INFO: task syz-executor.4:1010 blocked for more than 143 seconds. Not tainted 5.6.0-rc5-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D28224 1010 9593 0x80004004 Call Trace: schedule+0xd0/0x2a0 kernel/sched/core.c:4154 schedule_timeout+0x6db/0xba0 kernel/time/timer.c:1871 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common kernel/sched/completion.c:115 [inline] wait_for_completion+0x26a/0x3c0 kernel/sched/completion.c:136 io_queue_file_removal+0x1af/0x1e0 fs/io_uring.c:5829 __io_sqe_files_update.isra.0+0x3a1/0xb00 fs/io_uring.c:5870 io_sqe_files_update fs/io_uring.c:5921 [inline] __io_uring_register+0x377/0x2c00 fs/io_uring.c:7134 __do_sys_io_uring_register fs/io_uring.c:7205 [inline] __se_sys_io_uring_register fs/io_uring.c:7187 [inline] __x64_sys_io_uring_register+0x192/0x560 fs/io_uring.c:7187 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c679 Code: cc 64 48 8b 0c 25 f8 ff ff ff 48 3b 61 10 0f 86 8f 00 00 00 48 83 ec 68 48 89 6c 24 60 48 8d 6c 24 60 48 8b 5a 10 48 8b 72 18 <48> 8b 7a 20 4c 8b 42 40 4c 8b 4a 08 48 8b 4a 30 48 8b 52 28 48 85 RSP: 002b:00007f9878ebac78 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab RAX: ffffffffffffffda RBX: 00007f9878ebb6d4 RCX: 000000000045c679 RDX: 00000000200016c0 RSI: 0000000000000006 RDI: 0000000000000003 RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000008 R13: 00000000000001fe R14: 00000000004d2c00 R15: 0000000000000000 Showing all locks held in the system: 4 locks held by kworker/u4:0/7: 1 lock held by khungtaskd/1130: #0: ffffffff897accc0 (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5331 1 lock held by rsyslogd/9448: #0: ffff888097ae8660 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xe3/0x100 fs/file.c:821 2 locks held by getty/9538: #0: ffff88809f101090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc900017fb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x21d/0x1b30 drivers/tty/n_tty.c:2156 2 locks held by getty/9539: #0: ffff88809f1fb090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc9000181b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x21d/0x1b30 drivers/tty/n_tty.c:2156 2 locks held by getty/9540: #0: ffff88809f031090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc9000180b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x21d/0x1b30 drivers/tty/n_tty.c:2156 2 locks held by getty/9541: #0: ffff888095c90090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc900017e72e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x21d/0x1b30 drivers/tty/n_tty.c:2156 2 locks held by getty/9542: #0: ffff8880951a5090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc900017cb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x21d/0x1b30 drivers/tty/n_tty.c:2156 2 locks held by getty/9543: #0: ffff8880a9666090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc900017df2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x21d/0x1b30 drivers/tty/n_tty.c:2156 2 locks held by getty/9544: #0: ffff88809aa87090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267 #1: ffffc9000176b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x21d/0x1b30 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.4/1010: #0: ffff88805913d320 (&ctx->uring_lock){+.+.}, at: __do_sys_io_uring_register fs/io_uring.c:7204 [inline] #0: ffff88805913d320 (&ctx->uring_lock){+.+.}, at: __se_sys_io_uring_register fs/io_uring.c:7187 [inline] #0: ffff88805913d320 (&ctx->uring_lock){+.+.}, at: __x64_sys_io_uring_register+0x181/0x560 fs/io_uring.c:7187 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1130 Comm: khungtaskd Not tainted 5.6.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xa8c/0x1010 kernel/hung_task.c:289 kthread+0x357/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 5.6.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: krdsd rds_connect_worker RIP: 0010:ip6_skb_dst_mtu include/net/ip6_route.h:265 [inline] RIP: 0010:__ip6_finish_output+0x186/0xab0 net/ipv6/ip6_output.c:137 Code: 00 00 fc ff df 80 3c 02 00 0f 85 9f 08 00 00 4d 8b 7c 24 18 4d 85 ff 0f 84 12 07 00 00 e8 a2 58 bf fa 65 66 8b 35 f2 c8 50 79 <31> ff 89 74 24 04 e8 df 59 bf fa 8b 74 24 04 66 85 f6 0f 84 dd 03 RSP: 0018:ffffc90000cdf2f8 EFLAGS: 00000293 RAX: ffff8880a95de1c0 RBX: 0000000000000001 RCX: ffffffff86b2bfcf RDX: 0000000000000000 RSI: ffffffff86b20000 RDI: ffff888094902dd8 RBP: ffff888051894140 R08: ffff8880a95de1c0 R09: ffffed1015cc7074 R10: ffffed1015cc7073 R11: ffff8880ae63839b R12: ffff888094902dc0 R13: ffff88804490e380 R14: ffff888094902e18 R15: ffff88804490e380 FS: 0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 00000000a7f5f000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ip6_finish_output+0x34/0x1f0 net/ipv6/ip6_output.c:152 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip6_output+0x239/0x810 net/ipv6/ip6_output.c:175 dst_output include/net/dst.h:436 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip6_xmit+0xe1a/0x2090 net/ipv6/ip6_output.c:279 inet6_csk_xmit+0x339/0x610 net/ipv6/inet6_connection_sock.c:135 __tcp_transmit_skb+0x19d6/0x3740 net/ipv4/tcp_output.c:1234 __tcp_send_ack.part.0+0x3a9/0x590 net/ipv4/tcp_output.c:3771 __tcp_send_ack net/ipv4/tcp_output.c:3777 [inline] tcp_send_ack+0x7d/0xa0 net/ipv4/tcp_output.c:3777 tcp_rcv_synsent_state_process net/ipv4/tcp_input.c:6035 [inline] tcp_rcv_state_process+0x3b7c/0x52ca net/ipv4/tcp_input.c:6204 tcp_v6_do_rcv+0x7d2/0x1290 net/ipv6/tcp_ipv6.c:1463 sk_backlog_rcv include/net/sock.h:963 [inline] __release_sock+0x134/0x3a0 net/core/sock.c:2437 release_sock+0x54/0x1b0 net/core/sock.c:2953 inet_stream_connect+0x76/0xa0 net/ipv4/af_inet.c:720 rds_tcp_conn_path_connect+0x620/0x880 net/rds/tcp_connect.c:172 rds_connect_worker+0x1a5/0x2c0 net/rds/threads.c:176 process_one_work+0x94b/0x1690 kernel/workqueue.c:2266 worker_thread+0x96/0xe20 kernel/workqueue.c:2412 kthread+0x357/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352