lkml.org 
[lkml]   [2022]   [May]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v3 1/6] mm: memcontrol: introduce mem_cgroup_ino() and mem_cgroup_get_from_ino()
On Mon, May 23, 2022 at 11:12:12AM -0700, Roman Gushchin wrote:
> On Sun, May 22, 2022 at 03:05:33PM +0800, Muchun Song wrote:
> > On Mon, May 09, 2022 at 11:38:15AM -0700, Roman Gushchin wrote:
> > > Shrinker debugfs requires a way to represent memory cgroups without
> > > using full paths, both for displaying information and getting input
> > > from a user.
> > >
> > > Cgroup inode number is a perfect way, already used by bpf.
> > >
> > > This commit adds a couple of helper functions which will be used
> > > to handle memcg-aware shrinkers.
> > >
> > > Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
> > > ---
> > > include/linux/memcontrol.h | 21 +++++++++++++++++++++
> > > mm/memcontrol.c | 23 +++++++++++++++++++++++
> > > 2 files changed, 44 insertions(+)
> > >
> > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> > > index fe580cb96683..a6de9e5c1549 100644
> > > --- a/include/linux/memcontrol.h
> > > +++ b/include/linux/memcontrol.h
> > > @@ -831,6 +831,15 @@ static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg)
> > > }
> > > struct mem_cgroup *mem_cgroup_from_id(unsigned short id);
> > >
> > > +#ifdef CONFIG_SHRINKER_DEBUG
> > > +static inline unsigned long mem_cgroup_ino(struct mem_cgroup *memcg)
> > > +{
> > > + return memcg ? cgroup_ino(memcg->css.cgroup) : 0;
> > > +}
> > > +
> > > +struct mem_cgroup *mem_cgroup_get_from_ino(unsigned long ino);
> > > +#endif
> > > +
> > > static inline struct mem_cgroup *mem_cgroup_from_seq(struct seq_file *m)
> > > {
> > > return mem_cgroup_from_css(seq_css(m));
> > > @@ -1324,6 +1333,18 @@ static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
> > > return NULL;
> > > }
> > >
> > > +#ifdef CONFIG_SHRINKER_DEBUG
> > > +static inline unsigned long mem_cgroup_ino(struct mem_cgroup *memcg)
> > > +{
> > > + return 0;
> > > +}
> > > +
> > > +static inline struct mem_cgroup *mem_cgroup_get_from_ino(unsigned long ino)
> > > +{
> > > + return NULL;
> > > +}
> > > +#endif
> > > +
> > > static inline struct mem_cgroup *mem_cgroup_from_seq(struct seq_file *m)
> > > {
> > > return NULL;
> > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > > index 04cea4fa362a..e6472728fa66 100644
> > > --- a/mm/memcontrol.c
> > > +++ b/mm/memcontrol.c
> > > @@ -5018,6 +5018,29 @@ struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
> > > return idr_find(&mem_cgroup_idr, id);
> > > }
> > >
> > > +#ifdef CONFIG_SHRINKER_DEBUG
> > > +struct mem_cgroup *mem_cgroup_get_from_ino(unsigned long ino)
> > > +{
> > > + struct cgroup *cgrp;
> > > + struct cgroup_subsys_state *css;
> > > + struct mem_cgroup *memcg;
> > > +
> > > + cgrp = cgroup_get_from_id(ino);
> > > + if (!cgrp)
> > > + return ERR_PTR(-ENOENT);
> > > +
> > > + css = cgroup_get_e_css(cgrp, &memory_cgrp_subsys);
> > > + if (css)
> > > + memcg = container_of(css, struct mem_cgroup, css);
> > > + else
> > > + memcg = ERR_PTR(-ENOENT);
> > > +
> > > + cgroup_put(cgrp);
> >
> > I think it's better to use css_put() here since the refcount is get
> > via cgroup_get_e_css() which returns a css struct.
>
> cgroup_put() is matching cgroup_get_from_id().
>
> The reference grabbed by cgroup_get_e_css() shouldn't be dropped
> because mem_cgroup_get_from_ino() has a "get" semantics.
>

My bad. I have misread it here. Thanks.

\
 
 \ /
  Last update: 2022-05-24 04:01    [W:0.055 / U:0.724 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site