From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.133]:43950 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727531AbfIXJSR (ORCPT ); Tue, 24 Sep 2019 05:18:17 -0400 Date: Tue, 24 Sep 2019 11:17:14 +0200 From: Peter Zijlstra Subject: Re: [PATCH v6] numa: make node_to_cpumask_map() NUMA_NO_NODE aware Message-ID: <20190924091714.GJ2369@hirez.programming.kicks-ass.net> References: <1568724534-146242-1-git-send-email-linyunsheng@huawei.com> <20190923151519.GE2369@hirez.programming.kicks-ass.net> <20190923152856.GB17206@dhcp22.suse.cz> <20190923154852.GG2369@hirez.programming.kicks-ass.net> <20190923165235.GD17206@dhcp22.suse.cz> <20190923203410.GI2369@hirez.programming.kicks-ass.net> <20190924074751.GB23050@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190924074751.GB23050@dhcp22.suse.cz> Sender: linux-s390-owner@vger.kernel.org List-ID: To: Michal Hocko Cc: Yunsheng Lin , catalin.marinas@arm.com, will@kernel.org, mingo@redhat.com, bp@alien8.de, rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, heiko.carstens@de.ibm.com, gor@linux.ibm.com, borntraeger@de.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, ralf@linux-mips.org, paul.burton@mips.com, jhogan@kernel.org, jiaxun.yang@flygoat.com, chenhc@lemote.com, akpm@linux-foundation.org, rppt@linux.ibm.com, anshuman.khandual@arm.com, tglx@linutronix.de, cai@lca.pw, robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, hpa@zytor.com, x86@kernel.org, dave.hansen@linux.intel.com, luto@kernel.org, len.brown@intel.com, axboe@kernel.dk, dledford@redhat.com, jeffrey.t.kirsher@intel.com, linux-alpha@vger.kernel.org, naveen.n.rao@linux.vnet.ibm.com, mwb@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, tbogendoerfer@suse.de, linux-mips@vger.kernel.org, rafael@kernel.org, gregkh@linuxfoundation.org On Tue, Sep 24, 2019 at 09:47:51AM +0200, Michal Hocko wrote: > On Mon 23-09-19 22:34:10, Peter Zijlstra wrote: > > On Mon, Sep 23, 2019 at 06:52:35PM +0200, Michal Hocko wrote: > [...] > > > I even the > > > ACPI standard is considering this optional. Yunsheng Lin has referred to > > > the specific part of the standard in one of the earlier discussions. > > > Trying to guess the node affinity is worse than providing all CPUs IMHO. > > > > I'm saying the ACPI standard is wrong. > > Even if you were right on this the reality is that a HW is likely to > follow that standard and we cannot rule out NUMA_NO_NODE being > specified. As of now we would access beyond the defined array and that > is clearly a bug. Right, because the device node is wrong, so we fix _that_! > Let's assume that this is really a bug for a moment. What are you going > to do about that? BUG_ON? I do not really see any solution besides to either > provide something sensible or BUG_ON. If you are worried about a > conditional then this should be pretty easy to solve by starting the > array at -1 index and associate it with the online cpu mask. The same thing I proposed earlier; force the device node to 0 (or any other convenient random valid value) and issue a FW_BUG message to the console.