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=-12.9 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1,USER_IN_DEF_DKIM_WL 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 E36C6C282DD for ; Thu, 9 Jan 2020 18:52:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B599A206ED for ; Thu, 9 Jan 2020 18:52:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="eklIOp+z" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388589AbgAISwF (ORCPT ); Thu, 9 Jan 2020 13:52:05 -0500 Received: from mail-pj1-f68.google.com ([209.85.216.68]:51916 "EHLO mail-pj1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730273AbgAISwE (ORCPT ); Thu, 9 Jan 2020 13:52:04 -0500 Received: by mail-pj1-f68.google.com with SMTP id j11so1508334pjs.1 for ; Thu, 09 Jan 2020 10:52:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:in-reply-to:message-id:references :user-agent:mime-version; bh=2BBH+3AnXzeFa/U3IS7qGFZcMtEqxZT7wCj3mRBcmeM=; b=eklIOp+zakQC1CE30sXqMuWzAwbyxZX8INDxq4BFkauoMMbdQ17lXR/YY65/cbXQ45 WaN7oI/vJTlxvxToHdamg6mLQomJzQulnRCGUbZceY2CzjGzTD8sJeTKHRgIKWwwEevq rYiw6LQC0MJ7yxDH44OqGwqt74Nt03fWbVUE+CV+sFa+mMVT9MXWSPjDJB9QEKeWbMkS pu/xIlbtYzrdTy2A0YpgtvbfD6SPFwyDz7bhKJdo/Fqrxw9RrPP9Ya2Lv6KnwMa3B29w Q4qCIzysKksxVLY80Wshbr7UR+tk8nkzbwA6lSE1ht7jWyXNE8DH00YJQGQzk4S8T1hZ jd3A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version; bh=2BBH+3AnXzeFa/U3IS7qGFZcMtEqxZT7wCj3mRBcmeM=; b=MHS6feiNFoT6HxofNcox2rpOgGdCJ57q8BfaZ+ZWtLbNAj++VxQZld+qqg/YYF+R62 vp03aNlsmeGxwtgguyYjO3yRyuv3gKw3blZDn8g3yePIZxoKiDbCnySJO5bU0VZXKAp2 +WClaBO/gpk/Plbtdbq4j3u0QJxSyCOf1geif3TjDEe8DIfJ7D4HyBoRA2v/Dr9OLACb ahXDyOQ67lotmbMw5G/i7iDBfzxIjatmgpZeLFCOczZQRLaR0b++F8s0abJAIyX5pwO6 Xl2Yt9mUqZJtOjPPATem7pl73yE4iWnGGp0WZrma7FtRnOB/XTaKj7VDCMrYSJ3xIMIR Wg/w== X-Gm-Message-State: APjAAAUzq+pQRQ29E4v7YWGvda9PSYabxYcigbzVd/U/AaRY2zY3X0Xc kFE2rBY1hgYLYsw5jbI76liKpw== X-Google-Smtp-Source: APXvYqzu1AT5fUNssLnQhi7nJ1GkArk3aIGlfIGILpdyhzsUwYdHio63+zgbvvMa4cim9caHMu4yxw== X-Received: by 2002:a17:902:6bc3:: with SMTP id m3mr12900090plt.185.1578595923103; Thu, 09 Jan 2020 10:52:03 -0800 (PST) Received: from [2620:15c:17:3:3a5:23a7:5e32:4598] ([2620:15c:17:3:3a5:23a7:5e32:4598]) by smtp.gmail.com with ESMTPSA id y14sm8351242pfe.147.2020.01.09.10.52.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Jan 2020 10:52:02 -0800 (PST) Date: Thu, 9 Jan 2020 10:52:01 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Wei Yang cc: hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com, akpm@linux-foundation.org, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kirill.shutemov@linux.intel.com, yang.shi@linux.alibaba.com, alexander.duyck@gmail.com Subject: Re: [Patch v2] mm: thp: grab the lock before manipulation defer list In-Reply-To: <20200109143054.13203-1-richardw.yang@linux.intel.com> Message-ID: References: <20200109143054.13203-1-richardw.yang@linux.intel.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 9 Jan 2020, Wei Yang wrote: > As all the other places, we grab the lock before manipulate the defer list. > Current implementation may face a race condition. > > For example, the potential race would be: > > CPU1 CPU2 > mem_cgroup_move_account split_huge_page_to_list > !list_empty > lock > !list_empty > list_del > unlock > lock > # !list_empty might not hold anymore > list_del_init > unlock > > When this sequence happens, the list_del_init() in > mem_cgroup_move_account() would crash if CONFIG_DEBUG_LIST since the > page is already been removed by list_del in split_huge_page_to_list(). > > Fixes: 87eaceb3faa5 ("mm: thp: make deferred split shrinker memcg aware") > > Signed-off-by: Wei Yang > Acked-by: David Rientjes Thanks Wei! Andrew, I'd also suggest: Cc: stable@vger.kernel.org # 5.4+