From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: macvtap bug: using smp_processor_id() in preemptible code Date: Thu, 08 Aug 2013 06:21:12 -0700 Message-ID: <1375968072.4004.92.camel@edumazet-glaptop> References: <20130807164319.20aa2333@thhw500> <1375889211.4004.28.camel@edumazet-glaptop> <20130808102551.6aa47852@thhw500> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, Vlad Yasevich , "David S. Miller" , Eric Dumazet To: Thomas Huth Return-path: Received: from mail-pa0-f41.google.com ([209.85.220.41]:58812 "EHLO mail-pa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934221Ab3HHNVO (ORCPT ); Thu, 8 Aug 2013 09:21:14 -0400 Received: by mail-pa0-f41.google.com with SMTP id bj1so3458907pad.0 for ; Thu, 08 Aug 2013 06:21:13 -0700 (PDT) In-Reply-To: <20130808102551.6aa47852@thhw500> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 2013-08-08 at 10:25 +0200, Thomas Huth wrote: > Hi, > Thank you very much for your fast reply and the fix, it indeed fixes > the messages about macvtap_do_read! > However, I now noticed that there are more messages, which I just did > not see before because my dmesg output was already flooded with the > messages about macvtap_do_read. The other messages are all about > macvlan_start_xmit: > > BUG: using smp_processor_id() in preemptible [00000000] code: vhost-45897/45898 > caller is macvlan_start_xmit+0x10a/0x1b4 [macvlan] > CPU: 1 PID: 45898 Comm: vhost-45897 Not tainted 3.11.0-bisecttest #16 > 00000001189b3960 00000001189b3970 0000000000000002 0000000000000000 > 00000001189b3a00 00000001189b3978 00000001189b3978 00000000001127b4 > 0000000000000000 0000000000000001 0000000000000000 000000000000000b > 0000000000000060 000003fe00000008 0000000000000000 00000001189b39d0 > 00000000006ea2f0 00000000001127b4 00000001189b3960 00000001189b39b0 > Call Trace: > ([<00000000001126ee>] show_trace+0x126/0x144) > [<00000000001127d2>] show_stack+0xc6/0xd4 > [<000000000068bdb8>] dump_stack+0x74/0xd4 > [<0000000000481132>] debug_smp_processor_id+0xf6/0x114 > [<000003ff802b72ca>] macvlan_start_xmit+0x10a/0x1b4 [macvlan] > [<000003ff802ea69a>] macvtap_get_user+0x982/0xbc4 [macvtap] > [<000003ff802ea92a>] macvtap_sendmsg+0x4e/0x60 [macvtap] > [<000003ff8031947c>] handle_tx+0x494/0x5ec [vhost_net] > [<000003ff8028f77c>] vhost_worker+0x15c/0x1c4 [vhost] > [<000000000015f3ac>] kthread+0xd8/0xe4 > [<000000000069356e>] kernel_thread_starter+0x6/0xc > [<0000000000693568>] kernel_thread_starter+0x0/0xc > 2 locks held by vhost-45897/45898: > #0: (&vq->mutex){+.+.+.}, at: [<000003ff8031903c>] handle_tx+0x54/0x5ec [vhost_net] > #1: (rcu_read_lock){.+.+..}, at: [<000003ff802ea53c>] macvtap_get_user+0x824/0xbc4 [macvtap] > > Do you also have got an idea how to silence these messages? Sure, please try following cumulative patch, thanks ! diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index a98fb0e..b51db2a 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -818,10 +818,13 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m, skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY; skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG; } - if (vlan) + if (vlan) { + local_bh_disable(); macvlan_start_xmit(skb, vlan->dev); - else + local_bh_enable(); + } else { kfree_skb(skb); + } rcu_read_unlock(); return total_len; @@ -912,8 +915,11 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q, done: rcu_read_lock(); vlan = rcu_dereference(q->vlan); - if (vlan) + if (vlan) { + preempt_disable(); macvlan_count_rx(vlan, copied - vnet_hdr_len, ret == 0, 0); + preempt_enable(); + } rcu_read_unlock(); return ret ? ret : copied;