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=-5.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 4E391C433DF for ; Wed, 19 Aug 2020 20:15:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 251C4207DE for ; Wed, 19 Aug 2020 20:15:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="YXxWdcY4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726952AbgHSUP1 (ORCPT ); Wed, 19 Aug 2020 16:15:27 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:42301 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725997AbgHSUP0 (ORCPT ); Wed, 19 Aug 2020 16:15:26 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1597868124; h=from:from:reply-to:subject:subject: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=6wZSRsOZbW0ppoxwbf389BsXiaVqGjFLolCHa9KVfRI=; b=YXxWdcY4HFERidCUvivy2lAFiT9sXrCtM0CK/AmL6kUoEWhaG+fIW4x0YTqvfVAYBzQklc I2Embfj6ifM2Q14ueEhocZGy3f4hZj2HwTUbfF5HcbhHUSrnAzFaKmBv7gLIYJkJg86X52 JzjR4gxWQOcdUSJasVNzKl9Tlo6g25I= Received: from mail-pj1-f72.google.com (mail-pj1-f72.google.com [209.85.216.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-487-X3vWWMcLNg6XKdITSWTFnQ-1; Wed, 19 Aug 2020 16:15:22 -0400 X-MC-Unique: X3vWWMcLNg6XKdITSWTFnQ-1 Received: by mail-pj1-f72.google.com with SMTP id e2so2084101pjm.3 for ; Wed, 19 Aug 2020 13:15:22 -0700 (PDT) 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=6wZSRsOZbW0ppoxwbf389BsXiaVqGjFLolCHa9KVfRI=; b=OqtMZq7aMchOFdiqWlG4fCq+dvdmnJ7VbqOhLDeJar04E1xT+UDHOGzyAbmrKdM/XO pVZhuE+SdwWhpyQhP9U4UNl43pbhJbMIZDWRi3iG3gFQKMqqJPlveChp8vM1GsfhxkbS aWlui3pKW+KncGltfGr/fXYZsDeTKRaOSZ1GKCNEev53hvkbc3L0gB5E1XErrTLuA/5x bvc/Jrq719M73ktGQJ6ZZDFn1VbXTgYufWjimJqYfddSLNi5Q2LDNbjKLgPP8G7Cnou1 6LLtI2l+ZH7NyCmBCJ4ZwY7E6OKhEdG/Jg1RqyRxG5VxA3lmZwGphXKIlD9jV/z7DNve UJhQ== X-Gm-Message-State: AOAM533V/SzC1OM0YVV/jiyUqg+E+3CqK0yKtG/X6ojffEC4wPxhvMn7 v3XZcRYfBSqdv+T3V+ytFuOarSe/adXpRNYplZnLPd3UgHq6uD6/tZs0rIBwt4+/NlSiGsf4H1x 3Deuv1N4gIReaua0UXpySpUq1 X-Received: by 2002:a17:90a:fa06:: with SMTP id cm6mr5515130pjb.129.1597868121452; Wed, 19 Aug 2020 13:15:21 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxZ6K3xi/zuEXaLDp+AhVXh18fIyTkt9TT32R+RhUbJpOr/tX/cuBKSRunO6DGE9U7OgqK+kw== X-Received: by 2002:a17:90a:fa06:: with SMTP id cm6mr5515108pjb.129.1597868121185; Wed, 19 Aug 2020 13:15:21 -0700 (PDT) Received: from xiangao.remote.csb ([209.132.188.80]) by smtp.gmail.com with ESMTPSA id s125sm56651pfc.63.2020.08.19.13.15.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Aug 2020 13:15:20 -0700 (PDT) Date: Thu, 20 Aug 2020 04:15:09 +0800 From: Gao Xiang To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Rafael Aquini , Carlos Maiolino , Eric Sandeen , "Huang, Ying" , stable Subject: Re: [PATCH] mm, THP, swap: fix allocating cluster for swapfile by mistake Message-ID: <20200819201509.GA26216@xiangao.remote.csb> References: <20200819195613.24269-1-hsiangkao@redhat.com> <20200819130506.eea076dd618644cd7ff875b6@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200819130506.eea076dd618644cd7ff875b6@linux-foundation.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Andrew, On Wed, Aug 19, 2020 at 01:05:06PM -0700, Andrew Morton wrote: > On Thu, 20 Aug 2020 03:56:13 +0800 Gao Xiang wrote: > > > SWP_FS doesn't mean the device is file-backed swap device, > > which just means each writeback request should go through fs > > by DIO. Or it'll just use extents added by .swap_activate(), > > but it also works as file-backed swap device. > > This is very hard to understand :( Thanks for your reply... The related logic is in __swap_writepage() and setup_swap_extents(), and also see e.g generic_swapfile_activate() or iomap_swapfile_activate()... I will also talk with "Huang, Ying" in person if no response here. > > > So in order to achieve the goal of the original patch, > > SWP_BLKDEV should be used instead. > > > > FS corruption can be observed with SSD device + XFS + > > fragmented swapfile due to CONFIG_THP_SWAP=y. > > > > Fixes: f0eea189e8e9 ("mm, THP, swap: Don't allocate huge cluster for file backed swap device") > > Fixes: 38d8b4e6bdc8 ("mm, THP, swap: delay splitting THP during swap out") > > Why do you think it has taken three years to discover this? I'm not sure if the Redhat BZ is available for public, it can be reproduced since rhel 8 https://bugzilla.redhat.com/show_bug.cgi?id=1855474 It seems hard to believe, but I think just because rare user uses the SSD device + THP + file-backed swap device combination... maybe I'm wrong here, but my test shows as it is. Thanks, Gao Xiang > > >