Re: [PATCH] memcg: writeback: use memcg->cgwb_list directly

[Wang Long]

On 22/4/2018 8:43 PM, Michal Hocko wrote:
> On Sun 22-04-18 01:50:57, Jan Kara wrote:
> > On Sat 21-04-18 21:29:41, Wang Long wrote:
> > > Signed-off-by: Wang Long <wanglong19@xxxxxxxxxxx>
> > Yeah, looks good. I guess it was originally intended to avoid compilation
> > errors if CONFIG_CGROUP_WRITEBACK was disabled. But it doesn't seem likely
> > we'll ever need that list outside of code under CONFIG_CGROUP_WRITEBACK. So
> > you can add:
> Yeah. Trivial wrappers like these are usualy more harm than goot.  But
> please add _some_ words in the changelog.
ok, I will send the v2 patch.
> > Reviewed-by: Jan Kara <jack@xxxxxxx>
> >
> > 								Honza
> >
> > > ---
> > >   include/linux/memcontrol.h | 1 -
> > >   mm/backing-dev.c           | 4 ++--
> > >   mm/memcontrol.c            | 5 -----
> > >   3 files changed, 2 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> > > index d99b71b..c0056e0 100644
> > > --- a/include/linux/memcontrol.h
> > > +++ b/include/linux/memcontrol.h
> > > @@ -1093,7 +1093,6 @@ static inline void dec_lruvec_page_state(struct page *page,
> > >   
> > >   #ifdef CONFIG_CGROUP_WRITEBACK
> > >   
> > > -struct list_head *mem_cgroup_cgwb_list(struct mem_cgroup *memcg);
> > >   struct wb_domain *mem_cgroup_wb_domain(struct bdi_writeback *wb);
> > >   void mem_cgroup_wb_stats(struct bdi_writeback *wb, unsigned long *pfilepages,
> > >   			 unsigned long *pheadroom, unsigned long *pdirty,
> > > diff --git a/mm/backing-dev.c b/mm/backing-dev.c
> > > index 023190c..0a48e05 100644
> > > --- a/mm/backing-dev.c
> > > +++ b/mm/backing-dev.c
> > > @@ -555,7 +555,7 @@ static int cgwb_create(struct backing_dev_info *bdi,
> > >   	memcg = mem_cgroup_from_css(memcg_css);
> > >   	blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
> > >   	blkcg = css_to_blkcg(blkcg_css);
> > > -	memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
> > > +	memcg_cgwb_list = &memcg->cgwb_list;
> > >   	blkcg_cgwb_list = &blkcg->cgwb_list;
> > >   
> > >   	/* look up again under lock and discard on blkcg mismatch */
> > > @@ -734,7 +734,7 @@ static void cgwb_bdi_unregister(struct backing_dev_info *bdi)
> > >    */
> > >   void wb_memcg_offline(struct mem_cgroup *memcg)
> > >   {
> > > -	struct list_head *memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
> > > +	struct list_head *memcg_cgwb_list = &memcg->cgwb_list;
> > >   	struct bdi_writeback *wb, *next;
> > >   
> > >   	spin_lock_irq(&cgwb_lock);
> > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > > index e074f7c..d1adb9c 100644
> > > --- a/mm/memcontrol.c
> > > +++ b/mm/memcontrol.c
> > > @@ -3562,11 +3562,6 @@ static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
> > >   
> > >   #ifdef CONFIG_CGROUP_WRITEBACK
> > >   
> > > -struct list_head *mem_cgroup_cgwb_list(struct mem_cgroup *memcg)
> > > -{
> > > -	return &memcg->cgwb_list;
> > > -}
> > > -
> > >   static int memcg_wb_domain_init(struct mem_cgroup *memcg, gfp_t gfp)
> > >   {
> > >   	return wb_domain_init(&memcg->cgwb_domain, gfp);
> > > --
> > > 1.8.3.1
> > --
> > Jan Kara <jack@xxxxxxxx>
> > SUSE Labs, CR