Messages in this thread | | | Date | Tue, 18 May 2021 15:05:54 +0100 | From | Aaron Tomlin <> | Subject | Re: [PATCH] mm/page_alloc: try oom if reclaim is unable to make forward progress |
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Michal,
On Fri 2021-03-26 16:36 +0100, Michal Hocko wrote: > OK, I kinda expected this would be not easily reproducible.
Unfortunately, I'm still waiting for feedback on this.
> We should be focusing on the compaction retry logic and see whether we > can have some "run away" scenarios there. Seeing so many retries without > compaction bailing out sounds like a bug in that retry logic.
I suspect so.
This is indeed a case of excessive reclaim/compaction retries (i.e. the last known value stored in the no_progress_loops variable was 31,611,688).
What might be particularly unique about this situation is that a fatal signal was found pending. In this context, if I understand correctly, it does not make sense to retry compaction when the last known compact result was skipped and a fatal signal is pending.
Looking at try_to_compact_pages(), indeed COMPACT_SKIPPED can be returned; albeit, not every zone, on the zone list, would be considered in the case a fatal signal is found to be pending. Yet, in should_compact_retry(), given the last known compaction result, each zone, on the zone list, can be considered/or checked (see compaction_zonelist_suitable()). If a zone e.g. was found to succeed then reclaim/compaction would be tried again (notwithstanding the above).
-- Aaron Tomlin [unhandled content-type:application/pgp-signature] | |