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=1794425141; b=30bkAXvzd/+nhsRDiciyeuxCO9bJxCrtMjcMNdz4snbRjf6cIYrz0wKo6O/0pelXbvxR yRGQLqNGXFwgulhGXcYa4NgJEDoE6xxjevtB8H0PtmyQmK1G111rweRPYwMJ6cQBjYHoX IBqPutEHVQ8x9mi2Vwbt8GQQr2eWm4UDhUn2YroCZkExoSrvbx/ldzDnQnkU7PMwjUpiC G+6gnXCKgg5TMOn4TbAAWtj6DKFz4CJqkDxQJhlqnMomjaIU6BJ8aJZ6MvwPQQ3u4AisU v3j9jVox5emrEyxPC7IUnlDJNgZIYoUMt8ORwcFRiaX4Ne97bfLBzqjLeDBw1HuLokw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794425141; h=Received:DKIM-Signature:Received:Received:X-ME-Sender:X-ME-Received: X-ME-Proxy-Cause:X-ME-Proxy:Feedback-ID:Received:Date:From:To:Cc: Subject:Message-ID:References:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; bh=nLrVl/k3KgLHzXmtBoOIZdPXNZn+ttWx65joOkMlZPo=; b=fltTcomAvoLLenjxafiOr4jPwW4mZP99g5KZ3KYXhavJSDHeXywA0TMLVh/w8z7MldH+ zPoQmHwV+5QcYbyt6qrSPOEr7lgH26qU75cknxkPtjFf1vduEmfqYTWHdtD2eFK50fN7N A/TYgoqu+R/Wv8tbVwJcssBrzZ1PMf4++kXMGGJT3SSl0ZfjDcXpK0TbPLQD2SGAXdUQg wjzc5RovoKSicMr4wJlOub3g1KtRie8olPyem2t9oG5Mrkg0zh8TK7+XC143VlAnjYtjI nI8ALSlGDhLdZ3+y+ZletGn2SW5W/Mn+RPr+zdf0oBT7K8crkvajXENmHzzAMiKKweA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=gadnwvYG; 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 E1090606A321; Wed, 11 Nov 2026 19:25:40 +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=gadnwvYG Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F79C1F00A07; Wed, 11 Nov 2026 19:25:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794425140; bh=nLrVl/k3KgLHzXmtBoOIZdPXNZn+ttWx65joOkMlZPo=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=gadnwvYGYHAXYYVGk1JbKh/JDgeU8CHZAAEHkxHMQYEAdjkvpD8GlA+iOgSQ1gHaL 2WzgFZY6dMZD32ET9fMNrWhfaCiiC4Y34HIpRimS6mMDQa+GnhVjYmWL0criR6mOtK zgJJQ9YNM5t4J8cc/PQdZCvMpwY+05M13mf7H+QBNj6lYRfha3d3soNYgfiFNOolqF VYJoG90Garjxk7cNd08Ew9nNK6lpJvaAyiecaPHkl2rgqsykZnNfbzF/DGjbGZM8m+ 5qPOW61uhkaFVNmP1xkqi8Y9uKTeB9BtnxR6ewQC9bAdsv6tH3LqBSnOTHgYav5hxB IehLsKRBtSjyQ== Received: from phl-compute-02.internal (phl-compute-02.internal [10.202.2.42]) by mailfauth.ams.internal (Postfix) with ESMTP id 28E98198003A; Wed, 11 Nov 2026 14:25:30 -0500 (EST) Received: from phl-frontend-04 ([10.202.2.163]) by phl-compute-02.internal (MEProxy); Wed, 11 Nov 2026 14:25:36 -0500 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTGVCwJi64G/NFk0BwzEnaSuCMVZAMzOi2v2VfdLLUWVfoxG0mAp0ULnNCJcShF2US zpqvkUUooMNrb9VT5bI+vNxuhwJuht9BnZuyP6D7bvZpoK8a5uikkJGwYKWB4heRQ9E8Qp 8sFCVqzwGTCEaJn44LCyasSmVXfeqafjx/O0DiPO5mcDIuboMSbr92WRN5tGZf5rQpFY31 06/Afv0VFlX+JK/uyhMP0CiVCN8q3iMXiYF4dq1x7GZLlVF4MqhHo0IfHCmyrD1YpPu8fo 03njvV/FKfclnNsctu4TRqpZ7QfV9E18C6DC5sQImJkZh9i7ypzb+El+NDySjRQo2OVLmI GM/Jd7JhmF5Y9hVDkKokHMQIA4bJVVX0aPReG+1uGfuFZd8dJ5WNxaQuO1dD5m/6En8RPK fUMhgFo2c7IxI+em9h58OsEervXa2F08mHxIEqGlCjYMUwpIC7K970CUfnPFsukHH/piiy lCPIsBlh5O0aJWIWnYjPobC+oObXpKCZLinZ+jw1aWP1N+wt7+9ur7cXHwegSBM2LUJ8s1 yyfVCMVinA/PEJWsRAk+M0qK5itVdjSu/G85tdlBzL/yO3fxabKkS3ayTaNJDQ1MoTPQGb OuCHDUZmlNpKRYpF7Unv6Ca2ihvDHAJ43ZIC3u5t/aMPRgDoWkE6i8PBRRXA X-ME-Proxy: Feedback-ID: i10464835:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Wed, 11 Nov 2026 14:25:28 -0500 (EST) Date: Wed, 11 Nov 2026 19:25:27 +0000 From: Kiryl Shutsemau To: Tal Zussman Cc: Andrew Morton , Mike Rapoport , Peter Xu , James Houghton , Andrea Arcangeli , Suren Baghdasaryan , Balbir Singh , "Liam R. Howlett" , Lorenzo Stoakes , Vlastimil Babka , Jann Horn , Pedro Falcato , =?utf-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= , Andrei Vagin , Stephen Rothwell , Arnd Bergmann , Muhammad Usama Anjum , David Hildenbrand , Zi Yan , Matthew Brost , Joshua Hahn , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Chris Down , Muchun Song , Oscar Salvador , =?utf-8?Q?Miko=C5=82aj?= Lenczewski , Michal Hocko , Mike Kravetz , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 11/12] mm/madvise: send UFFD_EVENT_REMOVE when installing guard regions Message-ID: References: <20261111-uffd-state-fixes-v1-0-00713d368976@columbia.edu> <20261111-uffd-state-fixes-v1-11-00713d368976@columbia.edu> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261111-uffd-state-fixes-v1-11-00713d368976@columbia.edu> On Wed, Nov 11, 2026 at 12:55:19PM -0500, Tal Zussman wrote: > On an anonymous VMA, the zap drops uffd-wp and RWP protection along with > the pages. Writes and accesses to the range after the guard is removed > are then not reported, and the manager cannot know that it has to > protect the range again. For RWP this only holds if the range is registered without MISSING. The zap frees the pages, so with MISSING the first access after the guard is removed is reported as a missing fault. And there is nothing to protect again: RWP only covers present PTEs, and a page faulted back in shows up as accessed in PAGEMAP_SCAN. -- Kiryl Shutsemau / Kirill A. Shutemov