From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CBA55C43142 for ; Thu, 2 Aug 2018 09:15:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8C250214F1 for ; Thu, 2 Aug 2018 09:15:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8C250214F1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731994AbeHBLGM (ORCPT ); Thu, 2 Aug 2018 07:06:12 -0400 Received: from mx2.suse.de ([195.135.220.15]:52344 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726293AbeHBLGM (ORCPT ); Thu, 2 Aug 2018 07:06:12 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id CF0B5AE20; Thu, 2 Aug 2018 09:15:55 +0000 (UTC) Date: Thu, 2 Aug 2018 11:15:54 +0200 From: Michal Hocko To: Jeremy Linton Cc: linux-mm@kvack.org, cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, vbabka@suse.cz, Punit.Agrawal@arm.com, Lorenzo.Pieralisi@arm.com, linux-arm-kernel@lists.infradead.org, bhelgaas@google.com, linux-kernel@vger.kernel.org Subject: Re: [RFC 1/2] slub: Avoid trying to allocate memory on offline nodes Message-ID: <20180802091554.GE10808@dhcp22.suse.cz> References: <20180801200418.1325826-1-jeremy.linton@arm.com> <20180801200418.1325826-2-jeremy.linton@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180801200418.1325826-2-jeremy.linton@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 01-08-18 15:04:17, Jeremy Linton wrote: [...] > @@ -2519,6 +2519,8 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, > if (unlikely(!node_match(page, searchnode))) { > stat(s, ALLOC_NODE_MISMATCH); > deactivate_slab(s, page, c->freelist, c); > + if (!node_online(searchnode)) > + node = NUMA_NO_NODE; > goto new_slab; This is inherently racy. Numa node can get offline at any point after you check it here. Making it race free would involve some sort of locking and I am not really convinced this is a good idea. > } > } > -- > 2.14.3 > -- Michal Hocko SUSE Labs