Re: dom0 linux 3.6.0-rc4, crash due to ballooning althoug dom0_mem=X, max:X set

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Tue, Sep 04, 2012 at 02:07:11PM -0400, Ben Guthro wrote:
> We ran into the same issue, in newer kernels - but had not yet
> submitted this fix.
> 
> One of the developers here came up with a fix (attached, and CC'ed
> here) that fixes an issue where the p2m code reuses a structure member
> where it shouldn't.
> The patch adds a new "old_mfn"  member to the gnttab_map_grant_ref
> structure, instead of re-using  dev_bus_addr.

Wow. So that implies the m2p code had some new wonkiness in it.

Perhaps this b9e0d95c041ca2d7ad297ee37c2e9cfab67a188f
or
0930bba674e248b921ea659b036ff02564e5a5f4

both courtesy of Stefano (who is on vacation this week :-())
are at fault?

Would it be possible to revert one of them (or both) and see if the
issues disappear?

> 
> 
> If this also works for you, I can re-submit it with a Signed-off-by
> line, if you prefer, Konrad.
> 
> Ben
> 
> 
> On Tue, Sep 4, 2012 at 1:19 PM, Sander Eikelenboom <linux@eikelenboom.it> wrote:
> >
> > Tuesday, September 4, 2012, 6:33:47 PM, you wrote:
> >
> >> On Tue, Sep 04, 2012 at 06:37:57PM +0200, Sander Eikelenboom wrote:
> >>> Hi Konrad,
> >>>
> >>> This seems to happen only on a intel machine i'm trying to setup as a development machine (haven't seen it on my amd).
> >>> It boots fine, i have dom0_mem=1024M,max:1024M set, the machine has 2G of mem.
> >
> >> Is this only with Xen 4.2? As, does Xen 4.1 work?
> >>>
> >>> Dom0 and guest kernel are 3.6.0-rc4 with config:
> >
> >> If you back out:
> >
> >> f393387d160211f60398d58463a7e65
> >> Author: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> >> Date:   Fri Aug 17 16:43:28 2012 -0400
> >
> >>     xen/setup: Fix one-off error when adding for-balloon PFNs to the P2M.
> >
> >> Do you see this bug? (Either with Xen 4.1 or Xen 4.2)?
> >
> > With c96aae1f7f393387d160211f60398d58463a7e65 reverted i still see this bug (with Xen 4.2).
> >
> > Will use the debug patch you mailed and send back the results ...
> >
> >
> >>> [*] Xen memory balloon driver
> >>> [*]   Scrub pages before returning them to system
> >>>
> >>> From http://wiki.xen.org/wiki/Do%EF%BB%BFm0_Memory_%E2%80%94_Where_It_Has_Not_Gone , I thought this should be okay
> >>>
> >>> But when trying to start a PV guest with 512MB mem, the machine (dom0) crashes with the stacktrace below (complete serial-log.txt attached).
> >>>
> >>> From the:
> >>> "mapping kernel into physical memory
> >>> about to get started..."
> >>>
> >>> I would almost say it's trying to reload dom0 ?
> >>>
> >>>
> >>> [  897.161119] device vif1.0 entered promiscuous mode
> >>> mapping kernel into physical memory
> >>> about to get started...
> >>> [  897.696619] xen_bridge: port 1(vif1.0) entered forwarding state
> >>> [  897.716219] xen_bridge: port 1(vif1.0) entered forwarding state
> >>> [  898.129465] ------------[ cut here ]------------
> >>> [  898.132209] kernel BUG at drivers/xen/balloon.c:359!
> >>> [  898.132209] invalid opcode: 0000 [#1] PREEMPT SMP
> >
> >
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xen.org
> > http://lists.xen.org/xen-devel