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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 D39B4C433E2 for ; Wed, 16 Sep 2020 20:11:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7615A20936 for ; Wed, 16 Sep 2020 20:11:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="c6d1Pe73" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727295AbgIPULH (ORCPT ); Wed, 16 Sep 2020 16:11:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33320 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726959AbgIPRdl (ORCPT ); Wed, 16 Sep 2020 13:33:41 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4BE31C0698D9; Wed, 16 Sep 2020 04:46:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=hjBH8eVL+KDdz8o5+TTH4XgmzDXF3Ypdoh1lK++brXA=; b=c6d1Pe73asPhsa8UwmMbFCMHuc 30c0hUpFGmdZ3T+2maRv/Aphr+ijWpB6twr3lqPXo3SqRcE3m1fLfQHupLkwInCNBhg4EbNliywyp 5tn7MJ6HuZr1OyIOc1gZ6+tuezc1NNz6SnMqtbCc1g4R8I4h6PCPeLsLGwopt927alBBTvq2fJCBx yr9h4lzYKBVGV0lx5e8QpHoBDPBURlS8Y64isfcdaej5vhJdW+46SDYfJNHdv1OFxRBW4V7kIE0iP xNp2P2Bl0MwFONf+QJ3w3fKDjvhk+faEKwV+Qqwd/jYxU7uu6VwJmWjdk2v3nCspmSLdN4ZSQcQFv rc2+HYxw==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kIVth-0002Mx-Lo; Wed, 16 Sep 2020 11:46:49 +0000 Date: Wed, 16 Sep 2020 12:46:49 +0100 From: Matthew Wilcox To: Christoph Hellwig Cc: Alexander Viro , linux-fsdevel@vger.kernel.org, Hugh Dickins , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Song Liu , Rik van Riel , "Kirill A . Shutemov" , Johannes Weiner , Dave Chinner Subject: Re: [PATCH 2/2] fs: Do not update nr_thps for mappings which support THPs Message-ID: <20200916114649.GM5449@casper.infradead.org> References: <20200916032717.22917-1-willy@infradead.org> <20200916032717.22917-2-willy@infradead.org> <20200916052126.GA12923@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200916052126.GA12923@infradead.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 16, 2020 at 06:21:26AM +0100, Christoph Hellwig wrote: > On Wed, Sep 16, 2020 at 04:27:17AM +0100, Matthew Wilcox (Oracle) wrote: > > The nr_thps counter is to support THPs in the page cache when the > > filesystem doesn't understand THPs. Eventually it will be removed, but > > we should still support filesystems which do not understand THPs yet. > > Move the nr_thp manipulation functions to filemap.h since they're > > page-cache specific. > > Honestly I don't think we should support the read-only THP crap. We > should in fact never have merged that bandaid to start with given that > you did good progress on the real thing. I'd like to see the feature ripped out again, yes. Once we have a few more filesystems converted, I think that'll be a reasonable thing to do. It was a good step along the way; Song fixed a number of problems, and worked on other things that I never had to learn anything about (like uprobes and khugepaged). I wouldn't go so far as to say we should never have merged it, but I think we can remove it in about six months.