On (01/11/18 10:34), Petr Mladek wrote: [..] > > except that handing off a console_sem to atomic task when there > > is O(logbuf) > watchdog_thresh is a regression, basically... > > it is what it is. > > How this could be a regression? Is not the victim that handles > other printk's random? What protected the atomic task to > handle the other printks before this patch? the non-atomic -> atomic context console_sem transfer. we previously would have kept the console_sem owner to its non-atomic owner. we now will make sure that if printk from atomic context happens then it will make it to console_unlock() loop. emphasis on O(logbuf) > watchdog_thresh. - if the patch's goal is to bound (not necessarily to watchdog's threshold) the amount of time we spend in console_unlock(), then the patch is kinda overcomplicated. but no further questions in this case. - but if the patch's goal is to bound (to lockup threshold) the amount of time spent in console_unlock() in order to avoid lockups [uh, a reason], then the patch is rather oversimplified. claiming that for any given A, B, C the following is always true A * B < C where A is the amount of data to print in the worst case B the time call_console_drivers() needs to print a single char to all registered and enabled consoles C the watchdog's threshold is not really a step forward. and the "last console_sem owner prints all pending messages" rule is still there. > Or do you have a system that started to suffer from softlockups > with this patchset and did not do this before? [..] > Do you know about any system where this patch made the softlockup > deterministically or statistically more likely, please? I have explained many, many times why my boards die just like before. why would I bother collecting any numbers... -ss -- 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>
