From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793672120; b=i9rLIUsAA37y0darn2CJ0HmrEkpWXQtVAbmzi+bk15TIXd9LhH32K1+r08Ti/iGtiAqG g7UUTX21TQujH5seuYEwlG9sbuxr8yOLX0uzDWGjBXHlby8o/yRnJrW04K8PmELs8DNuy nndQv1/ckwiC0WnXhZck+DAnLU78PvIApJ3Mnx+WEWD4A0IE0j/b+pFESWdnFOlyZYnnx zMVsJR6rWyYpKwEAXgDSh0uzjWVPyV1+BrUUAgokR34W86KPir0QVZA3xKlXmHwqMBikJ 9Daoc0dr2n+SMuF7isOJ0wQAzhSkvLtiuqRn8v+QRWMTy5zbzvoluxU+XtnbUjtQVvQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793672120; h=Received:DKIM-Signature:Date:To:From:Subject:Message-Id; bh=FnwpCVjwydqlOHCUe4nN3SvfJ8VJHqAKOvkEjUan0cw=; b=FlDfVMiadvmrk9vQsDcBsaTeLHhCBPUua5gbefRTt8/O2Jm6boNVorYt1cq+7wa4jU6r kbimv4L+K0uzON0H4BNLq2VaL1r0e2mtpd+qL2IYjhOaEV/Y2l73VyKy/Vxbbg3ZiHArL XkoVkeVo3royLiKqLmkpz7TQMuDz4WfKWhNj29aYPLlgy4T0Emxe30kelSYiJAYVJ6hBm jjx52ZTqSOxzQNImG4f9iJI34t1pVo56HXmIhS0S7pX8LjFEeih169uHWfd8CIt6dX3gH T+PDmmkir7ArB+9DOTO00VrDCjGt68D7KVYmzXD0NhY+zS6cz51elRgRoX+4Y15+FOg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linux-foundation.org header.i=@linux-foundation.org header.a=rsa-sha256 header.s=korg header.b="d0qGcd/o"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C5484606A332; Tue, 3 Nov 2026 02:15:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux-foundation.org header.i=@linux-foundation.org header.a=rsa-sha256 header.s=korg header.b=d0qGcd/o Received: by smtp.kernel.org (Postfix) with ESMTPSA id 40CC21F000C1; Tue, 3 Nov 2026 02:15:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1793672119; bh=FnwpCVjwydqlOHCUe4nN3SvfJ8VJHqAKOvkEjUan0cw=; h=Date:To:From:Subject; b=d0qGcd/ofpymRWcPis2xAdBhz7WvtI9O2hsMstCPOt3Orc1V5yFmqSfUJbcKsbZzw eU877UnRfiFT+AxEQlPo5a9kIgyAtbjKSwv/a+Pa1Afc0e3fmksKb0TAx/woFd+YTN MoMbLmUK9HGSfJHnUpAgLFwSKiKYBwosOeZWAwME= Date: Mon, 02 Nov 2026 18:15:18 -0800 To: mm-commits@vger.kernel.org,vbabka@kernel.org,surenb@google.com, stable@vger.kernel.org,ryan.roberts@arm.com,rppt@kernel.org,mhocko@suse.com, ljs@kernel.org,liam@infradead.org,lance.yang@linux.dev,kylebot@openai.com, kas@kernel.org,huang.ying.caritas@gmail.com,hanchuanhua@oppo.com, baolin.wang@linux.alibaba.com,baohua@kernel.org,david@kernel.org, akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-hotfixes-stable] mm-fix-address-wraparound-when-scanning-large-folio-ptes.patch removed from -mm tree Message-Id: <20261103021519.40CC21F000C1@smtp.kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list The quilt patch titled Subject: mm: fix address wraparound when scanning large folio PTEs has been removed from the -mm tree. Its filename was mm-fix-address-wraparound-when-scanning-large-folio-ptes.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: "David Hildenbrand (Arm)" Subject: mm: fix address wraparound when scanning large folio PTEs Date: Wed, 14 Oct 2026 20:34:28 +0200 numa_rebuild_large_mapping() and do_swap_page() can be tricked into generating an address wraparound, crashing the kernel. All that's required is to map a tail page of a large folio close enough to the start/end of the address space to e.g., make unsigned long addr_start = addr - (nr << PAGE_SHIFT); to wrap around. Let's fix it by providing a better helper, folio_scan_range(), that takes care of staying within VMA and page table boundaries while handling possible wraparounds. There are some nasty details, like not being able to use pmd_addr_end() in this context. Add some helpful comments for these cases. Link: https://lore.kernel.org/20261014-folio_pte_scan_range-v2-1-00cf9bbaa364@kernel.org Fixes: d2136d749d76 ("mm: support multi-size THP numa balancing") Fixes: 508758960b8d ("mm: swap: entirely map large folios found in swapcache") Signed-off-by: David Hildenbrand (Arm) Signed-off-by: Andrew Morton Reported-by: Kyle Zeng Reviewed-by: Lorenzo Stoakes (ARM) Reviewed-by: Kiryl Shutsemau (Meta) Reviewed-by: Baolin Wang Reviewed-by: Lance Yang Reviewed-by: Barry Song Cc: Liam R. Howlett Cc: Vlastimil Babka Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Michal Hocko Cc: Ying Huang Cc: Ryan Roberts Cc: Chuanhua Han Cc: --- mm/memory.c | 50 ++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 36 insertions(+), 14 deletions(-) --- a/mm/memory.c~mm-fix-address-wraparound-when-scanning-large-folio-ptes +++ a/mm/memory.c @@ -4934,6 +4934,34 @@ static void check_swap_exclusive(struct } /* + * Get the address range in which a folio might be mapped, assuming its pages + * are mapped consecutively and the folio page at the given idx is mapped at + * the given address. + */ +static void folio_pte_range(const struct folio *folio, + const struct vm_area_struct *vma, unsigned long addr, + unsigned long idx, unsigned long *start, unsigned long *end) +{ + /* Stay within the page table and VMA boundaries. */ + const unsigned long pmd_start = addr & PMD_MASK; + const unsigned long pmd_end = pmd_start + PMD_SIZE; + const unsigned long lower = max(pmd_start, vma->vm_start); + /* + * We cannot use pmd_addr_end(), as it does not clamp reliably. To + * avoid wraparounds, compute using the inclusive end. + */ + const unsigned long upper = min(pmd_end - 1, vma->vm_end - 1) + 1; + const unsigned long offset = idx << PAGE_SHIFT; + + /* + * Avoid start/end addresses wrapping by not adding/subtracting more + * than the lower/upper limits would allow. + */ + *start = addr - min(addr - lower, offset); + *end = addr + min(upper - addr, folio_size(folio) - offset); +} + +/* * We enter with either the VMA lock or the mmap_lock held (see * FAULT_FLAG_VMA_LOCK), and pte mapped but not yet locked. * We return with pte unmapped and unlocked. @@ -5121,16 +5149,15 @@ vm_fault_t do_swap_page(struct vm_fault address = vmf->address; ptep = vmf->pte; if (folio_test_large(folio) && folio_test_swapcache(folio)) { - int nr = folio_nr_pages(folio); - unsigned long idx = folio_page_idx(folio, page); - unsigned long folio_start = address - idx * PAGE_SIZE; - unsigned long folio_end = folio_start + nr * PAGE_SIZE; + const int nr = folio_nr_pages(folio); + const unsigned long idx = folio_page_idx(folio, page); + unsigned long folio_start, folio_end; pte_t *folio_ptep; pte_t folio_pte; - if (unlikely(folio_start < max(address & PMD_MASK, vma->vm_start))) - goto check_folio; - if (unlikely(folio_end > pmd_addr_end(address, vma->vm_end))) + folio_pte_range(folio, vma, address, idx, &folio_start, + &folio_end); + if (unlikely((folio_end - folio_start) >> PAGE_SHIFT != nr)) goto check_folio; folio_ptep = vmf->pte - idx; @@ -6280,16 +6307,11 @@ static void numa_rebuild_large_mapping(s struct folio *folio, pte_t fault_pte, bool ignore_writable, bool pte_write_upgrade) { - int nr = pte_pfn(fault_pte) - folio_pfn(folio); + const unsigned long idx = pte_pfn(fault_pte) - folio_pfn(folio); unsigned long start, end, addr = vmf->address; - unsigned long addr_start = addr - (nr << PAGE_SHIFT); - unsigned long pt_start = ALIGN_DOWN(addr, PMD_SIZE); pte_t *start_ptep; - /* Stay within the VMA and within the page table. */ - start = max3(addr_start, pt_start, vma->vm_start); - end = min3(addr_start + folio_size(folio), pt_start + PMD_SIZE, - vma->vm_end); + folio_pte_range(folio, vma, addr, idx, &start, &end); start_ptep = vmf->pte - ((addr - start) >> PAGE_SHIFT); /* Restore all PTEs' mapping of the large folio */ _ Patches currently in -mm which might be from david@kernel.org are mm-memory-failure-fix-folio-refcount-leak-and-min_order_for_split-locking.patch