Merge branch 'akpm' (patches from Andrew)

Merge more fixes from Andrew Morton:
 "5 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  swap_readpage(): avoid blk_wake_io_task() if !synchronous
  devres: allow const resource arguments
  mm/vmscan.c: prevent useless kswapd loops
  fs/userfaultfd.c: disable irqs for fault_pending and event locks
  mm/page_alloc.c: fix regression with deferred struct page init

6 files changed, 55 insertions, 36 deletions

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index ae0b8b5f69e6..ccbdbd62f0d8 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -40,6 +40,16 @@ enum userfaultfd_state {
 /*
  * Start with fault_pending_wqh and fault_wqh so they're more likely
  * to be in the same cacheline.
+ *
+ * Locking order:
+ *	fd_wqh.lock
+ *		fault_pending_wqh.lock
+ *			fault_wqh.lock
+ *		event_wqh.lock
+ *
+ * To avoid deadlocks, IRQs must be disabled when taking any of the above locks,
+ * since fd_wqh.lock is taken by aio_poll() while it's holding a lock that's
+ * also taken in IRQ context.
  */
 struct userfaultfd_ctx {
 	/* waitqueue head for the pending (i.e. not read) userfaults */
@@ -458,7 +468,7 @@ vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason)
 	blocking_state = return_to_userland ? TASK_INTERRUPTIBLE :
 			 TASK_KILLABLE;
 
-	spin_lock(&ctx->fault_pending_wqh.lock);
+	spin_lock_irq(&ctx->fault_pending_wqh.lock);
 	/*
 	 * After the __add_wait_queue the uwq is visible to userland
 	 * through poll/read().
@@ -470,7 +480,7 @@ vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason)
 	 * __add_wait_queue.
 	 */
 	set_current_state(blocking_state);
-	spin_unlock(&ctx->fault_pending_wqh.lock);
+	spin_unlock_irq(&ctx->fault_pending_wqh.lock);
 
 	if (!is_vm_hugetlb_page(vmf->vma))
 		must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags,
@@ -552,13 +562,13 @@ vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason)
 	 * kernel stack can be released after the list_del_init.
 	 */
 	if (!list_empty_careful(&uwq.wq.entry)) {
-		spin_lock(&ctx->fault_pending_wqh.lock);
+		spin_lock_irq(&ctx->fault_pending_wqh.lock);
 		/*
 		 * No need of list_del_init(), the uwq on the stack
 		 * will be freed shortly anyway.
 		 */
 		list_del(&uwq.wq.entry);
-		spin_unlock(&ctx->fault_pending_wqh.lock);
+		spin_unlock_irq(&ctx->fault_pending_wqh.lock);
 	}
 
 	/*
@@ -583,7 +593,7 @@ static void userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
 	init_waitqueue_entry(&ewq->wq, current);
 	release_new_ctx = NULL;
 
-	spin_lock(&ctx->event_wqh.lock);
+	spin_lock_irq(&ctx->event_wqh.lock);
 	/*
 	 * After the __add_wait_queue the uwq is visible to userland
 	 * through poll/read().
@@ -613,15 +623,15 @@ static void userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
 			break;
 		}
 
-		spin_unlock(&ctx->event_wqh.lock);
+		spin_unlock_irq(&ctx->event_wqh.lock);
 
 		wake_up_poll(&ctx->fd_wqh, EPOLLIN);
 		schedule();
 
-		spin_lock(&ctx->event_wqh.lock);
+		spin_lock_irq(&ctx->event_wqh.lock);
 	}
 	__set_current_state(TASK_RUNNING);
-	spin_unlock(&ctx->event_wqh.lock);
+	spin_unlock_irq(&ctx->event_wqh.lock);
 
 	if (release_new_ctx) {
 		struct vm_area_struct *vma;
@@ -918,10 +928,10 @@ wakeup:
 	 * the last page faults that may have been already waiting on
 	 * the fault_*wqh.
 	 */
-	spin_lock(&ctx->fault_pending_wqh.lock);
+	spin_lock_irq(&ctx->fault_pending_wqh.lock);
 	__wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL, &range);
 	__wake_up(&ctx->fault_wqh, TASK_NORMAL, 1, &range);
-	spin_unlock(&ctx->fault_pending_wqh.lock);
+	spin_unlock_irq(&ctx->fault_pending_wqh.lock);
 
 	/* Flush pending events that may still wait on event_wqh */
 	wake_up_all(&ctx->event_wqh);
@@ -1134,7 +1144,7 @@ static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
 
 	if (!ret && msg->event == UFFD_EVENT_FORK) {
 		ret = resolve_userfault_fork(ctx, fork_nctx, msg);
-		spin_lock(&ctx->event_wqh.lock);
+		spin_lock_irq(&ctx->event_wqh.lock);
 		if (!list_empty(&fork_event)) {
 			/*
 			 * The fork thread didn't abort, so we can
@@ -1180,7 +1190,7 @@ static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
 			if (ret)
 				userfaultfd_ctx_put(fork_nctx);
 		}
-		spin_unlock(&ctx->event_wqh.lock);
+		spin_unlock_irq(&ctx->event_wqh.lock);
 	}
 
 	return ret;
@@ -1219,14 +1229,14 @@ static ssize_t userfaultfd_read(struct file *file, char __user *buf,
 static void __wake_userfault(struct userfaultfd_ctx *ctx,
 			     struct userfaultfd_wake_range *range)
 {
-	spin_lock(&ctx->fault_pending_wqh.lock);
+	spin_lock_irq(&ctx->fault_pending_wqh.lock);
 	/* wake all in the range and autoremove */
 	if (waitqueue_active(&ctx->fault_pending_wqh))
 		__wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL,
 				     range);
 	if (waitqueue_active(&ctx->fault_wqh))
 		__wake_up(&ctx->fault_wqh, TASK_NORMAL, 1, range);
-	spin_unlock(&ctx->fault_pending_wqh.lock);
+	spin_unlock_irq(&ctx->fault_pending_wqh.lock);
 }
 
 static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx,
@@ -1881,7 +1891,7 @@ static void userfaultfd_show_fdinfo(struct seq_file *m, struct file *f)
 	wait_queue_entry_t *wq;
 	unsigned long pending = 0, total = 0;
 
-	spin_lock(&ctx->fault_pending_wqh.lock);
+	spin_lock_irq(&ctx->fault_pending_wqh.lock);
 	list_for_each_entry(wq, &ctx->fault_pending_wqh.head, entry) {
 		pending++;
 		total++;
@@ -1889,7 +1899,7 @@ static void userfaultfd_show_fdinfo(struct seq_file *m, struct file *f)
 	list_for_each_entry(wq, &ctx->fault_wqh.head, entry) {
 		total++;
 	}
-	spin_unlock(&ctx->fault_pending_wqh.lock);
+	spin_unlock_irq(&ctx->fault_pending_wqh.lock);
 
 	/*
 	 * If more protocols will be added, there will be all shown
diff --git a/include/linux/device.h b/include/linux/device.h
index 848fc71c6ba6..4a295e324ac5 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -704,7 +704,8 @@ extern unsigned long devm_get_free_pages(struct device *dev,
 					 gfp_t gfp_mask, unsigned int order);
 extern void devm_free_pages(struct device *dev, unsigned long addr);
 
-void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res);
+void __iomem *devm_ioremap_resource(struct device *dev,
+				    const struct resource *res);
 
 void __iomem *devm_of_iomap(struct device *dev,
 			    struct device_node *node, int index,
diff --git a/lib/devres.c b/lib/devres.c
index 69bed2f38306..6a0e9bd6524a 100644
--- a/lib/devres.c
+++ b/lib/devres.c
@@ -131,7 +131,8 @@ EXPORT_SYMBOL(devm_iounmap);
  *	if (IS_ERR(base))
  *		return PTR_ERR(base);
  */
-void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res)
+void __iomem *devm_ioremap_resource(struct device *dev,
+				    const struct resource *res)
 {
 	resource_size_t size;
 	void __iomem *dest_ptr;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d66bc8abe0af..8e3bc949ebcc 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1826,7 +1826,8 @@ deferred_grow_zone(struct zone *zone, unsigned int order)
 						 first_deferred_pfn)) {
 		pgdat->first_deferred_pfn = ULONG_MAX;
 		pgdat_resize_unlock(pgdat, &flags);
-		return true;
+		/* Retry only once. */
+		return first_deferred_pfn != ULONG_MAX;
 	}
 
 	/*
diff --git a/mm/page_io.c b/mm/page_io.c
index 189415852077..a39aac2f8c8d 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -137,8 +137,10 @@ out:
 	unlock_page(page);
 	WRITE_ONCE(bio->bi_private, NULL);
 	bio_put(bio);
-	blk_wake_io_task(waiter);
-	put_task_struct(waiter);
+	if (waiter) {
+		blk_wake_io_task(waiter);
+		put_task_struct(waiter);
+	}
 }
 
 int generic_swapfile_activate(struct swap_info_struct *sis,
@@ -395,11 +397,12 @@ int swap_readpage(struct page *page, bool synchronous)
 	 * Keep this task valid during swap readpage because the oom killer may
 	 * attempt to access it in the page fault retry time check.
 	 */
-	get_task_struct(current);
-	bio->bi_private = current;
 	bio_set_op_attrs(bio, REQ_OP_READ, 0);
-	if (synchronous)
+	if (synchronous) {
 		bio->bi_opf |= REQ_HIPRI;
+		get_task_struct(current);
+		bio->bi_private = current;
+	}
 	count_vm_event(PSWPIN);
 	bio_get(bio);
 	qc = submit_bio(bio);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7889f583ced9..910e02c793ff 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3644,19 +3644,18 @@ out:
 }
 
 /*
- * pgdat->kswapd_classzone_idx is the highest zone index that a recent
- * allocation request woke kswapd for. When kswapd has not woken recently,
- * the value is MAX_NR_ZONES which is not a valid index. This compares a
- * given classzone and returns it or the highest classzone index kswapd
- * was recently woke for.
+ * The pgdat->kswapd_classzone_idx is used to pass the highest zone index to be
+ * reclaimed by kswapd from the waker. If the value is MAX_NR_ZONES which is not
+ * a valid index then either kswapd runs for first time or kswapd couldn't sleep
+ * after previous reclaim attempt (node is still unbalanced). In that case
+ * return the zone index of the previous kswapd reclaim cycle.
  */
 static enum zone_type kswapd_classzone_idx(pg_data_t *pgdat,
-					   enum zone_type classzone_idx)
+					   enum zone_type prev_classzone_idx)
 {
 	if (pgdat->kswapd_classzone_idx == MAX_NR_ZONES)
-		return classzone_idx;
-
-	return max(pgdat->kswapd_classzone_idx, classzone_idx);
+		return prev_classzone_idx;
+	return pgdat->kswapd_classzone_idx;
 }
 
 static void kswapd_try_to_sleep(pg_data_t *pgdat, int alloc_order, int reclaim_order,
@@ -3797,7 +3796,7 @@ kswapd_try_sleep:
 
 		/* Read the new order and classzone_idx */
 		alloc_order = reclaim_order = pgdat->kswapd_order;
-		classzone_idx = kswapd_classzone_idx(pgdat, 0);
+		classzone_idx = kswapd_classzone_idx(pgdat, classzone_idx);
 		pgdat->kswapd_order = 0;
 		pgdat->kswapd_classzone_idx = MAX_NR_ZONES;
 
@@ -3851,8 +3850,12 @@ void wakeup_kswapd(struct zone *zone, gfp_t gfp_flags, int order,
 	if (!cpuset_zone_allowed(zone, gfp_flags))
 		return;
 	pgdat = zone->zone_pgdat;
-	pgdat->kswapd_classzone_idx = kswapd_classzone_idx(pgdat,
-							   classzone_idx);
+
+	if (pgdat->kswapd_classzone_idx == MAX_NR_ZONES)
+		pgdat->kswapd_classzone_idx = classzone_idx;
+	else
+		pgdat->kswapd_classzone_idx = max(pgdat->kswapd_classzone_idx,
+						  classzone_idx);
 	pgdat->kswapd_order = max(pgdat->kswapd_order, order);
 	if (!waitqueue_active(&pgdat->kswapd_wait))
 		return;