------------[ cut here ]------------
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/0:0/9 is trying to acquire lock:
ffffffff8df31260 (console_owner){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:336 [inline]
ffffffff8df31260 (console_owner){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:335 [inline]
ffffffff8df31260 (console_owner){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:289 [inline]
ffffffff8df31260 (console_owner){....}-{0:0}, at: console_flush_all+0x13a/0xb10 kernel/printk/printk.c:3176

but task is already holding lock:
ffff88801fe397d8 (&pool->lock){-.-.}-{2:2}, at: start_flush_work kernel/workqueue.c:4186 [inline]
ffff88801fe397d8 (&pool->lock){-.-.}-{2:2}, at: __flush_work+0x1c8/0xbc0 kernel/workqueue.c:4237

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&pool->lock){-.-.}-{2:2}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
       __queue_work+0x809/0xfb0 kernel/workqueue.c:-1
       queue_work_on+0x181/0x270 kernel/workqueue.c:2392
       queue_work include/linux/workqueue.h:669 [inline]
       rpm_suspend+0xe54/0x1720 drivers/base/power/runtime.c:688
       __pm_runtime_idle+0x12f/0x1a0 drivers/base/power/runtime.c:1129
       pm_runtime_put include/linux/pm_runtime.h:563 [inline]
       __device_attach+0x342/0x400 drivers/base/dd.c:1049
       bus_probe_device+0x185/0x260 drivers/base/bus.c:537
       device_add+0x7b6/0xb50 drivers/base/core.c:3689
       serial_base_port_add+0x2e3/0x410 drivers/tty/serial/serial_base_bus.c:183
       serial_core_port_device_add drivers/tty/serial/serial_core.c:3284 [inline]
       serial_core_register_port+0x369/0x2800 drivers/tty/serial/serial_core.c:3323
       serial8250_register_8250_port+0x16db/0x2080 drivers/tty/serial/8250/8250_core.c:818
       serial_pnp_probe+0x527/0x790 drivers/tty/serial/8250/8250_pnp.c:480
       pnp_device_probe+0x30b/0x4c0 drivers/pnp/driver.c:111
       call_driver_probe drivers/base/dd.c:-1 [inline]
       really_probe+0x26d/0x9e0 drivers/base/dd.c:659
       __driver_probe_device+0x18c/0x2f0 drivers/base/dd.c:801
       driver_probe_device+0x4f/0x430 drivers/base/dd.c:831
       __driver_attach+0x452/0x700 drivers/base/dd.c:1217
       bus_for_each_dev+0x233/0x2b0 drivers/base/bus.c:370
       bus_add_driver+0x345/0x640 drivers/base/bus.c:678
       driver_register+0x23a/0x320 drivers/base/driver.c:249
       serial8250_init+0x8f/0x160 drivers/tty/serial/8250/8250_platform.c:320
       do_one_initcall+0x236/0x820 init/main.c:1283
       do_initcall_level+0x104/0x190 init/main.c:1345
       do_initcalls+0x59/0xa0 init/main.c:1361
       kernel_init_freeable+0x334/0x4b0 init/main.c:1593
       kernel_init+0x1d/0x1d0 init/main.c:1483
       ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #2 (&dev->power.lock){-...}-{3:3}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
       __pm_runtime_resume+0x10f/0x180 drivers/base/power/runtime.c:1196
       pm_runtime_get include/linux/pm_runtime.h:494 [inline]
       __uart_start+0x171/0x460 drivers/tty/serial/serial_core.c:149
       uart_write+0xdc/0x130 drivers/tty/serial/serial_core.c:633
       process_output_block drivers/tty/n_tty.c:561 [inline]
       n_tty_write+0xd27/0x1200 drivers/tty/n_tty.c:2377
       iterate_tty_write drivers/tty/tty_io.c:1006 [inline]
       file_tty_write+0x559/0xa20 drivers/tty/tty_io.c:1081
       new_sync_write fs/read_write.c:593 [inline]
       vfs_write+0x5c9/0xb30 fs/read_write.c:686
       ksys_write+0x145/0x250 fs/read_write.c:738
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&port_lock_key){-.-.}-{3:3}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
       uart_port_lock_irqsave include/linux/serial_core.h:717 [inline]
       serial8250_console_write+0x17e/0x1ba0 drivers/tty/serial/8250/8250_port.c:3301
       console_emit_next_record kernel/printk/printk.c:3111 [inline]
       console_flush_all+0x6f3/0xb10 kernel/printk/printk.c:3199
       __console_flush_and_unlock kernel/printk/printk.c:3258 [inline]
       console_unlock+0xbb/0x190 kernel/printk/printk.c:3298
       vprintk_emit+0x4c5/0x590 kernel/printk/printk.c:2423
       _printk+0xcf/0x120 kernel/printk/printk.c:2448
       register_console+0xa8b/0xf90 kernel/printk/printk.c:4099
       univ8250_console_init+0x3a/0x70 drivers/tty/serial/8250/8250_core.c:511
       console_init+0x10e/0x430 kernel/printk/printk.c:4298
       start_kernel+0x254/0x410 init/main.c:1048
       x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291
       common_startup_64+0x13e/0x147

-> #0 (console_owner){....}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
       __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       console_lock_spinning_enable kernel/printk/printk.c:1897 [inline]
       console_emit_next_record kernel/printk/printk.c:3105 [inline]
       console_flush_all+0x69c/0xb10 kernel/printk/printk.c:3199
       __console_flush_and_unlock kernel/printk/printk.c:3258 [inline]
       console_unlock+0xbb/0x190 kernel/printk/printk.c:3298
       vprintk_emit+0x4c5/0x590 kernel/printk/printk.c:2423
       _printk+0xcf/0x120 kernel/printk/printk.c:2448
       __warn_printk+0x232/0x340 kernel/panic.c:943
       check_flush_dependency+0x35b/0x400 kernel/workqueue.c:3746
       start_flush_work kernel/workqueue.c:4200 [inline]
       __flush_work+0x3bc/0xbc0 kernel/workqueue.c:4237
       flush_work kernel/workqueue.c:4294 [inline]
       flush_delayed_work+0x13e/0x190 kernel/workqueue.c:4316
       hfs_file_fsync+0xee/0x140 fs/hfs/inode.c:691
       generic_write_sync include/linux/fs.h:3046 [inline]
       dio_complete+0x5f4/0x790 fs/direct-io.c:313
       process_one_work kernel/workqueue.c:3263 [inline]
       process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
       worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
       kthread+0x711/0x8a0 kernel/kthread.c:463
       ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

other info that might help us debug this:

Chain exists of:
  console_owner --> &dev->power.lock --> &pool->lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&pool->lock);
                               lock(&dev->power.lock);
                               lock(&pool->lock);
  lock(console_owner);

 *** DEADLOCK ***

7 locks held by kworker/0:0/9:
 #0: ffff88803318d548 ((wq_completion)dio/loop0){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
 #0: ffff88803318d548 ((wq_completion)dio/loop0){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
 #1: ffffc900001b7ba0 ((work_completion)(&dio->complete_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
 #1: ffffc900001b7ba0 ((work_completion)(&dio->complete_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
 #2: ffff8880331d1ca0 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:980 [inline]
 #2: ffff8880331d1ca0 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: hfs_file_fsync+0x9a/0x140 fs/hfs/inode.c:684
 #3: ffffffff8df3d2e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #3: ffffffff8df3d2e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #3: ffffffff8df3d2e0 (rcu_read_lock){....}-{1:3}, at: start_flush_work kernel/workqueue.c:4179 [inline]
 #3: ffffffff8df3d2e0 (rcu_read_lock){....}-{1:3}, at: __flush_work+0xd2/0xbc0 kernel/workqueue.c:4237
 #4: ffff88801fe397d8 (&pool->lock){-.-.}-{2:2}, at: start_flush_work kernel/workqueue.c:4186 [inline]
 #4: ffff88801fe397d8 (&pool->lock){-.-.}-{2:2}, at: __flush_work+0x1c8/0xbc0 kernel/workqueue.c:4237
 #5: ffffffff8df312c0 (console_lock){+.+.}-{0:0}, at: _printk+0xcf/0x120 kernel/printk/printk.c:2448
 #6: ffffffff8de18b90 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:336 [inline]
 #6: ffffffff8de18b90 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:335 [inline]
 #6: ffffffff8de18b90 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:289 [inline]
 #6: ffffffff8de18b90 (console_srcu){....}-{0:0}, at: console_flush_all+0x13a/0xb10 kernel/printk/printk.c:3176

stack backtrace:
CPU: 0 UID: 0 PID: 9 Comm: kworker/0:0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: dio/loop0 dio_aio_complete_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043
 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 console_lock_spinning_enable kernel/printk/printk.c:1897 [inline]
 console_emit_next_record kernel/printk/printk.c:3105 [inline]
 console_flush_all+0x69c/0xb10 kernel/printk/printk.c:3199
 __console_flush_and_unlock kernel/printk/printk.c:3258 [inline]
 console_unlock+0xbb/0x190 kernel/printk/printk.c:3298
 vprintk_emit+0x4c5/0x590 kernel/printk/printk.c:2423
 _printk+0xcf/0x120 kernel/printk/printk.c:2448
 __warn_printk+0x232/0x340 kernel/panic.c:943
 check_flush_dependency+0x35b/0x400 kernel/workqueue.c:3746
 start_flush_work kernel/workqueue.c:4200 [inline]
 __flush_work+0x3bc/0xbc0 kernel/workqueue.c:4237
 flush_work kernel/workqueue.c:4294 [inline]
 flush_delayed_work+0x13e/0x190 kernel/workqueue.c:4316
 hfs_file_fsync+0xee/0x140 fs/hfs/inode.c:691
 generic_write_sync include/linux/fs.h:3046 [inline]
 dio_complete+0x5f4/0x790 fs/direct-io.c:313
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
workqueue: WQ_MEM_RECLAIM dio/loop0:dio_aio_complete_work is flushing !WQ_MEM_RECLAIM events_long:flush_mdb
WARNING: CPU: 0 PID: 9 at kernel/workqueue.c:3750 check_flush_dependency+0x35c/0x400 kernel/workqueue.c:3746
Modules linked in:
CPU: 0 UID: 0 PID: 9 Comm: kworker/0:0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: dio/loop0 dio_aio_complete_work
RIP: 0010:check_flush_dependency+0x35c/0x400 kernel/workqueue.c:3746
Code: 08 4c 89 f7 e8 25 1a 9d 00 49 8b 16 48 81 c3 78 01 00 00 48 c7 c7 a0 ee 69 8b 4c 89 e6 48 89 d9 4c 8b 04 24 e8 15 e8 f8 ff 90 <0f> 0b 90 90 e9 dc fe ff ff 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c
RSP: 0018:ffffc900001b7700 EFLAGS: 00010046
RAX: 11ffbfe9b1631800 RBX: ffff88801a067d78 RCX: ffff88801bebc900
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: 0000000000000008 R08: ffff88801fe24293 R09: 1ffff11003fc4852
R10: dffffc0000000000 R11: ffffed1003fc4853 R12: ffff88803318d578
R13: ffff8880119e4008 R14: ffff88801bea3718 R15: ffff88801bea3720
FS:  0000000000000000(0000) GS:ffff88808d733000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffffffff000 CR3: 000000003ef2a000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 start_flush_work kernel/workqueue.c:4200 [inline]
 __flush_work+0x3bc/0xbc0 kernel/workqueue.c:4237
 flush_work kernel/workqueue.c:4294 [inline]
 flush_delayed_work+0x13e/0x190 kernel/workqueue.c:4316
 hfs_file_fsync+0xee/0x140 fs/hfs/inode.c:691
 generic_write_sync include/linux/fs.h:3046 [inline]
 dio_complete+0x5f4/0x790 fs/direct-io.c:313
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>