Re: [Xen-devel] Got kernel BUG message while PCI pass-through to domU

[Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx>]

On Mon, Jan 23, 2012 at 11:22:28AM -0800, Eric Camachat wrote:
> Thanks,  Konrad.
> 
> Do you mean dom0 kernel? or The domU kernel?

Please don't top post.

The fix (and the bug) are both in xen_pciback - which is in the
dom0.

The fix I believe is this git commit:
commit b1766b62890e3bba1a778a20ef8bf9348d6096c2
Author: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date:   Fri Sep 16 14:43:14 2011 -0400

    xen/pciback: Use mutexes when working with Xenbus state transitions.
    
    The caller that orchestrates the state changes is xenwatch_thread
    and it takes a mutex. In our processing of Xenbus states we can take
    the luxery of going to sleep on a mutex, so lets do that and
    also fix this bug:
    
    BUG: sleeping function called from invalid context at
/linux/kernel/mutex.c:271
    in_atomic(): 1, irqs_disabled(): 0, pid: 32, name: xenwatch
    2 locks held by xenwatch/32:
     #0:  (xenwatch_mutex){......}, at: [<ffffffff813856ab>]
xenwatch_thread+0x4b/0x180
     #1:  (&(&pdev->dev_lock)->rlock){......}, at: [<ffffffff8138f05b>]
xen_pcibk_disconnect+0x1b/0x80
    Pid: 32, comm: xenwatch Not tainted 3.1.0-rc6-00015-g3ce340d #2
    Call Trace:
     [<ffffffff810892b2>] __might_sleep+0x102/0x130
     [<ffffffff8163b90f>] mutex_lock_nested+0x2f/0x50
     [<ffffffff81382c1c>] unbind_from_irq+0x2c/0x1b0
     [<ffffffff8110da66>] ? free_irq+0x56/0xb0
     [<ffffffff81382dbc>] unbind_from_irqhandler+0x1c/0x30
     [<ffffffff8138f06b>] xen_pcibk_disconnect+0x2b/0x80
     [<ffffffff81390348>] xen_pcibk_frontend_changed+0xe8/0x140
     [<ffffffff81387ac2>] xenbus_otherend_changed+0xd2/0x150
     [<ffffffff810895c1>] ? get_parent_ip+0x11/0x50
     [<ffffffff81387de0>] frontend_changed+0x10/0x20
     [<ffffffff81385712>] xenwatch_thread+0xb2/0x180
    
    Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

So it went in 3.1.

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