Re: [PATCH v3 1/2] memory_hotplug: Add a bounds check to check_hotplug_memory_range()

[Michal Hocko]

On Tue 24-09-19 11:13:31, David Hildenbrand wrote:
> On 24.09.19 11:09, Michal Hocko wrote:
> > On Tue 24-09-19 11:31:05, Alastair D'Silva wrote:
> >> On Mon, 2019-09-23 at 14:25 +0200, Michal Hocko wrote:
[...]
> >>> This will result in a silent failure (unlike misaligned case). Is
> >>> this
> >>> what we want?
> >>
> >> Good point - I guess it comes down to, is there anything we expect an
> >> end user to do about it? I'm not sure there is, in which case the bad
> >> RC, which is reported up every call chain that I can see, should be
> >> sufficient.
> > 
> > It seems like a clear HW/platform bug to me. And that should better be
> > reported loudly to the log to make sure people do complain to their FW
> > friends and have it fixed.
> > 
> 
> I don't agree in virtual environment. On s390x, MAX_PHYSMEM_BITS is
> configurable. For example, if you have paravirtualized memory hotplug
> (e.g., virtio-mem), you could add memory to the system that violates
> this constraint.

What happens if that is the case. Does the machine change the
configuration in runtime or it needs a reboot?

Anyway, seeing this to be the case in the log would help in whatever
action is necessary to deal with the issue, right?
-- 
Michal Hocko
SUSE Labs