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] 3.0.4: Soft lockup in netfront in SMP build

To: <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] 3.0.4: Soft lockup in netfront in SMP build
From: "Graham, Simon" <Simon.Graham@xxxxxxxxxxx>
Date: Sat, 21 Apr 2007 17:45:34 -0400
Delivery-date: Sat, 21 Apr 2007 14:44:13 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
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/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AceEXmQbVpZcSzczQ7SLQWqGyxSkMg==
Thread-topic: 3.0.4: Soft lockup in netfront in SMP build
Just run into a (real) soft lockup running 3.0.4 - stack is at the end of this, 
but basically:

. network_open acquires the rx spin lock with spin_lock() and then checks for
  work on the queue and calls (I think) netif_rx_schedule with the lock still 
held which
  can call into the hypervisor.
. An interrupt is delivered to the bottom half of netfront which ends up 
calling netif_poll
  which blocks attempting to acquire the rx spin lock.

Oops! 

I see from the unstable tree that this code was recently modified to use 
spin_lock_bh() instead of spin_lock() as part of a mega-merge of IA64 code - 
clearly we cant merge this changeset into 3.0.4.

I haven't looked too closely at all of the code yet, but I'm wondering if a 
judicious change of spin_lock to spin_lock_bh in netfront would be the best 
approach?

Simon

BUG: soft lockup detected on CPU#0!
Pid: 2973, comm:            ifconfig
EIP: 0061:[<c035868a>] CPU: 0
EIP is at _spin_lock+0xa/0x20
 EFLAGS: 00000286    Tainted: GF      (2.6.16.38-xen #1)
EAX: c13b840c EBX: c13b8000 ECX: 00000040 EDX: cf783dc0
ESI: 00000000 EDI: c1233274 EBP: cf783d28 DS: 007b ES: 007b
CR0: 8005003b CR2: b7eea198 CR3: 103f2000 CR4: 00000660
 [<c010595d>] show_trace+0xd/0x10
 [<c010344f>] show_regs+0x18f/0x1c0
 [<c01491f4>] softlockup_tick+0xe4/0x100
 [<c012c713>] do_timer+0x43/0xf0
 [<c010936a>] timer_interrupt+0x1fa/0x670
 [<c01494da>] handle_IRQ_event+0x6a/0xb0
 [<c01495a9>] __do_IRQ+0x89/0xf0
 [<c0106ee8>] do_IRQ+0x38/0x70
 [<c028dee0>] evtchn_do_upcall+0x90/0x110
 [<c01056a1>] hypervisor_callback+0x3d/0x48
 [<c02a5db2>] netif_poll+0x32/0x630
 [<c02dace8>] net_rx_action+0x148/0x230
 [<c01279d5>] __do_softirq+0x95/0x130
 [<c0127af5>] do_softirq+0x85/0xa0
 [<c0127bda>] irq_exit+0x3a/0x50
 [<c0106eed>] do_IRQ+0x3d/0x70
 [<c028dee0>] evtchn_do_upcall+0x90/0x110
 [<c01056a1>] hypervisor_callback+0x3d/0x48
 [<c02a461b>] network_open+0x13b/0x210
 [<c02d9564>] dev_open+0x74/0x90
 [<c02db482>] dev_change_flags+0x52/0x110
 [<c0320187>] devinet_ioctl+0x4f7/0x5a0
 [<c0322174>] inet_ioctl+0x94/0xc0
 [<c02cf84d>] sock_ioctl+0xed/0x250
 [<c01842d6>] do_ioctl+0x76/0x90
 [<c0184479>] vfs_ioctl+0x59/0x1d0
 [<c0184657>] sys_ioctl+0x67/0x80
 [<c01054cd>] syscall_call+0x7/0xb
crash>

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

<Prev in Thread] Current Thread [Next in Thread>