diff --git a/arch/tile/configs/tilegx_defconfig b/arch/tile/configs/tilegx_defconfig
index 8c5eff6d6df5..47684815e5c8 100644
--- a/arch/tile/configs/tilegx_defconfig
+++ b/arch/tile/configs/tilegx_defconfig
@@ -330,7 +330,6 @@ CONFIG_MD_RAID0=m
 CONFIG_MD_RAID1=m
 CONFIG_MD_RAID10=m
 CONFIG_MD_RAID456=m
-CONFIG_MULTICORE_RAID456=y
 CONFIG_MD_FAULTY=m
 CONFIG_BLK_DEV_DM=m
 CONFIG_DM_DEBUG=y
diff --git a/arch/tile/configs/tilepro_defconfig b/arch/tile/configs/tilepro_defconfig
index e7a3dfcbcda7..dd2b8f0c631f 100644
--- a/arch/tile/configs/tilepro_defconfig
+++ b/arch/tile/configs/tilepro_defconfig
@@ -324,7 +324,6 @@ CONFIG_MD_RAID0=m
 CONFIG_MD_RAID1=m
 CONFIG_MD_RAID10=m
 CONFIG_MD_RAID456=m
-CONFIG_MULTICORE_RAID456=y
 CONFIG_MD_FAULTY=m
 CONFIG_BLK_DEV_DM=m
 CONFIG_DM_DEBUG=y
diff --git a/drivers/md/md.c b/drivers/md/md.c
index fcb878f88796..aeceedfc530b 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -7663,10 +7663,8 @@ static int remove_and_add_spares(struct mddev *mddev)
 				removed++;
 			}
 		}
-	if (removed)
-		sysfs_notify(&mddev->kobj, NULL,
-			     "degraded");
-
+	if (removed && mddev->kobj.sd)
+		sysfs_notify(&mddev->kobj, NULL, "degraded");
 
 	rdev_for_each(rdev, mddev) {
 		if (rdev->raid_disk >= 0 &&
diff --git a/drivers/md/md.h b/drivers/md/md.h
index eca59c3074ef..d90fb1a879e1 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -506,7 +506,7 @@ static inline char * mdname (struct mddev * mddev)
 static inline int sysfs_link_rdev(struct mddev *mddev, struct md_rdev *rdev)
 {
 	char nm[20];
-	if (!test_bit(Replacement, &rdev->flags)) {
+	if (!test_bit(Replacement, &rdev->flags) && mddev->kobj.sd) {
 		sprintf(nm, "rd%d", rdev->raid_disk);
 		return sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
 	} else
@@ -516,7 +516,7 @@ static inline int sysfs_link_rdev(struct mddev *mddev, struct md_rdev *rdev)
 static inline void sysfs_unlink_rdev(struct mddev *mddev, struct md_rdev *rdev)
 {
 	char nm[20];
-	if (!test_bit(Replacement, &rdev->flags)) {
+	if (!test_bit(Replacement, &rdev->flags) && mddev->kobj.sd) {
 		sprintf(nm, "rd%d", rdev->raid_disk);
 		sysfs_remove_link(&mddev->kobj, nm);
 	}
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 3ee2912889e7..24909eb13fec 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -671,9 +671,11 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 			bi->bi_next = NULL;
 			if (rrdev)
 				set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
-			trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
-					      bi, disk_devt(conf->mddev->gendisk),
-					      sh->dev[i].sector);
+
+			if (conf->mddev->gendisk)
+				trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
+						      bi, disk_devt(conf->mddev->gendisk),
+						      sh->dev[i].sector);
 			generic_make_request(bi);
 		}
 		if (rrdev) {
@@ -701,9 +703,10 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 			rbi->bi_io_vec[0].bv_offset = 0;
 			rbi->bi_size = STRIPE_SIZE;
 			rbi->bi_next = NULL;
-			trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
-					      rbi, disk_devt(conf->mddev->gendisk),
-					      sh->dev[i].sector);
+			if (conf->mddev->gendisk)
+				trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
+						      rbi, disk_devt(conf->mddev->gendisk),
+						      sh->dev[i].sector);
 			generic_make_request(rbi);
 		}
 		if (!rdev && !rrdev) {
@@ -2280,17 +2283,6 @@ schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
 	int level = conf->level;
 
 	if (rcw) {
-		/* if we are not expanding this is a proper write request, and
-		 * there will be bios with new data to be drained into the
-		 * stripe cache
-		 */
-		if (!expand) {
-			sh->reconstruct_state = reconstruct_state_drain_run;
-			set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
-		} else
-			sh->reconstruct_state = reconstruct_state_run;
-
-		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
 
 		for (i = disks; i--; ) {
 			struct r5dev *dev = &sh->dev[i];
@@ -2303,6 +2295,21 @@ schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
 				s->locked++;
 			}
 		}
+		/* if we are not expanding this is a proper write request, and
+		 * there will be bios with new data to be drained into the
+		 * stripe cache
+		 */
+		if (!expand) {
+			if (!s->locked)
+				/* False alarm, nothing to do */
+				return;
+			sh->reconstruct_state = reconstruct_state_drain_run;
+			set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
+		} else
+			sh->reconstruct_state = reconstruct_state_run;
+
+		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
+
 		if (s->locked + conf->max_degraded == disks)
 			if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
 				atomic_inc(&conf->pending_full_writes);
@@ -2311,11 +2318,6 @@ schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
 		BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
 			test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
 
-		sh->reconstruct_state = reconstruct_state_prexor_drain_run;
-		set_bit(STRIPE_OP_PREXOR, &s->ops_request);
-		set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
-		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
-
 		for (i = disks; i--; ) {
 			struct r5dev *dev = &sh->dev[i];
 			if (i == pd_idx)
@@ -2330,6 +2332,13 @@ schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
 				s->locked++;
 			}
 		}
+		if (!s->locked)
+			/* False alarm - nothing to do */
+			return;
+		sh->reconstruct_state = reconstruct_state_prexor_drain_run;
+		set_bit(STRIPE_OP_PREXOR, &s->ops_request);
+		set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
+		set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
 	}
 
 	/* keep the parity disk(s) locked while asynchronous operations
@@ -2564,6 +2573,8 @@ handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
 	int i;
 
 	clear_bit(STRIPE_SYNCING, &sh->state);
+	if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
+		wake_up(&conf->wait_for_overlap);
 	s->syncing = 0;
 	s->replacing = 0;
 	/* There is nothing more to do for sync/check/repair.
@@ -2737,6 +2748,7 @@ static void handle_stripe_clean_event(struct r5conf *conf,
 {
 	int i;
 	struct r5dev *dev;
+	int discard_pending = 0;
 
 	for (i = disks; i--; )
 		if (sh->dev[i].written) {
@@ -2765,9 +2777,23 @@ static void handle_stripe_clean_event(struct r5conf *conf,
 						STRIPE_SECTORS,
 					 !test_bit(STRIPE_DEGRADED, &sh->state),
 						0);
-			}
-		} else if (test_bit(R5_Discard, &sh->dev[i].flags))
-			clear_bit(R5_Discard, &sh->dev[i].flags);
+			} else if (test_bit(R5_Discard, &dev->flags))
+				discard_pending = 1;
+		}
+	if (!discard_pending &&
+	    test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
+		clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
+		clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
+		if (sh->qd_idx >= 0) {
+			clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
+			clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
+		}
+		/* now that discard is done we can proceed with any sync */
+		clear_bit(STRIPE_DISCARD, &sh->state);
+		if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
+			set_bit(STRIPE_HANDLE, &sh->state);
+
+	}
 
 	if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
 		if (atomic_dec_and_test(&conf->pending_full_writes))
@@ -2826,8 +2852,10 @@ static void handle_stripe_dirtying(struct r5conf *conf,
 	set_bit(STRIPE_HANDLE, &sh->state);
 	if (rmw < rcw && rmw > 0) {
 		/* prefer read-modify-write, but need to get some data */
-		blk_add_trace_msg(conf->mddev->queue, "raid5 rmw %llu %d",
-				  (unsigned long long)sh->sector, rmw);
+		if (conf->mddev->queue)
+			blk_add_trace_msg(conf->mddev->queue,
+					  "raid5 rmw %llu %d",
+					  (unsigned long long)sh->sector, rmw);
 		for (i = disks; i--; ) {
 			struct r5dev *dev = &sh->dev[i];
 			if ((dev->towrite || i == sh->pd_idx) &&
@@ -2877,7 +2905,7 @@ static void handle_stripe_dirtying(struct r5conf *conf,
 				}
 			}
 		}
-		if (rcw)
+		if (rcw && conf->mddev->queue)
 			blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
 					  (unsigned long long)sh->sector,
 					  rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
@@ -3417,9 +3445,15 @@ static void handle_stripe(struct stripe_head *sh)
 		return;
 	}
 
-	if (test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
-		set_bit(STRIPE_SYNCING, &sh->state);
-		clear_bit(STRIPE_INSYNC, &sh->state);
+	if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
+		spin_lock(&sh->stripe_lock);
+		/* Cannot process 'sync' concurrently with 'discard' */
+		if (!test_bit(STRIPE_DISCARD, &sh->state) &&
+		    test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
+			set_bit(STRIPE_SYNCING, &sh->state);
+			clear_bit(STRIPE_INSYNC, &sh->state);
+		}
+		spin_unlock(&sh->stripe_lock);
 	}
 	clear_bit(STRIPE_DELAYED, &sh->state);
 
@@ -3579,6 +3613,8 @@ static void handle_stripe(struct stripe_head *sh)
 	    test_bit(STRIPE_INSYNC, &sh->state)) {
 		md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
 		clear_bit(STRIPE_SYNCING, &sh->state);
+		if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
+			wake_up(&conf->wait_for_overlap);
 	}
 
 	/* If the failed drives are just a ReadError, then we might need
@@ -3982,9 +4018,10 @@ static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
 		atomic_inc(&conf->active_aligned_reads);
 		spin_unlock_irq(&conf->device_lock);
 
-		trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
-				      align_bi, disk_devt(mddev->gendisk),
-				      raid_bio->bi_sector);
+		if (mddev->gendisk)
+			trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
+					      align_bi, disk_devt(mddev->gendisk),
+					      raid_bio->bi_sector);
 		generic_make_request(align_bi);
 		return 1;
 	} else {
@@ -4078,7 +4115,8 @@ static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
 		}
 		spin_unlock_irq(&conf->device_lock);
 	}
-	trace_block_unplug(mddev->queue, cnt, !from_schedule);
+	if (mddev->queue)
+		trace_block_unplug(mddev->queue, cnt, !from_schedule);
 	kfree(cb);
 }
 
@@ -4141,6 +4179,13 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi)
 		sh = get_active_stripe(conf, logical_sector, 0, 0, 0);
 		prepare_to_wait(&conf->wait_for_overlap, &w,
 				TASK_UNINTERRUPTIBLE);
+		set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
+		if (test_bit(STRIPE_SYNCING, &sh->state)) {
+			release_stripe(sh);
+			schedule();
+			goto again;
+		}
+		clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
 		spin_lock_irq(&sh->stripe_lock);
 		for (d = 0; d < conf->raid_disks; d++) {
 			if (d == sh->pd_idx || d == sh->qd_idx)
@@ -4153,6 +4198,7 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi)
 				goto again;
 			}
 		}
+		set_bit(STRIPE_DISCARD, &sh->state);
 		finish_wait(&conf->wait_for_overlap, &w);
 		for (d = 0; d < conf->raid_disks; d++) {
 			if (d == sh->pd_idx || d == sh->qd_idx)
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 18b2c4a8a1fd..b0b663b119a8 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -221,10 +221,6 @@ struct stripe_head {
 	struct stripe_operations {
 		int 		     target, target2;
 		enum sum_check_flags zero_sum_result;
-		#ifdef CONFIG_MULTICORE_RAID456
-		unsigned long	     request;
-		wait_queue_head_t    wait_for_ops;
-		#endif
 	} ops;
 	struct r5dev {
 		/* rreq and rvec are used for the replacement device when
@@ -323,6 +319,7 @@ enum {
 	STRIPE_COMPUTE_RUN,
 	STRIPE_OPS_REQ_PENDING,
 	STRIPE_ON_UNPLUG_LIST,
+	STRIPE_DISCARD,
 };
 
 /*