INFO: task syz.4.17831:3774 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.17831     state:D stack:25464 pid:3774  tgid:3767  ppid:8166   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_write_slowpath+0x87d/0x1080
 down_write+0x1bc/0x200
 do_lock_mount+0x2b0/0x970
 do_new_mount+0x478/0xdc0
 __se_sys_mount+0x31d/0x420
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5b1bb9f559
RSP: 002b:00007f5b19db4028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f5b1be26180 RCX: 00007f5b1bb9f559
RDX: 00002000000001c0 RSI: 0000200000000140 RDI: 0000200000000040
RBP: 00007f5b1bc36b20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000001000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5b1be26218 R14: 00007f5b1be26180 R15: 00007ffd53515538
 </TASK>
INFO: task syz.6.17838:3813 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.17838     state:D stack:25608 pid:3813  tgid:3813  ppid:19249  task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_write_slowpath+0x87d/0x1080
 down_write+0x1bc/0x200
 dissolve_on_fput+0x21a/0x390
 __fput+0x89f/0xa50
 task_work_run+0x1d9/0x270
 exit_to_user_mode_loop+0x204/0x770
 do_syscall_64+0x328/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f481739f559
RSP: 002b:00007ffffa4e5d08 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ffffa4e5df0 RCX: 00007f481739f559
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00000000001d48e1 R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b2ee20000 R11: 0000000000000246 R12: 00007ffffa4e5e30
R13: 00007f4817625fac R14: 00000000001d4918 R15: 00007f4817625fa0
 </TASK>
INFO: task syz.5.17844:3934 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.17844     state:D stack:28520 pid:3934  tgid:3933  ppid:25460  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_write_slowpath+0x87d/0x1080
 down_write+0x1bc/0x200
 do_lock_mount+0x2b0/0x970
 do_new_mount+0x478/0xdc0
 __se_sys_mount+0x31d/0x420
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbf0d59f559
RSP: 002b:00007fbf0e412028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fbf0d825fa0 RCX: 00007fbf0d59f559
RDX: 0000200000000040 RSI: 0000200000003c40 RDI: 0000000000000000
RBP: 00007fbf0d636b20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbf0d826038 R14: 00007fbf0d825fa0 R15: 00007fff75b4bd58
 </TASK>
INFO: task syz.5.17844:3939 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.17844     state:D stack:28168 pid:3939  tgid:3933  ppid:25460  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_write_slowpath+0x87d/0x1080
 down_write+0x1bc/0x200
 do_lock_mount+0x2a4/0x970
 do_new_mount+0x478/0xdc0
 __se_sys_mount+0x31d/0x420
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbf0d59f559
RSP: 002b:00007fbf0e3f1028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fbf0d826090 RCX: 00007fbf0d59f559
RDX: 00002000000000c0 RSI: 0000200000000080 RDI: 0000000000000000
RBP: 00007fbf0d636b20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000a145cf R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbf0d826128 R14: 00007fbf0d826090 R15: 00007fff75b4bd58
 </TASK>
INFO: task syz.5.17844:3943 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.17844     state:D stack:28552 pid:3943  tgid:3933  ppid:25460  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_write_slowpath+0x87d/0x1080
 down_write+0x1bc/0x200
 do_lock_mount+0x2a4/0x970
 do_new_mount+0x478/0xdc0
 __se_sys_mount+0x31d/0x420
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbf0d59f559
RSP: 002b:00007fbf0e3d0028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fbf0d826180 RCX: 00007fbf0d59f559
RDX: 0000200000000180 RSI: 0000200000000080 RDI: 0000000000000000
RBP: 00007fbf0d636b20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000002200892 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbf0d826218 R14: 00007fbf0d826180 R15: 00007fff75b4bd58
 </TASK>

Showing all locks held in the system:
locks held by khungtaskd/38: 1, last CPU#1:
 #0: ffffffff8fd5c8e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
locks held by getty/5424: 2, on CPU#1:
 #0: ffff888178cf10a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034932e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
locks held by syz.4.17831/3774: 2, on CPU#0:
 #0: ffff88810fd8db40 (&type->i_mutex_dir_key#9){++++}-{4:4}, at: do_lock_mount+0x2a4/0x970
 #1: ffffffff8fee9fc8 (namespace_sem){++++}-{4:4}, at: do_lock_mount+0x2b0/0x970
locks held by syz.4.17831/3780: 4, last CPU#0:
 #0: ffff8881124e4878 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xa4/0xca0
 #1: ffffffff8fee9fc8 (namespace_sem){++++}-{4:4}, at: m_start+0x4f/0x1b0
 #2: ffffffff8fd5c8e0 (rcu_read_lock){....}-{1:3}, at: prepend_path+0x4d/0x840
 #3: ffffffff8fd5c8e0 (rcu_read_lock){....}-{1:3}, at: prepend_path+0x4d/0x840
locks held by syz.6.17838/3813: 1, on CPU#0:
 #0: ffffffff8fee9fc8 (namespace_sem){++++}-{4:4}, at: dissolve_on_fput+0x21a/0x390
locks held by syz.5.17844/3934: 2, on CPU#0:
 #0: ffff888115f4cba8 (&type->i_mutex_dir_key#5){++++}-{4:4}, at: do_lock_mount+0x2a4/0x970
 #1: ffffffff8fee9fc8 (namespace_sem){++++}-{4:4}, at: do_lock_mount+0x2b0/0x970
locks held by syz.5.17844/3939: 1, on CPU#0:
 #0: ffff888115f4cba8 (&type->i_mutex_dir_key#5){++++}-{4:4}, at: do_lock_mount+0x2a4/0x970
locks held by syz.5.17844/3943: 1, on CPU#0:
 #0: ffff888115f4cba8 (&type->i_mutex_dir_key#5){++++}-{4:4}, at: do_lock_mount+0x2a4/0x970
locks held by syz-executor/4671: 1, on CPU#0:
 #0: ffffffff8fee9fc8 (namespace_sem){++++}-{4:4}, at: copy_mnt_ns+0x331/0xcc0
locks held by syz-executor/4677: 1, on CPU#1:
 #0: ffffffff8fee9fc8 (namespace_sem){++++}-{4:4}, at: copy_mnt_ns+0x331/0xcc0
locks held by syz-executor/4776: 1, on CPU#0:
 #0: ffffffff8fee9fc8 (namespace_sem){++++}-{4:4}, at: copy_mnt_ns+0x331/0xcc0
locks held by syz-executor/7928: 1, on CPU#1:
 #0: ffffffff8fee9fc8 (namespace_sem){++++}-{4:4}, at: copy_mnt_ns+0x331/0xcc0
locks held by syz-executor/7934: 1, on CPU#1:
 #0: ffffffff8fee9fc8 (namespace_sem){++++}-{4:4}, at: copy_mnt_ns+0x331/0xcc0
locks held by syz-executor/8044: 1, on CPU#0:
 #0: ffffffff8fee9fc8 (namespace_sem){++++}-{4:4}, at: copy_mnt_ns+0x331/0xcc0
locks held by syz-executor/11091: 1, on CPU#1:
 #0: ffffffff8fee9fc8 (namespace_sem){++++}-{4:4}, at: copy_mnt_ns+0x331/0xcc0
locks held by syz-executor/11097: 1, on CPU#1:
 #0: ffffffff8fee9fc8 (namespace_sem){++++}-{4:4}, at: copy_mnt_ns+0x331/0xcc0
locks held by syz-executor/11202: 1, on CPU#1:
 #0: ffffffff8fee9fc8 (namespace_sem){++++}-{4:4}, at: copy_mnt_ns+0x331/0xcc0

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 38 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+0x17d/0x390
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 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: 3780 Comm: syz.4.17831 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
RIP: 0010:prepend_path+0x2e0/0x840
Code: 4c 8d 6b 50 4c 89 e8 48 c1 e8 03 42 80 3c 30 00 74 08 4c 89 ef e8 c0 24 da ff 49 8b 6d 00 4c 89 f8 48 c1 e8 03 42 80 3c 30 00 <74> 08 4c 89 ff e8 a6 24 da ff 49 3b 1f 0f 84 ba 00 00 00 48 39 eb
RSP: 0018:ffffc90007ee7798 EFLAGS: 00000246
RAX: 1ffff1102daf5044 RBX: ffff88810799ad38 RCX: ffff88811f231e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888116c93810
RBP: ffff88810799ad38 R08: ffffffff917a727f R09: 1ffffffff22f4e4f
R10: dffffc0000000000 R11: fffffbfff22f4e50 R12: ffff888105b2a050
R13: ffff88810799ad88 R14: dffffc0000000000 R15: ffff88816d7a8220
FS:  00007f5b19d516c0(0000) GS:ffff88818c4bb000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7a8c9a9866 CR3: 000000011a464000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 __d_path+0x93/0x130
 seq_path_root+0x177/0x4c0
 show_vfsstat+0x215/0x470
 traverse+0x229/0x620
 seq_read_iter+0xb6a/0xca0
 do_iter_readv_writev+0x612/0x8c0
 vfs_readv+0x28d/0x850
 __se_sys_preadv2+0x177/0x2a0
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5b1bb9f559
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5b19d51028 EFLAGS: 00000246 ORIG_RAX: 0000000000000147
RAX: ffffffffffffffda RBX: 00007f5b1be26450 RCX: 00007f5b1bb9f559
RDX: 0000000000000007 RSI: 00002000000048c0 RDI: 0000000000000003
RBP: 00007f5b1bc36b20 R08: 0000000000000001 R09: 0000000000000005
R10: 00000000fb06e174 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5b1be264e8 R14: 00007f5b1be26450 R15: 00007ffd53515538
 </TASK>
