From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id DF3EF606A33A for ; Wed, 11 Nov 2026 07:30:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=XUpiXuE8 Received: by kanga.kvack.org (Postfix) id C29416B00EF; Wed, 11 Nov 2026 02:30:02 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C08566B05B0; Wed, 11 Nov 2026 02:30:02 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B16AA6B05B1; Wed, 11 Nov 2026 02:30:02 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 79C7E6B00EF for ; Wed, 11 Nov 2026 02:30:02 -0500 (EST) Received: from smtpin30.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay02.hostedemail.com (Postfix) with ESMTP id E35C412019C for ; Wed, 11 Nov 2026 07:30:01 +0000 (UTC) X-FDA: 85422014202.30.5E34D8B Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf13.hostedemail.com (Postfix) with ESMTP id 254BC20004 for ; Wed, 11 Nov 2026 07:30:00 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=XUpiXuE8; spf=pass (imf13.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 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=1794382200; 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=AboEUDy+0XQ7R2YYo0S+EhzsgQLMIlJ5QVM52GjU8mw=; b=Q7PL83xQcTSRb+UmfsIf99GOjBvl5a2PmtZmTSKGp+2JU1SdiA1EkQAN3L0g4a9D49xTT2 6mCMv0vGZSrTqN/LaxyvCPW5FZw+h5+g4lb2V8uTViaHHUklPi2/zs/ikM/RJS71fup6xV fFeTL1ncLet+MQX59V027YHCKMUNvDE= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1794382200; b=aFMPnWm/s9YvDkP+8myQo2mk00Y3pvXMZ7gJxP2q4QvW57eNuo6T0ISQZjJTA9ZP6yn3Tg MMS3GSVM/gaU2rrQp6AcO/9d8lu9crbjrEyG07ntgE3/iVWqYkAAclRIGhtvhmVUna5EmR WumMHyASXgKFVPYsrl99HQuCglksypc= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=XUpiXuE8; spf=pass (imf13.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 4B86B44000; Wed, 11 Nov 2026 07:29:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC2F01F00A05; Wed, 11 Nov 2026 07:29:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794382199; bh=AboEUDy+0XQ7R2YYo0S+EhzsgQLMIlJ5QVM52GjU8mw=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=XUpiXuE8rXjiH2ua6oHyBD487MrqG8UJeaDGf40ZXo/8ioaryGV/lvoSsT3CE9jdg d5Re3OgWK+IQwmV4HuF2KHYqjINbC9OFaZM0JLlbhYUw5JBaAXHEoUrKQDl6hEyxL5 S96+rq0QgC+Mr7Bv46sea7cDoxBo+QWn+U4qIhp4d9GZZoszGJwV7ArxXKanNchnDb pCj2Em/2pNRuWnS4qJ7WXOLl6i9BGKsXi3TnPUtDUpEl6XnPEZqmT1dhojVuAi1CH1 OYClegvaB7BTlPC6PuybmOtxsLfoxKC2J7PnCn1MBtsK3rvwIwIVFztWKdhcJ4M7s8 Opavd4+j83fLA== Message-ID: <856cdf21-7982-475a-b244-a7ceff4eb6aa@kernel.org> Date: Wed, 11 Nov 2026 08:29:50 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [SECURITY] mm: khugepaged collapse_file() drops RWP PTE markers To: Tal Zussman , n3rd <18670333770@163.com>, "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" Cc: "akpm@linux-foundation.org" , "ljs@kernel.org" , "kas@kernel.org" , "ziy@nvidia.com" , Mike Rapoport , "peterx@redhat.com" , "security@kernel.org" , "Jose A. Perez de Azpillaga" References: <606cae9e.bbec5.1a1c54f4f9f.Coremail.18670333770@163.com> <60541e98-b1f0-4f92-a155-8a29c0bb17dc@kernel.org> <44abb8ef-7711-4ad0-be9f-ca47206892a3@columbia.edu> 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: <44abb8ef-7711-4ad0-be9f-ca47206892a3@columbia.edu> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 254BC20004 X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=4.0.1 X-Stat-Signature: 9n3m1cju53yffuzbir3fttfkjctzaeuq X-Rspam-User: X-HE-Tag: 1794382200-435724 X-HE-Meta: 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 aO5SL9DY KH4lQzbA+gZzvkJZADUHDKMhmuA5WPlwnuNAXczx1X0s34zTfyH8EX2i6UvrVmT5t1/HuqhFxYmbhXcoul8qG6DPR8aCgxhXJKrvQItJO/m8bidpsKGiQtcFzWHlAP0+VUxgoLjNuvNBumG0EpEQA97k4P74FropNJ4UvHV2LhInm0qvNDbL60cK9c5klZk1/b/HvvfT5jm6R1MovHlgiHFwrtTS5Ug7kWfdDy1IdvFu7EZ8aB7OvYeLjzGjKk09Up4KsUZjy1GpMu+eRuLNjXFq2pQ6wfYmLsJAmfk08fFD/dgKFi1Vo43pbb7NWtxAMbZLDoxLhH19++p5ShzW3je7le8EkSvwBvNv3amo09m09P+ikQSRa5z3noamNnKypwjClmbREZoLoJNDMnYRjDvJbG//60gqVEl/FeUND/KPMFFPpOvtLbMpopfOrsQrt0/u4LXyZLWevyys= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 11/11/26 04:19, Tal Zussman wrote: > On 11/10/26 6:55 AM, David Hildenbrand (Arm) wrote: >> On 11/10/26 12:54, n3rd wrote: >>> >>> Hello, >>> >>> I am reporting a security bug in the Linux kernel. >> >> Stop sending uffd problems as security bugs. STOP IT NOW. >> >> Tal has a long list of uffd-related fixes he is about to send out. CCing him. >> > So this issue was originally on my list and I had a fix for it... but it was > REALLY ugly and a band-aid, so I dropped it. Yeah, RWP is a mess. > > I think the real solution is to just add actual markers for RWP and solve > all of these issues at once... but that should be a separate series from my > batch of fixes (which I'll be sending shortly). Is there a reason RWP > markers weren't done in the first place that I'm missing? Let's ask kiryl: why is it ok to drop RWP PTE bits during swapout, zap, collapse etc? https://kernel.org/doc/html/latest/admin-guide/mm/userfaultfd.html?utm_source=chatgpt.com states "Unlike WP (which persists via PTE_MARKER_UFFD_WP), there is no persistent RWP marker today. The user needs to re-arm the range with UFFDIO_RWPROTECT after any operation that explicitly frees PTEs." But requiring the user to re-arm is rather questionable design if the kernel can just zap these page table entries. @Jose, maybe you want to look into marker support for RWP to make RWP a bit less horrible? -- Cheers, David