TCP: request_sock_TCP: Possible SYN flooding on port 20002. Sending cookies. Check SNMP counters. INFO: task syz-executor2:9531 blocked for more than 120 seconds. Not tainted 4.15.0+ #305 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D20192 9531 4211 0x00000004 Call Trace: context_switch kernel/sched/core.c:2857 [inline] __schedule+0x8e2/0x2040 kernel/sched/core.c:3435 schedule+0xf5/0x430 kernel/sched/core.c:3494 io_schedule+0x1c/0x70 kernel/sched/core.c:5110 __blkdev_direct_IO_simple+0x7bd/0xf50 fs/block_dev.c:241 blkdev_direct_IO+0xccb/0x1060 fs/block_dev.c:428 generic_file_read_iter+0x4cc/0x28e0 mm/filemap.c:2343 blkdev_read_iter+0x105/0x170 fs/block_dev.c:1913 call_read_iter include/linux/fs.h:1775 [inline] generic_file_splice_read+0x3f9/0x7b0 fs/splice.c:307 do_splice_to+0x10a/0x160 fs/splice.c:880 splice_direct_to_actor+0x242/0x820 fs/splice.c:952 do_splice_direct+0x29b/0x3c0 fs/splice.c:1061 do_sendfile+0x5c9/0xe80 fs/read_write.c:1413 SYSC_sendfile64 fs/read_write.c:1468 [inline] SyS_sendfile64+0xbd/0x160 fs/read_write.c:1460 do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x26/0x9b RIP: 0033:0x453299 RSP: 002b:00007ff605e15c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000453299 RDX: 0000000020819000 RSI: 0000000000000013 RDI: 0000000000000013 RBP: 00000000000004a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000016fe2afc R11: 0000000000000212 R12: 00000000006f5fa0 R13: 00000000ffffffff R14: 00007ff605e166d4 R15: 0000000000000000 Showing all locks held in the system: 2 locks held by khungtaskd/760: #0: (rcu_read_lock){....}, at: [<00000000abde6429>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<00000000abde6429>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<00000000e8dd6b49>] debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4470 2 locks held by getty/4135: #0: (&tty->ldisc_sem){++++}, at: [<00000000140743b9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f945a2f7>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4136: #0: (&tty->ldisc_sem){++++}, at: [<00000000140743b9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f945a2f7>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4137: #0: (&tty->ldisc_sem){++++}, at: [<00000000140743b9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f945a2f7>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4138: #0: (&tty->ldisc_sem){++++}, at: [<00000000140743b9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f945a2f7>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4139: #0: (&tty->ldisc_sem){++++}, at: [<00000000140743b9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f945a2f7>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4140: #0: (&tty->ldisc_sem){++++}, at: [<00000000140743b9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f945a2f7>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/4141: #0: (&tty->ldisc_sem){++++}, at: [<00000000140743b9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000f945a2f7>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 760 Comm: khungtaskd Not tainted 4.15.0+ #305 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 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54