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 96B4FCCD19A for ; Fri, 17 Oct 2025 11:14:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E1FC78E005D; Fri, 17 Oct 2025 07:14:47 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DF7CA8E0016; Fri, 17 Oct 2025 07:14:47 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D35168E005D; Fri, 17 Oct 2025 07:14:47 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id C1A9F8E0016 for ; Fri, 17 Oct 2025 07:14:47 -0400 (EDT) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 7EFB983E32 for ; Fri, 17 Oct 2025 11:14:47 +0000 (UTC) X-FDA: 84007348614.29.8BD1B2D Received: from out-186.mta0.migadu.com (out-186.mta0.migadu.com [91.218.175.186]) by imf25.hostedemail.com (Postfix) with ESMTP id 99A8CA000D for ; Fri, 17 Oct 2025 11:14:45 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=rVS25rQ8; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf25.hostedemail.com: domain of lance.yang@linux.dev designates 91.218.175.186 as permitted sender) smtp.mailfrom=lance.yang@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1760699685; a=rsa-sha256; cv=none; b=VQokGW1LyqScj0DHKHDfGO3uVmKkFBZfJwk+kj6Op5X+JSm39GRk7F0FPBnbwF96nF+N5+ uxbNkMi6bnsJFOH7En01dPe5liH3JbnVs4+dHjivByLVXf+nQbj5m8st6fGQ4aiTGRXZMj bi3Pd5sHcysaGvIBFbkYmqD7afoLf9E= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=rVS25rQ8; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf25.hostedemail.com: domain of lance.yang@linux.dev designates 91.218.175.186 as permitted sender) smtp.mailfrom=lance.yang@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1760699685; 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=3YA/xLAG8p45THXYYw7JCFQ9A+nLtvOhAjcG32D7eHo=; b=MaYbCjjUDJa7Sa/mnupIVyHp5GO97OcKnSOhEHlm6tKJ3VR8ZzqHOfnF3lRNkkl4H5jF3Y tYjQ5G6VFHJ1ddOwNoXYGTHs+UAjU4hx0KYFKd47LHoPw854WZlONoHDnbPqfcd/Yv/Tk7 buRAv+On1+RaDetbxBeIu/sCS0gdyCw= Message-ID: <384aa808-1893-4f44-9c76-96a21c1989d2@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1760699683; h=from:from: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; bh=3YA/xLAG8p45THXYYw7JCFQ9A+nLtvOhAjcG32D7eHo=; b=rVS25rQ865xS2yGt3O/yQdSrncZauX78g1/G02hwqFi+vY+Kp8bbebzjrHfnBPsBlcHOSi MZU7eFIaVjCdjwWXgV10d1oD6IZmCf/q1+6CrAI8qaqEeiambsRra6jrOmeKlL3E5OWmJR tJsIReAZdoG59daw1s1T6JGuSc8jBOA= Date: Fri, 17 Oct 2025 19:14:32 +0800 MIME-Version: 1.0 Subject: Re: [PATCH 6.12.y 1/1] mm/rmap: fix soft-dirty and uffd-wp bit loss when remapping zero-filled mTHP subpage to shared zeropage Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Lance Yang To: Lorenzo Stoakes Cc: stable@vger.kernel.org, linux-mm@kvack.org, ioworker0@gmail.com, David Hildenbrand , Dev Jain , Zi Yan , "Liam R. Howlett" , Harry Yoo , Alistair Popple , Baolin Wang , Barry Song , Byungchul Park , Gregory Price , "Huang, Ying" , Jann Horn , Joshua Hahn , Mariano Pache , Mathew Brost , Peter Xu , Rakie Kim , Rik van Riel , Ryan Roberts , Usama Arif , Vlastimil Babka , Yu Zhao , Andrew Morton References: <2025101627-shortage-author-7f5b@gregkh> <20251017085106.16330-1-lance.yang@linux.dev> <121d5933-16d9-4eb5-b2b5-2edff9b36c16@lucifer.local> <3390d129-e540-42f0-aada-0c8b6fe96f26@linux.dev> In-Reply-To: <3390d129-e540-42f0-aada-0c8b6fe96f26@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 99A8CA000D X-Stat-Signature: tcpf7zpfwqeobme4ptippjwgpcn445y4 X-HE-Tag: 1760699685-649251 X-HE-Meta: U2FsdGVkX1/vhxmE8PZ2l+g+++pRieeQGEr9kxUR8SzgMGvdH2Md3FZ7SR53lFF8dVxSoRV3Ve+Td0ry9us8DRiF3qgGXUYBn0S72TvzviEPtkL710sovM779LzRgoOoFE/nT0BAQWJJz0z6i5xootluGrscdPbbs3Qcfugkni0wsFPOzElWWVIxZH7hVu4GfIzC72WhVjEJYrDm8FzKA2AJ1Uv11RCzFjmP22r78xF2PAQuRps1BHJuSdaYpyIngy73doNw8HLnzQWCJvvSMMx5AdV7pBdY5taJVToHBRWHvxc0/6NSUu34k3eOOxQ1OOHg+Oh4AMVfyYTJpFJUn86izimxhnESkV1msrDxbarPAHDY+Am7Mr/7JGojM3S5z12IvlTgWYhhX4utv4nbLJ7Ec7N2bTSiUB/fdD550q5iI92/SD/tjCRfMa+5t+Zyz4oeDuGHUJzZwnViapBUZSfuXvzfGSiL3wVCrhgZ+344HuGjeob2QU3hQmmJgUjcwFBBp8kaA8U/T9ubYb8KpZzCO7n5fNmKg06QjiHdtZdzTrC/q0KnnaadECshr3GtW4oHc7gnNuG5aGvV1zXROb1iT6gVdg4gGWmZE+78W67tZXZ48uWdXjW/EuOuicEu1S3C7HWhZgKpsuM5Oxr59DpfFu+Ai3ZRcL9MDqpqB/NDnb4ZPoLN9R7DDmvsbOP6K10RmbWBGAwZRFDUYkxMlqTjmXUOejJocKFXeqOXPyV5ZgHyMTtJK6q351Sv72huMT947JOIVAqrLBICWKd0P5zCOGIi+XpL8/8jeOYVV02t9OlqGjl1TBqqHgEueRcBBl1SiTSOPFfP7C/SdqZIbaI60uLI30YRkhPWbswaMTjNIvf8ZwSeYEhaWxLQaaiR7ZiUtxRoXW/j+42SdTEKsJuKDBvyVGC0bsZWGz0v1o8kEdmb0G/3XC5OZHe5J1cfQ7NeYO9Is2yE+hyMYNz MOW1TYqy J2gveI5Z4o1dxryZAtZd2shn2e4spuy8kj5HVEg3C35x01jKkrJcN6X57bXHtYIX5/m2so43yARiM0oCMkRNKdf5loTEL9oqqPlalXWOcZ7gI3+x3LV7Z+VE/X0G9d88gfy7hAnFPeC93kK8Mqg5WL0EFtCvHtdqFjg3aPmAp1JD1+sHhH1bLPIDBI53fXFTlZa3IahN5oz4qhepVnzM+I3dTWngs+N3FnWsgMrz4mpdmizxoJnxRNLHevEIm4Cgv3ZtyA5BqZ3ue4JLbyv7nd3ib2MJgbU2Wgfd9ICNn/46P5cyvqwRXQaxh0vpcENG0Fc1QoUcNoXX4wYSRsOitpsUU3qMR3kuV5DKfi7LKEOYAKjeDlhhsfWkUfSGh2DQBiG9d4rJJGak0NzGuKWG2WzvmdUIjDtCrP3tvW+g5lCo/+8wYmtVFdbJgMg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2025/10/17 18:25, Lance Yang wrote: > > > On 2025/10/17 17:52, Lorenzo Stoakes wrote: >> On Fri, Oct 17, 2025 at 04:51:06PM +0800, Lance Yang wrote: >>> From: Lance Yang >>> >>> When splitting an mTHP and replacing a zero-filled subpage with the >>> shared >>> zeropage, try_to_map_unused_to_zeropage() currently drops several >>> important PTE bits. >>> >>> For userspace tools like CRIU, which rely on the soft-dirty mechanism >>> for >>> incremental snapshots, losing the soft-dirty bit means modified pages >>> are >>> missed, leading to inconsistent memory state after restore. >>> >>> As pointed out by David, the more critical uffd-wp bit is also dropped. >>> This breaks the userfaultfd write-protection mechanism, causing >>> writes to >>> be silently missed by monitoring applications, which can lead to data >>> corruption. >>> >>> Preserve both the soft-dirty and uffd-wp bits from the old PTE when >>> creating the new zeropage mapping to ensure they are correctly tracked. >>> >>> Link: https://lkml.kernel.org/r/20250930081040.80926-1- >>> lance.yang@linux.dev >>> Fixes: b1f202060afe ("mm: remap unused subpages to shared zeropage >>> when splitting isolated thp") >>> Signed-off-by: Lance Yang >>> Suggested-by: David Hildenbrand >>> Suggested-by: Dev Jain >>> Acked-by: David Hildenbrand >>> Reviewed-by: Dev Jain >>> Acked-by: Zi Yan >>> Reviewed-by: Liam R. Howlett >>> Reviewed-by: Harry Yoo >> >> You're missing my R-b... > > Sorry, I missed it! I just cherry-picked the commit from > upstream and didn't notice ... > > Hopefully Greg can add your Reviewed-by when applying. Looking at the timeline again, the fix was actually merged upstream before your review arrived, so the commit I cherry-picked never had your tag to begin with :( Still hoping Greg can add it!