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 797A1344DB8 for ; Fri, 27 Mar 2026 16:57:11 +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=1774630631; cv=none; b=DteEIx/bUJnx04VJlJhkkGzIiI3bTvmtdf5V5Kmw62smSza0SV0mFwkiDQUY8n40ioLioUKa9rTCw/YEt/9RSGwM0pAcuJC6/NIOWLMRxYXcs0JqHRPqsCOhti3+0yS0GezyuscffuV151go6V9gGGEMJgR5ixGpgDYtHmzUVBs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774630631; c=relaxed/simple; bh=tewTlAfQ3NfyHAyVP63RBnCHjQJ2G7MM/v5u44/+dyE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=pRdlY/SMPDZCRv6cPjxEJMd+NakmF29MdGrJvmy7gJf+bwcgDxu5D+TiOwvAVzBl02ILgNvmXMh1W2ryFsFx+uUGmxnmvE5jYiFqmhGgYuHbAAQsShJAeAvWh4vKHc+vNfn1YjMK7giD+y5kp0SzgrACMjxi7u1n566tORSamtk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RJCM2Xe/; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="RJCM2Xe/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6D690C19423; Fri, 27 Mar 2026 16:57:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774630631; bh=tewTlAfQ3NfyHAyVP63RBnCHjQJ2G7MM/v5u44/+dyE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=RJCM2Xe/t/XgpG0euJgwFM7ipgJImehlk5+JXxy8aawzPm/LoeWOdY+G7jDNAgr2X W/PnqgH1fHpwBjKamHpBh3sRAGFf+cGgRBts7jsbgLtE+SpV8VW8ZrvgQajJPSbiPZ jjsgOXt9qCB/sh60a2NpoD7H/PoR+MnsOCEJE4Be+KnLDF6AweXA+BOyct0lk+LhpH 0YXHkg+b10uPpuskyXTkoLEEtTVRxkJZT+8/WNquBNW5T64q2ceqfS26oXZmedj1sp rZetRkX/sDC3pKYjvFlp8no4VpqLzGPUa9JpHhmYMTnwigAFUMhgg37Of1vfVYu09T 5YYOgJl80STSg== Message-ID: Date: Fri, 27 Mar 2026 17:57:06 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH mm-hotfixes] mm/mseal: update VMA end correctly on merge To: "Lorenzo Stoakes (Oracle)" , Andrew Morton Cc: "Liam R . Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , Jeff Xu , linux-mm@kvack.org, linux-kernel@vger.kernel.org, antonius References: <20260327090640.146308-1-ljs@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: <20260327090640.146308-1-ljs@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/27/26 10:06, Lorenzo Stoakes (Oracle) wrote: > Previously we stored the end of the current VMA in curr_end, and then upon > iterating to the next VMA updated curr_start to curr_end to advance to the > next VMA. > > However, this doesn't take into account the fact that a VMA might be > updated due to a merge by vma_modify_flags(), which can result in curr_end > being stale and thus, upon setting curr_start to curr_end, ending up with > an incorrect curr_start on the next iteration. > > Resolve the issue by setting curr_end to vma->vm_end unconditionally to > ensure this value remains updated should this occur. > > Signed-off-by: Lorenzo Stoakes (Oracle) > Fixes: 6c2da14ae1e0 ("mm/mseal: rework mseal apply logic") > Cc: > Reported-by: Antonius > Closes: https://lore.kernel.org/linux-mm/CAK8a0jyHXqBpt8Xe8v9SNDbnRiwz7OthA8SKY=NLRY7smPEP3Q@mail.gmail.com/ > --- > mm/mseal.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/mseal.c b/mm/mseal.c > index 316b5e1dec78..2d72a15d8ea1 100644 > --- a/mm/mseal.c > +++ b/mm/mseal.c > @@ -66,7 +66,7 @@ static int mseal_apply(struct mm_struct *mm, > prev = vma; > > for_each_vma_range(vmi, vma, end) { > - const unsigned long curr_end = MIN(vma->vm_end, end); > + unsigned long curr_end = MIN(vma->vm_end, end); > > if (!(vma->vm_flags & VM_SEALED)) { > vm_flags_t vm_flags = vma->vm_flags | VM_SEALED; > @@ -76,6 +76,7 @@ static int mseal_apply(struct mm_struct *mm, > if (IS_ERR(vma)) > return PTR_ERR(vma); > vm_flags_set(vma, VM_SEALED); > + curr_end = vma->vm_end; /* Merge may have updated. */ > } I was a bit confused why curr_start is allowed to not start within the VMA, but before it. Then I recalled that range_contains_unmapped() checks for no holes. Would the following also sort out the problem and even simplify the code? diff --git a/mm/mseal.c b/mm/mseal.c index 603df53ad267..e2093ae3d25c 100644 --- a/mm/mseal.c +++ b/mm/mseal.c @@ -56,7 +56,6 @@ static int mseal_apply(struct mm_struct *mm, unsigned long start, unsigned long end) { struct vm_area_struct *vma, *prev; - unsigned long curr_start = start; VMA_ITERATOR(vmi, mm, start); /* We know there are no gaps so this will be non-NULL. */ @@ -66,6 +65,7 @@ static int mseal_apply(struct mm_struct *mm, prev = vma; for_each_vma_range(vmi, vma, end) { + const unsigned long curr_start = MAX(vma->vm_start, start); const unsigned long curr_end = MIN(vma->vm_end, end); if (!vma_test(vma, VMA_SEALED_BIT)) { @@ -82,7 +82,6 @@ static int mseal_apply(struct mm_struct *mm, } prev = vma; - curr_start = curr_end; } return 0; diff --git a/mm/page_alloc.c b/mm/page_alloc.c I might be wrong about that, I've been staring at the screen for too long today. -- Cheers, David