On Fri, Jan 20, 2023 at 09:34:18AM -0500, Brian Foster wrote: > On Tue, Jan 17, 2023 at 11:59:57AM -0800, Nhat Pham wrote: > > + int memcgid; > > + struct pglist_data *pgdat; > > + unsigned long token; > > + > > + unpack_shadow(shadow, &memcgid, &pgdat, &token, workingset); > > + eviction_memcg = mem_cgroup_from_id(memcgid); > > + > > + lruvec = mem_cgroup_lruvec(eviction_memcg, pgdat); > > + lrugen = &lruvec->lrugen; > > + > > + min_seq = READ_ONCE(lrugen->min_seq[file]); > > + return !((token >> LRU_REFS_WIDTH) != (min_seq & (EVICTION_MASK >> LRU_REFS_WIDTH))); > > I think this might be more readable without the double negative. > > Also it looks like this logic is pulled from lru_gen_refault(). Any > reason the caller isn't refactored to use this helper, similar to how > workingset_refault() is modified? It seems like a potential landmine to > duplicate the logic here for cachestat purposes and somewhere else for > actual workingset management. The initial version was refactored. Yu explicitly requested it be duplicated [1] to cut down on some boiler plate. I have to agree with Brian on this one, though. The factored version is better for maintenance than duplicating the core logic here. Even if it ends up a bit more boiler plate - it's harder to screw that up, and easier to catch at compile time, than the duplicates diverging. [1] https://lore.kernel.org/lkml/CAOUHufZKTqoD2rFwrX9-eCknBmeWqP88rZ7X7A_5KHHbGBUP=A@xxxxxxxxxxxxxx/
