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    SubjectRe: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel panic
    On Thu 28-09-17 01:25:50, Yang Shi wrote:
    >
    >
    > On 9/27/17 3:45 AM, Michal Hocko wrote:
    > > On Wed 27-09-17 08:53:35, Yang Shi wrote:
    > > > Kernel may panic when oom happens without killable process sometimes it
    > > > is caused by huge unreclaimable slabs used by kernel.
    > > >
    > > > Although kdump could help debug such problem, however, kdump is not
    > > > available on all architectures and it might be malfunction sometime.
    > > > And, since kernel already panic it is worthy capturing such information
    > > > in dmesg to aid touble shooting.
    > > >
    > > > Print out unreclaimable slab info (used size and total size) which
    > > > actual memory usage is not zero (num_objs * size != 0) when:
    > > > - unreclaimable slabs : all user memory > unreclaim_slabs_oom_ratio
    > > > - panic_on_oom is set or no killable process
    > >
    > > OK, this is better but I do not see why this should be tunable via proc.
    >
    > Just thought someone might want to dump unreclaimable slab info
    > unconditionally.

    If that ever happens then we will eventually add it. But do not add proc
    knobs for theoretical usecases. We will have to maintain them and it
    can turn into a maint. pain. Like some others in the past.
    --
    Michal Hocko
    SUSE Labs

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