[syzbot] possible deadlock in tty_port_default_wakeup

From: syzbot
Date: Sat Nov 26 2022 - 12:05:42 EST

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Hello,

syzbot found the following issue on:

HEAD commit: eb7081409f94 Linux 6.1-rc6
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12340efd880000
kernel config: https://syzkaller.appspot.com/x/.config?x=5db36e7087dcccae
dashboard link: https://syzkaller.appspot.com/bug?extid=2bd4a8abdc688d6abb1d
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2bd4a8abdc688d6abb1d@xxxxxxxxxxxxxxxxxxxxxxxxx

======================================================
WARNING: possible circular locking dependency detected
6.1.0-rc6-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.1/4131 is trying to acquire lock:
ffff88802c93a9d8 (&pool->lock){-.-.}-{2:2}, at: __queue_work+0x367/0x13b0 kernel/workqueue.c:1474

but task is already holding lock:
ffff88801b767528 (&tty->write_wait){-.-.}-{2:2}, at: __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:136

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #4 (&tty->write_wait){-.-.}-{2:2}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3d/0x60 kernel/locking/spinlock.c:162
__wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:136
tty_port_default_wakeup+0x2a/0x40 drivers/tty/tty_port.c:71
serial8250_tx_chars+0x503/0xdb0 drivers/tty/serial/8250/8250_port.c:1859
serial8250_handle_irq.part.0+0x460/0x870 drivers/tty/serial/8250/8250_port.c:1949
serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1922 [inline]
serial8250_default_handle_irq+0xb6/0x230 drivers/tty/serial/8250/8250_port.c:1969
serial8250_interrupt+0xfc/0x200 drivers/tty/serial/8250/8250_core.c:126
__handle_irq_event_percpu+0x264/0x970 kernel/irq/handle.c:158
handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210
handle_edge_irq+0x263/0xd00 kernel/irq/chip.c:819
generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
handle_irq arch/x86/kernel/irq.c:231 [inline]
__common_interrupt+0xa1/0x210 arch/x86/kernel/irq.c:250
common_interrupt+0xa8/0xd0 arch/x86/kernel/irq.c:240
asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:640
native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
default_idle+0xf/0x10 arch/x86/kernel/process.c:730
default_idle_call+0x84/0xc0 kernel/sched/idle.c:109
cpuidle_idle_call kernel/sched/idle.c:191 [inline]
do_idle+0x410/0x590 kernel/sched/idle.c:303
cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:400
start_secondary+0x256/0x300 arch/x86/kernel/smpboot.c:262
secondary_startup_64_no_verify+0xce/0xdb

-> #3 (&port_lock_key){-.-.}-{2:2}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3d/0x60 kernel/locking/spinlock.c:162
serial8250_console_write+0x4ba/0x1010 drivers/tty/serial/8250/8250_port.c:3395
call_console_driver kernel/printk/printk.c:1942 [inline]
console_emit_next_record.constprop.0+0x3de/0x840 kernel/printk/printk.c:2731
console_flush_all kernel/printk/printk.c:2793 [inline]
console_unlock+0x3c2/0x600 kernel/printk/printk.c:2860
vprintk_emit+0x1bd/0x600 kernel/printk/printk.c:2268
vprintk+0x84/0xa0 kernel/printk/printk_safe.c:50
_printk+0xbe/0xf1 kernel/printk/printk.c:2289
register_console kernel/printk/printk.c:3208 [inline]
register_console+0x45e/0x820 kernel/printk/printk.c:3103
univ8250_console_init+0x3e/0x4a drivers/tty/serial/8250/8250_core.c:687
console_init+0x3bb/0x582 kernel/printk/printk.c:3298
start_kernel+0x303/0x498 init/main.c:1073
secondary_startup_64_no_verify+0xce/0xdb

-> #2 (console_owner){..-.}-{0:0}:
console_lock_spinning_enable kernel/printk/printk.c:1805 [inline]
console_emit_next_record.constprop.0+0x2dd/0x840 kernel/printk/printk.c:2728
console_flush_all kernel/printk/printk.c:2793 [inline]
console_unlock+0x3c2/0x600 kernel/printk/printk.c:2860
vprintk_emit+0x1bd/0x600 kernel/printk/printk.c:2268
vprintk+0x84/0xa0 kernel/printk/printk_safe.c:50
_printk+0xbe/0xf1 kernel/printk/printk.c:2289
build_zonelists.cold+0xe5/0x11f mm/page_alloc.c:6503
__build_all_zonelists+0x122/0x180 mm/page_alloc.c:6616
build_all_zonelists_init+0x35/0x12f mm/page_alloc.c:6641
build_all_zonelists+0x123/0x140 mm/page_alloc.c:6674
start_kernel+0xbd/0x498 init/main.c:967
secondary_startup_64_no_verify+0xce/0xdb

-> #1 (zonelist_update_seq.seqcount){...-}-{0:0}:
seqcount_lockdep_reader_access include/linux/seqlock.h:102 [inline]
read_seqbegin include/linux/seqlock.h:836 [inline]
zonelist_iter_begin mm/page_alloc.c:4727 [inline]
__alloc_pages_slowpath.constprop.0+0x1ae/0x23d0 mm/page_alloc.c:5049
__alloc_pages+0x4aa/0x5b0 mm/page_alloc.c:5568
__alloc_pages_node include/linux/gfp.h:223 [inline]
kmem_getpages mm/slab.c:1363 [inline]
cache_grow_begin+0x75/0x360 mm/slab.c:2570
cache_alloc_refill+0x27f/0x380 mm/slab.c:2943
____cache_alloc mm/slab.c:3019 [inline]
____cache_alloc mm/slab.c:3002 [inline]
__do_cache_alloc mm/slab.c:3202 [inline]
slab_alloc_node mm/slab.c:3250 [inline]
slab_alloc mm/slab.c:3265 [inline]
__kmem_cache_alloc_lru mm/slab.c:3442 [inline]
kmem_cache_alloc+0x364/0x460 mm/slab.c:3461
kmem_cache_zalloc include/linux/slab.h:679 [inline]
fill_pool+0x264/0x5c0 lib/debugobjects.c:168
__debug_object_init+0x7a/0xd10 lib/debugobjects.c:562
debug_object_init lib/debugobjects.c:617 [inline]
debug_object_activate+0x330/0x3e0 lib/debugobjects.c:703
debug_work_activate kernel/workqueue.c:510 [inline]
__queue_work+0x682/0x13b0 kernel/workqueue.c:1516
queue_work_on+0xf2/0x110 kernel/workqueue.c:1545
queue_work include/linux/workqueue.h:503 [inline]
schedule_work include/linux/workqueue.h:564 [inline]
wireless_send_event+0x6de/0xc40 net/wireless/wext-core.c:635
__cfg80211_ibss_joined+0x41d/0x540 net/wireless/ibss.c:56
cfg80211_process_wdev_events+0x391/0x5e0 net/wireless/util.c:986
cfg80211_process_rdev_events+0x9f/0x130 net/wireless/util.c:1012
cfg80211_event_work+0x2b/0x40 net/wireless/core.c:328
process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289
worker_thread+0x669/0x1090 kernel/workqueue.c:2436
kthread+0x2e8/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

-> #0 (&pool->lock){-.-.}-{2:2}:
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
lock_acquire kernel/locking/lockdep.c:5668 [inline]
lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
__queue_work+0x367/0x13b0 kernel/workqueue.c:1474
queue_work_on+0xf2/0x110 kernel/workqueue.c:1545
queue_work include/linux/workqueue.h:503 [inline]
schedule_work include/linux/workqueue.h:564 [inline]
p9_pollwake+0xc1/0x1d0 net/9p/trans_fd.c:538
__wake_up_common+0x147/0x650 kernel/sched/wait.c:107
__wake_up_common_lock+0xd0/0x130 kernel/sched/wait.c:137
tty_ldisc_lock+0x59/0xb0 drivers/tty/tty_ldisc.c:312
tty_set_ldisc+0x92/0x680 drivers/tty/tty_ldisc.c:530
tiocsetd drivers/tty/tty_io.c:2426 [inline]
tty_ioctl+0x655/0x1660 drivers/tty/tty_io.c:2707
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Chain exists of:
&pool->lock --> &port_lock_key --> &tty->write_wait

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&tty->write_wait);
lock(&port_lock_key);
lock(&tty->write_wait);
lock(&pool->lock);

*** DEADLOCK ***

3 locks held by syz-executor.1/4131:
#0: ffff88801b7671c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_set_ldisc+0x85/0x680 drivers/tty/tty_ldisc.c:529
#1: ffff88801b767528 (&tty->write_wait){-.-.}-{2:2}, at: __wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:136
#2: ffffffff8c58ce40 (rcu_read_lock){....}-{1:2}, at: __queue_work+0xca/0x13b0 kernel/workqueue.c:1437

stack backtrace:
CPU: 3 PID: 4131 Comm: syz-executor.1 Not tainted 6.1.0-rc6-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2177
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
lock_acquire kernel/locking/lockdep.c:5668 [inline]
lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
__queue_work+0x367/0x13b0 kernel/workqueue.c:1474
queue_work_on+0xf2/0x110 kernel/workqueue.c:1545
queue_work include/linux/workqueue.h:503 [inline]
schedule_work include/linux/workqueue.h:564 [inline]
p9_pollwake+0xc1/0x1d0 net/9p/trans_fd.c:538
__wake_up_common+0x147/0x650 kernel/sched/wait.c:107
__wake_up_common_lock+0xd0/0x130 kernel/sched/wait.c:137
tty_ldisc_lock+0x59/0xb0 drivers/tty/tty_ldisc.c:312
tty_set_ldisc+0x92/0x680 drivers/tty/tty_ldisc.c:530
tiocsetd drivers/tty/tty_io.c:2426 [inline]
tty_ioctl+0x655/0x1660 drivers/tty/tty_io.c:2707
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7eff5728c189
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007eff58003168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007eff573ac050 RCX: 00007eff5728c189
RDX: 0000000020000000 RSI: 0000000000005423 RDI: 0000000000000005
RBP: 00007eff572e7b01 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff20cbb7cf R14: 00007eff58003300 R15: 0000000000022000
</TASK>

---
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