> On Sun, Mar 05, 2017 at 10:48:50PM +0200, Meelis Roos wrote: > > Added some CC-s because of bisect find. Whole context should be still > > here. > > > > > > > > > > This is on my trusty IBM PC365, dual Pentium Pro. 4.10 worked > > > > > > > > fine, > > > > > > > > 4.10.0-09686-g9e314890292c and 4.10.0-10770-g2d6be4abf514 > > > > > > > > exhibit a > > > > > > > > problem. Ocassionally NMI watchdog kicks in and discovers one > > > > > > > > of the > > > > > > > > CPUs in LOCKUP. The system keeps running fine. The first lockup > > > > > > > > was > > > > > > > > different, all the others were from arch_cpu_idle. Sometime > > > > > > > > ecey couple > > > > > > > > of seconds (after some activity), sometimes nothing for a long > > > > > > > > time > > > > > > > > (idle, no SSH logins). > > > > > > > > > > > > > > The only watchdog related patch which hit after 4.10 is: > > > > > > > > > > > > > > 8dcde9def5a1 kernel/watchdog.c: do not hardcode CPU 0 as the > > > > > > > initial thread > > > > > > > > > > > > > > Can you try to revert that for a start? I'm not seeing why it > > > > > > > should be the > > > > > > > culprit from a quick glance, but ... > > > > > > > > > > > > Reverting this patch does not help. > > > > > > > > > > I did not expect that, but excluding it was a valid shot in the > > > > > dark. Thanmks for trying. > > > > > > > > > > To be honest, I have no idea what causes that at the moment, but I > > > > > will > > > > > come back to you tomorrow after thinking it through (with brain > > > > > awake) how > > > > > to debug this. > > > > > > > > Went through the related changes which came in during the merge window. > > > > One > > > > which affects the per cpu timers is: 914122c389d0 > > > > > > > > Can you try to revert that one please? > > > > > > Running out of obvious culprits. Any chance that you can do a bisect or > > > this too painful on that box? > > > > Done on a P4 where the problem also appeared. The bisecting resulted in > > this commit. Does it seem realistic? I will also try if this help son > > the old PPro. > > > > 93825f2ec736f30e034ab7c9d56b42849c5b00da is the first bad commit > > commit 93825f2ec736f30e034ab7c9d56b42849c5b00da > > Author: Frederic Weisbecker <fweis...@gmail.com> > > Date: Tue Jan 31 04:09:16 2017 +0100 > > > > jiffies: Reuse TICK_NSEC instead of NSEC_PER_JIFFY
[...] > Ouch, looking at that patch again, I probably had a delusional moment when I > wrote this: > > diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c > index a4a0e47..7906b3f 100644 > --- a/kernel/time/jiffies.c > +++ b/kernel/time/jiffies.c > @@ -125,7 +125,7 @@ int register_refined_jiffies(long cycles_per_second) > shift_hz += cycles_per_tick/2; > do_div(shift_hz, cycles_per_tick); > /* Calculate nsec_per_tick using shift_hz */ > - nsec_per_tick = (u64)NSEC_PER_SEC << 8; > + nsec_per_tick = (u64)TICK_NSEC << 8; > nsec_per_tick += (u32)shift_hz/2; > do_div(nsec_per_tick, (u32)shift_hz); > > > > Could you please retry after reverting this specific chunk? (that would be > the very fix > to apply). Reverting this chunk fixed both the PPro and the P4. -- Meelis Roos (mr...@linux.ee)
