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
Attachment:
signature.asc
Description: PGP signature
