INFO: task kworker/u4:4:2454 blocked for more than 140 seconds. Not tainted 4.19.95-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:4 D25040 2454 2 0x80000000 Workqueue: events_unbound flush_to_ldisc Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x866/0x1dc0 kernel/sched/core.c:3515 schedule+0x92/0x1c0 kernel/sched/core.c:3559 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3617 __mutex_lock_common kernel/locking/mutex.c:1002 [inline] __mutex_lock+0x726/0x1300 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 flush_to_ldisc+0x3d/0x390 drivers/tty/tty_buffer.c:500 process_one_work+0x989/0x1750 kernel/workqueue.c:2153 worker_thread+0x98/0xe40 kernel/workqueue.c:2296 kthread+0x354/0x420 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 INFO: task getty:22335 blocked for more than 140 seconds. Not tainted 4.19.95-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. getty D27720 22335 1 0x00000000 Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x866/0x1dc0 kernel/sched/core.c:3515 schedule+0x92/0x1c0 kernel/sched/core.c:3559 schedule_timeout+0x8c8/0xfc0 kernel/time/timer.c:1782 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common kernel/sched/completion.c:115 [inline] wait_for_completion+0x29c/0x440 kernel/sched/completion.c:136 __flush_work+0x49f/0x870 kernel/workqueue.c:2926 flush_work+0x18/0x20 kernel/workqueue.c:2947 tty_buffer_flush_work+0x16/0x19 drivers/tty/tty_buffer.c:613 n_tty_read+0xb1a/0x1b70 drivers/tty/n_tty.c:2197 tty_read+0x193/0x2a0 drivers/tty/tty_io.c:867 __vfs_read+0x114/0x800 fs/read_write.c:416 vfs_read+0x194/0x3d0 fs/read_write.c:452 ksys_read+0x14f/0x2d0 fs/read_write.c:579 __do_sys_read fs/read_write.c:589 [inline] __se_sys_read fs/read_write.c:587 [inline] __x64_sys_read+0x73/0xb0 fs/read_write.c:587 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f33059e2310 Code: Bad RIP value. RSP: 002b:00007ffcd9a2b2a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007f33060b76a8 RCX: 00007f33059e2310 RDX: 0000000000000001 RSI: 00007ffcd9a2b2f8 RDI: 0000000000000000 RBP: 00007ffcd9a2bae0 R08: 0000000000000000 R09: 00007f3305c98e90 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006075a0 R13: 00007ffcd9a2eeda R14: 0000000000000000 R15: 0000000000000000 Showing all locks held in the system: 1 lock held by khungtaskd/1082: #0: 0000000023945e72 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:4438 3 locks held by kworker/u4:4/2454: #0: 000000003411856b ((wq_completion)"events_unbound"){+.+.}, at: __write_once_size include/linux/compiler.h:220 [inline] #0: 000000003411856b ((wq_completion)"events_unbound"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 000000003411856b ((wq_completion)"events_unbound"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 000000003411856b ((wq_completion)"events_unbound"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline] #0: 000000003411856b ((wq_completion)"events_unbound"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 000000003411856b ((wq_completion)"events_unbound"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 000000003411856b ((wq_completion)"events_unbound"){+.+.}, at: process_one_work+0x87e/0x1750 kernel/workqueue.c:2124 #1: 0000000044477561 ((work_completion)(&buf->work)){+.+.}, at: process_one_work+0x8b4/0x1750 kernel/workqueue.c:2128 #2: 0000000017188089 (&buf->lock){+.+.}, at: flush_to_ldisc+0x3d/0x390 drivers/tty/tty_buffer.c:500 1 lock held by rsyslogd/8027: #0: 00000000514fe5f0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:767 2 locks held by getty/8149: #0: 0000000063d58eea (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000529d7de6 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by getty/8150: #0: 000000003825ff12 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 000000005855be75 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by getty/8151: #0: 000000006f0a63cc (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 0000000011fab559 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by getty/8152: #0: 0000000057dc8e92 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 0000000028ff4ca7 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by getty/8153: #0: 000000008b3cc54c (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 000000000c9876e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by getty/8154: #0: 00000000ecefb6ec (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 0000000041b5ecb8 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by getty/22335: #0: 0000000091fbe9ca (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:362 #1: 00000000f24f500c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2154 2 locks held by syz-executor.2/25692: ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1082 Comm: khungtaskd Not tainted 4.19.95-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1b0/0x1f8 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline] watchdog+0x9df/0xee0 kernel/hung_task.c:287 kthread+0x354/0x420 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 23638 Comm: kworker/u4:5 Not tainted 4.19.95-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_nc_worker RIP: 0010:check_memory_region+0x1f/0x190 mm/kasan/kasan.c:266 Code: 90 66 2e 0f 1f 84 00 00 00 00 00 48 85 f6 0f 84 21 01 00 00 48 b8 ff ff ff ff ff 7f ff ff 55 0f b6 d2 48 39 c7 48 89 e5 41 55 <41> 54 53 0f 86 f6 00 00 00 4c 8d 5c 37 ff 49 89 f8 48 b8 00 00 00 RSP: 0018:ffff888055f8f9c8 EFLAGS: 00000012 RAX: ffff7fffffffffff RBX: 0000000000000000 RCX: ffffffff8151e7db RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff8a834ae8 RBP: ffff888055f8f9d0 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000000 R14: ffff88805430a640 R15: ffff88805ecee488 FS: 0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 0000000089a2f000 CR4: 00000000001426f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: kasan_check_write+0x14/0x20 mm/kasan/kasan.c:278 atomic_inc include/asm-generic/atomic-instrumented.h:109 [inline] __lock_acquire+0x23b/0x49c0 kernel/locking/lockdep.c:3303 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3903 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x33/0x50 kernel/locking/spinlock.c:168 spin_lock_bh include/linux/spinlock.h:334 [inline] batadv_nc_purge_paths+0xd8/0x3a0 net/batman-adv/network-coding.c:453 batadv_nc_worker+0x29c/0x760 net/batman-adv/network-coding.c:731 process_one_work+0x989/0x1750 kernel/workqueue.c:2153 worker_thread+0x98/0xe40 kernel/workqueue.c:2296 kthread+0x354/0x420 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415