From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B4E23CC6B27 for ; Wed, 14 Oct 2026 08:04:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7B2166B008C; Wed, 14 Oct 2026 04:04:56 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7897B6B0092; Wed, 14 Oct 2026 04:04:56 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 62AE66B0098; Wed, 14 Oct 2026 04:04:56 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 3FBAE6B008C for ; Wed, 14 Oct 2026 04:04:56 -0400 (EDT) Received: from smtpin15.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id A80374045C for ; Wed, 14 Oct 2026 08:04:55 +0000 (UTC) X-FDA: 85320495750.15.833BB11 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf08.hostedemail.com (Postfix) with ESMTP id E8586160006 for ; Wed, 14 Oct 2026 08:04:53 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=GtJFiXxs; spf=pass (imf08.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1791965093; b=hYLJWiECSJbNCFgxFDLiJxDyU9oLPt7BDG0LkqmOpKvIhofIYhTgQSHw+g9Pkd9WaL/tRm 4QCV6FjOYrLwy9+hcj7WYt0FMQaKRDOCfbhvfzyViaqWbcahM6h5LSEseno0HtW2xmh7GD 8A2E/MxT7v5Pigj5MR7GQzh2VM41Rww= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=GtJFiXxs; spf=pass (imf08.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1791965093; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=QiKsa8Ig/ghze008rN6845jhkYU7VXnQAYeoEEL06go=; b=HKP1RorWlo8T5WJpj28VzPIT2s+3YFNHPAw14D3s563eMca4SAXC3jZhDqiAg97M1UyKZb FVvL7iWTOt1pmh3sh2muZUfts1gnVa7wdKLgH2LV0ImNNX28eR/TDRjHR9xhUkprr8y8yD D8r20FdPe9Wl1jhy/G5E+LNG5Z4yDYg= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 2B18760213; Wed, 14 Oct 2026 08:04:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E66851F000FF; Wed, 14 Oct 2026 08:04:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791965092; bh=QiKsa8Ig/ghze008rN6845jhkYU7VXnQAYeoEEL06go=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=GtJFiXxsKGSlfzuWOthSOmfiQNpfxaQlI6bcx/fGTgscsjDFyaWqjcLhYlKL7TJBp LtEekQF1iHC/qWP7/p/Cvfv2V2fqzXuW9ocLWw81yMIuU1nRSpDLn6mKXb83C8dLHf QaV9TwNonCKDkqqQWHJytB9y8f55GBeK7DSt0VR54FyE7me9TTeWSuUpu4e7VWDn05 xC97kkjWLQly6dLxK1jQz7qt/H49gyBY+1Ap7nHrjTg/6gW67abb5GCNqYSc1Xincc QfcSi1KUxTtV4BEnNV5EZ3hLmLINjB3InKbnq+0pljhDs3f51ctnVE8KzD789Lkl8n Bi4twOLPHRBbA== Message-ID: <0cc60b43-eae3-4264-87a2-1026490177e3@kernel.org> Date: Wed, 14 Oct 2026 10:04:45 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: fix address wraparound when scanning large folio PTEs To: Kiryl Shutsemau Cc: Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Ying Huang , Baolin Wang , Barry Song , Ryan Roberts , Chuanhua Han , Kyle Zeng , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20261013-folio_pte_scan_range-v1-1-c50dc30bf6ad@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: E8586160006 X-Stat-Signature: pxtp1g7qo1infh1uhoo9yg6sho75edg3 X-HE-Tag: 1791965093-717884 X-HE-Meta: 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 obrkeZCC MdL0lXGuOIhuJhMvFOAzS1lF4kVjhFcODDFHwX5UABHMQQqceBUZN2j0014kZRarkgHoAq3c7a5c2nfkVlp7lfYY72ANS+8LlagmBFkb63xO8W+smB65eRvMPo8Ff+AjcsiEgjy66+wb5gyIlL3wyRYXIYtaGrNMyhr7rcSpI7G/POF6zUYyj33Czs+3l0qYL0YWW/oC8VY8OayMibkAY8e9d2vzRumxiiMnUvgO2Ip3aHDqXW2QcPJKv6xsZPz095ydavh2tow5p56pYN0hts48l1YusXXJE59qi+q2CB16GWmOuG7x49a4c3mrnD2JkaIZo4gFBeDl22eS5qNgEolRMDJgb6xHAjEyMh+rAG/K+BHVfOIKgbugg9VH46nCy/bMY Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/13/26 14:57, Kiryl Shutsemau wrote: > On Tue, Oct 13, 2026 at 02:30:37PM +0200, David Hildenbrand (Arm) wrote: >> 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_pte_scan_range(), that >> takes care of staying within VMA and page table boundaries while >> handling possible wraparounds. >> >> Reported-by: Kyle Zeng >> Fixes: d2136d749d76 ("mm: support multi-size THP numa balancing") >> Fixes: 508758960b8d ("mm: swap: entirely map large folios found in swapcache") >> Cc: stable@vger.kernel.org >> Signed-off-by: David Hildenbrand (Arm) >> --- >> mm/memory.c | 43 +++++++++++++++++++++++++++++-------------- >> 1 file changed, 29 insertions(+), 14 deletions(-) >> >> diff --git a/mm/memory.c b/mm/memory.c >> index 1f5d5f7d39cd2..a3823010aa981 100644 >> --- a/mm/memory.c >> +++ b/mm/memory.c >> @@ -4933,6 +4933,27 @@ static void check_swap_exclusive(struct folio *folio, swp_entry_t entry, >> } while (--nr_pages); >> } >> >> +/* >> + * 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_scan_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); >> + const unsigned long upper = min(pmd_end - 1, vma->vm_end - 1) + 1; > > These -1/+1 gave me a pause. I guess it is for pmd_end wrapping to 0 in > the top PMD? A comment would be nice. I'll add a comment if I decide to leave that in as is, thanks! -- Cheers, David