blktrace: Concurrent blktraces are not allowed on nbd4
INFO: task syz-executor.0:31749 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.0  D28912 31749   6371 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: 0033:0x4177b1
RSP: 002b:00007fffc55fa2c0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00000000004177b1
RDX: 0000001b31a20000 RSI: 000000000000086e RDI: 0000000000000003
RBP: 0000000000000001 R08: 00000000216a486e R09: 00000000216a4872
R10: 00007fffc55fa3a0 R11: 0000000000000293 R12: ffffffffffffffff
R13: 000000000019fbb3 R14: 00000000000003e8 R15: 000000000118bf2c

Showing all locks held in the system:
1 lock held by khungtaskd/1060:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff814777f4>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 1060 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: 2332 Comm: kworker/u4:3 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: ffff8880a1552240 task.stack: ffff8880a1558000
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:779 [inline]
RIP: 0010:lock_release+0x41e/0x870 kernel/locking/lockdep.c:4020
RSP: 0018:ffff8880a155fc48 EFLAGS: 00000286
RAX: 1ffffffff0fa2d21 RBX: 1ffff110142abf8c RCX: 1ffff110142aa563
RDX: dffffc0000000000 RSI: 0000000000000003 RDI: 0000000000000286
RBP: ffff8880a1552240 R08: 0000000000000000 R09: 0000000000000002
R10: 0000000000000000 R11: ffff8880a1552240 R12: 547394533f85196e
R13: 0000000000000003 R14: ffff8880a1552240 R15: 0000000000000003
FS:  0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb45f80c000 CR3: 00000000a9430000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 rcu_lock_release include/linux/rcupdate.h:247 [inline]
 rcu_read_unlock include/linux/rcupdate.h:685 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:420 [inline]
 batadv_nc_worker+0x5a7/0xc50 net/batman-adv/network-coding.c:726
 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: 85 84 08 00 00 00 00 00 00 48 c1 e8 03 80 3c 10 00 0f 85 88 03 00 00 48 83 3d 16 1a 8a 06 00 0f 84 ba 01 00 00 48 8b 3c 24 57 9d <0f> 1f 44 00 00 48 b8 00 00 00 00 00 fc ff df 48 c7 04 03 00 00