Re: [Xen-ia64-devel] [Xen-devel][IPF][RFC] Error (12, 'Cannot allocate memory') when creating domain

[INAKOSHI Hiroya <inakoshi.hiroya@xxxxxxxxxxxxxx>]

Hi, Anthony,

It looks to me that you are mentioning bugzilla-#736.

http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=736

Please see the next URL and its followups.  The Tristan's patch seems
not yet in xen-ia64-unstable tree.

http://thread.gmane.org/gmane.comp.emulators.xen.ia64/3980/focus=3980

HTH,

Hiroya


Xu, Anthony wrote:
> Hi all,
> 
> When I create domain, XEN may complain Error (12, 'Cannot allocate memory') 
> even though there are plenty of memory available.
> I think kangkang had reported this bug.
> 
> After investigation, I found this is caused by copy_to_guest.
> 
> Dom0 calls increase_reservation hypercall to allocate memory for domain.
> At the end of this function, it will copy all mfns to guest address space.
> 
>         /* Inform the domain of the new page's machine address. */ 
>         if ( !guest_handle_is_null(extent_list) )
>         {
>             mfn = page_to_mfn(page);
>             if ( unlikely(__copy_to_guest_offset(extent_list, i, &mfn, 1)) )
>                 return i;
>         }
> 
> But __copy_to_guest_offset may fail in ia64 side, due to XEN may not record 
> this 
> tlb. Yes, increase_reservation function implements 'retry mechanism', it 
> hopes 
> dom0 will call it again from the failure point. But dom0 didn't use this  
> 'retry 
> mechanism', dom0 thought this hypercall fail, and dom0 reported mistakenly  
> Error (12, 'Cannot allocate memory')
> 
> Thanks,
> Anthony
> 
> _______________________________________________
> Xen-ia64-devel mailing list
> Xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-ia64-devel
> 
> 


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