From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 28 Jun 2011 10:59:58 +0200
Subject: net-flip-lock-dep-thingy.patch
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: 5a1b0457b0c55f133b7c5062270cf2b9e2bf9715
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension
=======================================================
[ INFO: possible circular locking dependency detected ]
3.0.0-rc3+ #26
-------------------------------------------------------
ip/1104 is trying to acquire lock:
(local_softirq_lock){+.+...}, at: [<ffffffff81056d12>] __local_lock+0x25/0x68
but task is already holding lock:
(sk_lock-AF_INET){+.+...}, at: [<ffffffff81433308>] lock_sock+0x10/0x12
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (sk_lock-AF_INET){+.+...}:
[<ffffffff810836e5>] lock_acquire+0x103/0x12e
[<ffffffff813e2781>] lock_sock_nested+0x82/0x92
[<ffffffff81433308>] lock_sock+0x10/0x12
[<ffffffff81433afa>] tcp_close+0x1b/0x355
[<ffffffff81453c99>] inet_release+0xc3/0xcd
[<ffffffff813dff3f>] sock_release+0x1f/0x74
[<ffffffff813dffbb>] sock_close+0x27/0x2b
[<ffffffff81129c63>] fput+0x11d/0x1e3
[<ffffffff81126577>] filp_close+0x70/0x7b
[<ffffffff8112667a>] sys_close+0xf8/0x13d
[<ffffffff814ae882>] system_call_fastpath+0x16/0x1b
-> #0 (local_softirq_lock){+.+...}:
[<ffffffff81082ecc>] __lock_acquire+0xacc/0xdc8
[<ffffffff810836e5>] lock_acquire+0x103/0x12e
[<ffffffff814a7e40>] _raw_spin_lock+0x3b/0x4a
[<ffffffff81056d12>] __local_lock+0x25/0x68
[<ffffffff81056d8b>] local_bh_disable+0x36/0x3b
[<ffffffff814a7fc4>] _raw_write_lock_bh+0x16/0x4f
[<ffffffff81433c38>] tcp_close+0x159/0x355
[<ffffffff81453c99>] inet_release+0xc3/0xcd
[<ffffffff813dff3f>] sock_release+0x1f/0x74
[<ffffffff813dffbb>] sock_close+0x27/0x2b
[<ffffffff81129c63>] fput+0x11d/0x1e3
[<ffffffff81126577>] filp_close+0x70/0x7b
[<ffffffff8112667a>] sys_close+0xf8/0x13d
[<ffffffff814ae882>] system_call_fastpath+0x16/0x1b
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(sk_lock-AF_INET);
lock(local_softirq_lock);
lock(sk_lock-AF_INET);
lock(local_softirq_lock);
*** DEADLOCK ***
1 lock held by ip/1104:
#0: (sk_lock-AF_INET){+.+...}, at: [<ffffffff81433308>] lock_sock+0x10/0x12
stack backtrace:
Pid: 1104, comm: ip Not tainted 3.0.0-rc3+ #26
Call Trace:
[<ffffffff81081649>] print_circular_bug+0x1f8/0x209
[<ffffffff81082ecc>] __lock_acquire+0xacc/0xdc8
[<ffffffff81056d12>] ? __local_lock+0x25/0x68
[<ffffffff810836e5>] lock_acquire+0x103/0x12e
[<ffffffff81056d12>] ? __local_lock+0x25/0x68
[<ffffffff81046c75>] ? get_parent_ip+0x11/0x41
[<ffffffff814a7e40>] _raw_spin_lock+0x3b/0x4a
[<ffffffff81056d12>] ? __local_lock+0x25/0x68
[<ffffffff81046c8c>] ? get_parent_ip+0x28/0x41
[<ffffffff81056d12>] __local_lock+0x25/0x68
[<ffffffff81056d8b>] local_bh_disable+0x36/0x3b
[<ffffffff81433308>] ? lock_sock+0x10/0x12
[<ffffffff814a7fc4>] _raw_write_lock_bh+0x16/0x4f
[<ffffffff81433c38>] tcp_close+0x159/0x355
[<ffffffff81453c99>] inet_release+0xc3/0xcd
[<ffffffff813dff3f>] sock_release+0x1f/0x74
[<ffffffff813dffbb>] sock_close+0x27/0x2b
[<ffffffff81129c63>] fput+0x11d/0x1e3
[<ffffffff81126577>] filp_close+0x70/0x7b
[<ffffffff8112667a>] sys_close+0xf8/0x13d
[<ffffffff814ae882>] system_call_fastpath+0x16/0x1b
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
---
net/core/sock.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2646,12 +2646,11 @@ void lock_sock_nested(struct sock *sk, i
if (sk->sk_lock.owned)
__lock_sock(sk);
sk->sk_lock.owned = 1;
- spin_unlock(&sk->sk_lock.slock);
+ spin_unlock_bh(&sk->sk_lock.slock);
/*
* The sk_lock has mutex_lock() semantics here:
*/
mutex_acquire(&sk->sk_lock.dep_map, subclass, 0, _RET_IP_);
- local_bh_enable();
}
EXPORT_SYMBOL(lock_sock_nested);