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From: "Jan Beulich" <JBeulich@suse.com>
To: Juergen Gross <jgross@suse.com>
Cc: Borislav Petkov <bp@alien8.de>,
	Stefano Stabellini <sstabellini@kernel.org>,
	the arch/x86 maintainers <x86@kernel.org>,
	linux-mm@kvack.org, tglx@linutronix.de,
	xen-devel <xen-devel@lists.xenproject.org>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	mingo@redhat.com, linux-kernel@vger.kernel.org, hpa@zytor.com
Subject: Re: [Xen-devel] [PATCH 2/2] x86/xen: dont add memory above max allowed allocation
Date: Tue, 22 Jan 2019 01:52:32 -0700	[thread overview]
Message-ID: <5C46D9D00200007800210007@prv1-mh.provo.novell.com> (raw)
In-Reply-To: <20190122080628.7238-3-jgross@suse.com>

>>> 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

WARNING: multiple messages have this Message-ID
From: "Jan Beulich" <JBeulich@suse.com>
To: "Juergen Gross" <jgross@suse.com>
Cc: "Borislav Petkov" <bp@alien8.de>,
	"Stefano Stabellini" <sstabellini@kernel.org>,
	"the arch/x86 maintainers" <x86@kernel.org>,<linux-mm@kvack.org>,
	<tglx@linutronix.de>,
	"xen-devel" <xen-devel@lists.xenproject.org>,
	"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
	<mingo@redhat.com>, <linux-kernel@vger.kernel.org>,
	<hpa@zytor.com>
Subject: Re: [Xen-devel] [PATCH 2/2] x86/xen: dont add memory above max allowed allocation
Date: Tue, 22 Jan 2019 01:52:32 -0700	[thread overview]
Message-ID: <5C46D9D00200007800210007@prv1-mh.provo.novell.com> (raw)
Message-ID: <20190122085232.3EbMoT2d_s-8RR8mXewYIu5TmMdUTdb7D9T3Rd7dW4Q@z> (raw)
In-Reply-To: <20190122080628.7238-3-jgross@suse.com>

>>> 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



  reply	other threads:[~2019-01-22  8:52 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-22  8:06 [PATCH 0/2] x86: respect memory size limits Juergen Gross
2019-01-22  8:06 ` [PATCH 1/2] x86: respect memory size limiting via mem= parameter Juergen Gross
2019-01-23 14:35   ` William Kucharski
2019-01-23 14:39     ` 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   ` Jan Beulich [this message]
2019-01-22  8:52     ` [Xen-devel] " Jan Beulich
2019-01-22  9:09 Juergen Gross

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