From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.133]:49208 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726073AbfJ3KOv (ORCPT ); Wed, 30 Oct 2019 06:14:51 -0400 Date: Wed, 30 Oct 2019 11:14:49 +0100 From: Peter Zijlstra Subject: Re: [PATCH v7] numa: make node_to_cpumask_map() NUMA_NO_NODE aware Message-ID: <20191030101449.GW4097@hirez.programming.kicks-ass.net> References: <1572428068-180880-1-git-send-email-linyunsheng@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1572428068-180880-1-git-send-email-linyunsheng@huawei.com> Sender: linux-s390-owner@vger.kernel.org List-ID: To: Yunsheng Lin Cc: 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, mhocko@kernel.org, gregkh@linuxfoundation.org, bhelgaas@google.com, linux-pci@vger.kernel.org, rjw@rjwysocki.net, lenb@kernel.org, linux-acpi@vger.kernel.org On Wed, Oct 30, 2019 at 05:34:28PM +0800, Yunsheng Lin wrote: > When passing the return value of dev_to_node() to cpumask_of_node() > without checking if the device's node id is NUMA_NO_NODE, there is > global-out-of-bounds detected by KASAN. > > From the discussion [1], NUMA_NO_NODE really means no node affinity, > which also means all cpus should be usable. So the cpumask_of_node() > should always return all cpus online when user passes the node id as > NUMA_NO_NODE, just like similar semantic that page allocator handles > NUMA_NO_NODE. > > But we cannot really copy the page allocator logic. Simply because the > page allocator doesn't enforce the near node affinity. It just picks it > up as a preferred node but then it is free to fallback to any other numa > node. This is not the case here and node_to_cpumask_map will only restrict > to the particular node's cpus which would have really non deterministic > behavior depending on where the code is executed. So in fact we really > want to return cpu_online_mask for NUMA_NO_NODE. > > Also there is a debugging version of node_to_cpumask_map() for x86 and > arm64, which is only used when CONFIG_DEBUG_PER_CPU_MAPS is defined, this > patch changes it to handle NUMA_NO_NODE as normal node_to_cpumask_map(). > > [1] https://lkml.org/lkml/2019/9/11/66 > Signed-off-by: Yunsheng Lin > Suggested-by: Michal Hocko > Acked-by: Michal Hocko > Acked-by: Paul Burton # MIPS bits Still: Nacked-by: Peter Zijlstra (Intel)