possible deadlock in console_unlock

[Yao HongBo]

hi, sergey:

As shown in that link, https://lkml.org/lkml/2018/6/6/397

On the linux kernel 5.0-rc6, Syzkaller also hit 'possible deadlock in 
console_unlock'
bug for several times in my environment.

This solution fixes things for me. Do you have a plan to submit patches to
solve this problem.

diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
        __printk_safe_enter();
        kmalloc(sizeof(struct tty_buffer) + 2 * size, GFP_ATOMIC);
        __printk_safe_exit();



Best regards,
Hongbo