Re: [PATCH] x86/pod: Do not fragment PoD memory allocations

From: Elliott Mitchell <ehem+xen@m5p.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: George Dunlap <george.dunlap@citrix.com>, Wei Liu <wl@xen.org>,
	Roger Pau Monn?? <roger.pau@citrix.com>,
	xen-devel@lists.xenproject.org,
	Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH] x86/pod: Do not fragment PoD memory allocations
Date: Thu, 28 Jan 2021 10:26:29 -0800	[thread overview]
Message-ID: <YBMB1VUhYd3RUuDO@mattapan.m5p.com> (raw)
In-Reply-To: <44450edc-9a64-8a6e-e8d3-3a3f726a96bc@suse.com>

On Thu, Jan 28, 2021 at 11:19:41AM +0100, Jan Beulich wrote:
> On 27.01.2021 23:28, Elliott Mitchell wrote:
> > On Wed, Jan 27, 2021 at 09:03:32PM +0000, Andrew Cooper wrote:
> >> So.?? What *should* happen is that if QEMU/OVMF dirties more memory than
> >> exists in the PoD cache, the domain gets terminated.
> >>
> >> Irrespective, Xen/dom0 dying isn't an expected consequence of any normal
> >> action like this.
> >>
> >> Do you have a serial log of the crash??? If not, can you set up a crash
> >> kernel environment to capture the logs, or alternatively reproduce the
> >> issue on a different box which does have serial?
> > 
> > No, I don't.  I'm setup to debug ARM failures, not x86 ones.
> 
> Then alternatively can you at least give conditions that need to
> be met to observe the problem, for someone to repro and then
> debug? (The less complex the better, of course.)

Multiple prior messages have included statements of what I believed to be
the minimal case to reproduce.  Presently I believe the minimal
constraints are, maxmem >= host memory, memory < free Xen memory, type
HVM.  A minimal kr45hme.cfg file:

type = "hvm"
memory = 1024
maxmem = 1073741824

I suspect maxmem > free Xen memory may be sufficient.  The instances I
can be certain of have been maxmem = total host memory *7.

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