From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936034AbdADN2g (ORCPT ); Wed, 4 Jan 2017 08:28:36 -0500 Received: from foss.arm.com ([217.140.101.70]:50742 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934629AbdADN2d (ORCPT ); Wed, 4 Jan 2017 08:28:33 -0500 Date: Wed, 4 Jan 2017 13:28:31 +0000 From: Will Deacon To: Ard Biesheuvel Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, catalin.marinas@arm.com, akpm@linux-foundation.org, hanjun.guo@linaro.org, xieyisheng1@huawei.com, rrichter@cavium.com, james.morse@arm.com Subject: Re: [PATCH 2/2] arm64: mm: enable CONFIG_HOLES_IN_ZONE for NUMA Message-ID: <20170104132831.GD18193@arm.com> References: <1481706707-6211-1-git-send-email-ard.biesheuvel@linaro.org> <1481706707-6211-3-git-send-email-ard.biesheuvel@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1481706707-6211-3-git-send-email-ard.biesheuvel@linaro.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 14, 2016 at 09:11:47AM +0000, Ard Biesheuvel wrote: > The NUMA code may get confused by the presence of NOMAP regions within > zones, resulting in spurious BUG() checks where the node id deviates > from the containing zone's node id. > > Since the kernel has no business reasoning about node ids of pages it > does not own in the first place, enable CONFIG_HOLES_IN_ZONE to ensure > that such pages are disregarded. > > Signed-off-by: Ard Biesheuvel > --- > arch/arm64/Kconfig | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 111742126897..0472afe64d55 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -614,6 +614,10 @@ config NEED_PER_CPU_EMBED_FIRST_CHUNK > def_bool y > depends on NUMA > > +config HOLES_IN_ZONE > + def_bool y > + depends on NUMA > + > source kernel/Kconfig.preempt > source kernel/Kconfig.hz I'm happy to apply this, but I'll hold off until the first patch is queued somewhere, since this doesn't help without the VM_BUG_ON being moved. Alternatively, I can queue both if somebody from the mm camp acks the first patch. Will