INFO: task syz.1.464:10126 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.464       state:D stack:24504 pid:10126 tgid:10125 ppid:8573   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x14ef/0x4fb0
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_read_slowpath+0x61e/0x920
 down_read+0x99/0x2e0
 super_lock+0x2d6/0x3d0
 __iterate_supers+0x126/0x290
 ksys_sync+0xa0/0x170
 __ia32_sys_sync+0xe/0x20
 do_syscall_64+0xe2/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb851f9acb9
RSP: 002b:00007fb8501f6028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fb852215fa0 RCX: 00007fb851f9acb9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fb852215fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb852216038 R14: 00007fb852215fa0 R15: 00007ffea1bcbd28
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/35:
 #0: ffffffff8e35a360 (
rcu_read_lock
){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5663:
 #0: ffff88811461c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc9000357b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13c0
2 locks held by syz-executor/5840:
1 lock held by syz.1.464/10126:
 #0: ffff888174b500e0 (&type->s_umount_key#56){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
2 locks held by syz.0.816/13739:
3 locks held by syz.0.816/13759:
1 lock held by syz.1.815/13744:
 #0: ffff888174b500e0 (&type->s_umount_key#56){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
1 lock held by syz.1.815/13745:
 #0: ffff888174b500e0 (&type->s_umount_key#56){++++}-{4:4}, at: super_lock+0x289/0x3d0

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

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+0xe8/0x150
 nmi_cpu_backtrace+0x274/0x2d0
 nmi_trigger_cpumask_backtrace+0x17a/0x300
 sys_info+0x135/0x170
 watchdog+0xf90/0xfe0
 kthread+0x726/0x8b0
 ret_from_fork+0x51b/0xa40
 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: 5274 Comm: klogd 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:unwind_get_return_address+0x1d/0x90
Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 41 57 41 56 53 48 89 fb 49 be 00 00 00 00 00 fc ff df 48 89 f8 48 c1 e8 03 <42> 0f b6 04 30 84 c0 75 4c 83 3b 00 74 3a 48 83 c3 48 49 89 df 49
RSP: 0018:ffffc90003557408 EFLAGS: 00000a02
RAX: 1ffff920006aae85 RBX: ffffc90003557428 RCX: 0000000000000046
RDX: 0000000000000000 RSI: ffffffff8dd38c5b RDI: ffffc90003557428
RBP: ffffc900035574b0 R08: ffffc90003557f38 R09: 0000000000000000
R10: ffffc90003557478 R11: fffff520006aae91 R12: ffff888172740000
R13: 00000000000000f0 R14: dffffc0000000000 R15: ffffc90003557428
FS:  00007f606677a380(0000) GS:ffff88818e328000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7ff93e1198 CR3: 0000000112b28000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 arch_stack_walk+0xfb/0x150
 stack_trace_save+0xa9/0x100
 kasan_save_track+0x3e/0x80
 __kasan_slab_alloc+0x6c/0x80
 kmem_cache_alloc_node_noprof+0x427/0x6f0
 __alloc_skb+0x1d7/0x390
 alloc_skb_with_frags+0xca/0x890
 sock_alloc_send_pskb+0x878/0x990
 unix_dgram_sendmsg+0x44e/0x17b0
 __sock_sendmsg+0x21c/0x270
 __sys_sendto+0x3c0/0x550
 __x64_sys_sendto+0xde/0x100
 do_syscall_64+0xe2/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f60668dc9b5
Code: 8b 44 24 08 48 83 c4 28 48 98 c3 48 98 c3 41 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 26 45 31 c9 45 31 c0 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 7a 48 8b 15 44 c4 0c 00 f7 d8 64 89 02 48 83
RSP: 002b:00007fff414443e8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f60668dc9b5
RDX: 0000000000000049 RSI: 000055a2bd7868e0 RDI: 0000000000000003
RBP: 000055a2bd77f910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000004000 R11: 0000000000000246 R12: 0000000000000013
R13: 00007f6066a6a212 R14: 00007fff414444e8 R15: 0000000000000000
 </TASK>
