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 9DB09383C7B for ; Thu, 10 Sep 2026 23:05:15 +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=1789081517; cv=none; b=EZIcMxbwpl8xDKqqizuUWLlJwUTHFm1LGvpQyaYGaIJzlLw/68KvYZVrIjmj1LV6PzgPMVhVfvLkLcvBgmPed0+O5X+4gTjpPci5cuT/9ro0uTnxjokQ2JetCtUVTOoEIYM0kcF3mBrTQngA0LYHbRNwabbpEz6xviNjkKHKLlI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789081517; c=relaxed/simple; bh=4KcAuqIG5XcYmSl2696jJn7pmPs/t31K28xZWIeJ754=; h=Date:To:From:Subject:Message-Id; b=VPbgOb6NEiblJp8IixEqYYMUYI42qwYtpsBZ+gJSaFE5zhO2buWfjVHq4eqqmcUosxLsE5K/WTjJ99p8rnTzIgEyk/AQd9hOKDr02sS+aKtcZOuuyLl31W//d4Rr/Fx62hUTORgyDjAo90tWdxsMTRu1RHE9WPQXeP15LQq4mXo= 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=V6O4Banv; 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="V6O4Banv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 71DDE1F000FF; Thu, 10 Sep 2026 23:05:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1789081515; bh=T1B9V6eFZOJ9s2iXVeFRF2tNMntknGDu0xcUZzffyLo=; h=Date:To:From:Subject; b=V6O4Banv7He5FyYYa5dOwrTPvMEHo8+0z0RYFc0i/TIgi59WCOnf4QsfMP0HYGYAG Z0AVQnJO2YssmgvXFF28NfuNf0rYKidGlqfelBBDcUDqzpI47IbXC9kpm4DeNkVM31 7MRoGYRawmZTU0b5/GurHVl358MXMWwCeEAIzDyQ= Date: Thu, 10 Sep 2026 16:05:15 -0700 To: mm-commits@vger.kernel.org,songmuchun@bytedance.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-sparse-vmemmap-initialize-shared-tail-vmemmap-pages-on-allocation.patch added to mm-unstable branch Message-Id: <20260910230515.71DDE1F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/sparse-vmemmap: initialize shared tail vmemmap pages on allocation has been added to the -mm mm-unstable branch. Its filename is mm-sparse-vmemmap-initialize-shared-tail-vmemmap-pages-on-allocation.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-sparse-vmemmap-initialize-shared-tail-vmemmap-pages-on-allocation.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Muchun Song Subject: mm/sparse-vmemmap: initialize shared tail vmemmap pages on allocation Date: Thu, 10 Sep 2026 14:32:43 +0800 The shared tail vmemmap page allocated in vmemmap_get_tail() used to be left uninitialized, because memmap_init_range() would later overwrite it. That forced users such as HugeTLB to defer the initialization to their own setup paths. Now that memmap_init_range() skips shared tail vmemmap pages, initialize them immediately in vmemmap_get_tail() with init_compound_tail() instead. This adds initialization at the point where the shared tail page is allocated. The existing HugeTLB initialization remains necessary until the compound page order is set and memmap_init_range() starts skipping shared tails. It is removed when HugeTLB switches to the section-based mechanism. Link: https://lore.kernel.org/20260910063256.64386-5-songmuchun@bytedance.com Signed-off-by: Muchun Song Acked-by: Mike Rapoport (Microsoft) Acked-by: Qi Zheng Cc: David Hildenbrand (Arm) Cc: David Laight Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Oscar Salvador Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/sparse-vmemmap.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) --- a/mm/sparse-vmemmap.c~mm-sparse-vmemmap-initialize-shared-tail-vmemmap-pages-on-allocation +++ a/mm/sparse-vmemmap.c @@ -338,19 +338,11 @@ static __meminit struct page *vmemmap_ge tail = zone->vmemmap_tails[idx]; if (tail) return tail; - - /* - * Only allocate the page, but do not initialize it. - * - * Any initialization done here will be overwritten by memmap_init(). - * - * hugetlb_bootmem_struct_page_init() will take care of initialization - * after memmap_init(). - */ - p = vmemmap_alloc_block_zero(PAGE_SIZE, node); if (!p) return NULL; + for (int i = 0; i < PAGE_SIZE / sizeof(struct page); i++) + init_compound_tail(p + i, NULL, order, zone); tail = virt_to_page(p); zone->vmemmap_tails[idx] = tail; _ Patches currently in -mm which might be from songmuchun@bytedance.com are mm-sparse-relax-struct-mem_section-size-constraints.patch mm-sparse-vmemmap-rename-hvo-order-macros.patch mm-mm_init-skip-initializing-shared-vmemmap-tail-pages.patch mm-sparse-vmemmap-initialize-shared-tail-vmemmap-pages-on-allocation.patch mm-sparse-vmemmap-support-section-based-vmemmap-accounting.patch mm-mm_init-factor-out-pfn_to_zone.patch mm-sparse-vmemmap-move-helpers-ahead-of-future-callers.patch mm-sparse-vmemmap-support-section-based-vmemmap-optimization.patch mm-sparse-initialize-memory-sections-earlier.patch mm-hugetlb-switch-hugetlb-to-section-based-vmemmap-optimization.patch mm-sparse-vmemmap-remove-sparsemem_vmemmap_preinit-support.patch mm-sparse-inline-usemap-allocation-into-sparse_init_nid.patch mm-sparse-remove-section_map_size.patch mm-hugetlb-remove-huge_bootmem_hvo.patch mm-hugetlb-remove-huge_bootmem_cma.patch mm-hugetlb-localize-struct-huge_bootmem_page.patch mm-hugetlb-localize-huge_bootmem_zones_valid.patch mm-sparse-vmemmap-introduce-config_sparsemem_vmemmap_optimization.patch mm-sparse-vmemmap-factor-out-shared-vmemmap-tail-page-allocation.patch mm-sparse-vmemmap-open-code-init_compound_tail.patch mm-sparse-vmemmap-prepare-dax-vmemmap-population-for-section-orders.patch mm-sparse-vmemmap-set-section-order-for-device-dax.patch mm-sparse-vmemmap-switch-device-dax-to-shared-tail-vmemmap-pages.patch mm-sparse-vmemmap-move-hvo-helpers-to-a-public-header.patch powerpc-mm-switch-device-dax-to-shared-tail-vmemmap-pages.patch mm-sparse-vmemmap-drop-the-extra-tail-page-from-device-dax-reservation.patch mm-sparse-vmemmap-drop-unused-section_nr_vmemmap_pages-arguments.patch documentation-mm-update-dax-vmemmap-deduplication-docs.patch