Messages in this thread | | | Date | Thu, 11 Jan 2018 12:50:59 +0100 | From | Petr Mladek <> | Subject | Re: [PATCH v5 0/2] printk: Console owner and waiter logic cleanup |
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On Thu 2018-01-11 19:38:45, Sergey Senozhatsky wrote: > 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.
Sergey, please, why do you completely and repeatedly ignore that argument about statistical effects?
Yes, the above scenario is possible. But Steven's patch might also move the owner from atomic context to a non-atomic one. The chances should be more or less equal. The main advantage is that the owner is moved. This should statistically lower the chance of a soft-lockup.
> > > 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...
Is it with your own printk stress tests or during "normal" work?
If it is during a normal work, is there any chance that we could have a look at the logs?
Best Regards, Petr
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