2 files changed, 21 insertions, 20 deletions

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 40cac122ec73..0e5985682642 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -228,7 +228,6 @@ static bool pages_correctly_probed(unsigned long start_pfn)
 /*
  * MEMORY_HOTPLUG depends on SPARSEMEM in mm/Kconfig, so it is
  * OK to have direct references to sparsemem variables in here.
- * Must already be protected by mem_hotplug_begin().
  */
 static int
 memory_block_action(unsigned long phys_index, unsigned long action, int online_type)
@@ -294,7 +293,6 @@ static int memory_subsys_online(struct device *dev)
         if (mem->online_type < 0)
                 mem->online_type = MMOP_ONLINE_KEEP;
 
-        /* Already under protection of mem_hotplug_begin() */
         ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
 
         /* clear online_type */
@@ -341,19 +339,11 @@ store_mem_state(struct device *dev,
                 goto err;
         }
 
-        /*
-         * Memory hotplug needs to hold mem_hotplug_begin() for probe to find
-         * the correct memory block to online before doing device_online(dev),
-         * which will take dev->mutex.  Take the lock early to prevent an
-         * inversion, memory_subsys_online() callbacks will be implemented by
-         * assuming it's already protected.
-         */
-        mem_hotplug_begin();
-
         switch (online_type) {
         case MMOP_ONLINE_KERNEL:
         case MMOP_ONLINE_MOVABLE:
         case MMOP_ONLINE_KEEP:
+                /* mem->online_type is protected by device_hotplug_lock */
                 mem->online_type = online_type;
                 ret = device_online(&mem->dev);
                 break;
@@ -364,7 +354,6 @@ store_mem_state(struct device *dev,
                 ret = -EINVAL; /* should never happen */
         }
 
-        mem_hotplug_done();
 err:
         unlock_device_hotplug();
 
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 39cc887bbdcc..61972da38d93 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -838,7 +838,6 @@ static struct zone * __meminit move_pfn_range(int online_type, int nid,
         return zone;
 }
 
-/* Must be protected by mem_hotplug_begin() or a device_lock */
 int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_type)
 {
         unsigned long flags;
@@ -850,6 +849,8 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
         struct memory_notify arg;
         struct memory_block *mem;
 
+        mem_hotplug_begin();
+
         /*
          * We can't use pfn_to_nid() because nid might be stored in struct page
          * which is not yet initialized. Instead, we find nid from memory block.
@@ -914,6 +915,7 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
 
         if (onlined_pages)
                 memory_notify(MEM_ONLINE, &arg);
+        mem_hotplug_done();
         return 0;
 
 failed_addition:
@@ -921,6 +923,7 @@ failed_addition:
                  (unsigned long long) pfn << PAGE_SHIFT,
                  (((unsigned long long) pfn + nr_pages) << PAGE_SHIFT) - 1);
         memory_notify(MEM_CANCEL_ONLINE, &arg);
+        mem_hotplug_done();
         return ret;
 }
 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
@@ -1125,20 +1128,20 @@ int __ref add_memory_resource(int nid, struct resource *res, bool online)
         /* create new memmap entry */
         firmware_map_add_hotplug(start, start + size, "System RAM");
 
+        /* device_online() will take the lock when calling online_pages() */
+        mem_hotplug_done();
+
         /* online pages if requested */
         if (online)
                 walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1),
                                   NULL, online_memory_block);
 
-        goto out;
-
+        return ret;
 error:
         /* rollback pgdat allocation and others */
         if (new_node)
                 rollback_node_hotadd(nid);
         memblock_remove(start, size);
-
-out:
         mem_hotplug_done();
         return ret;
 }
@@ -1555,10 +1558,16 @@ static int __ref __offline_pages(unsigned long start_pfn,
                 return -EINVAL;
         if (!IS_ALIGNED(end_pfn, pageblock_nr_pages))
                 return -EINVAL;
+
+        mem_hotplug_begin();
+
         /* This makes hotplug much easier...and readable.
            we assume this for now. .*/
-        if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start, &valid_end))
+        if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start,
+                                  &valid_end)) {
+                mem_hotplug_done();
                 return -EINVAL;
+        }
 
         zone = page_zone(pfn_to_page(valid_start));
         node = zone_to_nid(zone);
@@ -1567,8 +1576,10 @@ static int __ref __offline_pages(unsigned long start_pfn,
         /* set above range as isolated */
         ret = start_isolate_page_range(start_pfn, end_pfn,
                                        MIGRATE_MOVABLE, true);
-        if (ret)
+        if (ret) {
+                mem_hotplug_done();
                 return ret;
+        }
 
         arg.start_pfn = start_pfn;
         arg.nr_pages = nr_pages;
@@ -1639,6 +1650,7 @@ repeat:
         writeback_set_ratelimit();
 
         memory_notify(MEM_OFFLINE, &arg);
+        mem_hotplug_done();
         return 0;
 
 failed_removal:
@@ -1648,10 +1660,10 @@ failed_removal:
         memory_notify(MEM_CANCEL_OFFLINE, &arg);
         /* pushback to free area */
         undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
+        mem_hotplug_done();
         return ret;
 }
 
-/* Must be protected by mem_hotplug_begin() or a device_lock */
 int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 {
         return __offline_pages(start_pfn, start_pfn + nr_pages);