* Re: [syzbot] [usb?] INFO: task hung in i2c_tiny_usb_disconnect
[not found] <6963d09e.050a0220.eaf7.0070.GAE@google.com>
@ 2026-01-12 13:11 ` Wei Peng
2026-01-12 13:24 ` syzbot
2026-01-12 13:31 ` Wei Peng
2026-01-12 13:38 ` Wei Peng
2 siblings, 1 reply; 6+ messages in thread
From: Wei Peng @ 2026-01-12 13:11 UTC (permalink / raw)
To: syzbot; +Cc: linux-kernel, linux-i2c
#syz test
diff --git a/drivers/i2c/busses/i2c-tiny-usb.c b/drivers/i2c/busses/i2c-tiny-usb.c
index 57dfe5f1a7d9..ee41d0469882 100644
--- a/drivers/i2c/busses/i2c-tiny-usb.c
+++ b/drivers/i2c/busses/i2c-tiny-usb.c
@@ -12,6 +12,7 @@
#include <linux/slab.h>
#include <linux/string_choices.h>
#include <linux/types.h>
+#include <linux/workqueue.h>
/* include interfaces to usb layer */
#include <linux/usb.h>
@@ -172,6 +173,8 @@ struct i2c_tiny_usb {
struct usb_device *usb_dev; /* the usb device for this device */
struct usb_interface *interface; /* the interface for this device */
struct i2c_adapter adapter; /* i2c related things */
+ bool disconnected; /* set to true on disconnect */
+ struct work_struct release_work; /* work struct to release the adapter */
};
static int usb_read(struct i2c_adapter *adapter, int cmd,
@@ -184,6 +187,11 @@ static int usb_read(struct i2c_adapter *adapter, int cmd,
if (!dmadata)
return -ENOMEM;
+ if (READ_ONCE(dev->disconnected)) {
+ kfree(dmadata);
+ return -ENODEV;
+ }
+
/* do control transfer */
ret = usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
@@ -204,6 +212,11 @@ static int usb_write(struct i2c_adapter *adapter, int cmd,
if (!dmadata)
return -ENOMEM;
+ if (READ_ONCE(dev->disconnected)) {
+ kfree(dmadata);
+ return -ENODEV;
+ }
+
/* do control transfer */
ret = usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
@@ -219,6 +232,15 @@ static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
kfree(dev);
}
+static void i2c_tiny_usb_release(struct work_struct *work)
+{
+ struct i2c_tiny_usb *dev = container_of(work, struct i2c_tiny_usb,
+ release_work);
+
+ i2c_del_adapter(&dev->adapter);
+ i2c_tiny_usb_free(dev);
+}
+
static int i2c_tiny_usb_probe(struct usb_interface *interface,
const struct usb_device_id *id)
{
@@ -268,6 +290,8 @@ static int i2c_tiny_usb_probe(struct usb_interface *interface,
dev->adapter.dev.parent = &dev->interface->dev;
+ INIT_WORK(&dev->release_work, i2c_tiny_usb_release);
+
/* and finally attach to i2c layer */
i2c_add_adapter(&dev->adapter);
@@ -287,9 +311,9 @@ static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
{
struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
- i2c_del_adapter(&dev->adapter);
usb_set_intfdata(interface, NULL);
- i2c_tiny_usb_free(dev);
+ atomic_set(&dev->disconnected, 1);
+ queue_work(system_long_wq, &dev->release_work);
dev_dbg(&interface->dev, "disconnected\n");
}
On 2026/1/12 00:32, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: f0b9d8eb98df Merge tag 'nfsd-6.19-3' of git://git.kernel.o..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11086922580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=a11e0f726bfb6765
> dashboard link: https://syzkaller.appspot.com/bug?extid=30b78308ba7e64647ff8
> compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=179ba83a580000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=113511fc580000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/4dbba2a806a3/disk-f0b9d8eb.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/2a52c0f94de7/vmlinux-f0b9d8eb.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/5ddf9a24988b/bzImage-f0b9d8eb.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+30b78308ba7e64647ff8@syzkaller.appspotmail.com
>
> INFO: task kworker/1:0:24 blocked for more than 143 seconds.
> Not tainted syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:kworker/1:0 state:D stack:24120 pid:24 tgid:24 ppid:2 task_flags:0x4288060 flags:0x00080000
> Workqueue: usb_hub_wq hub_event
> Call Trace:
> <TASK>
> context_switch kernel/sched/core.c:5256 [inline]
> __schedule+0x1139/0x6150 kernel/sched/core.c:6863
> __schedule_loop kernel/sched/core.c:6945 [inline]
> schedule+0xe7/0x3a0 kernel/sched/core.c:6960
> schedule_timeout+0x257/0x290 kernel/time/sleep_timeout.c:75
> do_wait_for_common kernel/sched/completion.c:100 [inline]
> __wait_for_common+0x2fc/0x4e0 kernel/sched/completion.c:121
> i2c_del_adapter+0x640/0x850 drivers/i2c/i2c-core-base.c:1814
> i2c_tiny_usb_disconnect+0x42/0x100 drivers/i2c/busses/i2c-tiny-usb.c:290
> usb_unbind_interface+0x1dd/0x9e0 drivers/usb/core/driver.c:458
> device_remove drivers/base/dd.c:571 [inline]
> device_remove+0x125/0x170 drivers/base/dd.c:563
> __device_release_driver drivers/base/dd.c:1282 [inline]
> device_release_driver_internal+0x44b/0x620 drivers/base/dd.c:1305
> bus_remove_device+0x22f/0x450 drivers/base/bus.c:616
> device_del+0x396/0x9f0 drivers/base/core.c:3878
> usb_disable_device+0x355/0x820 drivers/usb/core/message.c:1418
> usb_disconnect+0x2e1/0x9e0 drivers/usb/core/hub.c:2345
> hub_port_connect drivers/usb/core/hub.c:5407 [inline]
> hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
> port_event drivers/usb/core/hub.c:5871 [inline]
> hub_event+0x1d84/0x52f0 drivers/usb/core/hub.c:5953
> process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257
> process_scheduled_works kernel/workqueue.c:3340 [inline]
> worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421
> kthread+0x3c5/0x780 kernel/kthread.c:463
> ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
> </TASK>
> INFO: task syz.0.273:6595 blocked for more than 143 seconds.
> Not tainted syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz.0.273 state:D stack:26256 pid:6595 tgid:6595 ppid:5924 task_flags:0x400040 flags:0x00080002
> Call Trace:
> <TASK>
> context_switch kernel/sched/core.c:5256 [inline]
> __schedule+0x1139/0x6150 kernel/sched/core.c:6863
> __schedule_loop kernel/sched/core.c:6945 [inline]
> schedule+0xe7/0x3a0 kernel/sched/core.c:6960
> schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7017
> __mutex_lock_common kernel/locking/mutex.c:692 [inline]
> __mutex_lock+0xc69/0x1ca0 kernel/locking/mutex.c:776
> device_lock include/linux/device.h:895 [inline]
> usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> chrdev_open+0x234/0x6a0 fs/char_dev.c:414
> do_dentry_open+0x748/0x1590 fs/open.c:962
> vfs_open+0x82/0x3f0 fs/open.c:1094
> do_open fs/namei.c:4628 [inline]
> path_openat+0x2078/0x3140 fs/namei.c:4787
> do_filp_open+0x20b/0x470 fs/namei.c:4814
> do_sys_openat2+0x121/0x290 fs/open.c:1430
> do_sys_open fs/open.c:1436 [inline]
> __do_sys_openat fs/open.c:1452 [inline]
> __se_sys_openat fs/open.c:1447 [inline]
> __x64_sys_openat+0x174/0x210 fs/open.c:1447
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f3b2d38df90
> RSP: 002b:00007ffdb4e6d020 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
> RAX: ffffffffffffffda RBX: 0000000000188301 RCX: 00007f3b2d38df90
> RDX: 0000000000188301 RSI: 00007ffdb4e6d0c0 RDI: 00000000ffffff9c
> RBP: 00007ffdb4e6d0c0 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000293 R12: cccccccccccccccd
> R13: 00007f3b2d5e5fa0 R14: 00007f3b2d5e5fa0 R15: 0000000000000003
> </TASK>
> INFO: task syz.2.274:6596 blocked for more than 144 seconds.
> Not tainted syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz.2.274 state:D stack:26224 pid:6596 tgid:6596 ppid:5932 task_flags:0x400040 flags:0x00080002
> Call Trace:
> <TASK>
> context_switch kernel/sched/core.c:5256 [inline]
> __schedule+0x1139/0x6150 kernel/sched/core.c:6863
> __schedule_loop kernel/sched/core.c:6945 [inline]
> schedule+0xe7/0x3a0 kernel/sched/core.c:6960
> schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7017
> __mutex_lock_common kernel/locking/mutex.c:692 [inline]
> __mutex_lock+0xc69/0x1ca0 kernel/locking/mutex.c:776
> device_lock include/linux/device.h:895 [inline]
> usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> chrdev_open+0x234/0x6a0 fs/char_dev.c:414
> do_dentry_open+0x748/0x1590 fs/open.c:962
> vfs_open+0x82/0x3f0 fs/open.c:1094
> do_open fs/namei.c:4628 [inline]
> path_openat+0x2078/0x3140 fs/namei.c:4787
> do_filp_open+0x20b/0x470 fs/namei.c:4814
> do_sys_openat2+0x121/0x290 fs/open.c:1430
> do_sys_open fs/open.c:1436 [inline]
> __do_sys_openat fs/open.c:1452 [inline]
> __se_sys_openat fs/open.c:1447 [inline]
> __x64_sys_openat+0x174/0x210 fs/open.c:1447
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7fd7cbb8df90
> RSP: 002b:00007fff0be25800 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
> RAX: ffffffffffffffda RBX: 0000000000188301 RCX: 00007fd7cbb8df90
> RDX: 0000000000188301 RSI: 00007fff0be258a0 RDI: 00000000ffffff9c
> RBP: 00007fff0be258a0 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000293 R12: cccccccccccccccd
> R13: 00007fd7cbde5fa0 R14: 00007fd7cbde5fa0 R15: 0000000000000003
> </TASK>
> INFO: task syz.3.275:6597 blocked for more than 144 seconds.
> Not tainted syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz.3.275 state:D stack:26256 pid:6597 tgid:6597 ppid:5934 task_flags:0x400040 flags:0x00080002
> Call Trace:
> <TASK>
> context_switch kernel/sched/core.c:5256 [inline]
> __schedule+0x1139/0x6150 kernel/sched/core.c:6863
> __schedule_loop kernel/sched/core.c:6945 [inline]
> schedule+0xe7/0x3a0 kernel/sched/core.c:6960
> schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7017
> __mutex_lock_common kernel/locking/mutex.c:692 [inline]
> __mutex_lock+0xc69/0x1ca0 kernel/locking/mutex.c:776
> device_lock include/linux/device.h:895 [inline]
> usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> chrdev_open+0x234/0x6a0 fs/char_dev.c:414
> do_dentry_open+0x748/0x1590 fs/open.c:962
> vfs_open+0x82/0x3f0 fs/open.c:1094
> do_open fs/namei.c:4628 [inline]
> path_openat+0x2078/0x3140 fs/namei.c:4787
> do_filp_open+0x20b/0x470 fs/namei.c:4814
> do_sys_openat2+0x121/0x290 fs/open.c:1430
> do_sys_open fs/open.c:1436 [inline]
> __do_sys_openat fs/open.c:1452 [inline]
> __se_sys_openat fs/open.c:1447 [inline]
> __x64_sys_openat+0x174/0x210 fs/open.c:1447
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f6f3df8df90
> RSP: 002b:00007ffe4db0dd90 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
> RAX: ffffffffffffffda RBX: 0000000000188301 RCX: 00007f6f3df8df90
> RDX: 0000000000188301 RSI: 00007ffe4db0de30 RDI: 00000000ffffff9c
> RBP: 00007ffe4db0de30 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000293 R12: cccccccccccccccd
> R13: 00007f6f3e1e5fa0 R14: 00007f6f3e1e5fa0 R15: 0000000000000003
> </TASK>
> INFO: task syz.1.276:6598 blocked for more than 144 seconds.
> Not tainted syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz.1.276 state:D stack:25704 pid:6598 tgid:6598 ppid:5930 task_flags:0x400040 flags:0x00080002
> Call Trace:
> <TASK>
> context_switch kernel/sched/core.c:5256 [inline]
> __schedule+0x1139/0x6150 kernel/sched/core.c:6863
> __schedule_loop kernel/sched/core.c:6945 [inline]
> schedule+0xe7/0x3a0 kernel/sched/core.c:6960
> schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7017
> __mutex_lock_common kernel/locking/mutex.c:692 [inline]
> __mutex_lock+0xc69/0x1ca0 kernel/locking/mutex.c:776
> device_lock include/linux/device.h:895 [inline]
> usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> chrdev_open+0x234/0x6a0 fs/char_dev.c:414
> do_dentry_open+0x748/0x1590 fs/open.c:962
> vfs_open+0x82/0x3f0 fs/open.c:1094
> do_open fs/namei.c:4628 [inline]
> path_openat+0x2078/0x3140 fs/namei.c:4787
> do_filp_open+0x20b/0x470 fs/namei.c:4814
> do_sys_openat2+0x121/0x290 fs/open.c:1430
> do_sys_open fs/open.c:1436 [inline]
> __do_sys_openat fs/open.c:1452 [inline]
> __se_sys_openat fs/open.c:1447 [inline]
> __x64_sys_openat+0x174/0x210 fs/open.c:1447
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f36b5b8df90
> RSP: 002b:00007ffd7720b280 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
> RAX: ffffffffffffffda RBX: 0000000000188301 RCX: 00007f36b5b8df90
> RDX: 0000000000188301 RSI: 00007ffd7720b320 RDI: 00000000ffffff9c
> RBP: 00007ffd7720b320 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000293 R12: cccccccccccccccd
> R13: 00007f36b5de5fa0 R14: 00007f36b5de5fa0 R15: 0000000000000003
> </TASK>
>
> Showing all locks held in the system:
> 5 locks held by kworker/1:0/24:
> #0: ffff8880212a0948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232
> #1: ffffc900001e7c90 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233
> #2: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #2: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: hub_event+0x1c0/0x52f0 drivers/usb/core/hub.c:5899
> #3: ffff888073ad6198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #3: ffff888073ad6198 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0x10a/0x9e0 drivers/usb/core/hub.c:2336
> #4: ffff88807976e160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #4: ffff88807976e160 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1104 [inline]
> #4: ffff88807976e160 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xa4/0x620 drivers/base/dd.c:1302
> 1 lock held by khungtaskd/31:
> #0: ffffffff8e3c96a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
> #0: ffffffff8e3c96a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
> #0: ffffffff8e3c96a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
> 1 lock held by klogd/5174:
> #0: ffff8880b853ac98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:639
> 2 locks held by getty/5581:
> #0: ffff88814d52e0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
> #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x1510 drivers/tty/n_tty.c:2211
> 1 lock held by syz.0.273/6595:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.2.274/6596:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.3.275/6597:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.1.276/6598:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.5.282/6719:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.6.283/6721:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.7.284/6723:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.8.285/6726:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.0.293/6836:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.2.294/6840:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.1.295/6841:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.9.292/6842:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.3.303/6904:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.7.305/6951:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.5.304/6961:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.6.306/6964:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.8.313/7018:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.0.315/7049:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.2.317/7073:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.9.316/7078:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.1.323/7112:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.3.325/7142:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.7.326/7193:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.5.328/7194:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.6.333/7234:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.8.335/7260:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.0.337/7304:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.2.338/7305:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.9.343/7345:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.1.344/7367:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.3.347/7416:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 2 locks held by kworker/u8:53/7419:
> #0: ffff8880b853ac98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:639
> #1: ffff8880b8524608 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:225 [inline]
> #1: ffff8880b8524608 (psi_seq){-.-.}-{0:0}, at: __schedule+0x19b1/0x6150 kernel/sched/core.c:6857
> 1 lock held by syz.5.348/7421:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz.7.352/7454:
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
> #0: ffff88802a025198 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x1b6/0x8b0 drivers/usb/core/devio.c:1054
> 1 lock held by syz-executor/7455:
> #0: ffffffff8e3d4df8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x284/0x3c0 kernel/rcu/tree_exp.h:311
> 3 locks held by kworker/0:14/7462:
> #0: ffff88813ff51948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232
> #1: ffffc9000f2c7c90 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233
> #2: ffff888035684240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x1b8/0x65f0 drivers/net/netdevsim/fib.c:1490
>
> =============================================
>
> NMI backtrace for cpu 0
> CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
> Call Trace:
> <TASK>
> __dump_stack lib/dump_stack.c:94 [inline]
> dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
> nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
> nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
> trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
> __sys_info lib/sys_info.c:157 [inline]
> sys_info+0x133/0x180 lib/sys_info.c:165
> check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
> watchdog+0xe66/0x1180 kernel/hung_task.c:515
> kthread+0x3c5/0x780 kernel/kthread.c:463
> ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
> </TASK>
> Sending NMI from CPU 0 to CPUs 1:
> NMI backtrace for cpu 1
> CPU: 1 UID: 0 PID: 7485 Comm: syz.6.354 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
> RIP: 0010:io_serial_in+0x87/0xb0 drivers/tty/serial/8250/8250_port.c:401
> Code: 75 8c fc 48 8d 7d 40 44 89 e1 48 b8 00 00 00 00 00 fc ff df 48 89 fa d3 e3 48 c1 ea 03 80 3c 02 00 75 1a 66 03 5d 40 89 da ec <5b> 0f b6 c0 5d 41 5c e9 3d d0 48 06 e8 38 4a f6 fc eb a2 e8 c1 4a
> RSP: 0018:ffffc9000f2a78c8 EFLAGS: 00000002
> RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
> RDX: 00000000000003fd RSI: ffffffff85327330 RDI: ffffffff9aeedc40
> RBP: ffffffff9aeedc00 R08: 0000000000000001 R09: 000000000000001f
> R10: 0000000000000000 R11: ffff888087e80b30 R12: 0000000000000000
> R13: 0000000000000020 R14: fffffbfff35ddbda R15: dffffc0000000000
> FS: 0000555573d50500(0000) GS:ffff8881249f5000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f00b51733e0 CR3: 00000000a834a000 CR4: 00000000003526f0
> Call Trace:
> <TASK>
> serial_in drivers/tty/serial/8250/8250.h:128 [inline]
> serial_lsr_in drivers/tty/serial/8250/8250.h:150 [inline]
> wait_for_lsr+0x13a/0x210 drivers/tty/serial/8250/8250_port.c:1961
> fifo_wait_for_lsr drivers/tty/serial/8250/8250_port.c:3234 [inline]
> serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3257 [inline]
> serial8250_console_write+0xf81/0x1890 drivers/tty/serial/8250/8250_port.c:3342
> console_emit_next_record kernel/printk/printk.c:3129 [inline]
> console_flush_one_record+0x796/0xc60 kernel/printk/printk.c:3215
> console_flush_all kernel/printk/printk.c:3289 [inline]
> __console_flush_and_unlock kernel/printk/printk.c:3319 [inline]
> console_unlock+0xef/0x240 kernel/printk/printk.c:3359
> vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2426
> _printk+0xc7/0x100 kernel/printk/printk.c:2451
> usb_gadget_register_driver_owner+0x1fb/0x330 drivers/usb/gadget/udc/core.c:1729
> raw_ioctl_run drivers/usb/gadget/legacy/raw_gadget.c:596 [inline]
> raw_ioctl+0x17ec/0x2e60 drivers/usb/gadget/legacy/raw_gadget.c:1307
> vfs_ioctl fs/ioctl.c:51 [inline]
> __do_sys_ioctl fs/ioctl.c:597 [inline]
> __se_sys_ioctl fs/ioctl.c:583 [inline]
> __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f00b518f34b
> Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00
> RSP: 002b:00007ffe8bc9e9d0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f00b518f34b
> RDX: 0000000000000000 RSI: 0000000000005501 RDI: 0000000000000003
> RBP: 00007ffe8bc9faa0 R08: 0000000000000000 R09: 00362e6364755f79
> R10: 0000000000000011 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007ffe8bc9ea70 R14: 0000200000000440 R15: 00007f00b5510320
> </TASK>
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
>
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
>
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
>
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
>
> If you want to undo deduplication, reply with:
> #syz undup
>
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [syzbot] [usb?] INFO: task hung in i2c_tiny_usb_disconnect
[not found] <6963d09e.050a0220.eaf7.0070.GAE@google.com>
2026-01-12 13:11 ` Wei Peng
@ 2026-01-12 13:31 ` Wei Peng
2026-01-12 13:38 ` Wei Peng
2 siblings, 0 replies; 6+ messages in thread
From: Wei Peng @ 2026-01-12 13:31 UTC (permalink / raw)
To: syzbot; +Cc: linux-kernel, linux-i2c
|Sorry! Please ignore the previous patch. It was sent by mistake. The
correct patch is attached below. |#syz test
diff --git a/drivers/i2c/busses/i2c-tiny-usb.c b/drivers/i2c/busses/i2c-tiny-usb.c
index 57dfe5f1a7d9..79b7c97514c9 100644
--- a/drivers/i2c/busses/i2c-tiny-usb.c
+++ b/drivers/i2c/busses/i2c-tiny-usb.c
@@ -12,6 +12,7 @@
#include <linux/slab.h>
#include <linux/string_choices.h>
#include <linux/types.h>
+#include <linux/workqueue.h>
/* include interfaces to usb layer */
#include <linux/usb.h>
@@ -172,6 +173,8 @@ struct i2c_tiny_usb {
struct usb_device *usb_dev; /* the usb device for this device */
struct usb_interface *interface; /* the interface for this device */
struct i2c_adapter adapter; /* i2c related things */
+ bool disconnected; /* set to true on disconnect */
+ struct work_struct release_work; /* work struct to release the adapter */
};
static int usb_read(struct i2c_adapter *adapter, int cmd,
@@ -184,6 +187,11 @@ static int usb_read(struct i2c_adapter *adapter, int cmd,
if (!dmadata)
return -ENOMEM;
+ if (READ_ONCE(dev->disconnected)) {
+ kfree(dmadata);
+ return -ENODEV;
+ }
+
/* do control transfer */
ret = usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
@@ -204,6 +212,11 @@ static int usb_write(struct i2c_adapter *adapter, int cmd,
if (!dmadata)
return -ENOMEM;
+ if (READ_ONCE(dev->disconnected)) {
+ kfree(dmadata);
+ return -ENODEV;
+ }
+
/* do control transfer */
ret = usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
@@ -219,6 +232,15 @@ static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
kfree(dev);
}
+static void i2c_tiny_usb_release(struct work_struct *work)
+{
+ struct i2c_tiny_usb *dev = container_of(work, struct i2c_tiny_usb,
+ release_work);
+
+ i2c_del_adapter(&dev->adapter);
+ i2c_tiny_usb_free(dev);
+}
+
static int i2c_tiny_usb_probe(struct usb_interface *interface,
const struct usb_device_id *id)
{
@@ -268,6 +290,8 @@ static int i2c_tiny_usb_probe(struct usb_interface *interface,
dev->adapter.dev.parent = &dev->interface->dev;
+ INIT_WORK(&dev->release_work, i2c_tiny_usb_release);
+
/* and finally attach to i2c layer */
i2c_add_adapter(&dev->adapter);
@@ -287,9 +311,9 @@ static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
{
struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
- i2c_del_adapter(&dev->adapter);
usb_set_intfdata(interface, NULL);
- i2c_tiny_usb_free(dev);
+ WRITE_ONCE(dev->disconnected, true);
+ queue_work(system_long_wq, &dev->release_work);
dev_dbg(&interface->dev, "disconnected\n");
}
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [syzbot] [usb?] INFO: task hung in i2c_tiny_usb_disconnect
[not found] <6963d09e.050a0220.eaf7.0070.GAE@google.com>
2026-01-12 13:11 ` Wei Peng
2026-01-12 13:31 ` Wei Peng
@ 2026-01-12 13:38 ` Wei Peng
2026-01-12 13:41 ` syzbot
2 siblings, 1 reply; 6+ messages in thread
From: Wei Peng @ 2026-01-12 13:38 UTC (permalink / raw)
To: syzbot; +Cc: linux-kernel, linux-i2c
#syz test
diff --git a/drivers/i2c/busses/i2c-tiny-usb.c
b/drivers/i2c/busses/i2c-tiny-usb.c
index 57dfe5f1a7d9..79b7c97514c9 100644
--- a/drivers/i2c/busses/i2c-tiny-usb.c
+++ b/drivers/i2c/busses/i2c-tiny-usb.c
@@ -12,6 +12,7 @@
#include <linux/slab.h>
#include <linux/string_choices.h>
#include <linux/types.h>
+#include <linux/workqueue.h>
/* include interfaces to usb layer */
#include <linux/usb.h>
@@ -172,6 +173,8 @@ struct i2c_tiny_usb {
struct usb_device *usb_dev; /* the usb device for this device */
struct usb_interface *interface; /* the interface for this device */
struct i2c_adapter adapter; /* i2c related things */
+ bool disconnected; /* set to true on disconnect */
+ struct work_struct release_work; /* work struct to release the
adapter */
};
static int usb_read(struct i2c_adapter *adapter, int cmd,
@@ -184,6 +187,11 @@ static int usb_read(struct i2c_adapter *adapter,
int cmd,
if (!dmadata)
return -ENOMEM;
+ if (READ_ONCE(dev->disconnected)) {
+ kfree(dmadata);
+ return -ENODEV;
+ }
+
/* do control transfer */
ret = usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
@@ -204,6 +212,11 @@ static int usb_write(struct i2c_adapter *adapter,
int cmd,
if (!dmadata)
return -ENOMEM;
+ if (READ_ONCE(dev->disconnected)) {
+ kfree(dmadata);
+ return -ENODEV;
+ }
+
/* do control transfer */
ret = usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
@@ -219,6 +232,15 @@ static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
kfree(dev);
}
+static void i2c_tiny_usb_release(struct work_struct *work)
+{
+ struct i2c_tiny_usb *dev = container_of(work, struct i2c_tiny_usb,
+ release_work);
+
+ i2c_del_adapter(&dev->adapter);
+ i2c_tiny_usb_free(dev);
+}
+
static int i2c_tiny_usb_probe(struct usb_interface *interface,
const struct usb_device_id *id)
{
@@ -268,6 +290,8 @@ static int i2c_tiny_usb_probe(struct usb_interface
*interface,
dev->adapter.dev.parent = &dev->interface->dev;
+ INIT_WORK(&dev->release_work, i2c_tiny_usb_release);
+
/* and finally attach to i2c layer */
i2c_add_adapter(&dev->adapter);
@@ -287,9 +311,9 @@ static void i2c_tiny_usb_disconnect(struct
usb_interface *interface)
{
struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
- i2c_del_adapter(&dev->adapter);
usb_set_intfdata(interface, NULL);
- i2c_tiny_usb_free(dev);
+ WRITE_ONCE(dev->disconnected, true);
+ queue_work(system_long_wq, &dev->release_work);
dev_dbg(&interface->dev, "disconnected\n");
}
^ permalink raw reply related [flat|nested] 6+ messages in thread