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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 7E670C433DB for ; Wed, 6 Jan 2021 16:14:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2ED6223130 for ; Wed, 6 Jan 2021 16:14:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727353AbhAFQOP (ORCPT ); Wed, 6 Jan 2021 11:14:15 -0500 Received: from mx2.suse.de ([195.135.220.15]:46258 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726661AbhAFQOO (ORCPT ); Wed, 6 Jan 2021 11:14:14 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1609949608; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=AOi5pYVGtWhmhkLhxN1VHSlGmbztJKzjsiPHFHewBmU=; b=aGj1bDy/JRpCkftBmuSI0gD7ypZdqUNoo4G9LvTymw2LI1WrDXgAZ9/bEyFDpnW6+GZw7B pwhAIRUOEbjz+RdURkBn09vdDGFeBeQQ1IwogZx6i/Zgl+uRnBj6arBNX2uX9aVxa5tc+x twevcxVsyXJk391Qp5lhfZRmBwTLamM= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id B9100B76C; Wed, 6 Jan 2021 16:13:28 +0000 (UTC) Date: Wed, 6 Jan 2021 17:13:27 +0100 From: Michal Hocko To: Muchun Song Cc: mike.kravetz@oracle.com, akpm@linux-foundation.org, n-horiguchi@ah.jp.nec.com, ak@linux.intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Yang Shi Subject: Re: [PATCH v2 1/6] mm: migrate: do not migrate HugeTLB page whose refcount is one Message-ID: <20210106161327.GR13207@dhcp22.suse.cz> References: <20210106084739.63318-1-songmuchun@bytedance.com> <20210106084739.63318-2-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210106084739.63318-2-songmuchun@bytedance.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 06-01-21 16:47:34, Muchun Song wrote: > If the refcount is one when it is migrated, it means that the page > was freed from under us. So we are done and do not need to migrate. Is this common enough that it would warrant the explicit check for each migration? -- Michal Hocko SUSE Labs