On Fri 2017-01-13 20:50:24, Sergey Senozhatsky wrote: > On (01/13/17 12:03), Petr Mladek wrote: > [..] > > > why can't we? > > > > Because it would newer call cond_resched() in non-preemptive kernel > > with CONFIG_PREEMPT_COUNT disabled. IMHO, we want to call it, > > for example, when we scroll the entire screen from tty_operations. > > > > Or do I miss anything? > > so... basically. it has never called cond_resched() there. right? > why is this suddenly a problem now? But it called cond_resched() when the very same code was called from tty operations under console_lock() that forced console_may_schedule = 1; It will never call cond_resched() from the tty operations when CONFIG_PREEMPT_COUNT is disabled and we try to detect the preemption automatically. Best Regards, Petr -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>