diff --git a/include/exec/ramlist.h b/include/exec/ramlist.h
index 2ad2a81acc..d9cfe530be 100644
--- a/include/exec/ramlist.h
+++ b/include/exec/ramlist.h
@@ -50,6 +50,7 @@ typedef struct RAMList {
     /* RCU-enabled, writes protected by the ramlist lock. */
     QLIST_HEAD(, RAMBlock) blocks;
     DirtyMemoryBlocks *dirty_memory[DIRTY_MEMORY_NUM];
+    unsigned int num_dirty_blocks;
     uint32_t version;
     QLIST_HEAD(, RAMBlockNotifier) ramblock_notifiers;
 } RAMList;
diff --git a/system/physmem.c b/system/physmem.c
index a63853a7bc..073e6c6124 100644
--- a/system/physmem.c
+++ b/system/physmem.c
@@ -1499,18 +1499,6 @@ static ram_addr_t find_ram_offset(ram_addr_t size)
     return offset;
 }
 
-static unsigned long last_ram_page(void)
-{
-    RAMBlock *block;
-    ram_addr_t last = 0;
-
-    RCU_READ_LOCK_GUARD();
-    RAMBLOCK_FOREACH(block) {
-        last = MAX(last, block->offset + block->max_length);
-    }
-    return last >> TARGET_PAGE_BITS;
-}
-
 static void qemu_ram_setup_dump(void *addr, ram_addr_t size)
 {
     int ret;
@@ -1763,13 +1751,11 @@ void qemu_ram_msync(RAMBlock *block, ram_addr_t start, ram_addr_t length)
 }
 
 /* Called with ram_list.mutex held */
-static void dirty_memory_extend(ram_addr_t old_ram_size,
-                                ram_addr_t new_ram_size)
+static void dirty_memory_extend(ram_addr_t new_ram_size)
 {
-    ram_addr_t old_num_blocks = DIV_ROUND_UP(old_ram_size,
-                                             DIRTY_MEMORY_BLOCK_SIZE);
-    ram_addr_t new_num_blocks = DIV_ROUND_UP(new_ram_size,
-                                             DIRTY_MEMORY_BLOCK_SIZE);
+    unsigned int old_num_blocks = ram_list.num_dirty_blocks;
+    unsigned int new_num_blocks = DIV_ROUND_UP(new_ram_size,
+                                               DIRTY_MEMORY_BLOCK_SIZE);
     int i;
 
     /* Only need to extend if block count increased */
@@ -1801,6 +1787,8 @@ static void dirty_memory_extend(ram_addr_t old_ram_size,
             g_free_rcu(old_blocks, rcu);
         }
     }
+
+    ram_list.num_dirty_blocks = new_num_blocks;
 }
 
 static void ram_block_add(RAMBlock *new_block, Error **errp)
@@ -1809,11 +1797,9 @@ static void ram_block_add(RAMBlock *new_block, Error **errp)
     const bool shared = qemu_ram_is_shared(new_block);
     RAMBlock *block;
     RAMBlock *last_block = NULL;
-    ram_addr_t old_ram_size, new_ram_size;
+    ram_addr_t ram_size;
     Error *err = NULL;
 
-    old_ram_size = last_ram_page();
-
     qemu_mutex_lock_ramlist();
     new_block->offset = find_ram_offset(new_block->max_length);
 
@@ -1841,11 +1827,8 @@ static void ram_block_add(RAMBlock *new_block, Error **errp)
         }
     }
 
-    new_ram_size = MAX(old_ram_size,
-              (new_block->offset + new_block->max_length) >> TARGET_PAGE_BITS);
-    if (new_ram_size > old_ram_size) {
-        dirty_memory_extend(old_ram_size, new_ram_size);
-    }
+    ram_size = (new_block->offset + new_block->max_length) >> TARGET_PAGE_BITS;
+    dirty_memory_extend(ram_size);
     /* Keep the list sorted from biggest to smallest block.  Unlike QTAILQ,
      * QLIST (which has an RCU-friendly variant) does not have insertion at
      * tail, so save the last element in last_block.