On Thu, Nov 30, 2023 at 11:40 AM Nhat Pham <[email protected]> wrote: > > This patch implements a helper function that try to get a reference to > an memcg's css, as well as checking if it is online. This new function > is almost exactly the same as the existing mem_cgroup_tryget(), except > for the onlineness check. In the !CONFIG_MEMCG case, it always returns > true, analogous to mem_cgroup_tryget(). This is useful for e.g to the > new zswap writeback scheme, where we need to select the next online > memcg as a candidate for the global limit reclaim. > > Signed-off-by: Nhat Pham <[email protected]>
Reviewed-by: Yosry Ahmed <[email protected]> > --- > include/linux/memcontrol.h | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index 7bdcf3020d7a..2bd7d14ace78 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -821,6 +821,11 @@ static inline bool mem_cgroup_tryget(struct mem_cgroup > *memcg) > return !memcg || css_tryget(&memcg->css); > } > > +static inline bool mem_cgroup_tryget_online(struct mem_cgroup *memcg) > +{ > + return !memcg || css_tryget_online(&memcg->css); > +} > + > static inline void mem_cgroup_put(struct mem_cgroup *memcg) > { > if (memcg) > @@ -1349,6 +1354,11 @@ static inline bool mem_cgroup_tryget(struct mem_cgroup > *memcg) > return true; > } > > +static inline bool mem_cgroup_tryget_online(struct mem_cgroup *memcg) > +{ > + return true; > +} > + > static inline void mem_cgroup_put(struct mem_cgroup *memcg) > { > } > -- > 2.34.1
