WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

[Xen-devel] Re: softirq warnings when calling dev_kfree_skb_irq - bug in

To: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Subject: [Xen-devel] Re: softirq warnings when calling dev_kfree_skb_irq - bug in conntrack?
From: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Date: Tue, 03 Aug 2010 09:04:34 +0200
Cc: "Xen-devel@xxxxxxxxxxxxxxxxxxx" <Xen-devel@xxxxxxxxxxxxxxxxxxx>, Ian Campbell <Ian.Campbell@xxxxxxxxxx>, Eric Dumazet <eric.dumazet@xxxxxxxxx>, NetDev <netdev@xxxxxxxxxxxxxxx>, "Xu, Dongxiao" <dongxiao.xu@xxxxxxxxx>, Patrick McHardy <kaber@xxxxxxxxx>
Delivery-date: Thu, 05 Aug 2010 06:55:49 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <4C571476.7070301@xxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <4C571476.7070301@xxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
On Mon, 2010-08-02 at 11:54 -0700, Jeremy Fitzhardinge wrote:

> ------------[ cut here ]------------
> WARNING: at kernel/softirq.c:143 local_bh_enable+0x40/0x87()
> Modules linked in: xt_state dm_mirror dm_region_hash dm_log microcode [last 
> unloaded: scsi_wait_scan]
> Pid: 0, comm: swapper Not tainted 2.6.35-rc6-next-20100729+ #29
> Call Trace:
>   <IRQ>   [<ffffffff81030de3>] warn_slowpath_common+0x80/0x98
>   [<ffffffff81030e10>] warn_slowpath_null+0x15/0x17
>   [<ffffffff81035ff3>] local_bh_enable+0x40/0x87
>   [<ffffffff814236e5>] destroy_conntrack+0x78/0x9e
>   [<ffffffff810bea55>] ? __kmalloc_track_caller+0xc3/0x135
>   [<ffffffff814203b4>] nf_conntrack_destroy+0x16/0x18
>   [<ffffffff813fadee>] skb_release_head_state+0x97/0xd9
>   [<ffffffff813fabbe>] __kfree_skb+0x11/0x7a
>   [<ffffffff813fac4e>] consume_skb+0x27/0x29
>   [<ffffffff81402d3a>] dev_kfree_skb_irq+0x18/0x62
>   [<ffffffff8130a762>] xennet_tx_buf_gc+0xfc/0x192
>   [<ffffffff8130a8fb>] smart_poll_function+0x50/0x121
>   [<ffffffff8130a8ab>] ? smart_poll_function+0x0/0x121
>   [<ffffffff8104b8d1>] __run_hrtimer+0xcc/0x127
>   [<ffffffff8104bad3>] hrtimer_interrupt+0x9c/0x17b

> It seems the basic problem is that xennet_tx_buf_gc() is being called in 
> interrupt context - with smartpoll it's from the timer interrupt, but 
> even without it is being called from xennet_interrupt(), which in turn 
> calls dev_kfree_skb_irq().
> 
> Since this should be perfectly OK, it appears the problem is actually in 
> conntrack.  I'm not sure where this bug started happening, but its 
> relatively recently I think.

I had this too:
http://article.gmane.org/gmane.linux.network/167590

But I'm not convinced it's conntrack, I'd think it's

commit 15e83ed78864d0625e87a85f09b297c0919a4797
Author: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Date:   Wed May 19 23:16:03 2010 +0000

    net: remove zap_completion_queue

which, from the looks of it, ought to be reverted because it failed to
take into account that dev_kfree_skb() can do more things that require
non-irq-context than just calling skb->destructor, like for instance the
conntrack thing we see here.

johannes


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel