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Re: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel panic

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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.

> Can we start with simple NR_SLAB_UNRECLAIMABLE > LRU_PAGES and place it
> into dump_header so that we get the report also during regular OOM
Yes.

Thanks,
Yang

> 

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[PATCH 0/3 v7] oom: capture unreclaimable slab info in oom message when kernel panic "Yang Shi" <yang.s@alibaba-inc.com> - 2017-09-27 03:00 +0200
  [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel panic "Yang Shi" <yang.s@alibaba-inc.com> - 2017-09-27 03:00 +0200
    Re: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel  panic Christopher Lameter <cl@linux.com> - 2017-09-27 09:20 +0200
      Re: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel  panic "Yang Shi" <yang.s@alibaba-inc.com> - 2017-09-27 19:30 +0200
        Re: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel  panic Christopher Lameter <cl@linux.com> - 2017-09-28 00:00 +0200
          Re: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel  panic "Yang Shi" <yang.s@alibaba-inc.com> - 2017-09-28 00:20 +0200
            Re: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel  panic Christopher Lameter <cl@linux.com> - 2017-10-01 08:50 +0200
              Re: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel  panic "Yang Shi" <yang.s@alibaba-inc.com> - 2017-10-02 22:50 +0200
    Re: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel  panic Michal Hocko <mhocko@kernel.org> - 2017-09-27 12:50 +0200
      Re: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel  panic "Yang Shi" <yang.s@alibaba-inc.com> - 2017-09-27 19:30 +0200
        Re: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel  panic Michal Hocko <mhocko@kernel.org> - 2017-10-02 09:30 +0200
          Re: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel  panic "Yang Shi" <yang.s@alibaba-inc.com> - 2017-10-02 22:50 +0200

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