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=-9.5 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 592C9C4320E for ; Wed, 25 Aug 2021 11:15:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3FF1E6113C for ; Wed, 25 Aug 2021 11:15:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236038AbhHYLQJ (ORCPT ); Wed, 25 Aug 2021 07:16:09 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:35616 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240087AbhHYLQJ (ORCPT ); Wed, 25 Aug 2021 07:16:09 -0400 Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 362FD200F2; Wed, 25 Aug 2021 11:15:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1629890121; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JsTZ/9+VRszmlL6hS/sFGVn+Amn3Nh4I4j0bZJL/75s=; b=I7Yi38O5i1rcyp1b3zu0aSxtw2cF3Go7OkwlsISIti7iULIxygNwNF0BH36F2+avkbLNcW 06YUDL+y1Hbvft7P8mvdvOug3JHSgTatWoeMMjAU6Kx57OmI+805Z/qH6eqDuglFihBtQJ CNQ9ji0e3uopyLcJZU5kVtj7OSQqX1U= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1629890121; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JsTZ/9+VRszmlL6hS/sFGVn+Amn3Nh4I4j0bZJL/75s=; b=A3w6EnRWXBALysZo9aIw4XjrVtAuedgCl1SGMlGblXmqQ2/TW5TK15Z3OuRoWQj96Fsrp8 vyntj+rs4FdH9vBQ== Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap1.suse-dmz.suse.de (Postfix) with ESMTPS id F408413732; Wed, 25 Aug 2021 11:15:20 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap1.suse-dmz.suse.de with ESMTPSA id JNBiOkgmJmH7GwAAGKfGzw (envelope-from ); Wed, 25 Aug 2021 11:15:20 +0000 Message-ID: Date: Wed, 25 Aug 2021 13:15:20 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.0.1 Subject: Re: [PATCH v1 02/14] mm: remove extra ZONE_DEVICE struct page refcount Content-Language: en-US To: Alex Sierra , akpm@linux-foundation.org, Felix.Kuehling@amd.com, linux-mm@kvack.org, rcampbell@nvidia.com, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org Cc: amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, hch@lst.de, jgg@nvidia.com, jglisse@redhat.com References: <20210825034828.12927-1-alex.sierra@amd.com> <20210825034828.12927-3-alex.sierra@amd.com> From: Vlastimil Babka In-Reply-To: <20210825034828.12927-3-alex.sierra@amd.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On 8/25/21 05:48, Alex Sierra wrote: > From: Ralph Campbell > > ZONE_DEVICE struct pages have an extra reference count that complicates the > code for put_page() and several places in the kernel that need to check the > reference count to see that a page is not being used (gup, compaction, > migration, etc.). Clean up the code so the reference count doesn't need to > be treated specially for ZONE_DEVICE. That's certainly welcome. I just wonder what was the reason to use 1 in the first place and why it's no longer necessary?