INFO: task hung in set_selection_kernel

Status: upstream: reported on 2026/07/30 13:51
Reported-by: syzbot+c4fb333a2e7ae2e736f6@syzkaller.appspotmail.com
First crash: 21d, last: 21d
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in set_selection_kernel serial 1 1 195d 195d 0/29 auto-obsoleted due to no activity on 2026/05/07 20:17

Sample crash report:
INFO: task syz.2.640:6282 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.640       state:D stack:27920 pid:6282  ppid:4279   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6698
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x548/0xae0 kernel/locking/mutex.c:747
 set_selection_kernel+0x32/0x17a0 drivers/tty/vt/selection.c:358
 set_selection_user+0xc1/0x100 drivers/tty/vt/selection.c:186
 vt_ioctl+0x449/0x1cc0 drivers/tty/vt/vt_ioctl.c:762
 tty_ioctl+0x7e6/0xba0 drivers/tty/tty_io.c:2776
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc49d99df99
RSP: 002b:00007fc49e81a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc49dc25fa0 RCX: 00007fc49d99df99
RDX: 0000200000000000 RSI: 000000000000541c RDI: 0000000000000004
RBP: 00007fc49da34ec4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc49dc26038 R14: 00007fc49dc25fa0 R15: 00007ffcc5c49d88
 </TASK>
INFO: task syz.2.640:6283 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.640       state:D stack:29136 pid:6283  ppid:4279   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6698
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x548/0xae0 kernel/locking/mutex.c:747
 set_selection_kernel+0x32/0x17a0 drivers/tty/vt/selection.c:358
 set_selection_user+0xc1/0x100 drivers/tty/vt/selection.c:186
 vt_ioctl+0x449/0x1cc0 drivers/tty/vt/vt_ioctl.c:762
 tty_ioctl+0x7e6/0xba0 drivers/tty/tty_io.c:2776
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc49d99df99
RSP: 002b:00007fc49e7f9028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc49dc26090 RCX: 00007fc49d99df99
RDX: 0000200000001900 RSI: 000000000000541c RDI: 0000000000000004
RBP: 00007fc49da34ec4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc49dc26128 R14: 00007fc49dc26090 R15: 00007ffcc5c49d88
 </TASK>

Showing all locks held in the system:
4 locks held by kworker/u4:0/9:
 #0: ffff88801761e938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc900000e7d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffffffff8dd4ead0 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x148/0xba0 net/core/net_namespace.c:594
 #3: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: wiphy_unregister+0x24d/0xb20 net/wireless/core.c:1091
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8cb2e4f0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8cb2ed10 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/27:
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6527
2 locks held by kworker/u4:2/29:
1 lock held by udevd/3639:
2 locks held by getty/4024:
 #0: ffff88814cc33098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41e/0x1360 drivers/tty/n_tty.c:2198
2 locks held by syz.1.479/5760:
1 lock held by syz.2.640/6282:
 #0: ffffffff8d298228 (vc_sel.lock){+.+.}-{3:3}, at: set_selection_kernel+0x32/0x17a0 drivers/tty/vt/selection.c:358
1 lock held by syz.2.640/6283:
 #0: ffffffff8d298228 (vc_sel.lock){+.+.}-{3:3}, at: set_selection_kernel+0x32/0x17a0 drivers/tty/vt/selection.c:358
2 locks held by syz.3.804/6806:
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
 #1: ffff88807f2251c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_init_dev+0x70/0x4c0 drivers/tty/tty_io.c:1414
1 lock held by syz.5.847/6952:
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
1 lock held by syz.6.870/7037:
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xcc/0x2c0 drivers/tty/pty.c:823
1 lock held by syz.8.877/7062:
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
1 lock held by syz.8.877/7065:
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
1 lock held by syz.9.943/7405:
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
1 lock held by syz.7.974/7534:
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
1 lock held by syz.7.974/7535:
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
1 lock held by syz.3.1107/8056:
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
1 lock held by syz.2.1124/8112:
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xcc/0x2c0 drivers/tty/pty.c:823
1 lock held by syz.4.1137/8166:
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
1 lock held by syz-executor/8215:

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3e6/0x460 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xf0e/0xf50 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/30 13:51 linux-6.1.y fb28aa725e05 2377cd3d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in set_selection_kernel
* Struck through repros no longer work on HEAD.