From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 2BC0143E4B5 for ; Tue, 28 Apr 2026 13:13:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777382017; cv=none; b=ihlvHFi2tf7DlNNY+yv72JkIRYhbFmqgMpU8ja6T23YGGadOVKEgf9TWwA009W58ETLUrsge2xFqcyBMqZEAwp0o+wCT1RoUTJY6/zGIerjDA10HT6ScrddgY85JKmrBbYOqtWcNNGcfk1bkKct774DBRVmhQO0/gjnPIHDzOTY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777382017; c=relaxed/simple; bh=DbEgO8WpYCBojTjpFcM38xrjiD2OEzeYX8QaqdoZjpI=; h=Date:To:From:Subject:Message-Id; b=akIE3kLSp+zOA7Z0t7GcCO0pNUOFELxdYub2sbN99vZuJ9aoIG28M5pmGxcj3eAimacfKL5I1UUPNwOoF9oxTxMPoDPj6NbJcwJE1X5xVaTaPKjvr+PeByn0c9CnJUvyRejD5L6QWxNrYaWxFDmFKCa3Zj6H4LKjFVBN9wGv0BQ= 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=L5vo9ycZ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="L5vo9ycZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C78D4C2BCAF; Tue, 28 Apr 2026 13:13:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1777382016; bh=DbEgO8WpYCBojTjpFcM38xrjiD2OEzeYX8QaqdoZjpI=; h=Date:To:From:Subject:From; b=L5vo9ycZPaP9Xt4fENspu96h/cBNu7SLJx4rHyfC5BzhIYwSNDddlNVm3HElkNF5S XYaqdch5xa0PgarzUUjwjE+oIHJYHZ675QBi5k61vXLc0cOF3et/CJSgO1AgWWENu/ OpFTlAO63jYrHa56AYmzm8CU4zZAfWEZY+/uzJ1U= Date: Tue, 28 Apr 2026 06:13:36 -0700 To: mm-commits@vger.kernel.org,songmuchun@bytedance.com,akpm@linux-foundation.org From: Andrew Morton Subject: [to-be-updated] mm-sparse-vmemmap-fix-dax-vmemmap-accounting-with-optimization.patch removed from -mm tree Message-Id: <20260428131336.C78D4C2BCAF@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: fix DAX vmemmap accounting with optimization has been removed from the -mm tree. Its filename was mm-sparse-vmemmap-fix-dax-vmemmap-accounting-with-optimization.patch This patch was dropped because an updated version will be issued ------------------------------------------------------ From: Muchun Song Subject: mm/sparse-vmemmap: fix DAX vmemmap accounting with optimization Date: Sun, 26 Apr 2026 17:26:38 +0800 When vmemmap optimization is enabled for DAX, the nr_memmap_pages counter in /proc/vmstat is incorrect. The current code always accounts for the full, non-optimized vmemmap size, but vmemmap optimization reduces the actual number of vmemmap pages by reusing tail pages. This causes the system to overcount vmemmap usage, leading to inaccurate page statistics in /proc/vmstat. Fix this by introducing section_nr_vmemmap_pages(), which returns the exact vmemmap page count for a given pfn range based on whether optimization is in effect. Link: https://lore.kernel.org/20260426092640.375967-5-songmuchun@bytedance.com Fixes: 15995a352474 ("mm: report per-page metadata information") Signed-off-by: Muchun Song Acked-by: Mike Rapoport (Microsoft) Acked-by: Oscar Salvador Acked-by: David Hildenbrand (Arm) Cc: "Aneesh Kumar K.V" Cc: Joao Martins Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Nicholas Piggin Cc: Suren Baghdasaryan Cc: Signed-off-by: Andrew Morton --- mm/sparse-vmemmap.c | 34 ++++++++++++++++++++++++++++++---- 1 file changed, 30 insertions(+), 4 deletions(-) --- a/mm/sparse-vmemmap.c~mm-sparse-vmemmap-fix-dax-vmemmap-accounting-with-optimization +++ a/mm/sparse-vmemmap.c @@ -647,6 +647,31 @@ void offline_mem_sections(unsigned long } } +static int __meminit section_nr_vmemmap_pages(unsigned long pfn, unsigned long nr_pages, + struct vmem_altmap *altmap, struct dev_pagemap *pgmap) +{ + const unsigned int order = pgmap ? pgmap->vmemmap_shift : 0; + const unsigned long pages_per_compound = 1UL << order; + + VM_WARN_ON_ONCE(!IS_ALIGNED(pfn | nr_pages, PAGES_PER_SUBSECTION)); + + if (!vmemmap_can_optimize(altmap, pgmap)) + return DIV_ROUND_UP(nr_pages * sizeof(struct page), PAGE_SIZE); + + if (order < PFN_SECTION_SHIFT) { + VM_WARN_ON_ONCE(!IS_ALIGNED(pfn | nr_pages, pages_per_compound)); + return VMEMMAP_RESERVE_NR * nr_pages / pages_per_compound; + } + + VM_WARN_ON_ONCE(!IS_ALIGNED(pfn | nr_pages, PAGES_PER_SECTION)); + VM_WARN_ON_ONCE(nr_pages > PAGES_PER_SECTION); + + if (IS_ALIGNED(pfn, pages_per_compound)) + return VMEMMAP_RESERVE_NR; + + return 0; +} + static struct page * __meminit populate_section_memmap(unsigned long pfn, unsigned long nr_pages, int nid, struct vmem_altmap *altmap, struct dev_pagemap *pgmap) @@ -654,7 +679,7 @@ static struct page * __meminit populate_ struct page *page = __populate_section_memmap(pfn, nr_pages, nid, altmap, pgmap); - memmap_pages_add(DIV_ROUND_UP(nr_pages * sizeof(struct page), PAGE_SIZE)); + memmap_pages_add(section_nr_vmemmap_pages(pfn, nr_pages, altmap, pgmap)); return page; } @@ -665,7 +690,7 @@ static void depopulate_section_memmap(un unsigned long start = (unsigned long) pfn_to_page(pfn); unsigned long end = start + nr_pages * sizeof(struct page); - memmap_pages_add(-1L * (DIV_ROUND_UP(nr_pages * sizeof(struct page), PAGE_SIZE))); + memmap_pages_add(-section_nr_vmemmap_pages(pfn, nr_pages, altmap, pgmap)); vmemmap_free(start, end, altmap); } @@ -673,9 +698,10 @@ static void free_map_bootmem(struct page { unsigned long start = (unsigned long)memmap; unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION); + unsigned long pfn = page_to_pfn(memmap); - memmap_boot_pages_add(-1L * (DIV_ROUND_UP(PAGES_PER_SECTION * sizeof(struct page), - PAGE_SIZE))); + memmap_boot_pages_add(-section_nr_vmemmap_pages(pfn, PAGES_PER_SECTION, + NULL, NULL)); vmemmap_free(start, end, NULL); } _ Patches currently in -mm which might be from songmuchun@bytedance.com are mm-memory_hotplug-fix-memory-block-reference-leak-on-remove.patch drivers-base-memory-fix-memory-block-reference-leak-in-poison-accounting.patch drivers-base-memory-fix-locking-for-poison-accounting-lookup.patch mm-sparse-remove-sparse-buffer-pre-allocation-mechanism.patch mm-mm_init-fix-pageblock-migratetype-for-zone_device-compound-pages.patch mm-mm_init-fix-uninitialized-struct-pages-for-zone_device.patch