1 files changed, 18 insertions, 16 deletions

diff --git a/block/genhd.c b/block/genhd.c
index 3993ebf4135..3c001fba80c 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -18,6 +18,7 @@
 #include <linux/mutex.h>
 #include <linux/idr.h>
 #include <linux/log2.h>
+#include <linux/pm_runtime.h>
 
 #include "blk.h"
 
@@ -25,7 +26,7 @@ static DEFINE_MUTEX(block_class_lock);
 struct kobject *block_depr;
 
 /* for extended dynamic devt allocation, currently only one major is used */
-#define MAX_EXT_DEVT		(1 << MINORBITS)
+#define NR_EXT_DEVT		(1 << MINORBITS)
 
 /* For extended devt allocation.  ext_devt_mutex prevents look up
  * results from going away underneath its user.
@@ -410,7 +411,7 @@ static int blk_mangle_minor(int minor)
 int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
 {
 	struct gendisk *disk = part_to_disk(part);
-	int idx, rc;
+	int idx;
 
 	/* in consecutive minor range? */
 	if (part->partno < disk->minors) {
@@ -419,19 +420,11 @@ int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
 	}
 
 	/* allocate ext devt */
-	do {
-		if (!idr_pre_get(&ext_devt_idr, GFP_KERNEL))
-			return -ENOMEM;
-		rc = idr_get_new(&ext_devt_idr, part, &idx);
-	} while (rc == -EAGAIN);
-
-	if (rc)
-		return rc;
-
-	if (idx > MAX_EXT_DEVT) {
-		idr_remove(&ext_devt_idr, idx);
-		return -EBUSY;
-	}
+	mutex_lock(&ext_devt_mutex);
+	idx = idr_alloc(&ext_devt_idr, part, 0, NR_EXT_DEVT, GFP_KERNEL);
+	mutex_unlock(&ext_devt_mutex);
+	if (idx < 0)
+		return idx == -ENOSPC ? -EBUSY : idx;
 
 	*devt = MKDEV(BLOCK_EXT_MAJOR, blk_mangle_minor(idx));
 	return 0;
@@ -534,6 +527,14 @@ static void register_disk(struct gendisk *disk)
 			return;
 		}
 	}
+
+	/*
+	 * avoid probable deadlock caused by allocating memory with
+	 * GFP_KERNEL in runtime_resume callback of its all ancestor
+	 * devices
+	 */
+	pm_runtime_set_memalloc_noio(ddev, true);
+
 	disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj);
 	disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj);
 
@@ -646,7 +647,6 @@ void del_gendisk(struct gendisk *disk)
 	disk_part_iter_exit(&piter);
 
 	invalidate_partition(disk, 0);
-	blk_free_devt(disk_to_dev(disk)->devt);
 	set_capacity(disk, 0);
 	disk->flags &= ~GENHD_FL_UP;
 
@@ -663,7 +663,9 @@ void del_gendisk(struct gendisk *disk)
 	disk->driverfs_dev = NULL;
 	if (!sysfs_deprecated)
 		sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));
+	pm_runtime_set_memalloc_noio(disk_to_dev(disk), false);
 	device_del(disk_to_dev(disk));
+	blk_free_devt(disk_to_dev(disk)->devt);
 }
 EXPORT_SYMBOL(del_gendisk);