syzbot

======================================================
WARNING: possible circular locking dependency detected
5.2.0-rc5+ #4 Not tainted
------------------------------------------------------
syz-executor155/8057 is trying to acquire lock:
000000009bd46550 (console_owner){-.-.}, at: console_trylock_spinning+0x12f/0x390 kernel/printk/printk.c:1718

but task is already holding lock:
0000000056678186 (&(&port->lock)->rlock){-.-.}, at: pty_write+0xbd/0x190 drivers/tty/pty.c:120

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&(&port->lock)->rlock){-.-.}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa1/0xc0 kernel/locking/spinlock.c:159
       tty_port_tty_get drivers/tty/tty_port.c:287 [inline]
       tty_port_default_wakeup+0x20/0xa0 drivers/tty/tty_port.c:47
       tty_port_tty_wakeup+0x5a/0x70 drivers/tty/tty_port.c:387
       uart_write_wakeup+0x48/0x60 drivers/tty/serial/serial_core.c:103
       serial8250_tx_chars+0x623/0x830 drivers/tty/serial/8250/8250_port.c:1806
       serial8250_handle_irq+0x255/0x390 drivers/tty/serial/8250/8250_port.c:1879
       serial8250_default_handle_irq+0xc5/0x1d0 drivers/tty/serial/8250/8250_port.c:1895
       serial8250_interrupt+0xad/0x190 drivers/tty/serial/8250/8250_core.c:125
       __handle_irq_event_percpu+0x113/0x560 kernel/irq/handle.c:149
       handle_irq_event_percpu kernel/irq/handle.c:189 [inline]
       handle_irq_event+0x10a/0x2f0 kernel/irq/handle.c:206
       handle_edge_irq+0x29f/0xca0 kernel/irq/chip.c:822
       generic_handle_irq_desc include/linux/irqdesc.h:156 [inline]
       handle_irq+0x3e/0x50 arch/x86/kernel/irq_64.c:34
       do_IRQ+0xc4/0x1a0 arch/x86/kernel/irq.c:247
       ret_from_intr+0x0/0x1e
       native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60
       arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:571
       default_idle_call kernel/sched/idle.c:94 [inline]
       cpuidle_idle_call kernel/sched/idle.c:154 [inline]
       do_idle+0x18a/0x760 kernel/sched/idle.c:263
       cpu_startup_entry+0x25/0x30 kernel/sched/idle.c:354
       start_secondary+0x425/0x4c0 arch/x86/kernel/smpboot.c:265
       secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243

-> #1 (&port_lock_key){-.-.}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa1/0xc0 kernel/locking/spinlock.c:159
       serial8250_console_write+0x1d1/0xba0 drivers/tty/serial/8250/8250_port.c:3245
       univ8250_console_write+0x50/0x70 drivers/tty/serial/8250/8250_core.c:586
       call_console_drivers kernel/printk/printk.c:1779 [inline]
       console_unlock+0x95f/0xf20 kernel/printk/printk.c:2463
       vprintk_emit+0x239/0x3a0 kernel/printk/printk.c:1986
       vprintk_default+0x28/0x30 kernel/printk/printk.c:2013
       vprintk_func+0x158/0x170 kernel/printk/printk_safe.c:386
       printk+0xc4/0x11d kernel/printk/printk.c:2046
       register_console+0xa81/0xe30 kernel/printk/printk.c:2788
       univ8250_console_init+0x4b/0x4d drivers/tty/serial/8250/8250_core.c:681
       console_init+0x56/0x9c kernel/printk/printk.c:2874
       start_kernel+0x49e/0x860 init/main.c:688
       x86_64_start_reservations+0x18/0x2e arch/x86/kernel/head64.c:470
       x86_64_start_kernel+0x7a/0x7d arch/x86/kernel/head64.c:451
       secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243

-> #0 (console_owner){-.-.}:
       lock_acquire+0x158/0x250 kernel/locking/lockdep.c:4303
       console_trylock_spinning+0x14f/0x390 kernel/printk/printk.c:1735
       vprintk_emit+0x21c/0x3a0 kernel/printk/printk.c:1985
       vprintk_default+0x28/0x30 kernel/printk/printk.c:2013
       vprintk_func+0x158/0x170 kernel/printk/printk_safe.c:386
       printk+0xc4/0x11d kernel/printk/printk.c:2046
       fail_dump lib/fault-inject.c:45 [inline]
       should_fail+0x5c5/0x860 lib/fault-inject.c:144
       __should_fail_alloc_page mm/page_alloc.c:3278 [inline]
       should_fail_alloc_page+0x55/0x60 mm/page_alloc.c:3315
       prepare_alloc_pages+0x283/0x460 mm/page_alloc.c:4598
       __alloc_pages_nodemask+0x11c/0x790 mm/page_alloc.c:4645
       __alloc_pages include/linux/gfp.h:473 [inline]
       __alloc_pages_node include/linux/gfp.h:486 [inline]
       kmem_getpages+0x46/0x480 mm/slab.c:1373
       cache_grow_begin+0x7e/0x2c0 mm/slab.c:2606
       cache_alloc_refill+0x311/0x3f0 mm/slab.c:2978
       ____cache_alloc mm/slab.c:3061 [inline]
       __do_cache_alloc mm/slab.c:3283 [inline]
       slab_alloc mm/slab.c:3318 [inline]
       __do_kmalloc mm/slab.c:3658 [inline]
       __kmalloc+0x2e5/0x310 mm/slab.c:3669
       kmalloc include/linux/slab.h:552 [inline]
       tty_buffer_alloc drivers/tty/tty_buffer.c:175 [inline]
       __tty_buffer_request_room+0x1ef/0x560 drivers/tty/tty_buffer.c:273
       tty_insert_flip_string_fixed_flag+0xa4/0x2b0 drivers/tty/tty_buffer.c:318
       tty_insert_flip_string include/linux/tty_flip.h:37 [inline]
       pty_write+0xe2/0x190 drivers/tty/pty.c:122
       tty_put_char+0x115/0x180 drivers/tty/tty_io.c:3031
       __process_echoes+0x19d/0x920 drivers/tty/n_tty.c:746
       flush_echoes drivers/tty/n_tty.c:829 [inline]
       __receive_buf drivers/tty/n_tty.c:1648 [inline]
       n_tty_receive_buf_common+0x297f/0x3080 drivers/tty/n_tty.c:1742
       n_tty_receive_buf+0x30/0x40 drivers/tty/n_tty.c:1771
       tiocsti drivers/tty/tty_io.c:2195 [inline]
       tty_ioctl+0xd63/0x15d0 drivers/tty/tty_io.c:2571
       do_vfs_ioctl+0x7d4/0x1890 fs/ioctl.c:46
       ksys_ioctl fs/ioctl.c:713 [inline]
       __do_sys_ioctl fs/ioctl.c:720 [inline]
       __se_sys_ioctl fs/ioctl.c:718 [inline]
       __x64_sys_ioctl+0xe3/0x120 fs/ioctl.c:718
       do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:301
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

other info that might help us debug this:

Chain exists of:
  console_owner --> &port_lock_key --> &(&port->lock)->rlock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&(&port->lock)->rlock);
                               lock(&port_lock_key);
                               lock(&(&port->lock)->rlock);
  lock(console_owner);

 *** DEADLOCK ***

4 locks held by syz-executor155/8057:
 #0: 00000000537d947b (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272
 #1: 00000000edca1b1e (&o_tty->termios_rwsem/1){++++}, at: n_tty_receive_buf_common+0x8b/0x3080 drivers/tty/n_tty.c:1705
 #2: 00000000e4a6cb09 (&ldata->output_lock){+.+.}, at: flush_echoes drivers/tty/n_tty.c:827 [inline]
 #2: 00000000e4a6cb09 (&ldata->output_lock){+.+.}, at: __receive_buf drivers/tty/n_tty.c:1648 [inline]
 #2: 00000000e4a6cb09 (&ldata->output_lock){+.+.}, at: n_tty_receive_buf_common+0x2940/0x3080 drivers/tty/n_tty.c:1742
 #3: 0000000056678186 (&(&port->lock)->rlock){-.-.}, at: pty_write+0xbd/0x190 drivers/tty/pty.c:120

stack backtrace:
CPU: 1 PID: 8057 Comm: syz-executor155 Not tainted 5.2.0-rc5+ #4
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+0x1d8/0x2f8 lib/dump_stack.c:113
 print_circular_bug+0xd34/0xf20 kernel/locking/lockdep.c:1564
 check_prev_add kernel/locking/lockdep.c:2310 [inline]
 check_prevs_add kernel/locking/lockdep.c:2418 [inline]
 validate_chain+0x59d0/0x84f0 kernel/locking/lockdep.c:2800
 __lock_acquire+0xcf7/0x1a40 kernel/locking/lockdep.c:3793
 lock_acquire+0x158/0x250 kernel/locking/lockdep.c:4303
 console_trylock_spinning+0x14f/0x390 kernel/printk/printk.c:1735
 vprintk_emit+0x21c/0x3a0 kernel/printk/printk.c:1985
 vprintk_default+0x28/0x30 kernel/printk/printk.c:2013
 vprintk_func+0x158/0x170 kernel/printk/printk_safe.c:386
 printk+0xc4/0x11d kernel/printk/printk.c:2046
 fail_dump lib/fault-inject.c:45 [inline]
 should_fail+0x5c5/0x860 lib/fault-inject.c:144
 __should_fail_alloc_page mm/page_alloc.c:3278 [inline]
 should_fail_alloc_page+0x55/0x60 mm/page_alloc.c:3315
 prepare_alloc_pages+0x283/0x460 mm/page_alloc.c:4598
 __alloc_pages_nodemask+0x11c/0x790 mm/page_alloc.c:4645
 __alloc_pages include/linux/gfp.h:473 [inline]
 __alloc_pages_node include/linux/gfp.h:486 [inline]
 kmem_getpages+0x46/0x480 mm/slab.c:1373
 cache_grow_begin+0x7e/0x2c0 mm/slab.c:2606
 cache_alloc_refill+0x311/0x3f0 mm/slab.c:2978
 ____cache_alloc mm/slab.c:3061 [inline]
 __do_cache_alloc mm/slab.c:3283 [inline]
 slab_alloc mm/slab.c:3318 [inline]
 __do_kmalloc mm/slab.c:3658 [inline]
 __kmalloc+0x2e5/0x310 mm/slab.c:3669
 kmalloc include/linux/slab.h:552 [inline]
 tty_buffer_alloc drivers/tty/tty_buffer.c:175 [inline]
 __tty_buffer_request_room+0x1ef/0x560 drivers/tty/tty_buffer.c:273
 tty_insert_flip_string_fixed_flag+0xa4/0x2b0 drivers/tty/tty_buffer.c:318
 tty_insert_flip_string include/linux/tty_flip.h:37 [inline]
 pty_write+0xe2/0x190 drivers/tty/pty.c:122
 tty_put_char+0x115/0x180 drivers/tty/tty_io.c:3031
 __process_echoes+0x19d/0x920 drivers/tty/n_tty.c:746
 flush_echoes drivers/tty/n_tty.c:829 [inline]
 __receive_buf drivers/tty/n_tty.c:1648 [inline]
 n_tty_receive_buf_common+0x297f/0x3080 drivers/tty/n_tty.c:1742
 n_tty_receive_buf+0x30/0x40 drivers/tty/n_tty.c:1771
 tiocsti drivers/tty/tty_io.c:2195 [inline]
 tty_ioctl+0xd63/0x15d0 drivers/tty/tty_io.c:2571
 do_vfs_ioctl+0x7d4/0x1890 fs/ioctl.c:46
 ksys_ioctl fs/ioctl.c:713 [inline]
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0xe3/0x120 fs/ioctl.c:718
 do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x441439
Code: e8 8c 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 eb 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffeff301068 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441439
RDX: 0000000020000040 RSI: 0000000000005412 RDI: 0000000000000004
RBP: 00007ffeff301080 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff
R13: 0000000000000005 R14: 0000000000000000 R15: 0000000000000000