Re: [syzbot] [usb?] INFO: task hung in unbind_store

[Michal Pecio <michal.pecio@gmail.com>]

On Wed, 26 Aug 2026 07:51:35 -0700, syzbot wrote:
> INFO: task syz.0.23:5988 blocked for more than 143 seconds.
>       Not tainted syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz.0.23        state:D stack:27344 pid:5988  tgid:5988  ppid:5772   task_flags:0x400140 flags:0x08080002
> Call Trace:
>  <TASK>
>  context_switch kernel/sched/core.c:5520 [inline]
>  __schedule+0x17d4/0x5820 kernel/sched/core.c:7270
>  __schedule_loop kernel/sched/core.c:7347 [inline]
>  schedule+0x164/0x2b0 kernel/sched/core.c:7362
>  schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7419
>  __mutex_lock_common kernel/locking/mutex.c:726 [inline]
>  __mutex_lock+0x7c1/0x1550 kernel/locking/mutex.c:821
>  device_lock include/linux/device.h:1104 [inline]
>  __device_driver_lock drivers/base/dd.c:1170 [inline]
>  device_release_driver_internal+0x93/0x880 drivers/base/dd.c:1369
>  unbind_store+0x1a1/0x1d0 drivers/base/bus.c:244

#syz test

--- a/drivers/usb/misc/sisusbvga/sisusbvga.c
+++ b/drivers/usb/misc/sisusbvga/sisusbvga.c
@@ -323,6 +323,7 @@ static int sisusb_send_bulk_msg(struct sisusb_usb_data *sisusb, int ep, int len,
 	unsigned int pipe;
 	char *buffer;
 
+	dev_info(&sisusb->sisusb_dev->dev, "sisusb_send_bulk_msg()\n");
 	(*bytes_written) = 0;
 
 	/* Sanity check */
@@ -378,7 +379,7 @@ static int sisusb_send_bulk_msg(struct sisusb_usb_data *sisusb, int ep, int len,
 
 			result = sisusb_bulkout_msg(sisusb, index, pipe,
 					buffer, thispass, &transferred_len,
-					async ? 0 : 5 * HZ, tflags);
+					async ? 0 : HZ / 2, tflags);
 
 			if (result == -ETIMEDOUT) {