On Mon, 27 Nov 2023 11:36:59 -0800 Nhat Pham <nphamcs@xxxxxxxxx> wrote: > The new zswap writeback scheme requires an online-only memcg hierarchy > traversal. Add a new parameter to mem_cgroup_iter() to check for > onlineness before returning. I get a few build errors, perhaps because of patch timing issues... mm/shrinker_debug.c: In function 'shrinker_debugfs_count_show': mm/shrinker_debug.c:64:17: error: too few arguments to function 'mem_cgroup_iter' 64 | memcg = mem_cgroup_iter(NULL, NULL, NULL); | ^~~~~~~~~~~~~~~ In file included from mm/shrinker_debug.c:7: ./include/linux/memcontrol.h:833:20: note: declared here 833 | struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *, | ^~~~~~~~~~~~~~~ mm/shrinker_debug.c:89:27: error: too few arguments to function 'mem_cgroup_iter' 89 | } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL); | ^~~~~~~~~~~~~~~ ./include/linux/memcontrol.h:833:20: note: declared here 833 | struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *, | ^~~~~~~~~~~~~~~ mm/damon/sysfs-schemes.c: In function 'damon_sysfs_memcg_path_to_id': mm/damon/sysfs-schemes.c:1594:22: error: too few arguments to function 'mem_cgroup_iter' 1594 | for (memcg = mem_cgroup_iter(NULL, NULL, NULL); memcg; | ^~~~~~~~~~~~~~~ In file included from ./include/linux/damon.h:11, from mm/damon/sysfs-common.h:8, from mm/damon/sysfs-schemes.c:10: ./include/linux/memcontrol.h:833:20: note: declared here 833 | struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *, | ^~~~~~~~~~~~~~~ mm/damon/sysfs-schemes.c:1595:33: error: too few arguments to function 'mem_cgroup_iter' 1595 | memcg = mem_cgroup_iter(NULL, memcg, NULL)) { | ^~~~~~~~~~~~~~~ ./include/linux/memcontrol.h:833:20: note: declared here 833 | struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *, | ^~~~~~~~~~~~~~~ > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -832,7 +832,7 @@ static inline void mem_cgroup_put(struct mem_cgroup *memcg) > > struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *, > struct mem_cgroup *, > - struct mem_cgroup_reclaim_cookie *); > + struct mem_cgroup_reclaim_cookie *, bool online); How many callsites do we expect to utilize the new `online' argument? Few, I suspect. How about we fix the above and simplify the patch by adding a new mem_cgroup_iter_online() and make mem_cgroup_iter() a one-line wrapper which calls that and adds the online=false argument? I also saw this, didn't investigate. drivers/android/binder_alloc.c: In function 'binder_update_page_range': drivers/android/binder_alloc.c:237:34: error: too few arguments to function 'list_lru_del' 237 | on_lru = list_lru_del(&binder_alloc_lru, &page->lru);