xt_TCPMSS: Only works on TCP SYN packets INFO: task syz-executor.5:27116 blocked for more than 140 seconds. Not tainted 4.14.197-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D28912 27116 5390 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x88b/0x1de0 kernel/sched/core.c:3384 schedule+0x8d/0x1b0 kernel/sched/core.c:3428 schedule_timeout+0x80a/0xe90 kernel/time/timer.c:1731 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common+0x272/0x430 kernel/sched/completion.c:123 ucma_close+0xfc/0x340 drivers/infiniband/core/ucma.c:1749 __fput+0x25f/0x7a0 fs/file_table.c:210 task_work_run+0x11f/0x190 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x416f01 RSP: 002b:00007fff34f67de0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000416f01 RDX: 0000000000000000 RSI: 000000000000086e RDI: 0000000000000004 RBP: 0000000000000001 R08: 00000000216a486e R09: 00000000216a4872 R10: 00007fff34f67ed0 R11: 0000000000000293 R12: 0000000001191748 R13: 00000000001ce3be R14: ffffffffffffffff R15: 000000000118cf4c Showing all locks held in the system: 1 lock held by khungtaskd/1068: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548 2 locks held by agetty/6066: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e3/0x1680 drivers/tty/n_tty.c:2156 2 locks held by agetty/6074: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:284 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e3/0x1680 drivers/tty/n_tty.c:2156 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1068 Comm: khungtaskd Not tainted 4.14.197-syzkaller #0 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+0x1b2/0x283 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x13a/0x17f lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x5b9/0xb40 kernel/hung_task.c:274 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 3646 Comm: systemd-journal Not tainted 4.14.197-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff888093c741c0 task.stack: ffff888093c78000 RIP: 0010:apic_timer_interrupt+0x0/0xa0 RSP: 0018:ffff888093c7fa18 EFLAGS: 00000046 RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 000000007fff0000 RDX: 1ffff1101278ff6b RSI: ffffc900018e4030 RDI: ffffc900018e4031 RBP: ffff888093c7fb58 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff86af3740 R13: 1ffff1101278ff50 R14: ffffc900018e4030 R15: ffff888093c7fb58 FS: 00007f46fb5fd8c0(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f46f81c5010 CR3: 0000000093d25000 CR4: 00000000001426f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: RIP: 0010:___bpf_prog_run+0x2ff0/0x5a70 kernel/bpf/core.c:982 RSP: 0018:ffff888093c7fa48 EFLAGS: 00000246 Code: fc e8 bc 22 a0 fa 48 89 e7 e8 9d 59 a0 fa e8 93 22 a0 fa e9 cc ee ff ff 0f 1f 00 4c 87 c1 e9 88 e5 d5 fa c3 90 90 90 90 90 90 90 <0f> 1f 00 68 10 ff ff ff fc f6 44 24 10 03 74 10 0f 01 f8 0f 1f