Re: [Qemu-devel] [RFC v2 3/6] memory: support unmapping of MemoryRegion mapped into HVA parent

[Michael S. Tsirkin]

On Wed, Jun 17, 2015 at 06:15:14PM +0200, Paolo Bonzini wrote:
> 
> 
> On 17/06/2015 17:10, Michael S. Tsirkin wrote:
> > > Actually memory_region_add_subregion(cannot fail) will continue to casue 
> > > problems
> > > in case one of the listeners fails and has no way to propagate error up 
> > > the stack.
> > > It could be that vhost_set_memory() or kvm_set_memslots() aren't able to 
> > > allocate
> > > memory for replacement table in low memory conditions and without
> > > way to report back QEMU is left with option to die.
> > 
> > mmap reserving memory just adds it to a data structure somewhere
> > within glibc, doesn't it? Looks like it's highly unlikely to fail,
> > so maybe killing QEMU if it does isn't a big deal.
> 
> It's in the kernel, but yes, a MAP_NORESERVE mmap is highly unlikely to
> fail.
> 
> Paolo

So let's ignore it for now, we always crash if e.g. close fails, too.