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Its semantics are unclear and >> inconsistent with other sites, which directly call page_counter_read for >> the same purpose. >> >> Remove this helper and replace its usage with page_counter_read for >> clarity. Additionally, rename the local variable 'cgroup_size' to 'usage' >> to better reflect its meaning. > > +1 > > I don't think the helper adds much. > >> --- a/mm/vmscan.c >> +++ b/mm/vmscan.c >> @@ -2451,6 +2451,7 @@ static inline void calculate_pressure_balance(struct scan_control *sc, >> static unsigned long apply_proportional_protection(struct mem_cgroup *memcg, >> struct scan_control *sc, unsigned long scan) >> { >> +#ifdef CONFIG_MEMCG >> unsigned long min, low; >> >> mem_cgroup_protection(sc->target_mem_cgroup, memcg, &min, &low); >> @@ -2485,7 +2486,7 @@ static unsigned long apply_proportional_protection(struct mem_cgroup *memcg, >> * again by how much of the total memory used is under >> * hard protection. >> */ >> - unsigned long cgroup_size = mem_cgroup_size(memcg); >> + unsigned long usage = page_counter_read(&memcg->memory); >> unsigned long protection; >> >> /* memory.low scaling, make sure we retry before OOM */ >> @@ -2497,9 +2498,9 @@ static unsigned long apply_proportional_protection(struct mem_cgroup *memcg, >> } >> >> /* Avoid TOCTOU with earlier protection check */ >> - cgroup_size = max(cgroup_size, protection); >> + usage = max(usage, protection); >> >> - scan -= scan * protection / (cgroup_size + 1); >> + scan -= scan * protection / (usage + 1); >> >> /* >> * Minimally target SWAP_CLUSTER_MAX pages to keep >> @@ -2508,6 +2509,7 @@ static unsigned long apply_proportional_protection(struct mem_cgroup *memcg, >> */ >> scan = max(scan, SWAP_CLUSTER_MAX); >> } >> +#endif > > To avoid the ifdef, how about making it > > bool mem_cgroup_protection(root, memcg, &min, &low, &usage) > > and branch the scaling on that return value. The compiler should be > able to eliminate the entire branch in the !CONFIG_MEMCG case. And it > keeps a cleaner split between memcg logic and reclaim logic. Much better, will update. -- Best regards, Ridong