INFO: task syz.4.5585:26126 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.5585      state:D stack:28760 pid:26126 tgid:26122 ppid:25774  task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x1821/0x5740
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_write_slowpath+0x883/0x1080
 down_write+0x1bc/0x200
 super_lock+0x289/0x3d0
 user_get_super+0xc8/0x120
 __se_sys_quotactl+0x540/0x9e0
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f862b79ce59
RSP: 002b:00007f862c6d6028 EFLAGS: 00000246 ORIG_RAX: 00000000000000b3
RAX: ffffffffffffffda RBX: 00007f862ba16180 RCX: 00007f862b79ce59
RDX: 0000000000000000 RSI: 0000200000000080 RDI: ffffffff80000301
RBP: 00007f862b832d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f862ba16218 R14: 00007f862ba16180 R15: 00007ffddb85d948
 </TASK>
INFO: task syz.3.5595:26158 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.5595      state:D stack:26200 pid:26158 tgid:26157 ppid:23443  task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x1821/0x5740
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_read_slowpath+0x6d9/0x940
 down_read+0x99/0x2e0
 super_lock+0x2d6/0x3d0
 __iterate_supers+0x126/0x250
 __se_sys_quotactl+0x3a7/0x9e0
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f861f79ce59
RSP: 002b:00007f862071a028 EFLAGS: 00000246 ORIG_RAX: 00000000000000b3
RAX: ffffffffffffffda RBX: 00007f861fa15fa0 RCX: 00007f861f79ce59
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff80000101
RBP: 00007f861f832d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f861fa16038 R14: 00007f861fa15fa0 R15: 00007ffce1b97ee8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
3 locks held by kworker/1:2/798:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860
 #1: ffffc9000544fc40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860
 #2: ffff8881072ab250 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x202/0x3d0
2 locks held by kworker/u10:4/812:
 #0: ffff8881000ac940 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860
 #1: ffffc900058e7c40 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860
5 locks held by kworker/u10:6/1111:
 #0: ffff88823c63aea0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x31/0x150
 #1: ffff88823c624588 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x53/0x880
 #2: ffff88823c626118 (&base->lock){-.-.}-{2:2}, at: __mod_timer+0x1ae/0xf30
 #3: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: ieee80211_sta_active_ibss+0xc3/0x330
 #4: ffff88823c63aea0 (&rq->__lock){-.-.}-{2:2}, at: finish_task_switch+0x15f/0xbe0
1 lock held by syslogd/5042:
 #0: ffff88823c63aea0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x31/0x150
2 locks held by getty/5440:
 #0: ffff8881125270a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034832e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0
2 locks held by syz-executor/18105:
1 lock held by syz.4.5585/26126:
 #0: ffff8881bdc9c0d8 (&type->s_umount_key#77){++++}-{4:4}, at: super_lock+0x289/0x3d0
1 lock held by syz.3.5595/26158:
 #0: ffff8881bdc9c0d8 (&type->s_umount_key#77){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
1 lock held by syz.5.6271/28968:
 #0: ffff8881bdc9c0d8 (&type->s_umount_key#77){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
2 locks held by syz.2.6373/29265:
2 locks held by modprobe/29291:

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

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+0xe8/0x150
 nmi_cpu_backtrace+0x274/0x2d0
 nmi_trigger_cpumask_backtrace+0x17a/0x300
 sys_info+0x135/0x170
 watchdog+0xfd3/0x1030
 kthread+0x389/0x470
 ret_from_fork+0x514/0xb70
 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: 24 Comm: kworker/1:0 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: mld mld_ifc_work
RIP: 0010:rcu_is_watching+0x69/0xb0
Code: e8 9c 26 86 00 48 c7 c3 d8 c9 3a 93 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 84 c0 75 34 8b 03 65 ff 0d c9 b1 8e 11 74 11 <83> e0 04 c1 e8 02 5b 41 5e 41 5f c3 cc cc cc cc cc e8 f1 bc 88 ff
RSP: 0018:ffffc900001e7778 EFLAGS: 00000286
RAX: 000000000005bdf4 RBX: ffff88823c6339d8 RCX: 0000000080000001
RDX: 0000000000000000 RSI: ffffffff8c28b640 RDI: ffffffff8c28b600
RBP: ffffc900001e7908 R08: 00000000000002ff R09: 1600000000000000
R10: 00000000000002ff R11: 1600000000000000 R12: dffffc0000000000
R13: ffffffff8a60857e R14: ffffffff8e26b798 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8882a9287000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f11981f0000 CR3: 00000001138ac000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 lock_release+0x4b/0x3c0
 mld_newpack+0x7b3/0xc90
 add_grhead+0x5a/0x2a0
 add_grec+0x1452/0x1740
 mld_ifc_work+0x6e6/0xe70
 process_scheduled_works+0xb5d/0x1860
 worker_thread+0xa53/0xfc0
 kthread+0x389/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
