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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 18785C43381 for ; Wed, 27 Mar 2019 13:07:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D041F206DF for ; Wed, 27 Mar 2019 13:07:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553692033; bh=ehdrA8XSdTsuYLvjpIvD3FM2sG47CInE45L5IymLs8g=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=hyF1uMKrG2ajTshyzSWI0jVhf/Ljs2dg6w5zHsK2uGy9+7sSpIh74ptvezx7EAxEg N7prK/OiemdNv3VUzMgiAm4Lx8kIlpM/IKUS4ZsNoNK2SxYVGs/roKp9Z+xrWa50Z7 3e/TwmHhV75OFHOZho2hba6/J8JiGo+RZq8GRwrQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730098AbfC0NHM (ORCPT ); Wed, 27 Mar 2019 09:07:12 -0400 Received: from mga03.intel.com ([134.134.136.65]:54578 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728101AbfC0NHM (ORCPT ); Wed, 27 Mar 2019 09:07:12 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 27 Mar 2019 06:07:11 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,276,1549958400"; d="scan'208";a="331140619" Received: from unknown (HELO localhost.localdomain) ([10.232.112.69]) by fmsmga006.fm.intel.com with ESMTP; 27 Mar 2019 06:07:10 -0700 Date: Wed, 27 Mar 2019 07:08:22 -0600 From: Keith Busch To: Yang Shi Cc: "mhocko@suse.com" , "mgorman@techsingularity.net" , "riel@surriel.com" , "hannes@cmpxchg.org" , "akpm@linux-foundation.org" , "Hansen, Dave" , "Busch, Keith" , "Williams, Dan J" , "Wu, Fengguang" , "Du, Fan" , "Huang, Ying" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 06/10] mm: vmscan: demote anon DRAM pages to PMEM node Message-ID: <20190327130822.GD7389@localhost.localdomain> References: <1553316275-21985-1-git-send-email-yang.shi@linux.alibaba.com> <1553316275-21985-7-git-send-email-yang.shi@linux.alibaba.com> <20190324222040.GE31194@localhost.localdomain> <20190327003541.GE4328@localhost.localdomain> <39d8fb56-df60-9382-9b47-59081d823c3c@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <39d8fb56-df60-9382-9b47-59081d823c3c@linux.alibaba.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 26, 2019 at 08:41:15PM -0700, Yang Shi wrote: > On 3/26/19 5:35 PM, Keith Busch wrote: > > migration nodes have higher free capacity than source nodes. And since > > your attempting THP's without ever splitting them, that also requires > > lower fragmentation for a successful migration. > > Yes, it is possible. However, migrate_pages() already has logic to > handle such case. If the target node has not enough space for migrating > THP in a whole, it would split THP then retry with base pages. Oh, you're right, my mistake on splitting. So you have a good best effort migrate, but I still think it can fail for legitimate reasons that should have a swap fallback.