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authorLai Jiangshan <laijs@cn.fujitsu.com>2009-01-07 18:07:36 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-08 08:31:02 -0800
commitb12b533fa523e94e0cc9dc23274ae4f9439f1313 (patch)
tree00a08a34388e835ae3103a6f00c96129d3fa59a4
parentc9d5409f8d46fd0d18b4a4481d9caa04076d87fc (diff)
cgroups: add lock for child->cgroups in cgroup_post_fork()
When cgroup_post_fork() is called, child is seen by find_task_by_vpid(), so child->cgroups maybe be changed, It'll incorrect. child->cgroups<old>'s refcnt is decreased child->cgroups<new>'s refcnt is increased but child->cg_list is added to child->cgroups<old>'s list. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Reviewed-by: Paul Menage <menage@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Balbir Singh <balbir@in.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/cgroup.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 220e0fd659f..d7ab4ffd8fd 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2792,8 +2792,10 @@ void cgroup_post_fork(struct task_struct *child)
{
if (use_task_css_set_links) {
write_lock(&css_set_lock);
+ task_lock(child);
if (list_empty(&child->cg_list))
list_add(&child->cg_list, &child->cgroups->tasks);
+ task_unlock(child);
write_unlock(&css_set_lock);
}
}