* Re: [Xen-devel] [PATCH 2/2] x86/xen: dont add memory above max allowed allocation
@ 2019-01-22 9:09 Juergen Gross
0 siblings, 0 replies; 2+ messages in thread
From: Juergen Gross @ 2019-01-22 9:09 UTC (permalink / raw)
To: Jan Beulich
Cc: Borislav Petkov, Stefano Stabellini, the arch/x86 maintainers,
linux-mm, Thomas Gleixner, xen-devel, Boris Ostrovsky, mingo,
lkml, H. Peter Anvin
On 22/01/2019 09:52, Jan Beulich wrote:
>>>> On 22.01.19 at 09:06, <jgross@suse.com> wrote:
>> Don't allow memory to be added above the allowed maximum allocation
>> limit set by Xen.
>
> This reads as if the hypervisor was imposing a limit here, but looking at
> xen_get_max_pages(), xen_foreach_remap_area(), and
> xen_count_remap_pages() I take it that it's a restriction enforced by
> the Xen subsystem in Linux. Furthermore from the cover letter I imply
> that the observed issue was on a Dom0, yet xen_get_max_pages()'s
> use of XENMEM_maximum_reservation wouldn't impose any limit there
> at all (without use of the hypervisor option "dom0_mem=max:..."),
> would it?
Oh yes, you are right, of course!
I need to check the current reservation and adjust the allowed limit
in case of ballooning and/or memory hotplug.
Thanks for noticing that!
Juergen
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [Xen-devel] [PATCH 2/2] x86/xen: dont add memory above max allowed allocation
2019-01-22 8:06 ` [PATCH 2/2] x86/xen: dont add memory above max allowed allocation Juergen Gross
@ 2019-01-22 8:52 ` Jan Beulich
0 siblings, 0 replies; 2+ messages in thread
From: Jan Beulich @ 2019-01-22 8:52 UTC (permalink / raw)
To: Juergen Gross
Cc: Borislav Petkov, Stefano Stabellini, the arch/x86 maintainers,
linux-mm, tglx, xen-devel, Boris Ostrovsky, mingo, linux-kernel,
hpa
>>> On 22.01.19 at 09:06, <jgross@suse.com> wrote:
> Don't allow memory to be added above the allowed maximum allocation
> limit set by Xen.
This reads as if the hypervisor was imposing a limit here, but looking at
xen_get_max_pages(), xen_foreach_remap_area(), and
xen_count_remap_pages() I take it that it's a restriction enforced by
the Xen subsystem in Linux. Furthermore from the cover letter I imply
that the observed issue was on a Dom0, yet xen_get_max_pages()'s
use of XENMEM_maximum_reservation wouldn't impose any limit there
at all (without use of the hypervisor option "dom0_mem=max:..."),
would it?
Jan
^ permalink raw reply [flat|nested] 2+ messages in thread
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2019-01-22 8:06 [PATCH 0/2] x86: respect memory size limits Juergen Gross
2019-01-22 8:06 ` [PATCH 2/2] x86/xen: dont add memory above max allowed allocation Juergen Gross
2019-01-22 8:52 ` [Xen-devel] " Jan Beulich
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