From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f72.google.com (mail-oi0-f72.google.com [209.85.218.72]) by kanga.kvack.org (Postfix) with ESMTP id B675D6B0003 for ; Wed, 20 Jun 2018 07:51:26 -0400 (EDT) Received: by mail-oi0-f72.google.com with SMTP id n63-v6so1702068oig.21 for ; Wed, 20 Jun 2018 04:51:26 -0700 (PDT) Received: from foss.arm.com (usa-sjc-mx-foss1.foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id b66-v6si788109oih.176.2018.06.20.04.51.24 for ; Wed, 20 Jun 2018 04:51:25 -0700 (PDT) From: Punit Agrawal Subject: Re: [PATCH 1/2] arm64: avoid alloc memory on offline node References: <20180611145330.GO13364@dhcp22.suse.cz> <87lgbk59gs.fsf@e105922-lin.cambridge.arm.com> <87bmce60y3.fsf@e105922-lin.cambridge.arm.com> <8b715082-14d4-f10b-d2d6-b23be7e4bf7e@huawei.com> <20180619120714.GE13685@dhcp22.suse.cz> <874lhz3pmn.fsf@e105922-lin.cambridge.arm.com> <20180619140818.GA16927@e107981-ln.cambridge.arm.com> <87wouu3jz1.fsf@e105922-lin.cambridge.arm.com> <20180619151425.GH13685@dhcp22.suse.cz> <87r2l23i2b.fsf@e105922-lin.cambridge.arm.com> <20180619163256.GA18952@e107981-ln.cambridge.arm.com> <814205eb-ae86-a519-bed0-f09b8e2d3a02@huawei.com> Date: Wed, 20 Jun 2018 12:51:22 +0100 In-Reply-To: <814205eb-ae86-a519-bed0-f09b8e2d3a02@huawei.com> (Xie XiuQi's message of "Wed, 20 Jun 2018 11:31:34 +0800") Message-ID: <87602d3ccl.fsf@e105922-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: Xie XiuQi Cc: Lorenzo Pieralisi , Michal Hocko , Hanjun Guo , Bjorn Helgaas , tnowicki@caviumnetworks.com, linux-pci@vger.kernel.org, Catalin Marinas , "Rafael J. Wysocki" , Will Deacon , Linux Kernel Mailing List , Jarkko Sakkinen , linux-mm@kvack.org, wanghuiqiang@huawei.com, Greg Kroah-Hartman , Bjorn Helgaas , Andrew Morton , zhongjiang , linux-arm Xie XiuQi writes: > Hi Lorenzo, Punit, > > > On 2018/6/20 0:32, Lorenzo Pieralisi wrote: >> On Tue, Jun 19, 2018 at 04:35:40PM +0100, Punit Agrawal wrote: >>> Michal Hocko writes: >>> >>>> On Tue 19-06-18 15:54:26, Punit Agrawal wrote: >>>> [...] >>>>> In terms of $SUBJECT, I wonder if it's worth taking the original patch >>>>> as a temporary fix (it'll also be easier to backport) while we work on >>>>> fixing these other issues and enabling memoryless nodes. >>>> >>>> Well, x86 already does that but copying this antipatern is not really >>>> nice. So it is good as a quick fix but it would be definitely much >>>> better to have a robust fix. Who knows how many other places might hit >>>> this. You certainly do not want to add a hack like this all over... >>> >>> Completely agree! I was only suggesting it as a temporary measure, >>> especially as it looked like a proper fix might be invasive. >>> >>> Another fix might be to change the node specific allocation to node >>> agnostic allocations. It isn't clear why the allocation is being >>> requested from a specific node. I think Lorenzo suggested this in one of >>> the threads. >> >> I think that code was just copypasted but it is better to fix the >> underlying issue. >> >>> I've started putting together a set fixing the issues identified in this >>> thread. It should give a better idea on the best course of action. >> >> On ACPI ARM64, this diff should do if I read the code correctly, it >> should be (famous last words) just a matter of mapping PXMs to nodes for >> every SRAT GICC entry, feel free to pick it up if it works. >> >> Yes, we can take the original patch just because it is safer for an -rc >> cycle even though if the patch below would do delaying the fix for a >> couple of -rc (to get it tested across ACPI ARM64 NUMA platforms) is >> not a disaster. > > I tested this patch on my arm board, it works. I am assuming you tried the patch without enabling support for memory-less nodes. The patch de-couples the onlining of numa nodes (as parsed from SRAT) from NR_CPUS restriction. When it comes to building zonelists, the node referenced by the PCI controller also has zonelists initialised. So it looks like a fallback node is setup even if we don't have memory-less nodes enabled. I need to stare some more at the code to see why we need memory-less nodes at all then ...