On Thu 15-12-16 01:36:07, Tetsuo Handa wrote: > Michal Hocko wrote: > > On Wed 14-12-16 20:37:07, Tetsuo Handa wrote: > > > Michal Hocko wrote: [...] > > > > So it would be really great if you could > > > > 1) test with the fixed throttling > > > > 2) loglevel=4 on the kernel command line > > > > 3) try the above with the same loglevel > > > > > > > > ideally 1) would be sufficient and that would make the most sense from > > > > the warn_alloc point of view. If this is 2 or 3 then we are hitting a > > > > more generic problem and I would be quite careful to hack it around. > > > > > > Thus, I don't think I can do these. > > > > i think this would be really valuable. > > OK. I tried 1) and 2). I didn't try 3) because printk() did not work as expected. > > Regarding 1), it did not help. I can still see "** XXX printk messages dropped **" > ( http://I-love.SAKURA.ne.jp/tmp/serial-20161215-1.txt.xz ). So we still manage to swamp the logbuffer. The question is whether you can still see the lockup. This is not obvious from the output to me. > Regarding 2), I can't tell whether it helped > ( http://I-love.SAKURA.ne.jp/tmp/serial-20161215-2.txt.xz ). > I can no longer see "** XXX printk messages dropped **", but sometimes they stalled. > In most cases, "Out of memory: " and "Killed process" lines are printed within 0.1 > second. But sometimes it took a few seconds. Less often it took longer than a minute. > There was one big stall which lasted for minutes. I changed loglevel to 7 and checked > memory information. Seems that watermark was low enough to call out_of_memory(). Isn't that what your test case essentially does though? Keep the system in OOM continually? Some stalls are to be expected I guess, the main question is whether there is a point with no progress at all. -- Michal Hocko SUSE Labs -- 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>