From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.133]:56104 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727879AbfIXMKe (ORCPT ); Tue, 24 Sep 2019 08:10:34 -0400 Date: Tue, 24 Sep 2019 14:09:43 +0200 From: Peter Zijlstra Subject: Re: [PATCH v6] numa: make node_to_cpumask_map() NUMA_NO_NODE aware Message-ID: <20190924120943.GP2349@hirez.programming.kicks-ass.net> References: <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> <20190924115401.GM23050@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190924115401.GM23050@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 01:54:01PM +0200, Michal Hocko wrote: > 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. Like I said; how does that physically work? The device needs to be somewhere. It _must_ have a preference. > 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". We can push back and say we don't respect the specification because it is batshit insane ;-) > 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? I just genuinely don't understand it. And I refuse to duct tape it. And as shown in that email here: https://lkml.kernel.org/r/5a188e2b-6c07-a9db-fbaa-561e9362d3ba@huawei.com there is a ton of broken... 15.061682] node node0: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. ... 15.285602] node node3: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. 15.360241] cpu cpu0: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. ... 24.768305] cpu cpu127: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. 39.623339] clockevents clockevent0: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. ... 48.769530] clockevents clockevent127: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. That's all broken for no reason.. those things actually _have_ a trivial node affinity. By silently accepting we let this stuff fester. Now granted; there's a number of virtual devices that really don't have a node affinity, but then, those are not hurt by forcing them onto a random node, they really don't do anything. Like: 48.913502] event_source armv8_pmuv3_0: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. 48.985462] event_source breakpoint: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. 49.057120] event_source uprobe: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. 49.128431] event_source kprobe: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. 49.199742] event_source tracepoint: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. 49.271399] event_source software: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. That's just fake devices to get a sysfs entry.