syzbot

------------[ cut here ]------------
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/0:2/986 is trying to acquire lock:
ffffffff8e94f140 (console_owner){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:305 [inline]
ffffffff8e94f140 (console_owner){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:428 [inline]
ffffffff8e94f140 (console_owner){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:291 [inline]
ffffffff8e94f140 (console_owner){....}-{0:0}, at: console_flush_one_record kernel/printk/printk.c:3246 [inline]
ffffffff8e94f140 (console_owner){....}-{0:0}, at: console_flush_all+0x123/0xb20 kernel/printk/printk.c:3343

but task is already holding lock:
ffff8880b863a5d8 (&pool->lock){-.-.}-{2:2}, at: start_flush_work kernel/workqueue.c:4267 [inline]
ffff8880b863a5d8 (&pool->lock){-.-.}-{2:2}, at: __flush_work+0x1ef/0xc50 kernel/workqueue.c:4318

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&pool->lock){-.-.}-{2:2}:
       __raw_spin_lock include/linux/spinlock_api_smp.h:158 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:158
       __queue_work+0x7ea/0xfc0 kernel/workqueue.c:-1
       queue_work_on+0x106/0x1d0 kernel/workqueue.c:2432
       queue_work include/linux/workqueue.h:696 [inline]
       rpm_suspend+0xe85/0x1720 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:551 [inline]
       __device_attach+0x34f/0x450 drivers/base/dd.c:1119
       device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1156
       bus_probe_device+0x12a/0x220 drivers/base/bus.c:613
       device_add+0x7e9/0xbb0 drivers/base/core.c:3706
       serial_base_port_add+0x18f/0x260 drivers/tty/serial/serial_base_bus.c:186
       serial_core_port_device_add drivers/tty/serial/serial_core.c:3260 [inline]
       serial_core_register_port+0x36f/0x2820 drivers/tty/serial/serial_core.c:3299
       serial8250_register_8250_port+0x1658/0x1fb0 drivers/tty/serial/8250/8250_core.c:822
       serial_pnp_probe+0x568/0x7f0 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+0x267/0xaf0 drivers/base/dd.c:709
       __driver_probe_device+0x1ef/0x380 drivers/base/dd.c:871
       driver_probe_device+0x4f/0x240 drivers/base/dd.c:901
       __driver_attach+0x34c/0x640 drivers/base/dd.c:1295
       bus_for_each_dev+0x23b/0x2c0 drivers/base/bus.c:383
       bus_add_driver+0x345/0x670 drivers/base/bus.c:756
       driver_register+0x23a/0x320 drivers/base/driver.c:249
       serial8250_init+0x8f/0x160 drivers/tty/serial/8250/8250_platform.c:317
       do_one_initcall+0x250/0x870 init/main.c:1392
       do_initcall_level+0x104/0x190 init/main.c:1454
       do_initcalls+0x59/0xa0 init/main.c:1470
       kernel_init_freeable+0x2a6/0x3e0 init/main.c:1703
       kernel_init+0x1d/0x1d0 init/main.c:1593
       ret_from_fork+0x514/0xb70 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}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
       _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
       __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+0x265/0xa10 drivers/tty/serial/serial_core.c:633
       process_output_block drivers/tty/n_tty.c:557 [inline]
       n_tty_write+0xd4f/0x1220 drivers/tty/n_tty.c:2366
       iterate_tty_write drivers/tty/tty_io.c:1006 [inline]
       file_tty_write+0x558/0xa10 drivers/tty/tty_io.c:1081
       new_sync_write fs/read_write.c:595 [inline]
       vfs_write+0x61d/0xb90 fs/read_write.c:688
       ksys_write+0x150/0x270 fs/read_write.c:740
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&port_lock_key){-...}-{3:3}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
       _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
       uart_port_lock_irqsave include/linux/serial_core.h:717 [inline]
       serial8250_console_write+0x150/0x1ba0 drivers/tty/serial/8250/8250_port.c:3316
       console_emit_next_record kernel/printk/printk.c:3183 [inline]
       console_flush_one_record kernel/printk/printk.c:3269 [inline]
       console_flush_all+0x718/0xb20 kernel/printk/printk.c:3343
       __console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
       console_unlock+0xd1/0x1c0 kernel/printk/printk.c:3413
       vprintk_emit+0x485/0x560 kernel/printk/printk.c:2479
       _printk+0xdd/0x130 kernel/printk/printk.c:2504
       register_console+0xbc2/0xfa0 kernel/printk/printk.c:4208
       univ8250_console_init+0x3a/0x70 drivers/tty/serial/8250/8250_core.c:515
       console_init+0x10b/0x4a0 kernel/printk/printk.c:4407
       start_kernel+0x230/0x3e0 init/main.c:1157
       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 kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
       lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
       console_lock_spinning_enable kernel/printk/printk.c:1902 [inline]
       console_emit_next_record kernel/printk/printk.c:3177 [inline]
       console_flush_one_record kernel/printk/printk.c:3269 [inline]
       console_flush_all+0x6c1/0xb20 kernel/printk/printk.c:3343
       __console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
       console_unlock+0xd1/0x1c0 kernel/printk/printk.c:3413
       vprintk_emit+0x485/0x560 kernel/printk/printk.c:2479
       _printk+0xdd/0x130 kernel/printk/printk.c:2504
       __report_bug+0x317/0x540 lib/bug.c:240
       report_bug_entry+0x19a/0x290 lib/bug.c:266
       handle_bug+0xce/0x200 arch/x86/kernel/traps.c:431
       exc_invalid_op+0x1a/0x50 arch/x86/kernel/traps.c:490
       asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:616
       check_flush_dependency+0x312/0x3c0 kernel/workqueue.c:3827
       start_flush_work kernel/workqueue.c:4281 [inline]
       __flush_work+0x411/0xc50 kernel/workqueue.c:4318
       hfs_file_fsync+0xee/0x140 fs/hfs/inode.c:693
       generic_write_sync include/linux/fs.h:2654 [inline]
       dio_complete+0x5f4/0x790 fs/direct-io.c:313
       process_one_work kernel/workqueue.c:3302 [inline]
       process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
       worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
       kthread+0x388/0x470 kernel/kthread.c:436
       ret_from_fork+0x514/0xb70 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/0:2/986:
 #0: ffff88807b444d40 ((wq_completion)dio/loop0){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3277 [inline]
 #0: ffff88807b444d40 ((wq_completion)dio/loop0){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860 kernel/workqueue.c:3385
 #1: ffffc9000524fc40 ((work_completion)(&dio->complete_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3278 [inline]
 #1: ffffc9000524fc40 ((work_completion)(&dio->complete_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860 kernel/workqueue.c:3385
 #2: ffff88803155b490 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1029 [inline]
 #2: ffff88803155b490 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: hfs_file_fsync+0x9a/0x140 fs/hfs/inode.c:686
 #3: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #3: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #3: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: start_flush_work kernel/workqueue.c:4260 [inline]
 #3: ffffffff8e95cd60 (rcu_read_lock){....}-{1:3}, at: __flush_work+0x100/0xc50 kernel/workqueue.c:4318
 #4: ffff8880b863a5d8 (&pool->lock){-.-.}-{2:2}, at: start_flush_work kernel/workqueue.c:4267 [inline]
 #4: ffff8880b863a5d8 (&pool->lock){-.-.}-{2:2}, at: __flush_work+0x1ef/0xc50 kernel/workqueue.c:4318
 #5: ffffffff8e94f1a0 (console_lock){+.+.}-{0:0}, at: _printk+0xdd/0x130 kernel/printk/printk.c:2504
 #6: ffffffff8e836a38 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:305 [inline]
 #6: ffffffff8e836a38 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:428 [inline]
 #6: ffffffff8e836a38 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:291 [inline]
 #6: ffffffff8e836a38 (console_srcu){....}-{0:0}, at: console_flush_one_record kernel/printk/printk.c:3246 [inline]
 #6: ffffffff8e836a38 (console_srcu){....}-{0:0}, at: console_flush_all+0x123/0xb20 kernel/printk/printk.c:3343

stack backtrace:
CPU: 0 UID: 0 PID: 986 Comm: kworker/0:2 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: dio/loop0 dio_aio_complete_work
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043
 check_noncircular+0x12e/0x150 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 kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
 console_lock_spinning_enable kernel/printk/printk.c:1902 [inline]
 console_emit_next_record kernel/printk/printk.c:3177 [inline]
 console_flush_one_record kernel/printk/printk.c:3269 [inline]
 console_flush_all+0x6c1/0xb20 kernel/printk/printk.c:3343
 __console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
 console_unlock+0xd1/0x1c0 kernel/printk/printk.c:3413
 vprintk_emit+0x485/0x560 kernel/printk/printk.c:2479
 _printk+0xdd/0x130 kernel/printk/printk.c:2504
 __report_bug+0x317/0x540 lib/bug.c:240
 report_bug_entry+0x19a/0x290 lib/bug.c:266
 handle_bug+0xce/0x200 arch/x86/kernel/traps.c:431
 exc_invalid_op+0x1a/0x50 arch/x86/kernel/traps.c:490
 asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:616
RIP: 0010:check_flush_dependency+0x312/0x3c0 kernel/workqueue.c:3827
Code: 00 00 fc ff df 80 3c 08 00 74 08 4c 89 f7 e8 35 6d a3 00 49 8b 16 48 81 c3 70 01 00 00 4c 89 ef 4c 89 e6 48 89 d9 4c 8b 04 24 <67> 48 0f b9 3a e9 53 ff ff ff 44 89 f1 80 e1 07 80 c1 03 38 c1 0f
RSP: 0018:ffffc9000524f840 EFLAGS: 00010082
RAX: 1ffff11004bd14e3 RBX: ffff88813fe42970 RCX: ffff88813fe42970
RDX: ffffffff82584d50 RSI: ffff88807b444d70 RDI: ffffffff90339190
RBP: ffff88807b13f008 R08: ffffffff82b1b7c0 R09: 1ffff1100695e628
R10: dffffc0000000000 R11: ffffed100695e629 R12: ffff88807b444d70
R13: ffffffff90339190 R14: ffff888025e8a718 R15: ffff888025e8a720
 start_flush_work kernel/workqueue.c:4281 [inline]
 __flush_work+0x411/0xc50 kernel/workqueue.c:4318
 hfs_file_fsync+0xee/0x140 fs/hfs/inode.c:693
 generic_write_sync include/linux/fs.h:2654 [inline]
 dio_complete+0x5f4/0x790 fs/direct-io.c:313
 process_one_work kernel/workqueue.c:3302 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 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: kernel/workqueue.c:3831 at check_flush_dependency+0x28f/0x3c0 kernel/workqueue.c:3827, CPU#0: kworker/0:2/986
Modules linked in:
CPU: 0 UID: 0 PID: 986 Comm: kworker/0:2 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: dio/loop0 dio_aio_complete_work
RIP: 0010:check_flush_dependency+0x312/0x3c0 kernel/workqueue.c:3827
Code: 00 00 fc ff df 80 3c 08 00 74 08 4c 89 f7 e8 35 6d a3 00 49 8b 16 48 81 c3 70 01 00 00 4c 89 ef 4c 89 e6 48 89 d9 4c 8b 04 24 <67> 48 0f b9 3a e9 53 ff ff ff 44 89 f1 80 e1 07 80 c1 03 38 c1 0f
RSP: 0018:ffffc9000524f840 EFLAGS: 00010082
RAX: 1ffff11004bd14e3 RBX: ffff88813fe42970 RCX: ffff88813fe42970
RDX: ffffffff82584d50 RSI: ffff88807b444d70 RDI: ffffffff90339190
RBP: ffff88807b13f008 R08: ffffffff82b1b7c0 R09: 1ffff1100695e628
R10: dffffc0000000000 R11: ffffed100695e629 R12: ffff88807b444d70
R13: ffffffff90339190 R14: ffff888025e8a718 R15: ffff888025e8a720
FS:  0000000000000000(0000) GS:ffff888125293000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005599e950a950 CR3: 0000000074547000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 start_flush_work kernel/workqueue.c:4281 [inline]
 __flush_work+0x411/0xc50 kernel/workqueue.c:4318
 hfs_file_fsync+0xee/0x140 fs/hfs/inode.c:693
 generic_write_sync include/linux/fs.h:2654 [inline]
 dio_complete+0x5f4/0x790 fs/direct-io.c:313
 process_one_work kernel/workqueue.c:3302 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	fc                   	cld
   3:	ff                   	lcall  (bad)
   4:	df 80 3c 08 00 74    	filds  0x7400083c(%rax)
   a:	08 4c 89 f7          	or     %cl,-0x9(%rcx,%rcx,4)
   e:	e8 35 6d a3 00       	call   0xa36d48
  13:	49 8b 16             	mov    (%r14),%rdx
  16:	48 81 c3 70 01 00 00 	add    $0x170,%rbx
  1d:	4c 89 ef             	mov    %r13,%rdi
  20:	4c 89 e6             	mov    %r12,%rsi
  23:	48 89 d9             	mov    %rbx,%rcx
  26:	4c 8b 04 24          	mov    (%rsp),%r8
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	e9 53 ff ff ff       	jmp    0xffffff87
  34:	44 89 f1             	mov    %r14d,%ecx
  37:	80 e1 07             	and    $0x7,%cl
  3a:	80 c1 03             	add    $0x3,%cl
  3d:	38 c1                	cmp    %al,%cl
  3f:	0f                   	.byte 0xf