From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:37390 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2440891AbfIXLyF (ORCPT ); Tue, 24 Sep 2019 07:54:05 -0400 Date: Tue, 24 Sep 2019 13:54:01 +0200 From: Michal Hocko Subject: Re: [PATCH v6] numa: make node_to_cpumask_map() NUMA_NO_NODE aware Message-ID: <20190924115401.GM23050@dhcp22.suse.cz> 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> <20190924091714.GJ2369@hirez.programming.kicks-ass.net> <20190924105622.GH23050@dhcp22.suse.cz> <20190924112349.GJ2332@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190924112349.GJ2332@hirez.programming.kicks-ass.net> Sender: linux-s390-owner@vger.kernel.org List-ID: To: Peter Zijlstra 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 24-09-19 13:23:49, Peter Zijlstra wrote: > On Tue, Sep 24, 2019 at 12:56:22PM +0200, Michal Hocko wrote: [...] > > To be honest I really fail to see why to object to a simple semantic > > that NUMA_NO_NODE imply all usable cpus. Could you explain that please? > > Because it feels wrong. The device needs to be _somewhere_. It simply > cannot be node-less. What if it doesn't have any numa preference for what ever reason? There is no other way to express that than NUMA_NO_NODE. Anyway, I am not going to argue more about this because it seems more of a discussion about "HW shouldn't be doing that although the specification allows that" which cannot really have any outcome except of "feels correct/wrong". If you really feel strongly about this then we should think of a proper way to prevent this to happen because an out-of-bound access is certainly not something we really want, right? -- Michal Hocko SUSE Labs