Messages in this thread | | | Subject | Re: [PATCH 0/2 v4] oom: capture unreclaimable slab info in oom message when kernel panic | From | "Yang Shi" <> | Date | Mon, 25 Sep 2017 23:55:19 +0800 |
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On 9/25/17 7:23 AM, Michal Hocko wrote: > On Thu 21-09-17 06:38:50, Yang Shi wrote: >> Recently we ran into a oom issue, kernel panic due to no killable process. >> The dmesg shows huge unreclaimable slabs used almost 100% memory, but kdump doesn't capture vmcore due to some reason. >> >> So, it may sound better to capture unreclaimable slab info in oom message when kernel panic to aid trouble shooting and cover the corner case. >> Since kernel already panic, so capturing more information sounds worthy and doesn't bother normal oom killer. >> >> With the patchset, tools/vm/slabinfo has a new option, "-U", to show unreclaimable slab only. >> >> And, oom will print all non zero (num_objs * size != 0) unreclaimable slabs in oom killer message. > > Well, I do undestand that this _might_ be useful but it also might > generates a _lot_ of output. The oom report can be quite verbose already > so is this something we want to have enabled by default?
The uneclaimable slub message will be just printed out when kernel panic (no killable process or panic_on_oom is set). So, it will not bother normal oom. Since kernel is already panic, so it might be preferred to have more information reported.
We definitely can add a proc knob to control it if we want to disable the message even if when kernel panic.
Thanks, Yang
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