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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7D326C3064D for ; Tue, 2 Jul 2024 11:52:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=iKYYOXSjV6RRPbg7Bfms1PwM/UzIDseBBxvA7pcGkIQ=; b=V+mQk8CQBP+PhVKz4A+9FGNDMB Gnp+JJNkE9HghhgCIxiryVAMu/tW8qq8SWdP7XawvE4rHbyV98oS4zB6ktR8PsUpeOIcVsO10GxhF cR6PAKEx3BZ3pJI4eUGX0ICb/NbHksNmipomge/9ll5cAPXrxH696AWOJG6OPSiQzXI8dafdANaBw vgSGqZyVidkhFjBVs1ctzEVMoBtr5FT8nRcalyigEFLEpsumBYiqsGYrtPi9vFrYYGCtfhH4IkdPt NlkMcnt4TLBVYS9TReKvh4hCOAnMyvrHc56u+VC/aPOomFZWLSZaOL9YXKOlWdTR6TCz9TZ4LFW2r T75Gsx5w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sOc3L-00000006ZFp-0UAJ; Tue, 02 Jul 2024 11:52:07 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sOc39-00000006ZDh-3Nwu for linux-arm-kernel@lists.infradead.org; Tue, 02 Jul 2024 11:51:57 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id D343968AA6; Tue, 2 Jul 2024 13:51:51 +0200 (CEST) Date: Tue, 2 Jul 2024 13:51:51 +0200 From: Christoph Hellwig To: Alistair Popple Cc: David Hildenbrand , dan.j.williams@intel.com, vishal.l.verma@intel.com, dave.jiang@intel.com, logang@deltatee.com, bhelgaas@google.com, jack@suse.cz, jgg@ziepe.ca, catalin.marinas@arm.com, will@kernel.org, mpe@ellerman.id.au, npiggin@gmail.com, dave.hansen@linux.intel.com, ira.weiny@intel.com, willy@infradead.org, djwong@kernel.org, tytso@mit.edu, linmiaohe@huawei.com, peterx@redhat.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, jhubbard@nvidia.com, hch@lst.de, david@fromorbit.com Subject: Re: [PATCH 07/13] huge_memory: Allow mappings of PUD sized pages Message-ID: <20240702115151.GA16313@lst.de> References: <874j98gjfg.fsf@nvdebian.thelocal> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <874j98gjfg.fsf@nvdebian.thelocal> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240702_045156_091575_E72791A9 X-CRM114-Status: GOOD ( 20.87 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jul 02, 2024 at 08:19:01PM +1000, Alistair Popple wrote: > > (B) As long as we have subpage mapcounts, this prevents vmemmap > > optimizations [1]. Is that only used for device-dax for now and are > > there no plans to make use of that for fs-dax? > > I don't have any plans to. This is purely focussed on refcounting pages > "like normal" so we can get rid of all the DAX special casing. > > > (C) We managed without so far :) > > Indeed, although Christoph has asked repeatedly ([1], [2] and likely > others) that this gets fixed and I finally got sick of it coming up > everytime I need to touch something with ZONE_DEVICE pages :) > > Also it removes the need for people to understand the special DAX page > recounting scheme and ends up removing a bunch of cruft as a bonus: > > 59 files changed, 485 insertions(+), 869 deletions(-) > > And that's before I clean up all the pgmap reference handling. It also > removes the pXX_trans_huge and pXX_leaf distinction. So we managed, but > things could be better IMHO. Yes. I can't wait for this series making the finish line. There might be more chance for cleanups and optimizations around ZONE_DEVICE, but this alone is a huge step forward.