INFO: task syz.1.1615:11614 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.1615      state:D stack:26024 pid:11614 tgid:11613 ppid:6188   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_read_slowpath+0x5fd/0x8f0
 down_read+0x98/0x2e0
 super_lock+0x2a9/0x3b0
 __iterate_supers+0x126/0x290
 ksys_sync+0x94/0x150
 __ia32_sys_sync+0xe/0x20
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f843af8f749
RSP: 002b:00007f843bdb9038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f843b1e5fa0 RCX: 00007f843af8f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f843b1e5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f843b1e6038 R14: 00007f843b1e5fa0 R15: 00007ffff6fbac88
 </TASK>
INFO: task syz.1.1615:11615 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.1615      state:D stack:28744 pid:11615 tgid:11613 ppid:6188   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_read_slowpath+0x5fd/0x8f0
 down_read+0x98/0x2e0
 super_lock+0x2a9/0x3b0
 __iterate_supers+0x126/0x290
 ksys_sync+0x94/0x150
 __ia32_sys_sync+0xe/0x20
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f843af8f749
RSP: 002b:00007f843bd98038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f843b1e6090 RCX: 00007f843af8f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f843b1e6090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f843b1e6128 R14: 00007f843b1e6090 R15: 00007ffff6fbac88
 </TASK>
INFO: task syz.1.1615:11616 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.1615      state:D stack:28744 pid:11616 tgid:11613 ppid:6188   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_read_slowpath+0x5fd/0x8f0
 down_read+0x98/0x2e0
 super_lock+0x2a9/0x3b0
 __iterate_supers+0x126/0x290
 ksys_sync+0x94/0x150
 __ia32_sys_sync+0xe/0x20
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f843af8f749
RSP: 002b:00007f843bd77038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f843b1e6180 RCX: 00007f843af8f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f843b1e6180 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f843b1e6218 R14: 00007f843b1e6180 R15: 00007ffff6fbac88
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/35:
 #0: ffffffff8df3d6a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5641:
 #0: ffff8881133b50a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc9000356b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
3 locks held by kworker/1:11/6876:
 #0: ffff888100075948 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc9000730fba0 (free_ipc_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffffffff8df43138 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730
2 locks held by syz-executor/10262:
1 lock held by syz.1.1615/11614:
 #0: ffff88816c1920e0 (&type->s_umount_key#51){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.1.1615/11615:
 #0: ffff88816c1920e0 (&type->s_umount_key#51){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.1.1615/11616:
 #0: ffff88816c1920e0 (&type->s_umount_key#51){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.8.1989/13461:
 #0: ffff88816c1920e0 (&type->s_umount_key#51){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.9.2137/14253:
 #0: ffff88816c1920e0 (&type->s_umount_key#51){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.5.2163/14344:
 #0: ffffffff8df43000 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x570

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 35 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 nmi_cpu_backtrace+0x39e/0x3d0
 nmi_trigger_cpumask_backtrace+0x17a/0x300
 watchdog+0xf60/0xfa0
 kthread+0x711/0x8a0
 ret_from_fork+0x4bc/0x870
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6890 Comm: kworker/0:15 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: events drain_vmap_area_work
RIP: 0010:rcu_is_watching+0x67/0xb0
Code: 89 f7 e8 5c b6 7f 00 48 c7 c3 d8 cf 6f 92 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 84 c0 75 34 8b 03 65 ff 0d 89 3c c8 10 <74> 11 83 e0 04 c1 e8 02 5b 41 5e 41 5f c3 cc cc cc cc cc e8 a1 d4
RSP: 0018:ffffc9000742f250 EFLAGS: 00000286
RAX: 00000000004acfd4 RBX: ffff888121232fd8 RCX: 66a33b2cf79d7c00
RDX: ffffffff90185601 RSI: ffffffff8bbf0fc0 RDI: ffffffff8bbf0f80
RBP: dffffc0000000000 R08: ffffc9000742f407 R09: 0000000000000000
R10: ffffc9000742f3f8 R11: fffff52000e85e81 R12: ffffc9000742f8a0
R13: ffffffff81739c45 R14: ffffffff8d92edd0 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff88818eb36000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3742287e20 CR3: 00000001710bc000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 lock_release+0x4b/0x3e0
 unwind_next_frame+0x19a9/0x2390
 arch_stack_walk+0x11c/0x150
 stack_trace_save+0x9c/0xe0
 save_stack+0xf5/0x1f0
 __reset_page_owner+0x71/0x1f0
 __free_frozen_pages+0xbc8/0xd30
 kasan_depopulate_vmalloc_pte+0x6d/0x90
 __apply_to_page_range+0xb66/0x13d0
 __kasan_release_vmalloc+0xa2/0xd0
 purge_vmap_node+0x214/0x8f0
 __purge_vmap_area_lazy+0x7a4/0xb40
 drain_vmap_area_work+0x27/0x40
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x4bc/0x870
 ret_from_fork_asm+0x1a/0x30
 </TASK>
