On Sun, 2022-04-03 at 21:51 +0200, Thomas Gleixner wrote: > > > There was no timer. If there's ever a timer on this base (BASE_DEF) then > > this doesn't happen. > > You said: > > > > > init_timer_cpu(0) base 0 clk=0xffff8ad0, next_expiry=0x13fff8acf > > > > init_timer_cpu(0) base 1 clk=0xffff8ad0, next_expiry=0x13fff8acf > > which confused me. It's actually initialized to: > > base->clk + NEXT_TIMER_MAX_DELTA > > but that's fine and it is overwritten by every timer which is inserted > to expire before that. So that's not an issue as the prandom timer is > firing and rearmed.
No, as I said before, there's never any timer with base 1 (BASE_DEF) in the config we have. The prandom timer is not TIMER_DEFERRABLE (it probably could be, but it's not now). There's no deferrable timer at all. Once there is at least one, the warning goes away. > That would not happen if next_expiry would stay at 0x13fff8acf. The > first one in your trace expires at 5339070200, i.e. 0x13e3bbef8, which > is way before that. But it's not a deferrable timer, so it's on another timer wheel (base), so it doesn't affect the "base 1" part above. > Can you please apply the debug patch below and run with the same > parameters as before? > > Thanks, > > tglx > --- > Hint: I tried to figure out how to use that time travel muck, but did > not get to the point where I bothered to try myself. Might be > either my incompetence or lack of documentation. Clearly the bug > report lacks any hint how to reproduce that problem. Well, the original bug report did have all the information, I gave the link to it before: https://lore.kernel.org/r/20220330110156.ga9...@axis.com With that kernel config and command line, you can reproduce it easily. All you need to know is to use "make ARCH=um" with that .config file :) > + trace_printk("RUN: now=%lu clk=%lu next_expiry=%lu > recalc=%d\n", > + jiffies, base->clk, base->next_expiry, > + base->next_expiry_recalc); IMHO all of this extra debug is a waste of time since you're not differentiating the two bases anywhere. You'll just get confused (as above) since timers do happen on BASE_STD, just not on BASE_DEF. johannes _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um
