Merge branch 'pm-sleep'

Merge system-wide power management updates for 6.8-rc1:

 - Fix possible deadlocks in the core system-wide PM code that occur if
   device-handling functions cannot be executed asynchronously during
   resune from system-wide suspend (Rafael J. Wysocki).

 - Clean up unnecessary local variable initializations in multiple
   places in the hibernation code (Wang chaodong, Li zeming).

 - Adjust core hibernation code to avoid missing wakeup events that
   occur after saving an image to persistent storage (Chris Feng).

 - Update hibernation code to enforce correct ordering during image
   compression and decompression (Hongchen Zhang).

 - Use kmap_local_page() instead of kmap_atomic() in copy_data_page()
   during hibernation and restore (Chen Haonan).

 - Adjust documentation and code comments to reflect recent task freezer
   changes (Kevin Hao).

 - Repair excess function parameter description warning in the
   hibernation image-saving code (Randy Dunlap).

* pm-sleep:
  PM: sleep: Fix possible deadlocks in core system-wide PM code
  async: Introduce async_schedule_dev_nocall()
  async: Split async_schedule_node_domain()
  PM: hibernate: Repair excess function parameter description warning
  PM: sleep: Remove obsolete comment from unlock_system_sleep()
  Documentation: PM: Adjust freezing-of-tasks.rst to the freezer changes
  PM: hibernate: Use kmap_local_page() in copy_data_page()
  PM: hibernate: Enforce ordering during image compression/decompression
  PM: hibernate: Avoid missing wakeup events during hibernation
  PM: hibernate: Do not initialize error in snapshot_write_next()
  PM: hibernate: Do not initialize error in swap_write_page()
  PM: hibernate: Drop unnecessary local variable initialization

Documentation/power/freezing-of-tasks.rst

@@ -14,27 +14,28 @@ architectures).
 II. How does it work?
 =====================
 
-There are three per-task flags used for that, PF_NOFREEZE, PF_FROZEN
-and PF_FREEZER_SKIP (the last one is auxiliary).  The tasks that have
-PF_NOFREEZE unset (all user space processes and some kernel threads) are
-regarded as 'freezable' and treated in a special way before the system enters a
-suspend state as well as before a hibernation image is created (in what follows
-we only consider hibernation, but the description also applies to suspend).
+There is one per-task flag (PF_NOFREEZE) and three per-task states
+(TASK_FROZEN, TASK_FREEZABLE and __TASK_FREEZABLE_UNSAFE) used for that.
+The tasks that have PF_NOFREEZE unset (all user space tasks and some kernel
+threads) are regarded as 'freezable' and treated in a special way before the
+system enters a sleep state as well as before a hibernation image is created
+(hibernation is directly covered by what follows, but the description applies
+to system-wide suspend too).
 
 Namely, as the first step of the hibernation procedure the function
 freeze_processes() (defined in kernel/power/process.c) is called.  A system-wide
-variable system_freezing_cnt (as opposed to a per-task flag) is used to indicate
-whether the system is to undergo a freezing operation. And freeze_processes()
-sets this variable.  After this, it executes try_to_freeze_tasks() that sends a
-fake signal to all user space processes, and wakes up all the kernel threads.
-All freezable tasks must react to that by calling try_to_freeze(), which
-results in a call to __refrigerator() (defined in kernel/freezer.c), which sets
-the task's PF_FROZEN flag, changes its state to TASK_UNINTERRUPTIBLE and makes
-it loop until PF_FROZEN is cleared for it. Then, we say that the task is
-'frozen' and therefore the set of functions handling this mechanism is referred
-to as 'the freezer' (these functions are defined in kernel/power/process.c,
-kernel/freezer.c & include/linux/freezer.h). User space processes are generally
-frozen before kernel threads.
+static key freezer_active (as opposed to a per-task flag or state) is used to
+indicate whether the system is to undergo a freezing operation. And
+freeze_processes() sets this static key.  After this, it executes
+try_to_freeze_tasks() that sends a fake signal to all user space processes, and
+wakes up all the kernel threads. All freezable tasks must react to that by
+calling try_to_freeze(), which results in a call to __refrigerator() (defined
+in kernel/freezer.c), which changes the task's state to TASK_FROZEN, and makes
+it loop until it is woken by an explicit TASK_FROZEN wakeup. Then, that task
+is regarded as 'frozen' and so the set of functions handling this mechanism is
+referred to as 'the freezer' (these functions are defined in
+kernel/power/process.c, kernel/freezer.c & include/linux/freezer.h). User space
+tasks are generally frozen before kernel threads.
 
 __refrigerator() must not be called directly.  Instead, use the
 try_to_freeze() function (defined in include/linux/freezer.h), that checks
@@ -43,31 +44,40 @@ if the task is to be frozen and makes the task enter __refrigerator().
 For user space processes try_to_freeze() is called automatically from the
 signal-handling code, but the freezable kernel threads need to call it
 explicitly in suitable places or use the wait_event_freezable() or
-wait_event_freezable_timeout() macros (defined in include/linux/freezer.h)
-that combine interruptible sleep with checking if the task is to be frozen and
-calling try_to_freeze().  The main loop of a freezable kernel thread may look
+wait_event_freezable_timeout() macros (defined in include/linux/wait.h)
+that put the task to sleep (TASK_INTERRUPTIBLE) or freeze it (TASK_FROZEN) if
+freezer_active is set. The main loop of a freezable kernel thread may look
 like the following one::
 
 	set_freezable();
-	do {
-		hub_events();
-		wait_event_freezable(khubd_wait,
-				!list_empty(&hub_event_list) ||
-				kthread_should_stop());
-	} while (!kthread_should_stop() || !list_empty(&hub_event_list));
-
-(from drivers/usb/core/hub.c::hub_thread()).
-
-If a freezable kernel thread fails to call try_to_freeze() after the freezer has
-initiated a freezing operation, the freezing of tasks will fail and the entire
-hibernation operation will be cancelled.  For this reason, freezable kernel
-threads must call try_to_freeze() somewhere or use one of the
+
+	while (true) {
+		struct task_struct *tsk = NULL;
+
+		wait_event_freezable(oom_reaper_wait, oom_reaper_list != NULL);
+		spin_lock_irq(&oom_reaper_lock);
+		if (oom_reaper_list != NULL) {
+			tsk = oom_reaper_list;
+			oom_reaper_list = tsk->oom_reaper_list;
+		}
+		spin_unlock_irq(&oom_reaper_lock);
+
+		if (tsk)
+			oom_reap_task(tsk);
+	}
+
+(from mm/oom_kill.c::oom_reaper()).
+
+If a freezable kernel thread is not put to the frozen state after the freezer
+has initiated a freezing operation, the freezing of tasks will fail and the
+entire system-wide transition will be cancelled.  For this reason, freezable
+kernel threads must call try_to_freeze() somewhere or use one of the
 wait_event_freezable() and wait_event_freezable_timeout() macros.
 
 After the system memory state has been restored from a hibernation image and
 devices have been reinitialized, the function thaw_processes() is called in
-order to clear the PF_FROZEN flag for each frozen task.  Then, the tasks that
-have been frozen leave __refrigerator() and continue running.
+order to wake up each frozen task.  Then, the tasks that have been frozen leave
+__refrigerator() and continue running.
 
 
 Rationale behind the functions dealing with freezing and thawing of tasks
@@ -96,7 +106,8 @@ III. Which kernel threads are freezable?
 Kernel threads are not freezable by default.  However, a kernel thread may clear
 PF_NOFREEZE for itself by calling set_freezable() (the resetting of PF_NOFREEZE
 directly is not allowed).  From this point it is regarded as freezable
-and must call try_to_freeze() in a suitable place.
+and must call try_to_freeze() or variants of wait_event_freezable() in a
+suitable place.
 
 IV. Why do we do that?
 ======================

drivers/base/power/main.c

@@ -579,7 +579,7 @@ bool dev_pm_skip_resume(struct device *dev)
 }
 
 /**
- * device_resume_noirq - Execute a "noirq resume" callback for given device.
+ * __device_resume_noirq - Execute a "noirq resume" callback for given device.
  * @dev: Device to handle.
  * @state: PM transition of the system being carried out.
  * @async: If true, the device is being resumed asynchronously.
@@ -587,7 +587,7 @@ bool dev_pm_skip_resume(struct device *dev)
  * The driver of @dev will not receive interrupts while this function is being
  * executed.
  */
-static int device_resume_noirq(struct device *dev, pm_message_t state, bool async)
+static void __device_resume_noirq(struct device *dev, pm_message_t state, bool async)
 {
 	pm_callback_t callback = NULL;
 	const char *info = NULL;
@@ -655,7 +655,13 @@ static int device_resume_noirq(struct device *dev, pm_message_t state, bool asyn
 Out:
 	complete_all(&dev->power.completion);
 	TRACE_RESUME(error);
-	return error;
+
+	if (error) {
+		suspend_stats.failed_resume_noirq++;
+		dpm_save_failed_step(SUSPEND_RESUME_NOIRQ);
+		dpm_save_failed_dev(dev_name(dev));
+		pm_dev_err(dev, state, async ? " async noirq" : " noirq", error);
+	}
 }
 
 static bool is_async(struct device *dev)
@@ -668,11 +674,15 @@ static bool dpm_async_fn(struct device *dev, async_func_t func)
 {
 	reinit_completion(&dev->power.completion);
 
-	if (is_async(dev)) {
-		get_device(dev);
-		async_schedule_dev(func, dev);
+	if (!is_async(dev))
+		return false;
+
+	get_device(dev);
+
+	if (async_schedule_dev_nocall(func, dev))
 		return true;
-	}
+
+	put_device(dev);
 
 	return false;
 }
@@ -680,15 +690,19 @@ static bool dpm_async_fn(struct device *dev, async_func_t func)
 static void async_resume_noirq(void *data, async_cookie_t cookie)
 {
 	struct device *dev = data;
-	int error;
-
-	error = device_resume_noirq(dev, pm_transition, true);
-	if (error)
-		pm_dev_err(dev, pm_transition, " async", error);
 
+	__device_resume_noirq(dev, pm_transition, true);
 	put_device(dev);
 }
 
+static void device_resume_noirq(struct device *dev)
+{
+	if (dpm_async_fn(dev, async_resume_noirq))
+		return;
+
+	__device_resume_noirq(dev, pm_transition, false);
+}
+
 static void dpm_noirq_resume_devices(pm_message_t state)
 {
 	struct device *dev;
@@ -698,14 +712,6 @@ static void dpm_noirq_resume_devices(pm_message_t state)
 	mutex_lock(&dpm_list_mtx);
 	pm_transition = state;
 
-	/*
-	 * Advanced the async threads upfront,
-	 * in case the starting of async threads is
-	 * delayed by non-async resuming devices.
-	 */
-	list_for_each_entry(dev, &dpm_noirq_list, power.entry)
-		dpm_async_fn(dev, async_resume_noirq);
-
 	while (!list_empty(&dpm_noirq_list)) {
 		dev = to_device(dpm_noirq_list.next);
 		get_device(dev);
@@ -713,17 +719,7 @@ static void dpm_noirq_resume_devices(pm_message_t state)
 
 		mutex_unlock(&dpm_list_mtx);
 
-		if (!is_async(dev)) {
-			int error;
-
-			error = device_resume_noirq(dev, state, false);
-			if (error) {
-				suspend_stats.failed_resume_noirq++;
-				dpm_save_failed_step(SUSPEND_RESUME_NOIRQ);
-				dpm_save_failed_dev(dev_name(dev));
-				pm_dev_err(dev, state, " noirq", error);
-			}
-		}
+		device_resume_noirq(dev);
 
 		put_device(dev);
 
@@ -751,14 +747,14 @@ void dpm_resume_noirq(pm_message_t state)
 }
 
 /**
- * device_resume_early - Execute an "early resume" callback for given device.
+ * __device_resume_early - Execute an "early resume" callback for given device.
  * @dev: Device to handle.
  * @state: PM transition of the system being carried out.
  * @async: If true, the device is being resumed asynchronously.
  *
  * Runtime PM is disabled for @dev while this function is being executed.
  */
-static int device_resume_early(struct device *dev, pm_message_t state, bool async)
+static void __device_resume_early(struct device *dev, pm_message_t state, bool async)
 {
 	pm_callback_t callback = NULL;
 	const char *info = NULL;
@@ -811,21 +807,31 @@ static int device_resume_early(struct device *dev, pm_message_t state, bool asyn
 
 	pm_runtime_enable(dev);
 	complete_all(&dev->power.completion);
-	return error;
+
+	if (error) {
+		suspend_stats.failed_resume_early++;
+		dpm_save_failed_step(SUSPEND_RESUME_EARLY);
+		dpm_save_failed_dev(dev_name(dev));
+		pm_dev_err(dev, state, async ? " async early" : " early", error);
+	}
 }
 
 static void async_resume_early(void *data, async_cookie_t cookie)
 {
 	struct device *dev = data;
-	int error;
-
-	error = device_resume_early(dev, pm_transition, true);
-	if (error)
-		pm_dev_err(dev, pm_transition, " async", error);
 
+	__device_resume_early(dev, pm_transition, true);
 	put_device(dev);
 }
 
+static void device_resume_early(struct device *dev)
+{
+	if (dpm_async_fn(dev, async_resume_early))
+		return;
+
+	__device_resume_early(dev, pm_transition, false);
+}
+
 /**
  * dpm_resume_early - Execute "early resume" callbacks for all devices.
  * @state: PM transition of the system being carried out.
@@ -839,14 +845,6 @@ void dpm_resume_early(pm_message_t state)
 	mutex_lock(&dpm_list_mtx);
 	pm_transition = state;
 
-	/*
-	 * Advanced the async threads upfront,
-	 * in case the starting of async threads is
-	 * delayed by non-async resuming devices.
-	 */
-	list_for_each_entry(dev, &dpm_late_early_list, power.entry)
-		dpm_async_fn(dev, async_resume_early);
-
 	while (!list_empty(&dpm_late_early_list)) {
 		dev = to_device(dpm_late_early_list.next);
 		get_device(dev);
@@ -854,17 +852,7 @@ void dpm_resume_early(pm_message_t state)
 
 		mutex_unlock(&dpm_list_mtx);
 
-		if (!is_async(dev)) {
-			int error;
-
-			error = device_resume_early(dev, state, false);
-			if (error) {
-				suspend_stats.failed_resume_early++;
-				dpm_save_failed_step(SUSPEND_RESUME_EARLY);
-				dpm_save_failed_dev(dev_name(dev));
-				pm_dev_err(dev, state, " early", error);
-			}
-		}
+		device_resume_early(dev);
 
 		put_device(dev);
 
@@ -888,12 +876,12 @@ void dpm_resume_start(pm_message_t state)
 EXPORT_SYMBOL_GPL(dpm_resume_start);
 
 /**
- * device_resume - Execute "resume" callbacks for given device.
+ * __device_resume - Execute "resume" callbacks for given device.
  * @dev: Device to handle.
  * @state: PM transition of the system being carried out.
  * @async: If true, the device is being resumed asynchronously.
  */
-static int device_resume(struct device *dev, pm_message_t state, bool async)
+static void __device_resume(struct device *dev, pm_message_t state, bool async)
 {
 	pm_callback_t callback = NULL;
 	const char *info = NULL;
@@ -975,20 +963,30 @@ static int device_resume(struct device *dev, pm_message_t state, bool async)
 
 	TRACE_RESUME(error);
 
-	return error;
+	if (error) {
+		suspend_stats.failed_resume++;
+		dpm_save_failed_step(SUSPEND_RESUME);
+		dpm_save_failed_dev(dev_name(dev));
+		pm_dev_err(dev, state, async ? " async" : "", error);
+	}
 }
 
 static void async_resume(void *data, async_cookie_t cookie)
 {
 	struct device *dev = data;
-	int error;
 
-	error = device_resume(dev, pm_transition, true);
-	if (error)
-		pm_dev_err(dev, pm_transition, " async", error);
+	__device_resume(dev, pm_transition, true);
 	put_device(dev);
 }
 
+static void device_resume(struct device *dev)
+{
+	if (dpm_async_fn(dev, async_resume))
+		return;
+
+	__device_resume(dev, pm_transition, false);
+}
+
 /**
  * dpm_resume - Execute "resume" callbacks for non-sysdev devices.
  * @state: PM transition of the system being carried out.
@@ -1008,27 +1006,17 @@ void dpm_resume(pm_message_t state)
 	pm_transition = state;
 	async_error = 0;
 
-	list_for_each_entry(dev, &dpm_suspended_list, power.entry)
-		dpm_async_fn(dev, async_resume);
-
 	while (!list_empty(&dpm_suspended_list)) {
 		dev = to_device(dpm_suspended_list.next);
+
 		get_device(dev);
-		if (!is_async(dev)) {
-			int error;
 
-			mutex_unlock(&dpm_list_mtx);
+		mutex_unlock(&dpm_list_mtx);
+
+		device_resume(dev);
 
-			error = device_resume(dev, state, false);
-			if (error) {
-				suspend_stats.failed_resume++;
-				dpm_save_failed_step(SUSPEND_RESUME);
-				dpm_save_failed_dev(dev_name(dev));
-				pm_dev_err(dev, state, "", error);
-			}
+		mutex_lock(&dpm_list_mtx);
 
-			mutex_lock(&dpm_list_mtx);
-		}
 		if (!list_empty(&dev->power.entry))
 			list_move_tail(&dev->power.entry, &dpm_prepared_list);
 

include/linux/async.h

@@ -90,6 +90,8 @@ async_schedule_dev(async_func_t func, struct device *dev)
 	return async_schedule_node(func, dev, dev_to_node(dev));
 }
 
+bool async_schedule_dev_nocall(async_func_t func, struct device *dev);
+
 /**
  * async_schedule_dev_domain - A device specific version of async_schedule_domain
  * @func: function to execute asynchronously

kernel/async.c

@@ -145,6 +145,39 @@ static void async_run_entry_fn(struct work_struct *work)
 	wake_up(&async_done);
 }
 
+static async_cookie_t __async_schedule_node_domain(async_func_t func,
+						   void *data, int node,
+						   struct async_domain *domain,
+						   struct async_entry *entry)
+{
+	async_cookie_t newcookie;
+	unsigned long flags;
+
+	INIT_LIST_HEAD(&entry->domain_list);
+	INIT_LIST_HEAD(&entry->global_list);
+	INIT_WORK(&entry->work, async_run_entry_fn);
+	entry->func = func;
+	entry->data = data;
+	entry->domain = domain;
+
+	spin_lock_irqsave(&async_lock, flags);
+
+	/* allocate cookie and queue */
+	newcookie = entry->cookie = next_cookie++;
+
+	list_add_tail(&entry->domain_list, &domain->pending);
+	if (domain->registered)
+		list_add_tail(&entry->global_list, &async_global_pending);
+
+	atomic_inc(&entry_count);
+	spin_unlock_irqrestore(&async_lock, flags);
+
+	/* schedule for execution */
+	queue_work_node(node, system_unbound_wq, &entry->work);
+
+	return newcookie;
+}
+
 /**
  * async_schedule_node_domain - NUMA specific version of async_schedule_domain
  * @func: function to execute asynchronously
@@ -186,29 +219,8 @@ async_cookie_t async_schedule_node_domain(async_func_t func, void *data,
 		func(data, newcookie);
 		return newcookie;
 	}
-	INIT_LIST_HEAD(&entry->domain_list);
-	INIT_LIST_HEAD(&entry->global_list);
-	INIT_WORK(&entry->work, async_run_entry_fn);
-	entry->func = func;
-	entry->data = data;
-	entry->domain = domain;
-
-	spin_lock_irqsave(&async_lock, flags);
-
-	/* allocate cookie and queue */
-	newcookie = entry->cookie = next_cookie++;
-
-	list_add_tail(&entry->domain_list, &domain->pending);
-	if (domain->registered)
-		list_add_tail(&entry->global_list, &async_global_pending);
-
-	atomic_inc(&entry_count);
-	spin_unlock_irqrestore(&async_lock, flags);
-
-	/* schedule for execution */
-	queue_work_node(node, system_unbound_wq, &entry->work);
 
-	return newcookie;
+	return __async_schedule_node_domain(func, data, node, domain, entry);
 }
 EXPORT_SYMBOL_GPL(async_schedule_node_domain);
 
@@ -231,6 +243,35 @@ async_cookie_t async_schedule_node(async_func_t func, void *data, int node)
 }
 EXPORT_SYMBOL_GPL(async_schedule_node);
 
+/**
+ * async_schedule_dev_nocall - A simplified variant of async_schedule_dev()
+ * @func: function to execute asynchronously
+ * @dev: device argument to be passed to function
+ *
+ * @dev is used as both the argument for the function and to provide NUMA
+ * context for where to run the function.
+ *
+ * If the asynchronous execution of @func is scheduled successfully, return
+ * true. Otherwise, do nothing and return false, unlike async_schedule_dev()
+ * that will run the function synchronously then.
+ */
+bool async_schedule_dev_nocall(async_func_t func, struct device *dev)
+{
+	struct async_entry *entry;
+
+	entry = kzalloc(sizeof(struct async_entry), GFP_KERNEL);
+
+	/* Give up if there is no memory or too much work. */
+	if (!entry || atomic_read(&entry_count) > MAX_WORK) {
+		kfree(entry);
+		return false;
+	}
+
+	__async_schedule_node_domain(func, dev, dev_to_node(dev),
+				     &async_dfl_domain, entry);
+	return true;
+}
+
 /**
  * async_synchronize_full - synchronize all asynchronous function calls
  *

kernel/power/hibernate.c

@@ -642,9 +642,9 @@ int hibernation_platform_enter(void)
  */
 static void power_down(void)
 {
-#ifdef CONFIG_SUSPEND
 	int error;
 
+#ifdef CONFIG_SUSPEND
 	if (hibernation_mode == HIBERNATION_SUSPEND) {
 		error = suspend_devices_and_enter(mem_sleep_current);
 		if (error) {
@@ -667,7 +667,13 @@ static void power_down(void)
 		kernel_restart(NULL);
 		break;
 	case HIBERNATION_PLATFORM:
-		hibernation_platform_enter();
+		error = hibernation_platform_enter();
+		if (error == -EAGAIN || error == -EBUSY) {
+			swsusp_unmark();
+			events_check_enabled = false;
+			pr_info("Wakeup event detected during hibernation, rolling back.\n");
+			return;
+		}
 		fallthrough;
 	case HIBERNATION_SHUTDOWN:
 		if (kernel_can_power_off())

kernel/power/main.c

@@ -60,22 +60,6 @@ EXPORT_SYMBOL_GPL(lock_system_sleep);
 
 void unlock_system_sleep(unsigned int flags)
 {
-	/*
-	 * Don't use freezer_count() because we don't want the call to
-	 * try_to_freeze() here.
-	 *
-	 * Reason:
-	 * Fundamentally, we just don't need it, because freezing condition
-	 * doesn't come into effect until we release the
-	 * system_transition_mutex lock, since the freezer always works with
-	 * system_transition_mutex held.
-	 *
-	 * More importantly, in the case of hibernation,
-	 * unlock_system_sleep() gets called in snapshot_read() and
-	 * snapshot_write() when the freezing condition is still in effect.
-	 * Which means, if we use try_to_freeze() here, it would make them
-	 * enter the refrigerator, thus causing hibernation to lockup.
-	 */
 	if (!(flags & PF_NOFREEZE))
 		current->flags &= ~PF_NOFREEZE;
 	mutex_unlock(&system_transition_mutex);

kernel/power/power.h

@@ -175,6 +175,8 @@ extern int swsusp_write(unsigned int flags);
 void swsusp_close(void);
 #ifdef CONFIG_SUSPEND
 extern int swsusp_unmark(void);
+#else
+static inline int swsusp_unmark(void) { return 0; }
 #endif
 
 struct __kernel_old_timeval;

kernel/power/snapshot.c

@@ -1119,7 +1119,7 @@ static void mark_nosave_pages(struct memory_bitmap *bm)
 int create_basic_memory_bitmaps(void)
 {
 	struct memory_bitmap *bm1, *bm2;
-	int error = 0;
+	int error;
 
 	if (forbidden_pages_map && free_pages_map)
 		return 0;
@@ -1487,11 +1487,11 @@ static bool copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
 	s_page = pfn_to_page(src_pfn);
 	d_page = pfn_to_page(dst_pfn);
 	if (PageHighMem(s_page)) {
-		src = kmap_atomic(s_page);
-		dst = kmap_atomic(d_page);
+		src = kmap_local_page(s_page);
+		dst = kmap_local_page(d_page);
 		zeros_only = do_copy_page(dst, src);
-		kunmap_atomic(dst);
-		kunmap_atomic(src);
+		kunmap_local(dst);
+		kunmap_local(src);
 	} else {
 		if (PageHighMem(d_page)) {
 			/*
@@ -1499,9 +1499,9 @@ static bool copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
 			 * data modified by kmap_atomic()
 			 */
 			zeros_only = safe_copy_page(buffer, s_page);
-			dst = kmap_atomic(d_page);
+			dst = kmap_local_page(d_page);
 			copy_page(dst, buffer);
-			kunmap_atomic(dst);
+			kunmap_local(dst);
 		} else {
 			zeros_only = safe_copy_page(page_address(d_page), s_page);
 		}
@@ -2778,7 +2778,7 @@ static void *get_buffer(struct memory_bitmap *bm, struct chain_allocator *ca)
 int snapshot_write_next(struct snapshot_handle *handle)
 {
 	static struct chain_allocator ca;
-	int error = 0;
+	int error;
 
 next:
 	/* Check if we have already loaded the entire image */

kernel/power/swap.c

@@ -451,7 +451,7 @@ static int get_swap_writer(struct swap_map_handle *handle)
 static int swap_write_page(struct swap_map_handle *handle, void *buf,
 		struct hib_bio_batch *hb)
 {
-	int error = 0;
+	int error;
 	sector_t offset;
 
 	if (!handle->cur)
@@ -606,11 +606,11 @@ static int crc32_threadfn(void *data)
 	unsigned i;
 
 	while (1) {
-		wait_event(d->go, atomic_read(&d->ready) ||
+		wait_event(d->go, atomic_read_acquire(&d->ready) ||
 		                  kthread_should_stop());
 		if (kthread_should_stop()) {
 			d->thr = NULL;
-			atomic_set(&d->stop, 1);
+			atomic_set_release(&d->stop, 1);
 			wake_up(&d->done);
 			break;
 		}
@@ -619,7 +619,7 @@ static int crc32_threadfn(void *data)
 		for (i = 0; i < d->run_threads; i++)
 			*d->crc32 = crc32_le(*d->crc32,
 			                     d->unc[i], *d->unc_len[i]);
-		atomic_set(&d->stop, 1);
+		atomic_set_release(&d->stop, 1);
 		wake_up(&d->done);
 	}
 	return 0;
@@ -649,12 +649,12 @@ static int lzo_compress_threadfn(void *data)
 	struct cmp_data *d = data;
 
 	while (1) {
-		wait_event(d->go, atomic_read(&d->ready) ||
+		wait_event(d->go, atomic_read_acquire(&d->ready) ||
 		                  kthread_should_stop());
 		if (kthread_should_stop()) {
 			d->thr = NULL;
 			d->ret = -1;
-			atomic_set(&d->stop, 1);
+			atomic_set_release(&d->stop, 1);
 			wake_up(&d->done);
 			break;
 		}
@@ -663,7 +663,7 @@ static int lzo_compress_threadfn(void *data)
 		d->ret = lzo1x_1_compress(d->unc, d->unc_len,
 		                          d->cmp + LZO_HEADER, &d->cmp_len,
 		                          d->wrk);
-		atomic_set(&d->stop, 1);
+		atomic_set_release(&d->stop, 1);
 		wake_up(&d->done);
 	}
 	return 0;
@@ -798,7 +798,7 @@ static int save_image_lzo(struct swap_map_handle *handle,
 
 			data[thr].unc_len = off;
 
-			atomic_set(&data[thr].ready, 1);
+			atomic_set_release(&data[thr].ready, 1);
 			wake_up(&data[thr].go);
 		}
 
@@ -806,12 +806,12 @@ static int save_image_lzo(struct swap_map_handle *handle,
 			break;
 
 		crc->run_threads = thr;
-		atomic_set(&crc->ready, 1);
+		atomic_set_release(&crc->ready, 1);
 		wake_up(&crc->go);
 
 		for (run_threads = thr, thr = 0; thr < run_threads; thr++) {
 			wait_event(data[thr].done,
-			           atomic_read(&data[thr].stop));
+				atomic_read_acquire(&data[thr].stop));
 			atomic_set(&data[thr].stop, 0);
 
 			ret = data[thr].ret;
@@ -850,7 +850,7 @@ static int save_image_lzo(struct swap_map_handle *handle,
 			}
 		}
 
-		wait_event(crc->done, atomic_read(&crc->stop));
+		wait_event(crc->done, atomic_read_acquire(&crc->stop));
 		atomic_set(&crc->stop, 0);
 	}
 
@@ -1132,12 +1132,12 @@ static int lzo_decompress_threadfn(void *data)
 	struct dec_data *d = data;
 
 	while (1) {
-		wait_event(d->go, atomic_read(&d->ready) ||
+		wait_event(d->go, atomic_read_acquire(&d->ready) ||
 		                  kthread_should_stop());
 		if (kthread_should_stop()) {
 			d->thr = NULL;
 			d->ret = -1;
-			atomic_set(&d->stop, 1);
+			atomic_set_release(&d->stop, 1);
 			wake_up(&d->done);
 			break;
 		}
@@ -1150,7 +1150,7 @@ static int lzo_decompress_threadfn(void *data)
 			flush_icache_range((unsigned long)d->unc,
 					   (unsigned long)d->unc + d->unc_len);
 
-		atomic_set(&d->stop, 1);
+		atomic_set_release(&d->stop, 1);
 		wake_up(&d->done);
 	}
 	return 0;
@@ -1335,7 +1335,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
 		}
 
 		if (crc->run_threads) {
-			wait_event(crc->done, atomic_read(&crc->stop));
+			wait_event(crc->done, atomic_read_acquire(&crc->stop));
 			atomic_set(&crc->stop, 0);
 			crc->run_threads = 0;
 		}
@@ -1371,7 +1371,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
 					pg = 0;
 			}
 
-			atomic_set(&data[thr].ready, 1);
+			atomic_set_release(&data[thr].ready, 1);
 			wake_up(&data[thr].go);
 		}
 
@@ -1390,7 +1390,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
 
 		for (run_threads = thr, thr = 0; thr < run_threads; thr++) {
 			wait_event(data[thr].done,
-			           atomic_read(&data[thr].stop));
+				atomic_read_acquire(&data[thr].stop));
 			atomic_set(&data[thr].stop, 0);
 
 			ret = data[thr].ret;
@@ -1421,7 +1421,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
 				ret = snapshot_write_next(snapshot);
 				if (ret <= 0) {
 					crc->run_threads = thr + 1;
-					atomic_set(&crc->ready, 1);
+					atomic_set_release(&crc->ready, 1);
 					wake_up(&crc->go);
 					goto out_finish;
 				}
@@ -1429,13 +1429,13 @@ static int load_image_lzo(struct swap_map_handle *handle,
 		}
 
 		crc->run_threads = thr;
-		atomic_set(&crc->ready, 1);
+		atomic_set_release(&crc->ready, 1);
 		wake_up(&crc->go);
 	}
 
 out_finish:
 	if (crc->run_threads) {
-		wait_event(crc->done, atomic_read(&crc->stop));
+		wait_event(crc->done, atomic_read_acquire(&crc->stop));
 		atomic_set(&crc->stop, 0);
 	}
 	stop = ktime_get();
@@ -1566,7 +1566,6 @@ int swsusp_check(bool exclusive)
 
 /**
  * swsusp_close - close resume device.
- * @exclusive: Close the resume device which is exclusively opened.
  */
 
 void swsusp_close(void)