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[23.128.96.18]) by mx.google.com with ESMTP id x12si5532650edr.120.2021.10.11.18.55.53; Mon, 11 Oct 2021 18:56:40 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=casper.20170209 header.b=Oz2gjdIn; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229872AbhJLByX (ORCPT + 99 others); Mon, 11 Oct 2021 21:54:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57590 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229544AbhJLByX (ORCPT ); Mon, 11 Oct 2021 21:54:23 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 56651C061570; Mon, 11 Oct 2021 18:52:22 -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=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: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.