From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v7] numa: make node_to_cpumask_map() NUMA_NO_NODE aware Date: Wed, 30 Oct 2019 11:14:49 +0100 Message-ID: <20191030101449.GW4097@hirez.programming.kicks-ass.net> References: <1572428068-180880-1-git-send-email-linyunsheng@huawei.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=1zcHzV6zD9O31in8kloh0B+z/m7z7NmzyB+w3XnQ5n0=; b=R7ox8vy3ZnrhdMdpFSPLH1wLK vjbto6CkcTHdr4TJVIm3ERYb4ndeFEeQFraxfzpfbDzos7ani8v/0uI6sWTJELWdkjkKUalPdsQTS tl22rW36Q/iROk+G23RItInYa+B+jvCzzSVzNfAC0wiLxfcUuKVXCXZdr3FIIXlZ4Dfyn1uQ24eFC tl9g8DX8oZgSYA/CFZEIb+KktE50EeCeJONwTWEYqijdFf1mF+EN+3YEMjzL688bnj5c8oJDrn7AL PYm6mywIXQC9HQN6Xo3gs0E/F0l18VtctAko4q2TDwWxQR7TP7OZ6PppUcsHNZII8/TcsME8CL183 Content-Disposition: inline In-Reply-To: <1572428068-180880-1-git-send-email-linyunsheng@huawei.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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.c 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)