INFO: task syz.5.120:6809 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.120       state:D stack:24344 pid:6809  tgid:6808  ppid:6688   task_flags:0x400140 flags:0x00004004
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/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc4aa18eba9
RSP: 002b:00007fc4aafe7038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fc4aa3d5fa0 RCX: 00007fc4aa18eba9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fc4aa3d5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc4aa3d6038 R14: 00007fc4aa3d5fa0 R15: 00007ffc9d1a1488
 </TASK>
INFO: task syz.7.132:7001 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.132       state:D stack:24392 pid:7001  tgid:7000  ppid:6922   task_flags:0x400140 flags:0x00004004
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/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ffb1eb8eba9
RSP: 002b:00007ffb1fa2a038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007ffb1edd5fa0 RCX: 00007ffb1eb8eba9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffb1edd5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffb1edd6038 R14: 00007ffb1edd5fa0 R15: 00007ffd0ddf5138
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8e13a0e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5674:
 #0: ffff8881106de0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900029032f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
2 locks held by syz-executor/6479:
1 lock held by syz.5.120/6809:
 #0: ffff888107b400e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.7.132/7001:
 #0: ffff888107b400e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.8.143/7204:
 #0: ffff888107b400e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.1.155/7405:
 #0: ffff888107b400e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.2.201/7946:
 #0: ffff888107b400e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.3.189/7984:
 #0: ffff888107b400e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x25c/0x3b0
1 lock held by syz.0.212/8074:
 #0: ffff888107b400e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.5.243/8353:
 #0: ffff888107b400e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.7.272/8504:
 #0: ffff888107b400e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.9.310/8869:
 #0: ffff888107b400e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.8.324/8902:
 #0: ffff888107b400e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.1.326/8913:
 #0: ffff888107b400e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.4.329/9036:
 #0: ffff888107b400e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.3.338/9095:
 #0: ffff888107b400e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz.2.346/9115:
 #0: ffff888107b400e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2a9/0x3b0
1 lock held by syz-executor/9126:
 #0: ffffffff8e13fb78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 34 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+0xf93/0xfe0
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 1179 Comm: kworker/u10:9 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: kvfree_rcu_reclaim kfree_rcu_work
RIP: 0010:unwind_next_frame+0x1334/0x2390
Code: 0f b6 04 08 84 c0 75 27 49 63 07 4c 01 f8 49 8d 4f 04 4c 39 e0 48 0f 46 e9 49 8d 47 fc 48 0f 47 d8 4d 0f 46 ef 48 39 dd 76 a2 <e9> 7b ef ff ff 44 89 f9 80 e1 07 80 c1 03 38 c1 7c cc 4c 89 ff 48
RSP: 0018:ffffc90007397478 EFLAGS: 00000212
RAX: ffffffff8fbee478 RBX: ffffffff8fbee47c RCX: ffffffff8fbee480
RDX: ffffffff8fbee47c RSI: ffffffff903e9888 RDI: ffffffff8be33e20
RBP: ffffffff8fbee480 R08: 0000000000000007 R09: ffffffff8172d195
R10: ffffc90007397598 R11: ffffffff81ac4b00 R12: ffffffff8204aa3c
R13: ffffffff8fbee47c R14: ffffc90007397548 R15: ffffffff8fbee47c
FS:  0000000000000000(0000) GS:ffff8881a3c15000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbb27105000 CR3: 000000010a85e000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 arch_stack_walk+0x11c/0x150
 stack_trace_save+0x9c/0xe0
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5b/0x80
 kmem_cache_free_bulk+0x2d1/0x520
 kvfree_rcu_bulk+0xe5/0x1f0
 kfree_rcu_work+0xed/0x170
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 ret_from_fork_asm+0x1a/0x30
 </TASK>
