1 files changed, 15 insertions, 74 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 7cd4377ac83e..8dccc317aac2 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -52,32 +52,17 @@ static void generic_online_page(struct page *page);
 static online_page_callback_t online_page_callback = generic_online_page;
 static DEFINE_MUTEX(online_page_callback_lock);
 
-/* The same as the cpu_hotplug lock, but for memory hotplug. */
-static struct {
-	struct task_struct *active_writer;
-	struct mutex lock; /* Synchronizes accesses to refcount, */
-	/*
-	 * Also blocks the new readers during
-	 * an ongoing mem hotplug operation.
-	 */
-	int refcount;
+DEFINE_STATIC_PERCPU_RWSEM(mem_hotplug_lock);
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-	struct lockdep_map dep_map;
-#endif
-} mem_hotplug = {
-	.active_writer = NULL,
-	.lock = __MUTEX_INITIALIZER(mem_hotplug.lock),
-	.refcount = 0,
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-	.dep_map = {.name = "mem_hotplug.lock" },
-#endif
-};
+void get_online_mems(void)
+{
+	percpu_down_read(&mem_hotplug_lock);
+}
 
-/* Lockdep annotations for get/put_online_mems() and mem_hotplug_begin/end() */
-#define memhp_lock_acquire_read() lock_map_acquire_read(&mem_hotplug.dep_map)
-#define memhp_lock_acquire()      lock_map_acquire(&mem_hotplug.dep_map)
-#define memhp_lock_release()      lock_map_release(&mem_hotplug.dep_map)
+void put_online_mems(void)
+{
+	percpu_up_read(&mem_hotplug_lock);
+}
 
 bool movable_node_enabled = false;
 
@@ -99,60 +84,16 @@ static int __init setup_memhp_default_state(char *str)
 }
 __setup("memhp_default_state=", setup_memhp_default_state);
 
-void get_online_mems(void)
-{
-	might_sleep();
-	if (mem_hotplug.active_writer == current)
-		return;
-	memhp_lock_acquire_read();
-	mutex_lock(&mem_hotplug.lock);
-	mem_hotplug.refcount++;
-	mutex_unlock(&mem_hotplug.lock);
-
-}
-
-void put_online_mems(void)
-{
-	if (mem_hotplug.active_writer == current)
-		return;
-	mutex_lock(&mem_hotplug.lock);
-
-	if (WARN_ON(!mem_hotplug.refcount))
-		mem_hotplug.refcount++; /* try to fix things up */
-
-	if (!--mem_hotplug.refcount && unlikely(mem_hotplug.active_writer))
-		wake_up_process(mem_hotplug.active_writer);
-	mutex_unlock(&mem_hotplug.lock);
-	memhp_lock_release();
-
-}
-
-/* Serializes write accesses to mem_hotplug.active_writer. */
-static DEFINE_MUTEX(memory_add_remove_lock);
-
 void mem_hotplug_begin(void)
 {
-	mutex_lock(&memory_add_remove_lock);
-
-	mem_hotplug.active_writer = current;
-
-	memhp_lock_acquire();
-	for (;;) {
-		mutex_lock(&mem_hotplug.lock);
-		if (likely(!mem_hotplug.refcount))
-			break;
-		__set_current_state(TASK_UNINTERRUPTIBLE);
-		mutex_unlock(&mem_hotplug.lock);
-		schedule();
-	}
+	cpus_read_lock();
+	percpu_down_write(&mem_hotplug_lock);
 }
 
 void mem_hotplug_done(void)
 {
-	mem_hotplug.active_writer = NULL;
-	mutex_unlock(&mem_hotplug.lock);
-	memhp_lock_release();
-	mutex_unlock(&memory_add_remove_lock);
+	percpu_up_write(&mem_hotplug_lock);
+	cpus_read_unlock();
 }
 
 /* add this memory to iomem resource */
@@ -1725,7 +1666,7 @@ repeat:
 		goto failed_removal;
 	ret = 0;
 	if (drain) {
-		lru_add_drain_all();
+		lru_add_drain_all_cpuslocked();
 		cond_resched();
 		drain_all_pages(zone);
 	}
@@ -1746,7 +1687,7 @@ repeat:
 		}
 	}
 	/* drain all zone's lru pagevec, this is asynchronous... */
-	lru_add_drain_all();
+	lru_add_drain_all_cpuslocked();
 	yield();
 	/* drain pcp pages, this is synchronous. */
 	drain_all_pages(zone);