INFO: task hung in fuse_sb_destroy

[syzbot <syzbot+6339eda9cb4ebbc4c37b@syzkaller.appspotmail.com>]

Hello,

syzbot found the following crash on:

HEAD commit:    59fc453b21f7 Merge branch 'akpm' (patches from Andrew)
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15fb2447400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ea045471e4c756e8
dashboard link: https://syzkaller.appspot.com/bug?extid=6339eda9cb4ebbc4c37b
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=178a105d400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16651133400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+6339eda9cb4ebbc4c37b@syzkaller.appspotmail.com

INFO: task syz-executor221:17414 blocked for more than 140 seconds.
       Not tainted 4.19.0+ #313
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor221 D23048 17414   5652 0x00000004
Call Trace:
  context_switch kernel/sched/core.c:2831 [inline]
  __schedule+0x8cf/0x21d0 kernel/sched/core.c:3472
  schedule+0xfe/0x460 kernel/sched/core.c:3516
  fuse_wait_aborted+0x20b/0x320 fs/fuse/dev.c:2155
  fuse_sb_destroy+0xe2/0x1d0 fs/fuse/inode.c:1224
  fuse_kill_sb_anon+0x15/0x20 fs/fuse/inode.c:1234
  deactivate_locked_super+0x97/0x100 fs/super.c:329
  deactivate_super+0x2bb/0x320 fs/super.c:360
  cleanup_mnt+0xbf/0x160 fs/namespace.c:1098
  __cleanup_mnt+0x16/0x20 fs/namespace.c:1105
  task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
  tracehook_notify_resume include/linux/tracehook.h:188 [inline]
  exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
  prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
  syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
  do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x446689
Code: e8 0c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 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 0f 83 7b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f621e979da8 EFLAGS: 00000293 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00000000006dbc28 RCX: 0000000000446689
RDX: 0000000000446689 RSI: 000000000000000a RDI: 0000000020000180
RBP: 00000000006dbc20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 00000000006dbc2c
R13: 0030656c69662f2e R14: 65646f6d746f6f72 R15: 0000000000000000

Showing all locks held in the system:
1 lock held by khungtaskd/1009:
  #0: 0000000095618e4f (rcu_read_lock){....}, at:  
debug_show_all_locks+0xd0/0x424 kernel/locking/lockdep.c:4379
5 locks held by rsyslogd/5530:
  #0: 0000000028bad575 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200  
fs/file.c:766
  #1: 00000000e31592cd (&rq->lock){-.-.}, at: rq_lock  
kernel/sched/sched.h:1126 [inline]
  #1: 00000000e31592cd (&rq->lock){-.-.}, at: __schedule+0x236/0x21d0  
kernel/sched/core.c:3410
  #2: 0000000095618e4f (rcu_read_lock){....}, at: trace_sched_stat_runtime  
include/trace/events/sched.h:418 [inline]
  #2: 0000000095618e4f (rcu_read_lock){....}, at: update_curr+0x383/0xbd0  
kernel/sched/fair.c:830
  #3: 00000000e31592cd (&rq->lock){-.-.}, at: rq_lock  
kernel/sched/sched.h:1126 [inline]
  #3: 00000000e31592cd (&rq->lock){-.-.}, at: ttwu_queue  
kernel/sched/core.c:1845 [inline]
  #3: 00000000e31592cd (&rq->lock){-.-.}, at: try_to_wake_up+0x9f6/0x1490  
kernel/sched/core.c:2057
  #4: 0000000095618e4f (rcu_read_lock){....}, at: trace_sched_stat_runtime  
include/trace/events/sched.h:418 [inline]
  #4: 0000000095618e4f (rcu_read_lock){....}, at: update_curr+0x383/0xbd0  
kernel/sched/fair.c:830
2 locks held by getty/5620:
  #0: 00000000492d5ad8 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
  #1: 0000000088c4d769 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/5621:
  #0: 00000000ed56cf3c (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
  #1: 00000000a8112d49 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/5622:
  #0: 00000000858703c2 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
  #1: 00000000b20ff0f8 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/5623:
  #0: 00000000a0163126 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
  #1: 00000000cb4be99e (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/5624:
  #0: 000000006eab39a0 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
  #1: 00000000341e7ea5 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/5625:
  #0: 00000000e1bb9e75 (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
  #1: 00000000e6c38e03 (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by getty/5626:
  #0: 00000000437eab2d (&tty->ldisc_sem){++++}, at:  
ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353
  #1: 00000000031acd5c (&ldata->atomic_read_lock){+.+.}, at:  
n_tty_read+0x335/0x1e80 drivers/tty/n_tty.c:2154
2 locks held by kworker/1:0/5718:
  #0: 0000000003693dce ((wq_completion)"rcu_gp"){+.+.}, at:  
__write_once_size include/linux/compiler.h:206 [inline]
  #0: 0000000003693dce ((wq_completion)"rcu_gp"){+.+.}, at:  
arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
  #0: 0000000003693dce ((wq_completion)"rcu_gp"){+.+.}, at: atomic64_set  
include/asm-generic/atomic-instrumented.h:40 [inline]
  #0: 0000000003693dce ((wq_completion)"rcu_gp"){+.+.}, at: atomic_long_set  
include/asm-generic/atomic-long.h:59 [inline]
  #0: 0000000003693dce ((wq_completion)"rcu_gp"){+.+.}, at: set_work_data  
kernel/workqueue.c:617 [inline]
  #0: 0000000003693dce ((wq_completion)"rcu_gp"){+.+.}, at:  
set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
  #0: 0000000003693dce ((wq_completion)"rcu_gp"){+.+.}, at:  
process_one_work+0xb43/0x1c40 kernel/workqueue.c:2124
  #1: 00000000fdcab2d3 ((work_completion)(&rew.rew_work)){+.+.}, at:  
process_one_work+0xb9a/0x1c40 kernel/workqueue.c:2128
1 lock held by syz-executor221/17414:
  #0: 000000003df3056e (&type->s_umount_key#39){+.+.}, at:  
deactivate_super+0x2b3/0x320 fs/super.c:359
1 lock held by syz-executor221/18647:
  #0: 00000000dd0c9ec5 (rcu_state.exp_mutex){+.+.}, at: exp_funnel_lock  
kernel/rcu/tree_exp.h:296 [inline]
  #0: 00000000dd0c9ec5 (rcu_state.exp_mutex){+.+.}, at:  
_synchronize_rcu_expedited.constprop.58+0x7c7/0x9d0  
kernel/rcu/tree_exp.h:620
1 lock held by syz-executor221/18653:
  #0: 00000000dd0c9ec5 (rcu_state.exp_mutex){+.+.}, at: exp_funnel_lock  
kernel/rcu/tree_exp.h:328 [inline]
  #0: 00000000dd0c9ec5 (rcu_state.exp_mutex){+.+.}, at:  
_synchronize_rcu_expedited.constprop.58+0x7af/0x9d0  
kernel/rcu/tree_exp.h:620

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

NMI backtrace for cpu 0
CPU: 0 PID: 1009 Comm: khungtaskd Not tainted 4.19.0+ #313
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x244/0x39d lib/dump_stack.c:113
  nmi_cpu_backtrace.cold.2+0x5c/0xa1 lib/nmi_backtrace.c:101
  nmi_trigger_cpumask_backtrace+0x1e8/0x22a lib/nmi_backtrace.c:62
  arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
  trigger_all_cpu_backtrace include/linux/nmi.h:144 [inline]
  check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
  watchdog+0xb51/0x1060 kernel/hung_task.c:289
  kthread+0x35a/0x440 kernel/kthread.c:246
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:350
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 18647 Comm: syz-executor221 Not tainted 4.19.0+ #313
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:outb arch/x86/include/asm/io.h:334 [inline]
RIP: 0010:io_serial_out+0x73/0x90 drivers/tty/serial/8250/8250_port.c:455
Code: 00 49 8d 7c 24 38 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03  
d3 e3 80 3c 02 00 75 19 41 03 5c 24 38 44 89 e8 89 da ee <5b> 41 5c 41 5d  
5d c3 e8 e1 66 e0 fd eb c0 e8 3a 67 e0 fd eb e0 0f
RSP: 0018:ffff8801cc666f90 EFLAGS: 00000006
RAX: 0000000000000000 RBX: 00000000000003f9 RCX: 0000000000000000
RDX: 00000000000003f9 RSI: ffffffff83e257a6 RDI: ffffffff8bae5158
RBP: ffff8801cc666fa8 R08: ffff8801bf0b0600 R09: ffffed00398ccde3
R10: ffffed00398ccde3 R11: 0000000000000003 R12: ffffffff8bae5120
R13: 0000000000000000 R14: 0000000000000001 R15: ffffffff8bae5168
FS:  00007f621e97a700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f313a840000 CR3: 00000001c3654000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  serial_port_out include/linux/serial_core.h:276 [inline]
  serial8250_console_write+0x34b/0xb10  
drivers/tty/serial/8250/8250_port.c:3276
  univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:586
  call_console_drivers kernel/printk/printk.c:1728 [inline]
  console_unlock+0xb1f/0x1190 kernel/printk/printk.c:2414
  vprintk_emit+0x391/0x990 kernel/printk/printk.c:1922
  vprintk_default+0x28/0x30 kernel/printk/printk.c:1964
  vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398
  printk+0xa7/0xcf kernel/printk/printk.c:1997
  kobject_cleanup lib/kobject.c:638 [inline]
  kobject_release lib/kobject.c:691 [inline]
  kref_put include/linux/kref.h:70 [inline]
  kobject_put.cold.9+0x83/0x2e4 lib/kobject.c:708
  put_device drivers/base/core.c:2024 [inline]
  device_unregister+0x28/0x30 drivers/base/core.c:2114
  bdi_unregister+0x5ed/0x880 mm/backing-dev.c:948
  release_bdi mm/backing-dev.c:964 [inline]
  kref_put include/linux/kref.h:70 [inline]
  bdi_put+0x153/0x180 mm/backing-dev.c:973
  generic_shutdown_super+0x3c8/0x530 fs/super.c:470
  kill_anon_super+0x3e/0x60 fs/super.c:1032
  fuse_kill_sb_anon+0x1d/0x20 fs/fuse/inode.c:1235
  deactivate_locked_super+0x97/0x100 fs/super.c:329
  deactivate_super+0x2bb/0x320 fs/super.c:360
  cleanup_mnt+0xbf/0x160 fs/namespace.c:1098
  __cleanup_mnt+0x16/0x20 fs/namespace.c:1105
  task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
  get_signal+0x1558/0x1980 kernel/signal.c:2347
  do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816
  exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162
  prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
  syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
  do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x446689
Code: e8 0c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 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 0f 83 7b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f621e979da8 EFLAGS: 00000293 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00000000006dbc28 RCX: 0000000000446689
RDX: 0000000000446689 RSI: 000000000000000a RDI: 0000000020000180
RBP: 00000000006dbc20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 00000000006dbc2c
R13: 0030656c69662f2e R14: 65646f6d746f6f72 R15: 0000000000000000
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.274  
msecs
kobject: '0:31' (0000000050d00699): fill_kobj_path: path  
= '/devices/virtual/bdi/0:31'
kobject: '0:32' (00000000d2d168d9): kobject_cleanup, parent           (null)
kobject: '0:31' (0000000050d00699): kobject_cleanup, parent           (null)
kobject: '0:32' (00000000d2d168d9): calling ktype release
kobject: '0:33' (00000000d76406a3): kobject_cleanup, parent           (null)
kobject: '0:28' (000000002da84317): calling ktype release
kobject: '0:29' (00000000e2434e73): kobject_cleanup, parent           (null)
kobject: '0:32': free name
kobject: '0:33' (00000000d76406a3): calling ktype release
kobject: '0:33': free name
kobject: '0:29' (00000000e2434e73): calling ktype release
kobject: '0:28': free name
kobject: '0:29': free name
kobject: '0:31' (0000000050d00699): calling ktype release
kobject: '0:28' (0000000080474e07): kobject_add_internal: parent: 'bdi',  
set: 'devices'
kobject: '0:29' (0000000051f8f0a5): kobject_add_internal: parent: 'bdi',  
set: 'devices'
kobject: '0:28' (0000000080474e07): kobject_uevent_env
kobject: '0:32' (0000000075558c25): kobject_add_internal: parent: 'bdi',  
set: 'devices'
kobject: '0:33' (00000000c8dd3226): kobject_add_internal: parent: 'bdi',  
set: 'devices'
kobject: '0:29' (0000000051f8f0a5): kobject_uevent_env
kobject: '0:33' (00000000c8dd3226): kobject_uevent_env
kobject: '0:31': free name
kobject: '0:28' (0000000080474e07): fill_kobj_path: path  
= '/devices/virtual/bdi/0:28'
kobject: '0:29' (0000000051f8f0a5): fill_kobj_path: path  
= '/devices/virtual/bdi/0:29'
kobject: '0:34' (000000008aa55f96): kobject_add_internal: parent: 'bdi',  
set: 'devices'
kobject: '0:33' (00000000c8dd3226): fill_kobj_path: path  
= '/devices/virtual/bdi/0:33'
kobject: '0:31' (000000008e78fdc7): kobject_add_internal: parent: 'bdi',  
set: 'devices'
kobject: '0:32' (0000000075558c25): kobject_uevent_env
kobject: '0:34' (000000008aa55f96): kobject_uevent_env
kobject: '0:32' (0000000075558c25): fill_kobj_path: path  
= '/devices/virtual/bdi/0:32'
kobject: '0:34' (000000008aa55f96): fill_kobj_path: path  
= '/devices/virtual/bdi/0:34'


---
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