From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53342) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e4OHf-0005iB-OL for qemu-devel@nongnu.org; Tue, 17 Oct 2017 05:35:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1e4OHZ-000743-1Z for qemu-devel@nongnu.org; Tue, 17 Oct 2017 05:35:35 -0400 Date: Tue, 17 Oct 2017 11:35:19 +0200 From: Cornelia Huck Message-ID: <20171017113519.1eb78f7c.cohuck@redhat.com> In-Reply-To: <07afc056-4a03-3644-d665-c165830776ba@redhat.com> References: <20171016202358.3633-1-david@redhat.com> <20171017104725.14971395.cohuck@redhat.com> <07afc056-4a03-3644-d665-c165830776ba@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v1 0/2] s390x/tcg: LAP support using immediate TLB invalidation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Hildenbrand Cc: qemu-devel@nongnu.org, qemu-s390x@nongnu.org, Thomas Huth , Richard Henderson , Alexander Graf , Peter Maydell On Tue, 17 Oct 2017 11:22:19 +0200 David Hildenbrand wrote: > On 17.10.2017 10:47, Cornelia Huck wrote: > > On Mon, 16 Oct 2017 22:23:56 +0200 > > David Hildenbrand wrote: > > > >> Details about Low-Address Protection can be found in description of > >> patch 1 and 2. It is basically a subpage protection of the first two > >> pages of every address space (for which it is enabled). > >> > >> We can achieve this by simply directly invalidating the TLB entry and > >> therefore forcing every write accesses onto these two pages into the slow > >> path. > >> > >> With this patch, I can boot Linux just fine (which uses LAP). This also > >> makes all related kvm-unit-tests that we have pass. > > > > Tested with a kernel based on the s390/features branch (4.14-rc2 + s390 > > patches) and the initrd from the debian installer, had udevd shot down > > by the oomkiller. That happened only once, so it was probably an > > unrelated fluke, but that combination worked well before. > > > > Very unlikely, on invalid programming exceptions you would get a kernel > panic, not run oom. (not saying it isn't possible, rather that it is > very unlikely). That's what I thought as well. > > Can you reproduce with more memory? Have you enabled SMP? (little higher > memory consumption) SMP is on. I could not reproduce it again... > > I am running (almost) the same setup with 500M and haven't observed any > such thing. ...so I think it really is an unrelated fluke (and I'll simply make the machine a bit larger).