On 2024/01/21 12:48, Hillf Danton wrote: > On Sat, 20 Jan 2024 19:34:02 +0900 Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> >> syzbot is reporting sleep in atomic context, for gsmld_write() is calling >> con_write() with spinlock held and IRQs disabled. > > ... > >> --- a/drivers/tty/vt/vt.c >> +++ b/drivers/tty/vt/vt.c >> @@ -2856,7 +2856,7 @@ static int do_con_write(struct tty_struct *tty, const u8 *buf, int count) >> struct vt_notifier_param param; >> bool rescan; >> >> - if (in_interrupt()) >> + if (in_interrupt() || irqs_disabled()) >> return count; >> >> console_lock(); > > Given console_lock(), no sense could be made by calling do_con_write() > with spin lock held at the first place, regardless irq. The question was how to detect it. Since in_atomic() is not a reliable method for detecting that a spin lock is held, this patch instead chose irqs_disabled(), for gsmld_write() is using spin_lock_irqsave(&gsm->tx_lock, flags).
