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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 DE253CA9EC1 for ; Sat, 10 Oct 2026 20:42:31 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4j2Fz96JZtz2yqT; Sun, 11 Oct 2026 07:42:29 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=172.105.4.254 ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1791664949; cv=none; b=YLUcLi7Y3EcyjooA/rEmR0ZkRHz7mN4kB9wUIdJwUc5Zq6PIvhGe+IsPDbxCT4oNnyLSDZTgjaFUthRoyTvvKF28nFoXSNicrFNyXcM3a8uSkHBuU6SRXnNH9dXD6FSVZ7DQMHE3p+cz4qhbNkWHXs1HNH0soak/MokRwa3BiXf4wQDCBCaC1cC0WGbxyBUd4j8ntaNzrhllWEZTdrKY/KH2h2bMhFl+AuE3Es0XBclUVjtRtw/ilLumE21Jn0hJMOyPDMuCfEBbaunhznBWayyixBmwdO5x77VZ0fomXAsc08ysLP9/hXLFCVo0/VCd7zxE66tjBUJxbQlFCm+LGg== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1791664949; c=relaxed/relaxed; bh=KaeVwRqfGMljaxW8Ah6Cx9zT6uiRBSSC1dP0zE7Q/ko=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=lmkBP2J1TrTHcc8UUng4WrfawpdR3cCHTJzvHEvcmAOriFV9/xypkkoS9sNT5HpY8Nz9CAcTd+ztN5JdRz3giSYUrXYzjs+0sEor4h0M6NeZJT9U2aMqy6n6ovX8bQtoElyAXEIuWN++HKrEjQU/DIZqNQHMSSyS8rBdnwEYcVUfITxAmKyg2J90FNoibDrlL4ro25AVPmFmwNg5wDDImg/nw92TXMz3OPwFIBT88iFrNNnJbfXQLj4Q929ym+Zl8MzihijI4f8vIBOFARLU5QDl9+8X9zQ5xxujgRCZQU0Z2D5MCEwV1EK25o3Lt1i/pQEWBhvuwkndu/r7ocxrqA== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org; dkim=pass (1024-bit key; unprotected) header.d=linux-foundation.org header.i=@linux-foundation.org header.a=rsa-sha256 header.s=korg header.b=RmLqUv8s; dkim-atps=neutral; spf=pass (client-ip=172.105.4.254; helo=tor.source.kernel.org; envelope-from=akpm@linux-foundation.org; receiver=lists.ozlabs.org) smtp.mailfrom=linux-foundation.org Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=linux-foundation.org header.i=@linux-foundation.org header.a=rsa-sha256 header.s=korg header.b=RmLqUv8s; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux-foundation.org (client-ip=172.105.4.254; helo=tor.source.kernel.org; envelope-from=akpm@linux-foundation.org; receiver=lists.ozlabs.org) Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4j2Fz76vHvz2yjp for ; Sun, 11 Oct 2026 07:42:27 +1100 (AEDT) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id D5CDB602CC; Sat, 10 Oct 2026 20:42:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 04A691F000FF; Sat, 10 Oct 2026 20:42:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1791664943; bh=KaeVwRqfGMljaxW8Ah6Cx9zT6uiRBSSC1dP0zE7Q/ko=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=RmLqUv8syW5KCaLrBRHaqB+hdxZmebnLFbyFQcAzsE8K8GyM/v72kmzM2p52+uyUk JY4X3rsdpU0z8m/Mytez5hAFfN73+lJQkTAJ2ZdwOIQwtDH7dUz67d2wNhBrUxR1xC zb3jPxE5vNJ3UNmy+gKrU8kH2wFXF/E3KA17J4EE= Date: Sat, 10 Oct 2026 13:42:22 -0700 From: Andrew Morton To: Muchun Song Cc: Madhavan Srinivasan , Mike Rapoport , David Hildenbrand , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Ritesh Harjani , Shrikanth Hegde , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Qi Zheng , Lance Yang , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, muchun.song@linux.dev Subject: Re: [PATCH v4 0/6] mm: Unify device DAX and HugeTLB vmemmap population paths Message-Id: <20261010134222.b6fdcb20d8fec5aaceab66ec@linux-foundation.org> In-Reply-To: <20261010075755.83339-1-songmuchun@bytedance.com> References: <20261010075755.83339-1-songmuchun@bytedance.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sat, 10 Oct 2026 15:57:49 +0800 Muchun Song wrote: > This v4 is based on mm-new commit d5207c6d152c, which contains v6 of > "mm: Switch device DAX to section-based vmemmap optimization" [1]. > > This series is split out from the earlier, larger series "mm: Generalize > HVO for HugeTLB and device DAX" [2]. While the parent series generalizes > vmemmap optimization across HugeTLB and device DAX, this subset addresses > a single, self-contained step: unifying their vmemmap population paths. > > After the preceding Device DAX conversion, both HugeTLB and Device DAX > describe optimized vmemmap mappings through memory-section metadata and > use per-zone shared tail vmemmap pages. The generic code, however, still > carries a Device DAX-specific population flag and compound-page population > path, along with arguments and helpers needed only by that path. > > This series first removes VMEMMAP_POPULATE_DAX and moves selection and > reference handling for the shared tail page into the common vmemmap > population path. It then removes the generic Device DAX-specific > compound-page population path and routes section vmemmap population > through vmemmap_populate(). The powerpc radix path continues to use its > architecture-specific compound-page population implementation for > optimizable sections. > > The remaining patches remove the unused ptpfn argument, open-code > vmemmap_populate_address() now that no caller needs its returned PTE, and > add a warning for inconsistent zone initialization of shared tail vmemmap > pages. > > This is the fourth smaller step toward the broader HVO generalization. > After this series, HugeTLB and Device DAX use the same population model > instead of parallel generic paths, while powerpc keeps its > architecture-specific implementation. Thanks, I've updated mm-unstable to this version, including the -fix. > v4: > - Rebase onto mm-new commit d5207c6d152c, which contains v6 of the Device > DAX section-based vmemmap series. > - Factor the zone mismatch check into a local helper as suggested by Mike > Rapoport. > - Collect Reviewed-by tags from Lance Yang. Here's how v4 altered mm.git: mm/mm_init.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) --- a/mm/mm_init.c~b +++ a/mm/mm_init.c @@ -593,6 +593,15 @@ out: node_states[N_MEMORY] = saved_node_state; } +static inline void vmemmap_optimization_verify_zone(struct page *page) +{ + const unsigned int order = pfn_to_section_compound_order(page_to_pfn(page)); + + VM_WARN_ON_ONCE(vmemmap_optimizable_order(order) && + page_zone_id(page + VMEMMAP_OPTIMIZATION_NR_STRUCT_PAGES) != + page_zone_id(page)); +} + void __meminit __init_single_page(struct page *page, unsigned long pfn, unsigned long zone, int nid) { @@ -609,9 +618,11 @@ void __meminit __init_single_page(struct if (!is_highmem_idx(zone)) set_page_address(page, __va(pfn << PAGE_SHIFT)); #endif - VM_WARN_ON_ONCE(vmemmap_optimizable_order(pfn_to_section_compound_order(pfn)) && - page_zone_id(page + VMEMMAP_OPTIMIZATION_NR_STRUCT_PAGES) != - page_zone_id(page)); + /* + * Shared tail struct pages are initialized during vmemmap population, + * before retained struct pages reach here. + */ + vmemmap_optimization_verify_zone(page); } #ifdef CONFIG_NUMA _