From: Zefan Li lizefan@huawei.com
[ Upstream commit 090e28b229af92dc5b40786ca673999d59e73056 ]
If systemd is configured to use hybrid mode which enables the use of both cgroup v1 and v2, systemd will create new cgroup on both the default root (v2) and netprio_cgroup hierarchy (v1) for a new session and attach task to the two cgroups. If the task does some network thing then the v2 cgroup can never be freed after the session exited.
One of our machines ran into OOM due to this memory leak.
In the scenario described above when sk_alloc() is called cgroup_sk_alloc() thought it's in v2 mode, so it stores the cgroup pointer in sk->sk_cgrp_data and increments the cgroup refcnt, but then sock_update_netprioidx() thought it's in v1 mode, so it stores netprioidx value in sk->sk_cgrp_data, so the cgroup refcnt will never be freed.
Currently we do the mode switch when someone writes to the ifpriomap cgroup control file. The easiest fix is to also do the switch when a task is attached to a new cgroup.
Fixes: bd1060a1d671 ("sock, cgroup: add sock->sk_cgroup") Reported-by: Yang Yingliang yangyingliang@huawei.com Tested-by: Yang Yingliang yangyingliang@huawei.com Signed-off-by: Zefan Li lizefan@huawei.com Acked-by: Tejun Heo tj@kernel.org Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/core/netprio_cgroup.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/net/core/netprio_cgroup.c +++ b/net/core/netprio_cgroup.c @@ -237,6 +237,8 @@ static void net_prio_attach(struct cgrou struct task_struct *p; struct cgroup_subsys_state *css;
+ cgroup_sk_alloc_disable(); + cgroup_taskset_for_each(p, css, tset) { void *v = (void *)(unsigned long)css->cgroup->id;