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[23.128.96.18]) by mx.google.com with ESMTP id j23si5291560ejt.141.2020.07.02.07.37.35; Thu, 02 Jul 2020 07:37:58 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729833AbgGBOhB (ORCPT + 99 others); Thu, 2 Jul 2020 10:37:01 -0400 Received: from mga14.intel.com ([192.55.52.115]:42838 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729482AbgGBOhA (ORCPT ); Thu, 2 Jul 2020 10:37:00 -0400 IronPort-SDR: xO8tR+mowZn4yl3flv0a/xv2gmfy6RHxIVwX/X9Rkv5YkZ5jgiYSgLBhtZuK5YD/KK5+9NMUm3 1OnDx79CB4qg== X-IronPort-AV: E=McAfee;i="6000,8403,9670"; a="145983041" X-IronPort-AV: E=Sophos;i="5.75,304,1589266800"; d="scan'208";a="145983041" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Jul 2020 07:36:58 -0700 IronPort-SDR: CM3DPPkyiJe3vZfIlaCmnewZRAKk5YPUkoRGcE7QBybvRLtdhW5RJJyrKnQtmfWFVSnytDV68M XVzKzjSILfbw== X-IronPort-AV: E=Sophos;i="5.75,304,1589266800"; d="scan'208";a="455540658" Received: from rapyeatx-mobl3.amr.corp.intel.com (HELO [10.255.2.31]) ([10.255.2.31]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Jul 2020 07:36:57 -0700 Subject: Re: [PATCH 1/3] mm/vmscan: restore zone_reclaim_mode ABI To: "Huang, Ying" , Dave Hansen Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, ben.widawsky@intel.com, alex.shi@linux.alibaba.com, dwagner@suse.de, tobin@kernel.org, cl@linux.com, akpm@linux-foundation.org, dan.j.williams@intel.com, cai@lca.pw, stable@vger.kernel.org References: <20200701152621.D520E62B@viggo.jf.intel.com> <20200701152623.384AF0A7@viggo.jf.intel.com> <87d05ejgug.fsf@yhuang-dev.intel.com> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <87d05ejgug.fsf@yhuang-dev.intel.com> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/2/20 4:28 AM, Huang, Ying wrote: >> But, when the bit was removed (bit 0) the _other_ bit locations also >> got changed. That's not OK because the bit values are documented to >> mean one specific thing and users surely rely on them meaning that one >> thing and not changing from kernel to kernel. The end result is that >> if someone had a script that did: >> >> sysctl vm.zone_reclaim_mode=1 >> >> That script went from doing nothing > Per my understanding, this script would have enabled node reclaim for > clean unmapped pages before commit 648b5cf368e0 ("mm/vmscan: remove > unused RECLAIM_OFF/RECLAIM_ZONE"). So we should revise the description > here? Yes, you're right. I updated the patch with the updated understanding about the implicit use of the bit but didn't update the changelog. I'll do that for v3.