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 02C7A40803D for ; Fri, 9 Oct 2026 05:58:57 +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=1791525539; cv=none; b=Mhb/C3y87ZVVpJLmFU7fGrY18dHq410WGai7sR/ppWaJjlQzcObqTZY+K1T0xwb0uJT89XmWMWqItOAivdsKERUqamZqcqqmeWXS9Axtuh+mTlSjgxE+9i3pyUsPqySeZp/cCX2MgSDOJqD9Ddysg/2IiQQtx8xc/UavlqK1TNI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791525539; c=relaxed/simple; bh=4jkLiqeUS+3AsSYkR0/RUUCBpwvoipiJzA14NRivYD0=; h=Date:To:From:Subject:Message-Id; b=JIIg3e2xmn2mI/we/J/WMcKyE38/7oIOkeIFbOIh4cqjdwY2wzmvMHWukCRH5Z7cC3Ry5K12i4sHLEHCKk58zwVH2aJWchBth5l/R9OkfjshvT0dzHPvL9ZLKqgJ1/7zm1XKjPTHbn8K36cotbLkO2dLvc4lZhbsv0oxjOelLb0= 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=ECHV8xo5; 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="ECHV8xo5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C53661F00893; Fri, 9 Oct 2026 05:58:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1791525536; bh=vBarOZkz+BF5KGIbREk8tcYzY2goT4SABicSiRYHdw0=; h=Date:To:From:Subject; b=ECHV8xo5AGIgq2C5ijSuH28hXZjvmFi59YKb2mOa22NNjvlUSfW7F8ERJsr2Oc6zT AnzONJGByjrDS2pcc0bm3otqbJouUuyiTirKe47U4yNmwZVliKN/km++ImTYlR15QR 1/N445CY4lf9Ee1m0O6NeB2zRMg4IZMHsyiACzPk= Date: Thu, 08 Oct 2026 22:58:56 -0700 To: mm-commits@vger.kernel.org,sshegde@linux.ibm.com,rppt@kernel.org,ritesh.list@gmail.com,rdunlap@infradead.org,qi.zheng@linux.dev,osalvador@suse.de,npiggin@gmail.com,mpe@ellerman.id.au,maddy@linux.ibm.com,ljs@kernel.org,lance.yang@linux.dev,david@kernel.org,corbet@lwn.net,chleroy@kernel.org,muchun.song@linux.dev,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-sparse-vmemmap-set-compound-page-order-for-device-dax.patch removed from -mm tree Message-Id: <20261009055856.C53661F00893@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm/sparse-vmemmap: set compound page order for device DAX has been removed from the -mm tree. Its filename was mm-sparse-vmemmap-set-compound-page-order-for-device-dax.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Muchun Song Subject: mm/sparse-vmemmap: set compound page order for device DAX Date: Wed, 30 Sep 2026 22:06:21 +0800 Device DAX can use vmemmap optimization only when a full section is populated with a compound-page geometry. Record that geometry as the compound page order in section metadata before populating the section, so later vmemmap accounting and population decisions can use the section state directly. Clear the compound page order when the section becomes empty again. Also reject partial additions to a section that already has optimized vmemmap mappings. compound_nr_pages() determines how many struct pages to initialize with a section as the smallest granularity. A section therefore cannot safely mix optimized and ordinary vmemmap layouts. Partial additions continue to use ordinary vmemmap population, so they do not save vmemmap memory. Such additions are uncommon, and the lost saving is negligible. Link: https://lore.kernel.org/20260930140627.57431-7-songmuchun@bytedance.com Signed-off-by: Muchun Song Signed-off-by: Andrew Morton Acked-by: Qi Zheng Acked-by: David Hildenbrand (Arm) Cc: Oscar Salvador Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Jonathan Corbet Cc: Lorenzo Stoakes Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Christophe Leroy Cc: Ritesh Harjani (IBM) Cc: Shrikanth Hegde Cc: Randy Dunlap Cc: Lance Yang --- mm/mm_init.c | 15 +++++---------- mm/sparse-vmemmap.c | 16 ++++++++++++---- 2 files changed, 17 insertions(+), 14 deletions(-) --- a/mm/mm_init.c~mm-sparse-vmemmap-set-compound-page-order-for-device-dax +++ a/mm/mm_init.c @@ -1049,16 +1049,11 @@ static void zone_device_page_init_from_t * of an altmap. See vmemmap_populate_compound_pages(). */ static inline unsigned long compound_nr_pages(unsigned long pfn, - struct vmem_altmap *altmap, struct dev_pagemap *pgmap) { - /* - * If DAX memory is hot-plugged into an unoccupied subsection - * of an early section, the unoptimized boot memmap is reused. - * See section_activate(). - */ - if (early_section(__pfn_to_section(pfn)) || - !vmemmap_can_optimize(altmap, pgmap)) + const struct mem_section *ms = __pfn_to_section(pfn); + + if (!section_vmemmap_optimizable(ms)) return pgmap_vmemmap_nr(pgmap); return VMEMMAP_RESERVE_NR * (PAGE_SIZE / sizeof(struct page)); @@ -1144,7 +1139,7 @@ void __ref memmap_init_zone_device(struc memcpy(&template, page, sizeof(*page)); if (pfns_per_compound != 1) memmap_init_compound(page, pfn, zone_idx, nid, pgmap, - compound_nr_pages(pfn, altmap, pgmap)); + compound_nr_pages(pfn, pgmap)); pfn += pfns_per_compound; /* Initialize the remaining head pages from template. */ @@ -1160,7 +1155,7 @@ void __ref memmap_init_zone_device(struc continue; memmap_init_compound(page, pfn, zone_idx, nid, pgmap, - compound_nr_pages(pfn, altmap, pgmap)); + compound_nr_pages(pfn, pgmap)); } pageblock_migratetype_init_range(start_pfn, nr_pages, MIGRATE_MOVABLE, --- a/mm/sparse-vmemmap.c~mm-sparse-vmemmap-set-compound-page-order-for-device-dax +++ a/mm/sparse-vmemmap.c @@ -135,14 +135,14 @@ int __meminit section_nr_vmemmap_pages(u struct vmem_altmap *altmap, struct dev_pagemap *pgmap) { const struct mem_section *ms = __pfn_to_section(pfn); - const int order = pgmap ? pgmap->vmemmap_shift : section_compound_order(ms); + const int order = section_compound_order(ms); const int vmemmap_pages = pgmap ? VMEMMAP_RESERVE_NR : VMEMMAP_OPTIMIZATION_PAGES; const unsigned long pages_per_compound = 1UL << order; VM_WARN_ON_ONCE(!IS_ALIGNED(pfn | nr_pages, PAGES_PER_SUBSECTION)); VM_WARN_ON_ONCE(nr_pages > PAGES_PER_SECTION); - if (!vmemmap_can_optimize(altmap, pgmap) && !section_vmemmap_optimizable(ms)) + if (!section_vmemmap_optimizable(ms)) return DIV_ROUND_UP(nr_pages * sizeof(struct page), PAGE_SIZE); if (order < PFN_SECTION_SHIFT) { @@ -612,7 +612,7 @@ struct page * __meminit __populate_secti !IS_ALIGNED(nr_pages, PAGES_PER_SUBSECTION))) return NULL; - if (vmemmap_can_optimize(altmap, pgmap)) + if (pgmap && section_vmemmap_optimizable(__pfn_to_section(pfn))) r = vmemmap_populate_compound_pages(pfn, start, end, nid, pgmap); else r = vmemmap_populate(start, end, nid, altmap); @@ -831,8 +831,10 @@ static void section_deactivate(unsigned else if (memmap) free_map_bootmem(memmap); - if (empty) + if (empty) { ms->section_mem_map = (unsigned long)NULL; + section_set_compound_order(ms, 0); + } } static struct page * __meminit section_activate(int nid, unsigned long pfn, @@ -842,8 +844,13 @@ static struct page * __meminit section_a struct mem_section *ms = __pfn_to_section(pfn); struct mem_section_usage *usage = NULL; struct page *memmap; + unsigned int order; int rc; + order = vmemmap_can_optimize(altmap, pgmap) ? pgmap->vmemmap_shift : 0; + if (nr_pages < PAGES_PER_SECTION && section_compound_order(ms)) + return ERR_PTR(-EOPNOTSUPP); + if (!ms->usage) { usage = kzalloc(mem_section_usage_size(), GFP_KERNEL); if (!usage) @@ -869,6 +876,7 @@ static struct page * __meminit section_a if (nr_pages < PAGES_PER_SECTION && early_section(ms)) return pfn_to_page(pfn); + section_set_compound_order_range(pfn, nr_pages, order); memmap = populate_section_memmap(pfn, nr_pages, nid, altmap, pgmap); if (!memmap) { section_deactivate(pfn, nr_pages, altmap, pgmap); _ Patches currently in -mm which might be from muchun.song@linux.dev are mm-sparse-vmemmap-drop-vmemmap_populate_dax.patch mm-sparse-vmemmap-support-device-dax-in-common-vmemmap-path.patch mm-sparse-vmemmap-drop-device-dax-specific-population-path.patch mm-sparse-vmemmap-remove-the-unused-ptpfn-argument.patch mm-sparse-vmemmap-open-code-vmemmap_populate_address.patch mm-mm_init-add-zone-mismatch-warning-during-page-init.patch