INFO: task syz-executor.1:4039 blocked for more than 140 seconds. Not tainted 4.14.198-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D28912 4039 6377 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: 0033:0x417901 RSP: 002b:00007fff563ed3c0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000417901 RDX: 0000001b31f20000 RSI: 0000000000001392 RDI: 0000000000000003 RBP: 0000000000000001 R08: 00000000f179d396 R09: 0000000000000000 R10: 00007fff563ed4b0 R11: 0000000000000293 R12: 0000000001190710 R13: 0000000000076d14 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 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1068 Comm: khungtaskd Not tainted 4.14.198-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: 8691 Comm: kworker/u4:8 Not tainted 4.14.198-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_nc_worker task: ffff8880a0dc0500 task.stack: ffff8880552f8000 RIP: 0010:batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:413 [inline] RIP: 0010:batadv_nc_worker+0x8b/0xc50 net/batman-adv/network-coding.c:726 RSP: 0018:ffff8880552ffcd8 EFLAGS: 00000a02 RAX: 0000000000000000 RBX: ffff8880971c1bf0 RCX: ffff8880971c1240 RDX: 1ffff11014992ca2 RSI: 00000000ffffffff RDI: ffff8880971c12c0 RBP: ffff8880971c1bf0 R08: ffffffff8a0aed78 R09: 00000000000405d2 R10: ffff8880a0dc0db0 R11: ffff8880a0dc0500 R12: ffff8880971c1c00 R13: ffff888088dcb800 R14: ffff88812fe0a8c0 R15: ffff88809af4b800 FS: 0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fd888f7c018 CR3: 0000000094b7d000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: process_one_work+0x793/0x14a0 kernel/workqueue.c:2116 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Code: 09 00 00 e8 a8 1c 1e fb 48 8b 44 24 38 48 83 c0 10 48 89 44 24 40 48 c1 e8 03 48 89 c2 48 b8 00 00 00 00 00 fc ff df 0f b6 04 02 <84> c0 74 08 3c 03 0f 8e a2 0b 00 00 48 8b 44 24 38 8b 48 10 85