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 49E4825D1E9; Tue, 10 Mar 2026 23:02:32 +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=1773183752; cv=none; b=eEMQL2UfGxR9YdhPp9ZPP141fda89/NSC9e/wAQm+Lz8J+ZxZ4pHe+jaI6GDTWjL2rNpzawkqiV/MTuBkorVFw6qn3/JA0dbfOCDHE0RBnMM3ZNrH/UPLZE2Koy102hifiGAq8kRVo3iXLnbqZjLVd1922bIDkrUZ/nxRTgJ1Wo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773183752; c=relaxed/simple; bh=M+VKA4ChCcvxW8CW96dd1zKEULo7g2MAkyiVB7pi7IQ=; h=Date:To:From:Subject:Message-Id; b=ufF7jO/7XIUAP7ZJdTojvGpTzxM3+qwEA/WPeQstPvEFDypT6xYtsSow8LgP7FUgYc/o2nRJboxetjfpGF1WAaKd6qiaGzMsQz6APZzUNkn4HXJhXO/VtVdjoAgV76XrtoO/TYiZcVpCtR69Q2yzLqOKgIckphNEwDSb4NlMUF4= 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=UjOelnH/; 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="UjOelnH/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D5D6DC19423; Tue, 10 Mar 2026 23:02:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1773183751; bh=M+VKA4ChCcvxW8CW96dd1zKEULo7g2MAkyiVB7pi7IQ=; h=Date:To:From:Subject:From; b=UjOelnH/kHLIgAjgqdsPXCwBmMaO4Slstrqnp8oTvOV66gcQjlltViiMYZ3YBdvUP TTDkeGg4BnMWHnEUrNEtmbv7Cb9XKc8t95GT1S7ZtPbvTHNAP5L9ElPEJp5/SBB+bQ e8U+uqcCPzhr9+i8foh5s9Bu+Mru/Y3IdFP59FqA= Date: Tue, 10 Mar 2026 16:02:31 -0700 To: mm-commits@vger.kernel.org,stable@vger.kernel.org,lorenzo.stoakes@oracle.com,david@kernel.org,chris@chrisdown.name,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-hotfixes-stable] mm-huge_memory-fix-use-of-null-folio-in-move_pages_huge_pmd.patch removed from -mm tree Message-Id: <20260310230231.D5D6DC19423@smtp.kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm/huge_memory: fix use of NULL folio in move_pages_huge_pmd() has been removed from the -mm tree. Its filename was mm-huge_memory-fix-use-of-null-folio-in-move_pages_huge_pmd.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Chris Down Subject: mm/huge_memory: fix use of NULL folio in move_pages_huge_pmd() Date: Tue, 3 Mar 2026 07:21:21 +0000 move_pages_huge_pmd() handles UFFDIO_MOVE for both normal THPs and huge zero pages. For the huge zero page path, src_folio is explicitly set to NULL, and is used as a sentinel to skip folio operations like lock and rmap. In the huge zero page branch, src_folio is NULL, so folio_mk_pmd(NULL, pgprot) passes NULL through folio_pfn() and page_to_pfn(). With SPARSEMEM_VMEMMAP this silently produces a bogus PFN, installing a PMD pointing to non-existent physical memory. On other memory models it is a NULL dereference. Use page_folio(src_page) to obtain the valid huge zero folio from the page, which was obtained from pmd_page() and remains valid throughout. After commit d82d09e48219 ("mm/huge_memory: mark PMD mappings of the huge zero folio special"), moved huge zero PMDs must remain special so vm_normal_page_pmd() continues to treat them as special mappings. move_pages_huge_pmd() currently reconstructs the destination PMD in the huge zero page branch, which drops PMD state such as pmd_special() on architectures with CONFIG_ARCH_HAS_PTE_SPECIAL. As a result, vm_normal_page_pmd() can treat the moved huge zero PMD as a normal page and corrupt its refcount. Instead of reconstructing the PMD from the folio, derive the destination entry from src_pmdval after pmdp_huge_clear_flush(), then handle the PMD metadata the same way move_huge_pmd() does for moved entries by marking it soft-dirty and clearing uffd-wp. Link: https://lkml.kernel.org/r/a1e787dd-b911-474d-8570-f37685357d86@lucifer.local Fixes: e3981db444a0 ("mm: add folio_mk_pmd()") Signed-off-by: Chris Down Signed-off-by: Lorenzo Stoakes Reviewed-by: Lorenzo Stoakes Tested-by: Lorenzo Stoakes Acked-by: David Hildenbrand (Arm) Cc: Signed-off-by: Andrew Morton --- mm/huge_memory.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/mm/huge_memory.c~mm-huge_memory-fix-use-of-null-folio-in-move_pages_huge_pmd +++ a/mm/huge_memory.c @@ -2797,7 +2797,8 @@ int move_pages_huge_pmd(struct mm_struct _dst_pmd = pmd_mkwrite(pmd_mkdirty(_dst_pmd), dst_vma); } else { src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd); - _dst_pmd = folio_mk_pmd(src_folio, dst_vma->vm_page_prot); + _dst_pmd = move_soft_dirty_pmd(src_pmdval); + _dst_pmd = clear_uffd_wp_pmd(_dst_pmd); } set_pmd_at(mm, dst_addr, dst_pmd, _dst_pmd); _ Patches currently in -mm which might be from chris@chrisdown.name are selftests-mm-add-uffdio_move-huge-zeropage-pmd-regression-test.patch