return 0;
 }

mm/memory_hotplug.c

@@ -520,8 +520,6 @@ static void __remove_section(struct zone *zone, struct mem_section *ms,
 	if (WARN_ON_ONCE(!valid_section(ms)))
 		return;
 
-	unregister_memory_section(ms);
-
 	scn_nr = __section_nr(ms);
 	start_pfn = section_nr_to_pfn((unsigned long)scn_nr);
 	__remove_zone(zone, start_pfn);
@@ -1834,6 +1832,9 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
 	memblock_free(start, size);
 	memblock_remove(start, size);
 
+	/* remove memory block devices before removing memory */
+	remove_memory_block_devices(start, size);
+
 	arch_remove_memory(nid, start, size, NULL);
 	__release_memory_resource(start, size);