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=-3.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT 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 F2332C43444 for ; Fri, 21 Dec 2018 10:28:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BFC0A2190A for ; Fri, 21 Dec 2018 10:28:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="cSG9ZZA3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389701AbeLUK2c (ORCPT ); Fri, 21 Dec 2018 05:28:32 -0500 Received: from mail-pf1-f194.google.com ([209.85.210.194]:36413 "EHLO mail-pf1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388453AbeLUK2a (ORCPT ); Fri, 21 Dec 2018 05:28:30 -0500 Received: by mail-pf1-f194.google.com with SMTP id b85so2418281pfc.3 for ; Fri, 21 Dec 2018 02:28:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=MgbpNXZ6syJHgHjQ8P1oZ35HgImgeEw19kIRzY6x14U=; b=cSG9ZZA3fT8HYV/V9anzC5xuETlC9Aib/IxtvWOWI2Nhq0RklUAvHyM0uIMIMK3WZg GYtK1unGm577Sa2IcIYo8tA3SXjFCTRBkpPf5+6Zx1CGIvcIS9icWHqLAsQNUYHMaIWa eEO0Qin2XepxyOoW8z5+DZE8aSVn/5w7ytRXogLhtScCU66HQBKi1HcsWOvj5sJpauQT IIqm1+D+/i112y4e4Iq+bYDvfnuVdMS7RS/03MNZcII398DR+kdZ2RgTrttTUAn0mK5y ngbjnJwd3m7rFp59k8vV6MD9R3dpY6GoajZqgNV/MInCYnqNQ4vOYGn8u+HgEnsnw3JQ 5sIg== 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:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=MgbpNXZ6syJHgHjQ8P1oZ35HgImgeEw19kIRzY6x14U=; b=KCvqo8zEV6x4B5Rbtux5hyhCo8Khq63A0zBy7ku5KyIXnv43ohq2QeAUsa1py2F0NA YpKmZn4bY5xGjBpX/N9HPq9EeaVDBM4ezN26mp9Bdkg875NLYDvQ0kCzA+O+rzhL6wZO uJhLt6dEi9FzX3F1gcCmALLywH6Y5akOU0lvfz22Sjl0D0KbI/CQp34b1YTLgDmTfLqa oqJNNIqB8QXI0Bc8nbFg+dTAPgvK9RAvYWF0wzP+/aAlfKNjWRLq/6E/o+v1NMIVsfdZ kKOnuM7/YiB/VjAP/xHdIfAHHwmRD+a0hbUaDEJjewnGR54OUsyqBcaEMhSRZ9WkbXcd jlaw== X-Gm-Message-State: AJcUuke4cweECNXowgOQ/ucPtrEQ+CEcMFm5YdIA2Ru5gM50LEpX4CEZ aqn/dCQI6Pkt+fVPD46xLZyJuA== X-Google-Smtp-Source: ALg8bN7neVcA9AyznbeQA/+AEASrdVOx3pWQWTYxFrg4kai4vlauWcjPXwi6ZWnFCRAu6drNKoD55g== X-Received: by 2002:a65:448a:: with SMTP id l10mr1823475pgq.387.1545388109580; Fri, 21 Dec 2018 02:28:29 -0800 (PST) Received: from kshutemo-mobl1.localdomain (fmdmzpr04-ext.fm.intel.com. [192.55.54.39]) by smtp.gmail.com with ESMTPSA id s190sm30628986pfb.103.2018.12.21.02.28.28 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 21 Dec 2018 02:28:28 -0800 (PST) Received: by kshutemo-mobl1.localdomain (Postfix, from userid 1000) id 90C24300816; Fri, 21 Dec 2018 13:28:24 +0300 (+03) Date: Fri, 21 Dec 2018 13:28:24 +0300 From: "Kirill A. Shutemov" To: Mike Kravetz Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Michal Hocko , Hugh Dickins , Naoya Horiguchi , "Aneesh Kumar K . V" , Andrea Arcangeli , "Kirill A . Shutemov" , Davidlohr Bueso , Prakash Sangappa , Andrew Morton , stable@vger.kernel.org Subject: Re: [PATCH v2 2/2] hugetlbfs: Use i_mmap_rwsem to fix page fault/truncate race Message-ID: <20181221102824.5v36l6l5t2zthpgr@kshutemo-mobl1> References: <20181218223557.5202-1-mike.kravetz@oracle.com> <20181218223557.5202-3-mike.kravetz@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181218223557.5202-3-mike.kravetz@oracle.com> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 18, 2018 at 02:35:57PM -0800, Mike Kravetz wrote: > Instead of writing the required complicated code for this rare > occurrence, just eliminate the race. i_mmap_rwsem is now held in read > mode for the duration of page fault processing. Hold i_mmap_rwsem > longer in truncation and hold punch code to cover the call to > remove_inode_hugepages. One of remove_inode_hugepages() callers is noticeably missing -- hugetlbfs_evict_inode(). Why? It at least deserves a comment on why the lock rule doesn't apply to it. -- Kirill A. Shutemov