Re: [PATCH v2] tty: use printk_deferred() at tty_msg()

2021-04-07 Thread Tetsuo Handa
On 2021/04/07 22:48, Greg Kroah-Hartman wrote: >> By the way, as soon as applying this patch, I guess that syzkaller starts >> generating hung task reports because /dev/ttyprintk can trivially trigger >> flood of >> >> tty_warn(tty, "%s: tty->count = 1 port count = %d\n", __func__, >>

Re: [PATCH v2] tty: use printk_deferred() at tty_msg()

2021-04-07 Thread Greg Kroah-Hartman
On Wed, Apr 07, 2021 at 10:26:21PM +0900, Tetsuo Handa wrote: > syzbot is reporting circular locking dependency due to calling printk() > with port lock held [1]. Update tty_msg() to use printk_deferred() in > order to break this dependency. Since tty_info_ratelimited() is used by > only tty_init_d

[PATCH v2] tty: use printk_deferred() at tty_msg()

2021-04-07 Thread Tetsuo Handa
syzbot is reporting circular locking dependency due to calling printk() with port lock held [1]. Update tty_msg() to use printk_deferred() in order to break this dependency. Since tty_info_ratelimited() is used by only tty_init_dev() which is called without holding port lock, just redirect tty_info