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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 80C16C433F5 for ; Tue, 12 Oct 2021 01:51:59 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EBC21608FB for ; Tue, 12 Oct 2021 01:51:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org EBC21608FB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 56680900002; Mon, 11 Oct 2021 21:51:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4EF0F6B0071; Mon, 11 Oct 2021 21:51:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3B74C900002; Mon, 11 Oct 2021 21:51:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0191.hostedemail.com [216.40.44.191]) by kanga.kvack.org (Postfix) with ESMTP id 274DF6B006C for ; Mon, 11 Oct 2021 21:51:58 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id D68C318215475 for ; Tue, 12 Oct 2021 01:51:57 +0000 (UTC) X-FDA: 78686109474.05.50F109D Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf15.hostedemail.com (Postfix) with ESMTP id 44815D001F1E for ; Tue, 12 Oct 2021 01:51:56 +0000 (UTC) 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=dd8fiic3/qE9q03XuQ9MOapfyT7FLJ6jvivOZB26mnA=; b=Oz2gjdInsPkhTAMX25u5a08HFk pDYQ8i04D79tm/NhINUzjbgIuZ9avdlFhJpU3BaS+EXIDQWAR+ejPr1RjkBuVynLWBTZL0rimm5Fg Q8JUDnD3kPS5pbKpDIyHunSoE/FWXwMKT8X3jHg653Lh6ow1tVe61ywM3+fkQE9evU3OanzSWBgXq /iwk459XpM6hKeaSv88wEcacpr1Ffbmz99wF+ITlARN4Py09pBkzOG4z5AsWN6VeLhyGLrYZ0DszP 1G5boyDk6Uu6AXoRxXPi5iBShlxilCuBWTcKtpP0SqwP8emmnd+FuvBZq1pCXzpyyLK8WC8Qx50u4 KAeO5BUg==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1ma6wB-0068Pi-5j; Tue, 12 Oct 2021 01:51:00 +0000 Date: Tue, 12 Oct 2021 02:50:39 +0100 From: Matthew Wilcox To: Christoph Hellwig Cc: Rongwei Wang , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org, viro@zeniv.linux.org.uk, song@kernel.org, william.kucharski@oracle.com, hughd@google.com, shy828301@gmail.com, linmiaohe@huawei.com, peterx@redhat.com Subject: Re: [PATCH 0/3] mm, thp: introduce a new sysfs interface to facilitate file THP for .text Message-ID: References: <20211009092658.59665-1-rongwei.wang@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 44815D001F1E X-Stat-Signature: 69hg8g7ffztmogzstxzej7a89zskk3c4 Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=Oz2gjdIn; spf=none (imf15.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-HE-Tag: 1634003516-833070 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 Mon, Oct 11, 2021 at 09:06:37AM +0100, Christoph Hellwig wrote: > Can we please just get proper pagecache THP (through folios) merged > instead of piling hacks over hacks here? The whole readonly THP already > was more than painful enough due to all the hacks involved. This was my initial reaction too. But read the patches. They're nothing to do with the implementation of THP / folios in the page cache. They're all to make sure that mappings are PMD aligned. I think there's a lot to criticise in the patches (eg, a system-wide setting is probably a bad idea. and a lot of this stuff seems to be fixing userspace bugs in the kernel). But let's criticise what's actually in the patches, because these are problems that exist regardless of RO_THP vs folios.