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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 1B3A3C433E6 for ; Wed, 13 Jan 2021 11:21:00 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6D6A12336F for ; Wed, 13 Jan 2021 11:20:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6D6A12336F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=bytedance.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 952788D003B; Wed, 13 Jan 2021 06:20:58 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 903438D002E; Wed, 13 Jan 2021 06:20:58 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 819978D003B; Wed, 13 Jan 2021 06:20:58 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0132.hostedemail.com [216.40.44.132]) by kanga.kvack.org (Postfix) with ESMTP id 6BB508D002E for ; Wed, 13 Jan 2021 06:20:58 -0500 (EST) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 28B34824556B for ; Wed, 13 Jan 2021 11:20:58 +0000 (UTC) X-FDA: 77700509796.29.twist84_4e07c352751d Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin29.hostedemail.com (Postfix) with ESMTP id 07C9318086CD9 for ; Wed, 13 Jan 2021 11:20:58 +0000 (UTC) X-HE-Tag: twist84_4e07c352751d X-Filterd-Recvd-Size: 3772 Received: from mail-pj1-f53.google.com (mail-pj1-f53.google.com [209.85.216.53]) by imf02.hostedemail.com (Postfix) with ESMTP for ; Wed, 13 Jan 2021 11:20:57 +0000 (UTC) Received: by mail-pj1-f53.google.com with SMTP id y12so942450pji.1 for ; Wed, 13 Jan 2021 03:20:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=4itm2nFdFTo23gw4YVK9Laikkc7ZPrs4G1cHd0Rl8Ls=; b=a9Oq9XAprkYfHTeno/RpjsivMC4RbCA+3vBkjxxyfqFTC71dxJ2G5qR3WgFOT3jBo/ 8pgkarOizjJnjl4QQPw0DmOUrDUoNa7g7H7/dHFrgMJtLhoiy2NAz5B1G/Uf2Z0ymdH1 dhqIHSIKpt4reg8jmn6//yNnaJIaAavy7ZSQo1m3+TO8NBHbbklUJHg5twUl8OtM687m CbXDwukYkh02uPKsGy/vUQZMF8DmcI1aJ/fDfdy2hs8N3w0nFtrBIIAoz/vqAWBcFjuO slgy8wfoIY3+c4YszaTJPy4A6Ew6cUMPnmxc6cgnQiy7IECZla5FL/LDzL7B9uKsw3pA LUng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=4itm2nFdFTo23gw4YVK9Laikkc7ZPrs4G1cHd0Rl8Ls=; b=IQtDACIi5q8ZcusOpaPI7XrH6ktsWoLQ0ejW5QtUR7PcPe77TB5ROINIXb464VUAvI HePMgyTPCOeTs/rmMSCNVingL+X7aqGLZD0HY168xPx+CgLt2Ccuw2hNlYr+fH6Hahlt OEx+d+Sr+FhJJaqy4/n8VKj98XYHe1og5dEgsmaBY5r3uuQbFbGmfvVjobc/hAB/5oyo dF3+f40d/sGmSSji3vKuq6fijovUQkQX1ngReOtiiRtgIl00SGV8aC6hIVbIAVIMaM4m Rj0zY3hUcjvntnLKI3xwy+jL1hH0XropTMa0ncdPJ8G8Pwyggv4HRNrg/ARG8KmbDL2v 9g9g== X-Gm-Message-State: AOAM533OxYiwP2AHg5ps5dYq036ivo1kyt3oPaiOr9bhCv8y7zMxaxdP 9vb0A4XiQMoRf3tSVo66duCfNY2Ex78s5tU/stUHpw== X-Google-Smtp-Source: ABdhPJyv8BplOZEuDtAFQyPEJVczxKgdzpmehJ9wH/oHDDrs0Yhu/BkS4+qjxB526x/b//CCgcLydpIqQ/wNwUdvZKA= X-Received: by 2002:a17:902:8503:b029:dc:44f:62d8 with SMTP id bj3-20020a1709028503b02900dc044f62d8mr1743880plb.34.1610536856321; Wed, 13 Jan 2021 03:20:56 -0800 (PST) MIME-Version: 1.0 References: <20210113052209.75531-1-songmuchun@bytedance.com> <20210113052209.75531-5-songmuchun@bytedance.com> <20210113093331.GV22493@dhcp22.suse.cz> <20210113103836.GW22493@dhcp22.suse.cz> <20210113111449.GA26873@linux> In-Reply-To: <20210113111449.GA26873@linux> From: Muchun Song Date: Wed, 13 Jan 2021 19:20:17 +0800 Message-ID: Subject: Re: [External] Re: [PATCH v4 4/6] mm: hugetlb: retry dissolve page when hitting race To: Oscar Salvador Cc: Michal Hocko , Mike Kravetz , Andrew Morton , Naoya Horiguchi , Andi Kleen , Linux Memory Management List , LKML Content-Type: text/plain; charset="UTF-8" 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, Jan 13, 2021 at 7:15 PM Oscar Salvador wrote: > > On Wed, Jan 13, 2021 at 07:11:06PM +0800, Muchun Song wrote: > > If there is no task to be scheduled. Here is just a while loop. > > The cpu_relax is a good thing to insert into busy-wait loops, > > right? > > But if the race window is that small, does it make sense? Actually, there is one exception. The race window could become larger. If the page is freed via a workqueue (see free_huge_page()). In this case, the cpu_relax() can make sense. Right? > > -- > Oscar Salvador > SUSE L3