[PATCH] mm: memcg: expose mem_cgroup_put API

[PATCH] mm: memcg: expose mem_cgroup_put API

[Shakeel Butt]

This patch exports mem_cgroup_put API to put the refcnt of the memory
cgroup.

Signed-off-by: Shakeel Butt <shakeelb@google.com>
---
 include/linux/memcontrol.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index c46016bb25eb..0da79e116a07 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -344,6 +344,11 @@ struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css){
 	return css ? container_of(css, struct mem_cgroup, css) : NULL;
 }
 
+static inline void mem_cgroup_put(struct mem_cgroup *memcg)
+{
+	css_put(&memcg->css);
+}
+
 #define mem_cgroup_from_counter(counter, member)	\
 	container_of(counter, struct mem_cgroup, member)
 
@@ -789,6 +794,10 @@ static inline bool task_in_mem_cgroup(struct task_struct *task,
 	return true;
 }
 
+static inline void mem_cgroup_put(struct mem_cgroup *memcg)
+{
+}
+
 static inline struct mem_cgroup *
 mem_cgroup_iter(struct mem_cgroup *root,
 		struct mem_cgroup *prev,
-- 
2.16.2.395.g2e18187dfd-goog

Re: [PATCH] mm: memcg: expose mem_cgroup_put API

[Andrew Morton]

On Wed,  7 Mar 2018 18:48:50 -0800 Shakeel Butt <shakeelb@google.com> wrote:

> This patch exports mem_cgroup_put API to put the refcnt of the memory
> cgroup.

Not the best of changelogs :(

Why is this patch being added?

It's a prerequisite for <I-forget-which-patch> isn't it?

Re: [PATCH] mm: memcg: expose mem_cgroup_put API

[Andrew Morton]

On Wed,  7 Mar 2018 18:48:50 -0800 Shakeel Butt <shakeelb@google.com> wrote:

> This patch exports mem_cgroup_put API to put the refcnt of the memory
> cgroup.

OK, I remember now.  This is intended to make
fs-fsnotify-account-fsnotify-metadata-to-kmemcg.patch independent of
mm-oom-cgroup-aware-oom-killer.patch by extracting mem_cgroup_put()
from mm-oom-cgroup-aware-oom-killer.patch.

However it will not permit me to stage
fs-fsnotify-account-fsnotify-metadata-to-kmemcg.patch ahead of
mm-oom-cgroup-aware-oom-killer.patch because there are quite a lot of
syntactic clashes.

I can resolve those if needed, but am keenly hoping that the
mm-oom-cgroup-aware-oom-killer.patch issues are resolved soon so there
isn't a need to do this.

Re: [PATCH] mm: memcg: expose mem_cgroup_put API

[Shakeel Butt]

On Thu, Mar 8, 2018 at 3:45 PM, Andrew Morton <akpm@linux-foundation.org> wrote:
> On Wed,  7 Mar 2018 18:48:50 -0800 Shakeel Butt <shakeelb@google.com> wrote:
>
>> This patch exports mem_cgroup_put API to put the refcnt of the memory
>> cgroup.
>
> OK, I remember now.  This is intended to make
> fs-fsnotify-account-fsnotify-metadata-to-kmemcg.patch independent of
> mm-oom-cgroup-aware-oom-killer.patch by extracting mem_cgroup_put()
> from mm-oom-cgroup-aware-oom-killer.patch.

Yes, you are right, it is needed by the above fsnotify patch.

> However it will not permit me to stage
> fs-fsnotify-account-fsnotify-metadata-to-kmemcg.patch ahead of
> mm-oom-cgroup-aware-oom-killer.patch because there are quite a lot of
> syntactic clashes.
>
> I can resolve those if needed, but am keenly hoping that the
> mm-oom-cgroup-aware-oom-killer.patch issues are resolved soon so there
> isn't a need to do this.
>

Sounds good to me.