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=HEADER_FROM_DIFFERENT_DOMAINS, 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 5E896C4321D for ; Tue, 21 Aug 2018 12:30:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 12EE0214DD for ; Tue, 21 Aug 2018 12:30:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 12EE0214DD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=techadventures.net 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 S1727415AbeHUPuY (ORCPT ); Tue, 21 Aug 2018 11:50:24 -0400 Received: from mail-wr1-f68.google.com ([209.85.221.68]:40052 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727043AbeHUPuX (ORCPT ); Tue, 21 Aug 2018 11:50:23 -0400 Received: by mail-wr1-f68.google.com with SMTP id n2-v6so5230064wrw.7 for ; Tue, 21 Aug 2018 05:30:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=RT1SNjDjJjENmAIpbmSZQgEfAJp/COrESxQvq7RVcWk=; b=V+ld3rCTcqrcKP/68xcwJy7FTI+AGxvdoC8npqso8RMn10aBrKKmRT3BNOGfCYnjsl JHeV4ODS0TODVurV95MtPgPRg5x7AoA3ja/7s/Eee98PfrWhgzipoAaWfj+CmKviB+9a oXx4Cu5qcUuXRK7f7Gsepcer0lgMb9TaQv6VGT7Xa1vrdZrhzNap/yjOVo38ccCVMIbA dlWXaem4+bdn/1ee1s4Lsm9A0MLWnsqR3BkFuizAfMxREbq+S1TvgzP8S8SXhLh0C4no iogFuis9gH67/maubm0Yk4w/TEMsr1An3drWly9NdEbsD45qhzQlPmgVl7Lf3hb1jNuA fW1g== X-Gm-Message-State: AOUpUlFxU1OD/RTAJJ9QUMPmQuQHhMfBDYCLRteSAcUk4jflFkizgV00 O0Zo10NdQWK68Yq1R6Qy0Yb2vAoc X-Google-Smtp-Source: AA+uWPyA87MPa9EnJXbwiWvh03b7KHBjGItqdOR7/20Q11Ajry5YxwBYc3dhV85vRRlN9I8r8MUzgw== X-Received: by 2002:adf:dd07:: with SMTP id a7-v6mr30730648wrm.2.1534854625400; Tue, 21 Aug 2018 05:30:25 -0700 (PDT) Received: from techadventures.net (techadventures.net. [62.201.165.239]) by smtp.gmail.com with ESMTPSA id w3-v6sm8270782wrn.16.2018.08.21.05.30.24 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 21 Aug 2018 05:30:24 -0700 (PDT) Received: by techadventures.net (Postfix, from userid 1000) id 20FB41249C0; Tue, 21 Aug 2018 14:30:24 +0200 (CEST) Date: Tue, 21 Aug 2018 14:30:24 +0200 From: Oscar Salvador To: Michal Hocko Cc: Andrew Morton , tglx@linutronix.de, joe@perches.com, arnd@arndb.de, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Oscar Salvador Subject: Re: [PATCH] mm: Fix comment for NODEMASK_ALLOC Message-ID: <20180821123024.GA9489@techadventures.net> References: <20180820085516.9687-1-osalvador@techadventures.net> <20180820142440.1f9ccbebefc5d617c881b41e@linux-foundation.org> <20180821121734.GA29735@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180821121734.GA29735@dhcp22.suse.cz> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 21, 2018 at 02:17:34PM +0200, Michal Hocko wrote: > We do have CONFIG_NODES_SHIFT=10 in our SLES kernels for quite some > time (around SLE11-SP3 AFAICS). > > Anyway, isn't NODES_ALLOC over engineered a bit? Does actually even do > larger than 1024 NUMA nodes? This would be 128B and from a quick glance > it seems that none of those functions are called in deep stacks. I > haven't gone through all of them but a patch which checks them all and > removes NODES_ALLOC would be quite nice IMHO. No, maximum we can get is 1024 NUMA nodes. I checked this when writing another patch [1], and since having gone through all archs Kconfigs, CONFIG_NODES_SHIFT=10 is the limit. NODEMASK_ALLOC gets only called from: - unregister_mem_sect_under_nodes() (not anymore after [1]) - __nr_hugepages_store_common (This does not seem to have a deep stack, we could use a normal nodemask_t) But is also used for NODEMASK_SCRATCH (mainly used for mempolicy): struct nodemask_scratch { nodemask_t mask1; nodemask_t mask2; }; that would make 256 bytes in case CONFIG_NODES_SHIFT=10. I am not familiar with mempolicy code, I am not sure if we can do without that and figure out another way to achieve the same. [1] https://patchwork.kernel.org/patch/10566673/#22179663 -- Oscar Salvador SUSE L3