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> } > #else > static inline int folio_last_cpupid(struct folio *folio) > { > return (folio->flags >> LAST_CPUPID_PGSHIFT) & LAST_CPUPID_MASK; > } > #endif > #else /* !CONFIG_NUMA_BALANCING */ > static inline int folio_last_cpupid(struct folio *folio) > { > return folio_nid(folio); /* XXX */ > } > ... > #endif > > Obviously we don't have to care about the !NUMAB case, but what a silly > muxing we have going on here (I get it, space is tight - the interfaces > are just confusing is all). I really didn't realize the usage in !NUMAB case, thanks. > > My question is whether there's some kind of race condition here if the > mode changes between isolate and fetch. Can we "fetch a node id" and > end up with a cpupid because someone toggled the between tiering and > balancing? Good question. I need to check all such cases where inadvertent reset or reuse/repurposing of last_cpupid field of an isolated folio becomes possible. > > If we can answer that, then implementing folio_last_cpupid and > folio_last_access_nid can return -1 if called in the wrong mode > (assuming this check isn't too expensive). That would be a nice cleanup > for readability sake. Right. Regards, Bharata.