3 files changed, 55 insertions, 0 deletions

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 83d0b17ba1c2..a51007b79032 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -693,6 +693,12 @@ int offline_memory_block(struct memory_block *mem)
         return ret;
 }
 
+/* return true if the memory block is offlined, otherwise, return false */
+bool is_memblock_offlined(struct memory_block *mem)
+{
+        return mem->state == MEM_OFFLINE;
+}
+
 /*
  * Initialize the sysfs support for memory devices...
  */
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 4a45c4e50025..8dd0950a6a7a 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -247,6 +247,7 @@ extern int add_memory(int nid, u64 start, u64 size);
 extern int arch_add_memory(int nid, u64 start, u64 size);
 extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
 extern int offline_memory_block(struct memory_block *mem);
+extern bool is_memblock_offlined(struct memory_block *mem);
 extern int remove_memory(u64 start, u64 size);
 extern int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
                                                                 int nr_pages);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 6a82972aeae5..5d350f5c68e5 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1429,6 +1429,54 @@ repeat:
                 goto repeat;
         }
 
+        lock_memory_hotplug();
+
+        /*
+         * we have offlined all memory blocks like this:
+         *   1. lock memory hotplug
+         *   2. offline a memory block
+         *   3. unlock memory hotplug
+         *
+         * repeat step1-3 to offline the memory block. All memory blocks
+         * must be offlined before removing memory. But we don't hold the
+         * lock in the whole operation. So we should check whether all
+         * memory blocks are offlined.
+         */
+
+        mem = NULL;
+        for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+                section_nr = pfn_to_section_nr(pfn);
+                if (!present_section_nr(section_nr))
+                        continue;
+
+                section = __nr_to_section(section_nr);
+                /* same memblock? */
+                if (mem)
+                        if ((section_nr >= mem->start_section_nr) &&
+                            (section_nr <= mem->end_section_nr))
+                                continue;
+
+                mem = find_memory_block_hinted(section, mem);
+                if (!mem)
+                        continue;
+
+                ret = is_memblock_offlined(mem);
+                if (!ret) {
+                        pr_warn("removing memory fails, because memory "
+                                "[%#010llx-%#010llx] is onlined\n",
+                                PFN_PHYS(section_nr_to_pfn(mem->start_section_nr)),
+                                PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1)) - 1);
+
+                        kobject_put(&mem->dev.kobj);
+                        unlock_memory_hotplug();
+                        return ret;
+                }
+        }
+
+        if (mem)
+                kobject_put(&mem->dev.kobj);
+        unlock_memory_hotplug();
+
         return 0;
 }
 #else