From: Lai Jiangshan Date: Thu, 8 Jan 2009 02:07:36 +0000 (-0800) Subject: cgroups: add lock for child->cgroups in cgroup_post_fork() X-Git-Tag: v2.6.29-rc1~153 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=b12b533fa523e94e0cc9dc23274ae4f9439f1313;p=karo-tx-linux.git 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's refcnt is decreased child->cgroups's refcnt is increased but child->cg_list is added to child->cgroups's list. Signed-off-by: Lai Jiangshan Reviewed-by: Paul Menage Cc: KAMEZAWA Hiroyuki Cc: Pavel Emelyanov Cc: Balbir Singh Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 220e0fd659fa..d7ab4ffd8fd9 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); } }