diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 5070851cf924..9213a5716f95 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1222,16 +1222,12 @@ static inline void blk_flush_plug(struct blk_plug *plug, bool async)
 		__blk_flush_plug(plug, async);
 }
 
-/*
- * tsk == current here
- */
-static inline void blk_plug_invalidate_ts(struct task_struct *tsk)
+static __always_inline void blk_plug_invalidate_ts(void)
 {
-	struct blk_plug *plug = tsk->plug;
-
-	if (plug)
-		plug->cur_ktime = 0;
-	current->flags &= ~PF_BLOCK_TS;
+	if (unlikely(current->flags & PF_BLOCK_TS)) {
+		current->plug->cur_ktime = 0;
+		current->flags &= ~PF_BLOCK_TS;
+	}
 }
 
 int blkdev_issue_flush(struct block_device *bdev);
@@ -1257,7 +1253,7 @@ static inline void blk_flush_plug(struct blk_plug *plug, bool async)
 {
 }
 
-static inline void blk_plug_invalidate_ts(struct task_struct *tsk)
+static inline void blk_plug_invalidate_ts(void)
 {
 }
 
diff --git a/kernel/fork.c b/kernel/fork.c
index 892a95214c54..13e38e89a1f3 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2338,6 +2338,7 @@ __latent_entropy struct task_struct *copy_process(
 
 #ifdef CONFIG_BLOCK
 	p->plug = NULL;
+	p->flags &= ~PF_BLOCK_TS;
 #endif
 	futex_init_task(p);
 
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 3cc6fb1d2054..96226707c2f6 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5368,6 +5368,12 @@ static struct rq *finish_task_switch(struct task_struct *prev)
 	 */
 	kmap_local_sched_in();
 
+	/*
+	 * Any cached block-layer timestamp (plug->cur_ktime) is stale now,
+	 * invalidate it.
+	 */
+	blk_plug_invalidate_ts();
+
 	fire_sched_in_preempt_notifiers(current);
 	/*
 	 * When switching through a kernel thread, the loop in
@@ -7290,12 +7296,10 @@ static inline void sched_submit_work(struct task_struct *tsk)
 
 static void sched_update_worker(struct task_struct *tsk)
 {
-	if (tsk->flags & (PF_WQ_WORKER | PF_IO_WORKER | PF_BLOCK_TS)) {
-		if (tsk->flags & PF_BLOCK_TS)
-			blk_plug_invalidate_ts(tsk);
+	if (tsk->flags & (PF_WQ_WORKER | PF_IO_WORKER)) {
 		if (tsk->flags & PF_WQ_WORKER)
 			wq_worker_running(tsk);
-		else if (tsk->flags & PF_IO_WORKER)
+		else
 			io_wq_worker_running(tsk);
 	}
 }