Events should be removed after rmdir of cgroup directory, but before
destroying subsystem state objects. Let's take reference to cgroup
directory dentry to do that.
Signed-off-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
---
include/linux/cgroup.h | 3 ---
kernel/cgroup.c | 8 ++++++++
mm/memcontrol.c | 9 ---------
3 files changed, 8 insertions(+), 12 deletions(-)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 64cebfe..1719c75 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -395,9 +395,6 @@ struct cftype {
* closes the eventfd or on cgroup removing.
* This callback must be implemented, if you want provide
* notification functionality.
- *
- * Be careful. It can be called after destroy(), so you have
- * to keep all nesessary data, until all events are removed.
*/
int (*unregister_event)(struct cgroup *cgrp, struct cftype *cft,
struct eventfd_ctx *eventfd);
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 46903cb..d142524 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2979,6 +2979,7 @@ static void cgroup_event_remove(struct work_struct *work)
eventfd_ctx_put(event->eventfd);
kfree(event);
+ dput(cgrp->dentry);
}
/*
@@ -3099,6 +3100,13 @@ static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft,
goto fail;
}
+ /*
+ * Events should be removed after rmdir of cgroup directory, but before
+ * destroying subsystem state objects. Let's take reference to cgroup
+ * directory dentry to do that.
+ */
+ dget(cgrp->dentry);
+
spin_lock(&cgrp->event_list_lock);
list_add(&event->list, &cgrp->event_list);
spin_unlock(&cgrp->event_list_lock);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a443c30..8fe6e7f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3358,12 +3358,6 @@ static int mem_cgroup_register_event(struct cgroup *cgrp, struct cftype *cft,
}
}
- /*
- * We need to increment refcnt to be sure that all thresholds
- * will be unregistered before calling __mem_cgroup_free()
- */
- mem_cgroup_get(memcg);
-
if (type == _MEM)
rcu_assign_pointer(memcg->thresholds, thresholds_new);
else
@@ -3457,9 +3451,6 @@ assign:
/* To be sure that nobody uses thresholds before freeing it */
synchronize_rcu();
- for (i = 0; i < thresholds->size - size; i++)
- mem_cgroup_put(memcg);
-
kfree(thresholds);
unlock:
mutex_unlock(&memcg->thresholds_lock);
--
1.6.6.2
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