Re: OOM Killer and add_to_page_cache_locked

From: Piotr Nowojski
Date: Tue Jun 11 2013 - 04:35:34 EST

W dniu 07.06.2013 17:36, Michal Hocko pisze:
On Fri 07-06-13 17:13:55, Piotr Nowojski wrote:
W dniu 06.06.2013 17:57, Michal Hocko pisze:
In our system we have hit some very annoying situation (bug?) with
cgroups. I'm writing to you, because I have found your posts on
mailing lists with similar topic. Maybe you could help us or point
some direction where to look for/ask.

We have system with ~15GB RAM (+2GB SWAP), and we are running ~10
heavy IO processes. Each process is using constantly 200-210MB RAM
(RSS) and a lot of page cache. All processes are in cgroup with
following limits:

/sys/fs/cgroup/taskell2 $ cat memory.limit_in_bytes
I assume that memory.use_hierarchy is 1, right?
System has been rebooted since last test, so I can not guarantee
that it was set for 100%, but it should have been. Currently I'm
rerunning this scenario that lead to the described problem with:

/sys/fs/cgroup/taskell2# cat memory.use_hierarchy ../memory.use_hierarchy
OK, good. Your numbers suggeste that the hierachy _is_ in use. I just
wanted to be 100% sure.

I don't know what has solved this problem, but we weren't able to reproduce this problem during whole weekend. Most likely there was some problem with our code initializing cgroups configuration regarding use_hierarchy (can writing 1 to memory.use_hierarchy silently fail?). I have added assertions for checking this parameter before starting and after initialization of our application. If problem reoccur, I will proceed as you suggested before - trying latest kernels.

Thanks, Piotr Nowojski
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