2016-10-21 02:46:04

by Andrei Vagin

Subject: [PATCH net-next] net: allow to kill a task which waits net_mutex in copy_new_ns

From: Andrey Vagin <[email protected]>

net_mutex can be locked for a long time. It may be because many
namespaces are being destroyed or many processes decide to create
a network namespace.

Both these operations are heavy, so it is better to have an ability to
kill a process which is waiting net_mutex.

Cc: "David S. Miller" <[email protected]>
Cc: Eric W. Biederman <[email protected]>
Signed-off-by: Andrei Vagin <[email protected]>
---
net/core/net_namespace.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 989434f..b9243b1 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -379,7 +379,14 @@ struct net *copy_net_ns(unsigned long flags,

get_user_ns(user_ns);

- mutex_lock(&net_mutex);
+ rv = mutex_lock_killable(&net_mutex);
+ if (rv < 0) {
+ net_free(net);
+ dec_net_namespaces(ucounts);
+ put_user_ns(user_ns);
+ return ERR_PTR(rv);
+ }
+
net->ucounts = ucounts;
rv = setup_net(net, user_ns);
if (rv == 0) {
--
2.7.4

2016-10-23 21:34:16

by David Miller

Subject: Re: [PATCH net-next] net: allow to kill a task which waits net_mutex in copy_new_ns

From: Andrei Vagin <[email protected]>
Date: Thu, 20 Oct 2016 19:45:43 -0700

> From: Andrey Vagin <[email protected]>
>
> net_mutex can be locked for a long time. It may be because many
> namespaces are being destroyed or many processes decide to create
> a network namespace.
>
> Both these operations are heavy, so it is better to have an ability to
> kill a process which is waiting net_mutex.
>
> Cc: "David S. Miller" <[email protected]>
> Cc: Eric W. Biederman <[email protected]>
> Signed-off-by: Andrei Vagin <[email protected]>

Applied, thanks.