On (03/14/17 09:14), Dmitry Vyukov wrote:
> Another one now involving rds_tcp_listen_stop
:
> kworker/u4:1/19 is trying to acquire lock:
> (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff8409a6ec>] lock_sock
> include/net/sock.h:1460 [inline]
> (sk_lock-AF_INET){+.+.+.}, at: [<ffffffff8409a6ec>]
> rds_tcp_listen_stop+0x5c/0x150 net/rds/tcp_listen.c:288
>
> but task is already holding lock:
> (rtnl_mutex){+.+.+.}, at: [<ffffffff8370b057>] rtnl_lock+0x17/0x20
> net/core/rtnetlink.c:70
Is this also a false positive?
genl_lock_dumpit takes the genl_lock and then waits on the rtnl_lock
(e.g., out of tipc_nl_bearer_dump).
netdev_run_todo takes the rtnl_lock and then wants lock_sock()
for the TCP/IPv4 socket.
Why is lockdep seeing a circular dependancy here? Same pattern
seems to be happening for
http://www.spinics.net/lists/netdev/msg423368.html
and maybe also http://www.spinics.net/lists/netdev/msg423323.html?
--Sowmini
> Chain exists of:
> sk_lock-AF_INET --> genl_mutex --> rtnl_mutex
>
> Possible unsafe locking scenario:
>
> CPU0 CPU1
> ---- ----
> lock(rtnl_mutex);
> lock(genl_mutex);
> lock(rtnl_mutex);
> lock(sk_lock-AF_INET);
>
> *** DEADLOCK ***
>
> 4 locks held by kworker/u4:1/19:
> #0: ("%s""netns"){.+.+.+}, at: [<ffffffff81497943>]
> __write_once_size include/linux/compiler.h:283 [inline]
> #0: ("%s""netns"){.+.+.+}, at: [<ffffffff81497943>] atomic64_set
> arch/x86/include/asm/atomic64_64.h:33 [inline]
> #0: ("%s""netns"){.+.+.+}, at: [<ffffffff81497943>] atomic_long_set
> include/asm-generic/atomic-long.h:56 [inline]
> #0: ("%s""netns"){.+.+.+}, at: [<ffffffff81497943>] set_work_data
> kernel/workqueue.c:617 [inline]
> #0: ("%s""netns"){.+.+.+}, at: [<ffffffff81497943>]
> set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
> #0: ("%s""netns"){.+.+.+}, at: [<ffffffff81497943>]
> process_one_work+0xab3/0x1c10 kernel/workqueue.c:2089
> #1: (net_cleanup_work){+.+.+.}, at: [<ffffffff81497997>]
> process_one_work+0xb07/0x1c10 kernel/workqueue.c:2093
> #2: (net_mutex){+.+.+.}, at: [<ffffffff836965cb>]
> cleanup_net+0x22b/0xa90 net/core/net_namespace.c:429
> #3: (rtnl_mutex){+.+.+.}, at: [<ffffffff8370b057>]
> rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
>
