Re: [Xen-devel] vfree crash

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Petre Ovidiu PIRCALABU <ppircalabu@xxxxxxxxxxxxxxx>
> Sent: 01 July 2019 09:46
> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>; xen-devel@xxxxxxxxxxxxxxxxxxxx; 
> Andrew Cooper
> <Andrew.Cooper3@xxxxxxxxxx>
> Cc: Alexandru Stefan ISAILA <aisaila@xxxxxxxxxxxxxxx>; 
> rcojocaru@xxxxxxxxxxxxxxx
> Subject: Re: vfree crash
> 
> On Mon, 2019-07-01 at 08:29 +0000, Paul Durrant wrote:
> > > -----Original Message-----
> > > From: Xen-devel <xen-devel-bounces@xxxxxxxxxxxxxxxxxxxx> On Behalf
> > > Of Petre Ovidiu PIRCALABU
> > > Sent: 28 June 2019 19:00
> > > To: xen-devel@xxxxxxxxxxxxxxxxxxxx; Andrew Cooper <
> > > Andrew.Cooper3@xxxxxxxxxx>
> > > Cc: Alexandru Stefan ISAILA <aisaila@xxxxxxxxxxxxxxx>;
> > > rcojocaru@xxxxxxxxxxxxxxx
> > > Subject: [Xen-devel] vfree crash
> > >
> > > Hello,
> > >
> > > I need your help to pinpoint the root cause of a problem. To my
> > > understanding vfree should be used when allocating memory with
> > > vmalloc.
> > >
> > > But, I have the following scenario which results in a XEN crash:
> > > - allocate a number of frames using vmalloc (vzalloc) (e.g. using a
> > > domctl) and assign them to the calling domain
> > > - map the frames using xenforeignmemory_map_resource
> >
> > Do you really mean xenforeignmemory_map_resource()? If the memory is
> > assigned to the calling domain then this is quite likely not to work.
> > There were reference counting problems with that code, which is why
> > caller assigned resources were dropped.
> >
> >   Paul
> >
> 
> The problem lies with vfree because it creates a new list with the
> pages, unmaps the va pointer and then frees the pages. If I do these
> steps manually (without adding them to a new list) it works.

So, looking at the code, I don't think it is intended that v[m|z]alloced pages 
get assigned to a domain. Could you point at where the assignment is happening?

  Paul

> 
> Many thanks,
> Petre
> 

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