diff --git a/drivers/md/md-multipath.c b/drivers/md/md-multipath.c
index e40065bdbfc8..0a7e99d62c69 100644
--- a/drivers/md/md-multipath.c
+++ b/drivers/md/md-multipath.c
@@ -157,7 +157,7 @@ static void multipath_status(struct seq_file *seq, struct mddev *mddev)
 		seq_printf (seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
 	}
 	rcu_read_unlock();
-	seq_printf (seq, "]");
+	seq_putc(seq, ']');
 }
 
 static int multipath_congested(struct mddev *mddev, int bits)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index bc67ab6844f0..254e44e44668 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -801,6 +801,9 @@ void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
 	struct bio *bio;
 	int ff = 0;
 
+	if (!page)
+		return;
+
 	if (test_bit(Faulty, &rdev->flags))
 		return;
 
@@ -5452,6 +5455,7 @@ int md_run(struct mddev *mddev)
 	 * the only valid external interface is through the md
 	 * device.
 	 */
+	mddev->has_superblocks = false;
 	rdev_for_each(rdev, mddev) {
 		if (test_bit(Faulty, &rdev->flags))
 			continue;
@@ -5465,6 +5469,9 @@ int md_run(struct mddev *mddev)
 				set_disk_ro(mddev->gendisk, 1);
 		}
 
+		if (rdev->sb_page)
+			mddev->has_superblocks = true;
+
 		/* perform some consistency tests on the device.
 		 * We don't want the data to overlap the metadata,
 		 * Internal Bitmap issues have been handled elsewhere.
@@ -5497,8 +5504,10 @@ int md_run(struct mddev *mddev)
 	}
 	if (mddev->sync_set == NULL) {
 		mddev->sync_set = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
-		if (!mddev->sync_set)
-			return -ENOMEM;
+		if (!mddev->sync_set) {
+			err = -ENOMEM;
+			goto abort;
+		}
 	}
 
 	spin_lock(&pers_lock);
@@ -5511,7 +5520,8 @@ int md_run(struct mddev *mddev)
 		else
 			pr_warn("md: personality for level %s is not loaded!\n",
 				mddev->clevel);
-		return -EINVAL;
+		err = -EINVAL;
+		goto abort;
 	}
 	spin_unlock(&pers_lock);
 	if (mddev->level != pers->level) {
@@ -5524,7 +5534,8 @@ int md_run(struct mddev *mddev)
 	    pers->start_reshape == NULL) {
 		/* This personality cannot handle reshaping... */
 		module_put(pers->owner);
-		return -EINVAL;
+		err = -EINVAL;
+		goto abort;
 	}
 
 	if (pers->sync_request) {
@@ -5593,7 +5604,7 @@ int md_run(struct mddev *mddev)
 		mddev->private = NULL;
 		module_put(pers->owner);
 		bitmap_destroy(mddev);
-		return err;
+		goto abort;
 	}
 	if (mddev->queue) {
 		bool nonrot = true;
@@ -5655,6 +5666,18 @@ int md_run(struct mddev *mddev)
 	sysfs_notify_dirent_safe(mddev->sysfs_action);
 	sysfs_notify(&mddev->kobj, NULL, "degraded");
 	return 0;
+
+abort:
+	if (mddev->bio_set) {
+		bioset_free(mddev->bio_set);
+		mddev->bio_set = NULL;
+	}
+	if (mddev->sync_set) {
+		bioset_free(mddev->sync_set);
+		mddev->sync_set = NULL;
+	}
+
+	return err;
 }
 EXPORT_SYMBOL_GPL(md_run);
 
@@ -8049,6 +8072,7 @@ EXPORT_SYMBOL(md_done_sync);
 bool md_write_start(struct mddev *mddev, struct bio *bi)
 {
 	int did_change = 0;
+
 	if (bio_data_dir(bi) != WRITE)
 		return true;
 
@@ -8081,6 +8105,8 @@ bool md_write_start(struct mddev *mddev, struct bio *bi)
 	rcu_read_unlock();
 	if (did_change)
 		sysfs_notify_dirent_safe(mddev->sysfs_state);
+	if (!mddev->has_superblocks)
+		return true;
 	wait_event(mddev->sb_wait,
 		   !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) ||
 		   mddev->suspended);
@@ -8543,6 +8569,19 @@ void md_do_sync(struct md_thread *thread)
 	set_mask_bits(&mddev->sb_flags, 0,
 		      BIT(MD_SB_CHANGE_PENDING) | BIT(MD_SB_CHANGE_DEVS));
 
+	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
+			!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
+			mddev->delta_disks > 0 &&
+			mddev->pers->finish_reshape &&
+			mddev->pers->size &&
+			mddev->queue) {
+		mddev_lock_nointr(mddev);
+		md_set_array_sectors(mddev, mddev->pers->size(mddev, 0, 0));
+		mddev_unlock(mddev);
+		set_capacity(mddev->gendisk, mddev->array_sectors);
+		revalidate_disk(mddev->gendisk);
+	}
+
 	spin_lock(&mddev->lock);
 	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
 		/* We completed so min/max setting can be forgotten if used. */
@@ -8569,6 +8608,10 @@ static int remove_and_add_spares(struct mddev *mddev,
 	int removed = 0;
 	bool remove_some = false;
 
+	if (this && test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+		/* Mustn't remove devices when resync thread is running */
+		return 0;
+
 	rdev_for_each(rdev, mddev) {
 		if ((this == NULL || rdev == this) &&
 		    rdev->raid_disk >= 0 &&
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 58cd20a5e85e..fbc925cce810 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -468,6 +468,8 @@ struct mddev {
 	void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
 	struct md_cluster_info		*cluster_info;
 	unsigned int			good_device_nr;	/* good device num within cluster raid */
+
+	bool	has_superblocks:1;
 };
 
 enum recovery_flags {
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index f978eddc7a21..fe872dc6712e 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1809,6 +1809,17 @@ static int raid1_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
 			struct md_rdev *repl =
 				conf->mirrors[conf->raid_disks + number].rdev;
 			freeze_array(conf, 0);
+			if (atomic_read(&repl->nr_pending)) {
+				/* It means that some queued IO of retry_list
+				 * hold repl. Thus, we cannot set replacement
+				 * as NULL, avoiding rdev NULL pointer
+				 * dereference in sync_request_write and
+				 * handle_write_finished.
+				 */
+				err = -EBUSY;
+				unfreeze_array(conf);
+				goto abort;
+			}
 			clear_bit(Replacement, &repl->flags);
 			p->rdev = repl;
 			conf->mirrors[conf->raid_disks + number].rdev = NULL;
diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h
index c7294e7557e0..eb84bc68e2fd 100644
--- a/drivers/md/raid1.h
+++ b/drivers/md/raid1.h
@@ -26,6 +26,18 @@
 #define BARRIER_BUCKETS_NR_BITS		(PAGE_SHIFT - ilog2(sizeof(atomic_t)))
 #define BARRIER_BUCKETS_NR		(1<<BARRIER_BUCKETS_NR_BITS)
 
+/* Note: raid1_info.rdev can be set to NULL asynchronously by raid1_remove_disk.
+ * There are three safe ways to access raid1_info.rdev.
+ * 1/ when holding mddev->reconfig_mutex
+ * 2/ when resync/recovery is known to be happening - i.e. in code that is
+ *    called as part of performing resync/recovery.
+ * 3/ while holding rcu_read_lock(), use rcu_dereference to get the pointer
+ *    and if it is non-NULL, increment rdev->nr_pending before dropping the
+ *    RCU lock.
+ * When .rdev is set to NULL, the nr_pending count checked again and if it has
+ * been incremented, the pointer is put back in .rdev.
+ */
+
 struct raid1_info {
 	struct md_rdev	*rdev;
 	sector_t	head_position;
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 99c9207899a7..c5e6c60fc0d4 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -141,7 +141,7 @@ static void r10bio_pool_free(void *r10_bio, void *data)
 #define RESYNC_WINDOW (1024*1024)
 /* maximum number of concurrent requests, memory permitting */
 #define RESYNC_DEPTH (32*1024*1024/RESYNC_BLOCK_SIZE)
-#define CLUSTER_RESYNC_WINDOW (16 * RESYNC_WINDOW)
+#define CLUSTER_RESYNC_WINDOW (32 * RESYNC_WINDOW)
 #define CLUSTER_RESYNC_WINDOW_SECTORS (CLUSTER_RESYNC_WINDOW >> 9)
 
 /*
@@ -2655,7 +2655,8 @@ static void handle_write_completed(struct r10conf *conf, struct r10bio *r10_bio)
 		for (m = 0; m < conf->copies; m++) {
 			int dev = r10_bio->devs[m].devnum;
 			rdev = conf->mirrors[dev].rdev;
-			if (r10_bio->devs[m].bio == NULL)
+			if (r10_bio->devs[m].bio == NULL ||
+				r10_bio->devs[m].bio->bi_end_io == NULL)
 				continue;
 			if (!r10_bio->devs[m].bio->bi_status) {
 				rdev_clear_badblocks(
@@ -2670,7 +2671,8 @@ static void handle_write_completed(struct r10conf *conf, struct r10bio *r10_bio)
 					md_error(conf->mddev, rdev);
 			}
 			rdev = conf->mirrors[dev].replacement;
-			if (r10_bio->devs[m].repl_bio == NULL)
+			if (r10_bio->devs[m].repl_bio == NULL ||
+				r10_bio->devs[m].repl_bio->bi_end_io == NULL)
 				continue;
 
 			if (!r10_bio->devs[m].repl_bio->bi_status) {
@@ -3782,7 +3784,7 @@ static int raid10_run(struct mddev *mddev)
 		if (fc > 1 || fo > 0) {
 			pr_err("only near layout is supported by clustered"
 				" raid10\n");
-			goto out;
+			goto out_free_conf;
 		}
 	}
 
@@ -4830,17 +4832,11 @@ static void raid10_finish_reshape(struct mddev *mddev)
 		return;
 
 	if (mddev->delta_disks > 0) {
-		sector_t size = raid10_size(mddev, 0, 0);
-		md_set_array_sectors(mddev, size);
 		if (mddev->recovery_cp > mddev->resync_max_sectors) {
 			mddev->recovery_cp = mddev->resync_max_sectors;
 			set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 		}
-		mddev->resync_max_sectors = size;
-		if (mddev->queue) {
-			set_capacity(mddev->gendisk, mddev->array_sectors);
-			revalidate_disk(mddev->gendisk);
-		}
+		mddev->resync_max_sectors = mddev->array_sectors;
 	} else {
 		int d;
 		rcu_read_lock();
diff --git a/drivers/md/raid10.h b/drivers/md/raid10.h
index db2ac22ac1b4..e2e8840de9bf 100644
--- a/drivers/md/raid10.h
+++ b/drivers/md/raid10.h
@@ -2,6 +2,19 @@
 #ifndef _RAID10_H
 #define _RAID10_H
 
+/* Note: raid10_info.rdev can be set to NULL asynchronously by
+ * raid10_remove_disk.
+ * There are three safe ways to access raid10_info.rdev.
+ * 1/ when holding mddev->reconfig_mutex
+ * 2/ when resync/recovery/reshape is known to be happening - i.e. in code
+ *    that is called as part of performing resync/recovery/reshape.
+ * 3/ while holding rcu_read_lock(), use rcu_dereference to get the pointer
+ *    and if it is non-NULL, increment rdev->nr_pending before dropping the
+ *    RCU lock.
+ * When .rdev is set to NULL, the nr_pending count checked again and if it has
+ * been incremented, the pointer is put back in .rdev.
+ */
+
 struct raid10_info {
 	struct md_rdev	*rdev, *replacement;
 	sector_t	head_position;
diff --git a/drivers/md/raid5-log.h b/drivers/md/raid5-log.h
index 0c76bcedfc1c..a001808a2b77 100644
--- a/drivers/md/raid5-log.h
+++ b/drivers/md/raid5-log.h
@@ -44,6 +44,7 @@ extern void ppl_write_stripe_run(struct r5conf *conf);
 extern void ppl_stripe_write_finished(struct stripe_head *sh);
 extern int ppl_modify_log(struct r5conf *conf, struct md_rdev *rdev, bool add);
 extern void ppl_quiesce(struct r5conf *conf, int quiesce);
+extern int ppl_handle_flush_request(struct r5l_log *log, struct bio *bio);
 
 static inline bool raid5_has_ppl(struct r5conf *conf)
 {
@@ -104,7 +105,7 @@ static inline int log_handle_flush_request(struct r5conf *conf, struct bio *bio)
 	if (conf->log)
 		ret = r5l_handle_flush_request(conf->log, bio);
 	else if (raid5_has_ppl(conf))
-		ret = 0;
+		ret = ppl_handle_flush_request(conf->log, bio);
 
 	return ret;
 }
diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
index 2764c2290062..42890a08375b 100644
--- a/drivers/md/raid5-ppl.c
+++ b/drivers/md/raid5-ppl.c
@@ -693,6 +693,16 @@ void ppl_quiesce(struct r5conf *conf, int quiesce)
 	}
 }
 
+int ppl_handle_flush_request(struct r5l_log *log, struct bio *bio)
+{
+	if (bio->bi_iter.bi_size == 0) {
+		bio_endio(bio);
+		return 0;
+	}
+	bio->bi_opf &= ~REQ_PREFLUSH;
+	return -EAGAIN;
+}
+
 void ppl_stripe_write_finished(struct stripe_head *sh)
 {
 	struct ppl_io_unit *io;
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 50d01144b805..b5d2601483e3 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2196,15 +2196,16 @@ static int grow_one_stripe(struct r5conf *conf, gfp_t gfp)
 static int grow_stripes(struct r5conf *conf, int num)
 {
 	struct kmem_cache *sc;
+	size_t namelen = sizeof(conf->cache_name[0]);
 	int devs = max(conf->raid_disks, conf->previous_raid_disks);
 
 	if (conf->mddev->gendisk)
-		sprintf(conf->cache_name[0],
+		snprintf(conf->cache_name[0], namelen,
 			"raid%d-%s", conf->level, mdname(conf->mddev));
 	else
-		sprintf(conf->cache_name[0],
+		snprintf(conf->cache_name[0], namelen,
 			"raid%d-%p", conf->level, conf->mddev);
-	sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
+	snprintf(conf->cache_name[1], namelen, "%.27s-alt", conf->cache_name[0]);
 
 	conf->active_name = 0;
 	sc = kmem_cache_create(conf->cache_name[conf->active_name],
@@ -6764,9 +6765,7 @@ static void free_conf(struct r5conf *conf)
 
 	log_exit(conf);
 
-	if (conf->shrinker.nr_deferred)
-		unregister_shrinker(&conf->shrinker);
-
+	unregister_shrinker(&conf->shrinker);
 	free_thread_groups(conf);
 	shrink_stripes(conf);
 	raid5_free_percpu(conf);
@@ -8001,13 +8000,7 @@ static void raid5_finish_reshape(struct mddev *mddev)
 
 	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
 
-		if (mddev->delta_disks > 0) {
-			md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
-			if (mddev->queue) {
-				set_capacity(mddev->gendisk, mddev->array_sectors);
-				revalidate_disk(mddev->gendisk);
-			}
-		} else {
+		if (mddev->delta_disks <= 0) {
 			int d;
 			spin_lock_irq(&conf->device_lock);
 			mddev->degraded = raid5_calc_degraded(conf);
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 2e6123825095..3f8da26032ac 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -450,6 +450,18 @@ enum {
  * HANDLE gets cleared if stripe_handle leaves nothing locked.
  */
 
+/* Note: disk_info.rdev can be set to NULL asynchronously by raid5_remove_disk.
+ * There are three safe ways to access disk_info.rdev.
+ * 1/ when holding mddev->reconfig_mutex
+ * 2/ when resync/recovery/reshape is known to be happening - i.e. in code that
+ *    is called as part of performing resync/recovery/reshape.
+ * 3/ while holding rcu_read_lock(), use rcu_dereference to get the pointer
+ *    and if it is non-NULL, increment rdev->nr_pending before dropping the RCU
+ *    lock.
+ * When .rdev is set to NULL, the nr_pending count checked again and if
+ * it has been incremented, the pointer is put back in .rdev.
+ */
+
 struct disk_info {
 	struct md_rdev	*rdev, *replacement;
 	struct page	*extra_page; /* extra page to use in prexor */