INFO: task syz-executor.1:3434 blocked for more than 140 seconds. Not tainted 4.9.141+ #23 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D29816 3434 3432 0x20020000 ffff8801d06fdf00 0000000000000000 ffff8801d2f4f380 ffff8801da6b2f80 ffff8801db721018 ffff8801d13b7b80 ffffffff828075c2 ffffffff8432c608 ffffffff83cc61c0 ffff8801d06fe7d8 00000000000031cb ffff8801db7218f0 Call Trace: [] schedule+0x7f/0x1b0 kernel/sched/core.c:3553 [] schedule_timeout+0x735/0xe20 kernel/time/timer.c:1771 [] do_wait_for_common kernel/sched/completion.c:75 [inline] [] __wait_for_common kernel/sched/completion.c:93 [inline] [] wait_for_common+0x3ef/0x5d0 kernel/sched/completion.c:101 [] wait_for_completion+0x18/0x20 kernel/sched/completion.c:122 [] SYSC_io_destroy fs/aio.c:1414 [inline] [] SyS_io_destroy+0x2c0/0x340 fs/aio.c:1392 [] do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline] [] do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390 [] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137 Showing all locks held in the system: 2 locks held by khungtaskd/24: #0: (rcu_read_lock){......}, at: [] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline] #0: (rcu_read_lock){......}, at: [] watchdog+0x11c/0xa20 kernel/hung_task.c:239 #1: (tasklist_lock){.+.+..}, at: [] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336 2 locks held by getty/2020: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142 1 lock held by syz-executor.4/2297: #0: (tasklist_lock){.+.+..}, at: [] release_task.part.4+0x148/0x14b0 kernel/exit.c:183 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.141+ #23 ffff8801d9907d08 ffffffff81b42e79 0000000000000000 0000000000000001 0000000000000001 0000000000000001 ffffffff810983b0 ffff8801d9907d40 ffffffff81b4df89 0000000000000001 0000000000000000 0000000000000003 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] nmi_cpu_backtrace.cold.0+0x48/0x87 lib/nmi_backtrace.c:99 [] nmi_trigger_cpumask_backtrace+0x12c/0x151 lib/nmi_backtrace.c:60 [] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [] check_hung_task kernel/hung_task.c:125 [inline] [] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline] [] watchdog+0x6ad/0xa20 kernel/hung_task.c:239 [] kthread+0x26d/0x300 kernel/kthread.c:211 [] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 2298 Comm: syz-executor.5 Not tainted 4.9.141+ #23 task: ffff8801c7815f00 task.stack: ffff8801cae48000 RIP: 0010:[] c [] wait_consider_task+0x2f9/0x3620 kernel/exit.c:1401 RSP: 0018:ffff8801cae4fa30 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffff8801c5c64768 RCX: 0000000000000000 RDX: 1ffff10038b8c8ed RSI: ffffffff810e9220 RDI: 0000000000000246 RBP: ffff8801cae4fb88 R08: ffffed00395c9f1f R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8801c5c64740 R14: ffff8801cae4fc9c R15: ffff8801cae4fc98 FS: 0000000000000000(0000) GS:ffff8801db600000(0063) knlGS:000000000a363900 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 00007fba78a3ef44 CR3: 00000001d4909000 CR4: 00000000001606b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: 0000000000000000c ffff8801c78167d2c ffff8801cae4fc00c 0000000000000046c ffff8801cae4fb08c ffff8801c789f338c ffff8801cae4fa70c ffffffff81243c87c ffff8801cae4fb28c 0000000000000046c 0000000000000046c ffff8801c7815f00c Call Trace: [] do_wait_thread kernel/exit.c:1490 [inline] [] do_wait+0x423/0x950 kernel/exit.c:1561 [] SYSC_wait4 kernel/exit.c:1693 [inline] [] SyS_wait4+0x12b/0x1f0 kernel/exit.c:1658 [] C_SYSC_wait4 kernel/compat.c:543 [inline] [] compat_SyS_wait4+0x254/0x290 kernel/compat.c:536 [] sys32_waitpid+0x25/0x30 arch/x86/ia32/sys_ia32.c:172 [] do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline] [] do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390 [] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137 Code: c23 c00 c49 c8d c5d c28 c48 cb8 c00 c00 c00 c00 c00 cfc cff cdf c48 c89 cda c48 cc1 cea c03 c0f cb6 c04 c02 c84 cc0 c74 c08 c3c c03 c0f c8e c26 c14 c00 c00 c45 c8b c5d c28 c<45> c85 cdb c0f c85 c34 c15 c00 c00 ce8 c09 c28 c23 c00 c41 c83 cfc c20 c0f c84 c09 c