TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies. Check SNMP counters. INFO: task syz-executor1:1632 blocked for more than 140 seconds. Not tainted 4.9.112-g9e79039 #59 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor1 D27992 1632 3896 0x00000004 ffff8801a2113000 ffff88018cfc5f80 ffff8801bea08540 ffff88018e48c800 ffff8801db321c18 ffff8801cd51f320 ffffffff839e907d 1ffff10039aa3e58 ffffffff85542200 0000000041b58ab3 00ffffff843c36c0 ffff8801db3224e8 Call Trace: [] schedule+0x7f/0x1b0 kernel/sched/core.c:3557 [] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768 [] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:5180 [] io_schedule include/linux/sched.h:460 [inline] [] dio_await_one fs/direct-io.c:461 [inline] [] dio_await_completion fs/direct-io.c:515 [inline] [] do_blockdev_direct_IO+0x2d5b/0x5a80 fs/direct-io.c:1331 [] __blockdev_direct_IO+0xa5/0xd0 fs/direct-io.c:1360 [] blkdev_direct_IO+0xa0/0xd0 fs/block_dev.c:183 [] generic_file_read_iter+0x660/0x1a90 mm/filemap.c:1951 [] blkdev_read_iter+0x105/0x170 fs/block_dev.c:1738 [] generic_file_splice_read+0x2c9/0x4f0 fs/splice.c:309 [] do_splice_to+0x10c/0x170 fs/splice.c:899 [] splice_direct_to_actor+0x23f/0x7e0 fs/splice.c:971 [] do_splice_direct+0x1a3/0x270 fs/splice.c:1080 [] do_sendfile+0x4f0/0xc60 fs/read_write.c:1393 [] SYSC_sendfile64 fs/read_write.c:1448 [inline] [] SyS_sendfile64+0xd1/0x160 fs/read_write.c:1440 [] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282 [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Showing all locks held in the system: 2 locks held by khungtaskd/519: #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/3781: #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 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.112-g9e79039 #59 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ffff8801d859fd08 ffffffff81eb3249 0000000000000000 0000000000000000 0000000000000000 0000000000000001 ffffffff810b9bd0 ffff8801d859fd40 ffffffff81ebe547 0000000000000000 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.2+0x48/0x87 lib/nmi_backtrace.c:99 [] nmi_trigger_cpumask_backtrace+0x12a/0x14f 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+0x6b4/0xa20 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 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff839f8b86