[Xen-devel] Re: Regression: patch " hvc_console: display printk messages on console." causing infinite loop with 3.2-rc0 + Xen.

[Miche Baker-Harvey <miche@xxxxxxxxxx>]

Bummer.  Sorry about that.

Konrad, could you give me a hand figuring out what's up with this - I'm not running Zen here.  (If there's a test suite I could have run, mea culpa, and please point me in the right direction.)

The "console [hvc0] enabled" message is coming from register_console() in printk.c, and it doesn't have any loops.

It's called from hvc_console_init(), hvc_instantiate(), and hvc_alloc(), none of which have loops.  The call in hvc_alloc() is the one I added, so either I've inadvertently made one of the other two repeat (I'm guestting hvc_instantiate() is the one you're using), or you're infinitely calling hvc_alloc().  There's a calls to hvc_alloc() in hvc_xen.c::xen_hvc_init(), and in init_port_console() in virtio_console.c, but again, no loops.  Similarly for hvc_instantiate().

So, could I trouble you to put a breakpoint in register_console() and send me the stack?

Thanks,

Miche

On Wed, Oct 26, 2011 at 10:48 PM, Greg KH <gregkh@xxxxxxx> wrote:

On Thu, Oct 27, 2011 at 01:30:08AM -0400, Konrad Rzeszutek Wilk wrote:

> Hey Miche.
>
> The git commit 361162459f62dc0826b82c9690a741a940f457f0:
>
>     hvc_console: display printk messages on console.
>
> is causing an infinite loop when booting Linux under Xen, as so:
>
> [    2.382984] console [hvc0] enabled
> [    2.382984] console [hvc0] enabled
> [    2.382984] console [hvc0] enabled
> [    2.382984] console [hvc0] enabled
> [    2.382984] console [hvc0] enabled
> [    2.382984] console [hvc0] enabled
> ..
>
> (see attached file titled bad.log)
>
> If I use Linus's latest git tree and revert your patch I get the kernel
> to bootup (see good.log file),

Ick, not good, thanks for letting us know.

Miche, want me to just revert this, or do you think you can fix it?

thanks,

greg k-h

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