From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CDAAD41685B for ; Sat, 10 Oct 2026 20:42:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791664945; cv=none; b=VpLN8MipQBzz5447lNUTIfCU0/OxtR/mRsnzKc5/f/z0sSCaDgMbNVFRgzA1J28cdCdXUtQlfyOahNxlrK/CkBJHI2Tghg0hs0GT4TFjxbfUkSh2jeEzCDHrZj7cdMBp7Ezfg9DxX4tjtMjeFQshnn7o/8RMGdyJkWRWYQDVsZU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791664945; c=relaxed/simple; bh=v1ymWsKW63A8MOrrRvFTmqsOaMqs2jH6fAtmQ+2ssag=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=P0dK/ClvZXVXmU+tfRwzPLDbzSlHT74mXtTLBOkK6YIzRgxyJJQPsGcypY2BaLKd/YjrcnZSbpUvFkD3nqwRA6kb7M2yHDjZhrC8llUt+9wWFWaJbf7+gMQ1JChc90bfAYOAqjdGVUT67R3d3fTIZ8jpU0MNzx/P8wKVVT0XT+0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=RmLqUv8s; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="RmLqUv8s" 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) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 _