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 58CBBC433E0 for ; Wed, 6 Jan 2021 16:13:32 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DB9072246B for ; Wed, 6 Jan 2021 16:13:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DB9072246B Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3C7CA6B029A; Wed, 6 Jan 2021 11:13:31 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 39DEC6B029C; Wed, 6 Jan 2021 11:13:31 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2B3F46B029D; Wed, 6 Jan 2021 11:13:31 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0190.hostedemail.com [216.40.44.190]) by kanga.kvack.org (Postfix) with ESMTP id 125916B029A for ; Wed, 6 Jan 2021 11:13:31 -0500 (EST) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id CC5411E1F for ; Wed, 6 Jan 2021 16:13:30 +0000 (UTC) X-FDA: 77675845380.21.wool43_3e1066f274e2 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin21.hostedemail.com (Postfix) with ESMTP id A46B7180442C0 for ; Wed, 6 Jan 2021 16:13:30 +0000 (UTC) X-HE-Tag: wool43_3e1066f274e2 X-Filterd-Recvd-Size: 1908 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf35.hostedemail.com (Postfix) with ESMTP for ; Wed, 6 Jan 2021 16:13:30 +0000 (UTC) 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> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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