From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f72.google.com (mail-it0-f72.google.com [209.85.214.72]) by kanga.kvack.org (Postfix) with ESMTP id 68E636B0253 for ; Wed, 4 Jan 2017 08:50:22 -0500 (EST) Received: by mail-it0-f72.google.com with SMTP id b123so461940330itb.3 for ; Wed, 04 Jan 2017 05:50:22 -0800 (PST) Received: from mail-it0-x231.google.com (mail-it0-x231.google.com. [2607:f8b0:4001:c0b::231]) by mx.google.com with ESMTPS id 64si49738750iov.239.2017.01.04.05.50.21 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 04 Jan 2017 05:50:21 -0800 (PST) Received: by mail-it0-x231.google.com with SMTP id k132so13909272ita.1 for ; Wed, 04 Jan 2017 05:50:21 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <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> <20170104132831.GD18193@arm.com> From: Ard Biesheuvel Date: Wed, 4 Jan 2017 13:50:20 +0000 Message-ID: Subject: Re: [PATCH 2/2] arm64: mm: enable CONFIG_HOLES_IN_ZONE for NUMA Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Will Deacon Cc: "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , Catalin Marinas , Andrew Morton , Hanjun Guo , Yisheng Xie , Robert Richter , James Morse On 4 January 2017 at 13:28, Will Deacon wrote: > 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. > Actually, I am not convinced the discussion is finalized. These patches do fix the issue, but Robert also suggested an alternative fix which may be preferable. http://marc.info/?l=linux-arm-kernel&m=148190753510107&w=2 I haven't responded to it yet, due to the holidays, but I'd like to explore that solution a bit further before applying anything, if you don't mind. Thanks, Ard. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org