On Sun 2018-04-22 18:27:38, Michal Hocko wrote: > On Sun 22-04-18 10:43:00, vcap...@pengaru.com wrote: > > On Sun, Apr 22, 2018 at 12:16:54PM +0200, Pavel Machek wrote: > > > On Thu 2018-04-19 21:13:35, Ferry Toth wrote: > > > > It appears any ordinary user can easily create a DOS on linux. > > > > > > > > One sure way to reproduce this is to open gitk on the linux kernel repo > > > > (SIC) on a machine with 8GB RAM 16 GB swap on a HDD with btrfs and quad > > > > core > > > > + hyperthreading. But I will be easy enough to get the same effect with > > > > more > > > > RAM, other fs etc. > > > > > > You may want to disable swap. > > > > > > > I run without swap on my laptops, and still observe long periods of > > thrashing on the road towards OOM. What seems to occur is the active > > file-backed mappings of executables/libraries become a sort of swap > > area, repeatedly being discarded and faulted back in as the context > > switches occur. > > > > If there's any good way to prevent this, I'd like to know. > > I am afraid there is none yet. Johannes had some ground work for > page cache trashing detection > https://marc.info/?i=20170727153010.23347-1-hannes%40cmpxchg.org > but there was no version of the patchseries for quite some time and > there was no integration into the oom detection which would be > non-trivial as well. > > I realize this sucks. But the reality is that this is far from trivial > to resolve without introducing pre-mature OOM killer invocations.
Another problem is that what "unusable machine" in X/web browser
situation may be normal load for build server...
I guess one way would be "hey, this is my X server; if it is waiting
for disk for more than 10 seconds, you probably want to OOM kill
someone. Ouch and same goes for my window manager".
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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