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authorJohannes Weiner <hannes@cmpxchg.org>2014-12-11 02:42:42 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-11 04:41:05 +0300
commite8ea14cc6eadfe2ea63e9989e16e62625a2619f8 (patch)
tree8109a731e199928c2fd87d3633a56a3251d85245 /include/linux/cgroup.h
parent5ac8fb31ad2ebd6492d1c5e8f31846b532f03945 (diff)
downloadlinux-e8ea14cc6eadfe2ea63e9989e16e62625a2619f8.tar.xz
mm: memcontrol: take a css reference for each charged page
Charges currently pin the css indirectly by playing tricks during css_offline(): user pages stall the offlining process until all of them have been reparented, whereas kmemcg acquires a keep-alive reference if outstanding kernel pages are detected at that point. In preparation for removing all this complexity, make the pinning explicit and acquire a css references for every charged page. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: David Rientjes <rientjes@google.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/cgroup.h')
-rw-r--r--include/linux/cgroup.h26
1 files changed, 26 insertions, 0 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 1d5196889048..9f96b25965c2 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -113,6 +113,19 @@ static inline void css_get(struct cgroup_subsys_state *css)
}
/**
+ * css_get_many - obtain references on the specified css
+ * @css: target css
+ * @n: number of references to get
+ *
+ * The caller must already have a reference.
+ */
+static inline void css_get_many(struct cgroup_subsys_state *css, unsigned int n)
+{
+ if (!(css->flags & CSS_NO_REF))
+ percpu_ref_get_many(&css->refcnt, n);
+}
+
+/**
* css_tryget - try to obtain a reference on the specified css
* @css: target css
*
@@ -159,6 +172,19 @@ static inline void css_put(struct cgroup_subsys_state *css)
percpu_ref_put(&css->refcnt);
}
+/**
+ * css_put_many - put css references
+ * @css: target css
+ * @n: number of references to put
+ *
+ * Put references obtained via css_get() and css_tryget_online().
+ */
+static inline void css_put_many(struct cgroup_subsys_state *css, unsigned int n)
+{
+ if (!(css->flags & CSS_NO_REF))
+ percpu_ref_put_many(&css->refcnt, n);
+}
+
/* bits in struct cgroup flags field */
enum {
/* Control Group requires release notifications to userspace */