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    SubjectRe: [patch -mm 4/9 v2] oom: remove compulsory panic_on_oom mode
    On Tue, 16 Feb 2010 15:54:50 -0800 (PST)
    David Rientjes <> wrote:

    > On Wed, 17 Feb 2010, KAMEZAWA Hiroyuki wrote:
    > > Then, please leave panic_on_oom=always.
    > > Even with mempolicy or cpuset 's OOM, we need panic_on_oom=always option.
    > > And yes, I'll add something similar to memcg. freeze_at_oom or something.
    > >
    > Memcg isn't a special case here, it should also panic the machine if
    > panic_on_oom == 2, so if we aren't going to remove this option then I
    > agree with Nick that we need to panic from mem_cgroup_out_of_memory() as
    > well. Some users use cpusets, for example, for the same effect of memory
    > isolation as you use memcg, so panicking in one scenario and not the other
    > is inconsistent.
    Hmm, I have a few reason to add special behavior to memcg rather than panic.

    - freeze_at_oom is enough.
    If OOM can be notified, the management daemon can do useful jobs. Shutdown
    all other cgroups or migrate them to other host and do kdump.

    - memcg's oom is not very complicated.
    Because we just counts RSS+FileCache

    But, Hmm...I'd like to go this way.

    1. At first, support panic_on_oom=2 in memcg.

    2. Second, I'll add OOM-notifier and freeze_at_oom to memcg.
    and don't call memcg_out_of_memory in oom_kill.c in this case. Because
    we don't kill anything. Taking coredumps of all procs in memcg is not
    very difficult.

    I need to discuss with memcg guys. But this will be a way to go, I think


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