syzbot

INFO: task syz.4.20:5671 blocked for more than 144 seconds.
      Not tainted 6.14.0-rc5-syzkaller-00218-g2a520073e74f #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.20        state:D stack:27552 pid:5671  tgid:5670  ppid:5459   task_flags:0x400040 flags:0x00000004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5378 [inline]
 __schedule+0x190e/0x4c90 kernel/sched/core.c:6765
 __schedule_loop kernel/sched/core.c:6842 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6857
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6914
 __mutex_lock_common kernel/locking/mutex.c:662 [inline]
 __mutex_lock+0x817/0x1010 kernel/locking/mutex.c:730
 rtnl_net_lock include/linux/rtnetlink.h:129 [inline]
 dev_ioctl+0x86e/0x1340 net/core/dev_ioctl.c:852
 sock_ioctl+0x7ef/0x8e0 net/socket.c:1245
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4ff418d169
RSP: 002b:00007f4ff4f34038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f4ff43a5fa0 RCX: 00007f4ff418d169
RDX: 0000400000000080 RSI: 00000000000089f0 RDI: 0000000000000003
RBP: 00007f4ff420e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f4ff43a5fa0 R15: 00007ffdc314fef8
 </TASK>
INFO: task kworker/u4:13:5674 blocked for more than 147 seconds.
      Not tainted 6.14.0-rc5-syzkaller-00218-g2a520073e74f #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:13   state:D stack:28272 pid:5674  tgid:5674  ppid:2      task_flags:0x4208060 flags:0x00004000
Workqueue: events_unbound linkwatch_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5378 [inline]
 __schedule+0x190e/0x4c90 kernel/sched/core.c:6765
 __schedule_loop kernel/sched/core.c:6842 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6857
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6914
 __mutex_lock_common kernel/locking/mutex.c:662 [inline]
 __mutex_lock+0x817/0x1010 kernel/locking/mutex.c:730
 linkwatch_event+0xe/0x60 net/core/link_watch.c:285
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xabe/0x18e0 kernel/workqueue.c:3319
 worker_thread+0x870/0xd30 kernel/workqueue.c:3400
 kthread+0x7a9/0x920 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/0:0/9:
3 locks held by kworker/u4:0/12:
1 lock held by khungtaskd/26:
 #0: ffffffff8eb39320 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8eb39320 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8eb39320 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6746
2 locks held by kworker/u4:2/31:
3 locks held by kworker/u4:3/47:
3 locks held by kworker/u4:4/56:
2 locks held by kworker/0:2/58:
3 locks held by kworker/u4:6/1034:
3 locks held by kworker/u4:8/1042:
3 locks held by kworker/u4:9/1135:
 #0: ffff888035b17948 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff888035b17948 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x98b/0x18e0 kernel/workqueue.c:3319
 #1: ffffc9000260fc60 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc9000260fc60 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9c6/0x18e0 kernel/workqueue.c:3319
 #2: ffffffff8fed5c08 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:129 [inline]
 #2: ffffffff8fed5c08 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x10e/0x16a0 net/ipv6/addrconf.c:4190
3 locks held by kworker/u4:10/4411:
1 lock held by dhcpcd/5024:
 #0: ffffffff8fed5c08 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:129 [inline]
 #0: ffffffff8fed5c08 (rtnl_mutex){+.+.}-{4:4}, at: inet6_rtm_newaddr+0x7bf/0xf10 net/ipv6/addrconf.c:5023
2 locks held by getty/5107:
 #0: ffff8880005990a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000019b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x616/0x1770 drivers/tty/n_tty.c:2211