On Tue, Jul 21, 2020 at 12:52:52AM -0400, Paul Gortmaker wrote: > [Re: 5.8-rc*: kernel BUG at kernel/signal.c:1917] On 20/07/2020 (Mon 16:21) > Peter Zijlstra wrote: > > > On Mon, Jul 20, 2020 at 04:02:24PM +0200, Oleg Nesterov wrote: > > > I have to admit, I do not understand the usage of prev_state in > > > schedule(), > > > it looks really, really subtle... > > > > Right, so commit dbfb089d360 solved a problem where schedule() re-read > > prev->state vs prev->on_rq = 0. That is, schedule()'s dequeue and > > ttwu()'s enqueue disagreed over sched_contributes_to_load. and as a > > result load-accounting went wobbly. > > > > Now, looking at that commit again, I might've solved the problem twice > > :-P > > [...] > > > That said, in a crossed email, I just proposed we could simplify all > > this like so.. but now I need to go ask people to re-validate that > > loadavg muck again :-/ > > After a two hour "quick" sanity test I then gave it a full 7h run (which > always seemed to break before dbfb089d360) and I didn't see any stuck > load average with master from today + this change. > > Paul. > > root@t5610:/home/paul/git/linux-head# > [1]+ Done nohup > tools/testing/selftests/rcutorture/bin/kvm.sh --cpus 24 --duration 420 > --configs TREE03 --trust-make > /tmp/kvm.sh.out 2>&1 > root@t5610:/home/paul/git/linux-head# cat /proc/version > Linux version 5.8.0-rc6-00001-g5714ee50bb43-dirty (paul@t5610) (gcc (Ubuntu > 9.3.0-10ubuntu2) 9.3.0, GNU ld (GNU Binutils for Ubuntu) 2.34) #3 SMP Mon Jul > 20 12:30:33 EDT 2020 > root@t5610:/home/paul/git/linux-head# uptime > 00:49:18 up 7:41, 2 users, load average: 0.01, 0.00, 0.63 > root@t5610:/home/paul/git/linux-head# > > --
Thanks a lot for re-testing that Paul, much appreciated! Let me go write a Changelog for this then...