Re: [Xen-devel] Live vm migration broken in latest xen-unstable

[Ewan Mellor <ewan@xxxxxxxxxxxxx>]

On Fri, Sep 01, 2006 at 05:36:00PM -0400, sanjay kushwaha wrote:

> Folks,
> I am experiencing that live migration is not working in latest
> xen-unstable. I get the following message during migration
> 
> [root@pc5 ksanjay]# xm migrate --live 1 [1]199.77.138.23
> Error: /usr/lib/xen/bin/xc_save 18 1 0 0 1 failed
> [root@pc5 ksanjay]#
> 
> I traced the problem to a function in xen named set_sh_allocation() in
> file xen/arch/x86/mm/shadow/common.c
> 
> tools/libxc/xc_linux_save.c:xc_linux_save() is called from the python
> script which makes the following hypercall
> 
>     if (live) {
>         if (xc_shadow_control(xc_handle, dom,
>                               XEN_DOMCTL_SHADOW_OP_ENABLE_LOGDIRTY,
>                               NULL, 0, NULL, 0, NULL) < 0) {
>             ERR("Couldn't enable shadow mode");
>             goto out;
>         }
>         last_iter = 0;
>     } else {
> -----------
> 
> this particular hypercall leads to the call of set_sh_allocation which
> fails in the following code
> 
>         if ( d-> arch.shadow.total_pages < pages )
>         {
>             /* Need to allocate more memory from domheap */
>             pg = alloc_domheap_pages(NULL, SHADOW_MAX_ORDER, 0);
>             if ( pg == NULL )
>             {
>                 SHADOW_PRINTK("failed to allocate shadow pages.\n");
>                 return -ENOMEM;
>             }
> 
> alloc_domheap_pages fails and returns NULL. however I think I have enough
> memory available so this function should not fail.
> 
> Is there anybody else experiencing the same problem? Could someone please
> tell me how to fix it?

I've put some changes into xen-unstable today which might help.  The last fix
is on its way through testing now.  Look out for xen-unstable changeset
11422, and try that, see how you get on.

Cheers,

Ewan.

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