diff --git a/Documentation/admin-guide/iostats.rst b/Documentation/admin-guide/iostats.rst
index 5d63b18bd6d1..60c45c916f7d 100644
--- a/Documentation/admin-guide/iostats.rst
+++ b/Documentation/admin-guide/iostats.rst
@@ -99,7 +99,7 @@ Field 10 -- # of milliseconds spent doing I/Os
 
     Since 5.0 this field counts jiffies when at least one request was
     started or completed. If request runs more than 2 jiffies then some
-    I/O time will not be accounted unless there are other requests.
+    I/O time might be not accounted in case of concurrent requests.
 
 Field 11 -- weighted # of milliseconds spent doing I/Os
     This field is incremented at each I/O start, I/O completion, I/O
@@ -133,6 +133,9 @@ are summed (possibly overflowing the unsigned long variable they are
 summed to) and the result given to the user.  There is no convenient
 user interface for accessing the per-CPU counters themselves.
 
+Since 4.19 request times are measured with nanoseconds precision and
+truncated to milliseconds before showing in this interface.
+
 Disks vs Partitions
 -------------------
 
diff --git a/block/bio.c b/block/bio.c
index f07739300dfe..24704bc2ad6f 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1754,14 +1754,14 @@ defer:
 	schedule_work(&bio_dirty_work);
 }
 
-void update_io_ticks(struct hd_struct *part, unsigned long now)
+void update_io_ticks(struct hd_struct *part, unsigned long now, bool end)
 {
 	unsigned long stamp;
 again:
 	stamp = READ_ONCE(part->stamp);
 	if (unlikely(stamp != now)) {
 		if (likely(cmpxchg(&part->stamp, stamp, now) == stamp)) {
-			__part_stat_add(part, io_ticks, 1);
+			__part_stat_add(part, io_ticks, end ? now - stamp : 1);
 		}
 	}
 	if (part->partno) {
@@ -1777,7 +1777,7 @@ void generic_start_io_acct(struct request_queue *q, int op,
 
 	part_stat_lock();
 
-	update_io_ticks(part, jiffies);
+	update_io_ticks(part, jiffies, false);
 	part_stat_inc(part, ios[sgrp]);
 	part_stat_add(part, sectors[sgrp], sectors);
 	part_inc_in_flight(q, part, op_is_write(op));
@@ -1795,7 +1795,7 @@ void generic_end_io_acct(struct request_queue *q, int req_op,
 
 	part_stat_lock();
 
-	update_io_ticks(part, now);
+	update_io_ticks(part, now, true);
 	part_stat_add(part, nsecs[sgrp], jiffies_to_nsecs(duration));
 	part_stat_add(part, time_in_queue, duration);
 	part_dec_in_flight(q, part, op_is_write(req_op));
diff --git a/block/blk-core.c b/block/blk-core.c
index ca6b67735686..81aafb601df0 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1334,7 +1334,7 @@ void blk_account_io_done(struct request *req, u64 now)
 		part_stat_lock();
 		part = req->part;
 
-		update_io_ticks(part, jiffies);
+		update_io_ticks(part, jiffies, true);
 		part_stat_inc(part, ios[sgrp]);
 		part_stat_add(part, nsecs[sgrp], now - req->start_time_ns);
 		part_stat_add(part, time_in_queue, nsecs_to_jiffies64(now - req->start_time_ns));
@@ -1376,7 +1376,7 @@ void blk_account_io_start(struct request *rq, bool new_io)
 		rq->part = part;
 	}
 
-	update_io_ticks(part, jiffies);
+	update_io_ticks(part, jiffies, false);
 
 	part_stat_unlock();
 }
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 62a2ec9f17df..c1bf9956256f 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -419,7 +419,7 @@ static inline void free_part_info(struct hd_struct *part)
 	kfree(part->info);
 }
 
-void update_io_ticks(struct hd_struct *part, unsigned long now);
+void update_io_ticks(struct hd_struct *part, unsigned long now, bool end);
 
 /* block/genhd.c */
 extern void device_add_disk(struct device *parent, struct gendisk *disk,