On 22. 04. 24, 9:18, Jeongjun Park wrote:
========================================================
WARNING: possible irq lock inversion dependency detected
6.8.0-rc3-syzkaller-00041-g547ab8fc4cb0 #0 Not tainted
--------------------------------------------------------
...
... key at: [<ffffffff947ae860>] port_lock_key+0x0/0x20
... acquired at:
lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
__raw_read_lock include/linux/rwlock_api_smp.h:150 [inline]
_raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:228
ap_get drivers/net/ppp/ppp_async.c:136 [inline]
ppp_asynctty_wakeup+0x20/0x210 drivers/net/ppp/ppp_async.c:352
tty_wakeup+0xbb/0x100 drivers/tty/tty_io.c:523
tty_port_default_wakeup+0xa6/0xf0 drivers/tty/tty_port.c:69
serial8250_tx_chars+0x6ad/0x8a0 drivers/tty/serial/8250/8250_port.c:1835
This is the stack trace for the issue causing the deadlock reported
by syzbot. I think there is definitely a problem with ap_get() and
this needs to be fixed.
OK, but read_unlock_irq() is not the right way to do it. It would enable
irqs unconditionally, so serial8250_tx_chars() would not thank you in
the above call chain.
Plus the issues Jakub had with the patch.
And what about ppp_synctty?
thanks,
--
js
suse labs
