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 188273E8C49; Wed, 29 Apr 2026 11:54:54 +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=1777463695; cv=none; b=TONuP6+QqEEQP0a0DlVu7nbe55+esAk3KFSVyL+u1k3H5MI+MqEVJORyL6LxR1mfKoEjPQ/Qspqy33Uhu6tA6BvHx371Pk0r6q4IYjoUsixURLlQ8HkjW7IwbwtBcuBdnQzeo9DHPyZbnnyMe18mpdPCRVCJoXoM5xa0NG9Y42U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777463695; c=relaxed/simple; bh=FdZn2aKtKAfbY3SHzbUAI2dxsrv/92v7leXVaVUavoc=; h=Date:To:From:Subject:Message-Id; b=PF+bjoG9k2kftv0qfKPQYxZqtX2n3eXHTeHd+Y9q6YZcADv5i8m7ldTrlytvDLpFQLkQok3TO3a857MON7R/1xsJazKcC5b+JwGiiua0uThX6TQR/sWbwM+VOOsPk2gxK/8Ybn1Vtw0ASrKA2JqYjDrbU5AT35Q+9ZHucqAgN24= 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=CIyg/cMq; 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="CIyg/cMq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9F26AC19425; Wed, 29 Apr 2026 11:54:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1777463694; bh=FdZn2aKtKAfbY3SHzbUAI2dxsrv/92v7leXVaVUavoc=; h=Date:To:From:Subject:From; b=CIyg/cMqPMd8QePSJMPAwuhKCNk8z78Yl5uIiruoSVX89OjhDEy9L6HzbzSDfHW6C bqc0RRhnY5PvW9oml94paQ238yuQphOHtty6JFxK8TA+yIYn9SHlsiSpcDJEETc79Y VQfDYfJGb9p50dXjVInv6wUYM7R4JGlqdOfkMcK0= Date: Wed, 29 Apr 2026 04:54:54 -0700 To: mm-commits@vger.kernel.org,stable@vger.kernel.org,rppt@kernel.org,peterz@infradead.org,mingo@redhat.com,luto@kernel.org,lance.yang@linux.dev,jgg@ziepe.ca,hpa@zytor.com,bp@alien8.de,baolu.lu@linux.intel.com,david@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + x86-mm-fix-freeing-of-pmd-sized-vmemmap-pages.patch added to mm-hotfixes-unstable branch Message-Id: <20260429115454.9F26AC19425@smtp.kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: x86/mm: fix freeing of PMD-sized vmemmap pages has been added to the -mm mm-hotfixes-unstable branch. Its filename is x86-mm-fix-freeing-of-pmd-sized-vmemmap-pages.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/x86-mm-fix-freeing-of-pmd-sized-vmemmap-pages.patch This patch will later appear in the mm-hotfixes-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: "David Hildenbrand (Arm)" Subject: x86/mm: fix freeing of PMD-sized vmemmap pages Date: Wed, 29 Apr 2026 12:49:14 +0200 In commit bf9e4e30f353 ("x86/mm: use pagetable_free()"), we switched from freeing non-boot page tables through __free_pages() to pagetable_free(). However, the function is also called to free vmemmap pages. Given that vmemmap pages are not page tables, already the page_ptdesc(page) is wrong. But worse, pagetable_free() calls __free_pages(page, compound_order(page)); As vmemmap pages are not compound pages (see vmemmap_alloc_block()) -- except for HVO, which doesn't apply here -- we will only free the first page when freeing a PMD-sized vmemmap page, leaking the other ones. Fix it by properly decoupling pagetable and vmemmap freeing. free_pagetable() no longer has to mess with SECTION_INFO, as only the vmemmap is marked like that in register_page_bootmem_memmap(). The indentation in remove_pmd_table() is messed up, let's fix that while touching it. Note that we'll try to get rid of that bootmem info handling soon. For now, we'll handle it similar to free_pagetable(), just avoiding the ifdef. Link: https://lore.kernel.org/20260429-vmemmap-v2-1-8dfcacffd877@kernel.org Fixes: bf9e4e30f353 ("x86/mm: use pagetable_free()") Signed-off-by: David Hildenbrand (Arm) Tested-by: Lance Yang Acked-by: Mike Rapoport (Microsoft) Cc: Andy Lutomirski Cc: Baolu Lu Cc: "Borislav Petkov (AMD)" Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Jason Gunthorpe Cc: Peter Zijlstra Cc: Signed-off-by: Andrew Morton --- arch/x86/mm/init_64.c | 40 ++++++++++++++++++++++++++-------------- 1 file changed, 26 insertions(+), 14 deletions(-) --- a/arch/x86/mm/init_64.c~x86-mm-fix-freeing-of-pmd-sized-vmemmap-pages +++ a/arch/x86/mm/init_64.c @@ -1014,7 +1014,7 @@ static void __meminit free_pagetable(str #ifdef CONFIG_HAVE_BOOTMEM_INFO_NODE enum bootmem_type type = bootmem_type(page); - if (type == SECTION_INFO || type == MIX_SECTION_INFO) { + if (type == MIX_SECTION_INFO) { while (nr_pages--) put_page_bootmem(page++); } else { @@ -1028,13 +1028,24 @@ static void __meminit free_pagetable(str } } -static void __meminit free_hugepage_table(struct page *page, +static void __meminit free_vmemmap_pages(struct page *page, unsigned int order, struct vmem_altmap *altmap) { - if (altmap) - vmem_altmap_free(altmap, PMD_SIZE / PAGE_SIZE); - else - free_pagetable(page, get_order(PMD_SIZE)); + unsigned long nr_pages = 1u << order; + + if (altmap) { + vmem_altmap_free(altmap, nr_pages); + } else if (PageReserved(page)) { + if (IS_ENABLED(CONFIG_HAVE_BOOTMEM_INFO_NODE) && + bootmem_type(page) == SECTION_INFO) { + while (nr_pages--) + put_page_bootmem(page++); + } else { + free_reserved_pages(page, nr_pages); + } + } else { + __free_pages(page, order); + } } static void __meminit free_pte_table(pte_t *pte_start, pmd_t *pmd) @@ -1118,7 +1129,8 @@ remove_pte_table(pte_t *pte_start, unsig return; if (!direct) - free_pagetable(pte_page(*pte), 0); + /* We never populate base pages from the altmap. */ + free_vmemmap_pages(pte_page(*pte), 0, NULL); spin_lock(&init_mm.page_table_lock); pte_clear(&init_mm, addr, pte); @@ -1153,19 +1165,19 @@ remove_pmd_table(pmd_t *pmd_start, unsig if (IS_ALIGNED(addr, PMD_SIZE) && IS_ALIGNED(next, PMD_SIZE)) { if (!direct) - free_hugepage_table(pmd_page(*pmd), - altmap); + free_vmemmap_pages(pmd_page(*pmd), + PMD_ORDER, altmap); spin_lock(&init_mm.page_table_lock); pmd_clear(pmd); spin_unlock(&init_mm.page_table_lock); pages++; } else if (vmemmap_pmd_is_unused(addr, next)) { - free_hugepage_table(pmd_page(*pmd), - altmap); - spin_lock(&init_mm.page_table_lock); - pmd_clear(pmd); - spin_unlock(&init_mm.page_table_lock); + free_vmemmap_pages(pmd_page(*pmd), PMD_ORDER, + altmap); + spin_lock(&init_mm.page_table_lock); + pmd_clear(pmd); + spin_unlock(&init_mm.page_table_lock); } continue; } _ Patches currently in -mm which might be from david@kernel.org are mm-page_alloc-fix-initialization-of-tags-of-the-huge-zero-folio-with-init_on_free.patch x86-mm-fix-freeing-of-pmd-sized-vmemmap-pages.patch sh-use-folio_mapped-instead-of-page_mapped-in-sh4_flush_cache_page.patch bpf-arena-use-page_ref_count-instead-of-page_mapped-in-arena_free_pages.patch mm-remove-page_mapped.patch