INFO: task syzkaller726993:4168 blocked for more than 120 seconds. Not tainted 4.15.0+ #209 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syzkaller726993 D22288 4168 4166 0x20020000 Call Trace: context_switch kernel/sched/core.c:2845 [inline] __schedule+0x8eb/0x2060 kernel/sched/core.c:3421 schedule+0xf5/0x430 kernel/sched/core.c:3480 __lock_sock+0x1dc/0x2f0 net/core/sock.c:2247 lock_sock_nested+0xf3/0x110 net/core/sock.c:2771 lock_sock include/net/sock.h:1463 [inline] ipv6_getorigdst+0x1dd/0x990 net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c:233 compat_nf_sockopt net/netfilter/nf_sockopt.c:141 [inline] compat_nf_getsockopt+0xfd/0x130 net/netfilter/nf_sockopt.c:163 compat_ipv6_getsockopt+0x20b/0x390 net/ipv6/ipv6_sockglue.c:1413 compat_udpv6_getsockopt+0x45/0x80 net/ipv6/udp.c:1450 compat_sock_common_getsockopt+0xb2/0x140 net/core/sock.c:2945 C_SYSC_getsockopt net/compat.c:523 [inline] compat_SyS_getsockopt+0x182/0x420 net/compat.c:506 do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline] do_fast_syscall_32+0x3ee/0xfa1 arch/x86/entry/common.c:392 entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:129 RIP: 0023:0xf7fd3c79 RSP: 002b:00000000ffa6a42c EFLAGS: 00000282 ORIG_RAX: 000000000000016d RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000000029 RDX: 0000000000000050 RSI: 0000000020028000 RDI: 000000002000d000 RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Showing all locks held in the system: 2 locks held by khungtaskd/757: #0: (rcu_read_lock){....}, at: [<00000000559bda5b>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<00000000559bda5b>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<00000000f32840fe>] debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4470 2 locks held by getty/4137: #0: (&tty->ldisc_sem){++++}, at: [<000000006495c1b9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000b266d8bb>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4138: #0: (&tty->ldisc_sem){++++}, at: [<000000006495c1b9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000b266d8bb>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4139: #0: (&tty->ldisc_sem){++++}, at: [<000000006495c1b9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000b266d8bb>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4140: #0: (&tty->ldisc_sem){++++}, at: [<000000006495c1b9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000b266d8bb>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4141: #0: (&tty->ldisc_sem){++++}, at: [<000000006495c1b9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000b266d8bb>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4142: #0: (&tty->ldisc_sem){++++}, at: [<000000006495c1b9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000b266d8bb>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4143: #0: (&tty->ldisc_sem){++++}, at: [<000000006495c1b9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000b266d8bb>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 1 lock held by syzkaller726993/4168: #0: (sk_lock-AF_INET6){+.+.}, at: [<00000000ac15f9b4>] lock_sock include/net/sock.h:1463 [inline] #0: (sk_lock-AF_INET6){+.+.}, at: [<00000000ac15f9b4>] compat_ipv6_getsockopt+0x1f1/0x390 net/ipv6/ipv6_sockglue.c:1412 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 757 Comm: khungtaskd Not tainted 4.15.0+ #209 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x122/0x180 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:138 [inline] check_hung_task kernel/hung_task.c:132 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline] watchdog+0x90c/0xd60 kernel/hung_task.c:249 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:429 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.15.0+ #209 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:apic_eoi arch/x86/include/asm/apic.h:407 [inline] RIP: 0010:ack_APIC_irq arch/x86/include/asm/apic.h:451 [inline] RIP: 0010:smp_reschedule_interrupt+0xa2/0x670 arch/x86/kernel/smp.c:262 RSP: 0018:ffff8801db407ea0 EFLAGS: 00000046 RAX: 1ffffffff0d17434 RBX: 1ffff1003b680fd4 RCX: 0000000000000000 RDX: dffffc0000000000 RSI: 0000000000000001 RDI: ffffffff868ba1a0 RBP: ffff8801db407fe8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8801db407fc0 R14: ffffffff87268da0 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8801db400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000002000d000 CR3: 0000000006a22004 CR4: 00000000001606f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: reschedule_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:849 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 RSP: 0018:ffffffff86a07c38 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffffffff0d40f8a RCX: 0000000000000000 RDX: 1ffffffff0d59278 RSI: 0000000000000001 RDI: ffffffff86ac93c0 RBP: ffffffff86a07c38 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff86a07cf0 R14: ffffffff87268da0 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:93 [inline] default_idle+0xbf/0x430 arch/x86/kernel/process.c:354 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:345 default_idle_call+0x36/0x90 kernel/sched/idle.c:98 cpuidle_idle_call kernel/sched/idle.c:156 [inline] do_idle+0x24a/0x3b0 kernel/sched/idle.c:246 cpu_startup_entry+0x104/0x120 kernel/sched/idle.c:351 rest_init+0xed/0xf0 init/main.c:436 start_kernel+0x7f1/0x819 init/main.c:716 x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:378 x86_64_start_kernel+0x77/0x7a arch/x86/kernel/head64.c:359 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:237 Code: f2 f2 f2 f2 c7 40 14 00 f2 f2 f2 c7 40 18 f2 f2 f2 f2 c7 40 1c 00 f2 f2 f2 c7 40 20 f3 f3 f3 f3 48 89 f8 48 c1 e8 03 80 3c 10 00 <0f> 85 68 05 00 00 4c 8b 25 f1 5b eb 00 48 b8 00 00 00 00 00 fc