From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DE340606A322 for ; Tue, 27 Oct 2026 00:14:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=qOtZvdKn; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=V8D5TG2q DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Reply-To:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:Date: Content-Transfer-Encoding:Content-Type:References:In-Reply-To:Cc:To:Subject: From:Message-ID:MIME-Version:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=V4AbOjSd8nLqrtcumv1Oed6an9beVtdQXmRt91Erfqw=; b=qOtZvdKngqg2F6F1jpFAnx58j3 DzMh2ajkT3WsBpn+nwmv3oQgEhbqGedyric054cG/ERlBx4wAjnuko+sRtMBHQVftgW/Y3Z1zK/4N Q3YAp8J6VQJ+On4stHKJ7BYCpnoFkHHzXIOW4z2ESwTFLAJ/dL215+W3H14eVllTpxoIOZ0FLtIXO njsmXrdK4pv7hGXiMV6DP2o+cVu7VxWMvbH93srQ1av0wHPjg7SGdVeLjo6J3jH/FkUdh5EPHvsOl 1ok1YDDNyTiUA7920/lK/WXyuSWwGTXfvVXmhK79dIrgX6W+vOzaeIaImKPWvkusLH7ZH3lQwJKlZ hhHnQE+Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xLUpJ-00000003W1e-2TJH; Tue, 27 Oct 2026 00:14:05 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xLUpH-00000003W11-3sEm for kexec@lists.infradead.org; Tue, 27 Oct 2026 00:14:03 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id A4BA44322E; Tue, 27 Oct 2026 00:14:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EEC951F01828; Tue, 27 Oct 2026 00:14:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793060043; bh=V4AbOjSd8nLqrtcumv1Oed6an9beVtdQXmRt91Erfqw=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=V8D5TG2qYUAIB/BlTBUWx2qDQG4CnM5GhxgZiAzJlj6IHivJaSx5Lgpeb2H48flyJ gyDT6Ax27niFQCd1BQGb2TvrnuX12snyi9r8mj2/9iw0OJQhIbL4PbzbxNzJMcGdqH m0YHTjDArzysFONEjqiKHtF8ouQ3zwjgijdQcVKU34O63uMABKWxvzT2NiFhjDckFV iwHTVcke7B48plSr3pgS01pUaQRm8jsGvGWfu6ujIzc5cEicBPRFLhuPw9JjfzmTp9 ODigG+4f9+YxGh+zqvwbbYW0eqXcE16s/1AI12+65ij3EwdOKXUiO6aSl0rOiJSahl QMZ6+Y9Q3Up0w== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH 37/46] mm: fix deadlock of mremap() against UFFDIO_MOVE To: =?utf-8?b?RGF2aWQgSGlsZGVuYnJhbmQgKEFybSk=?= , "Andrew Morton" , "Johannes Weiner" , "Michal Hocko" , "Qi Zheng" , "Shakeel Butt" , "Lorenzo Stoakes" , "Kairui Song" , "Barry Song" , "Axel Rasmussen" , "Yuanchu Xie" , "Wei Xu" , "Baoquan He" , "Baolin Wang" , "Liam R. Howlett" , "Vlastimil Babka" , "Mike Rapoport" , "Suren Baghdasaryan" , "Michal Hocko" , "Kees Cook" , "Peter Zijlstra" , "Jann Horn" , "Pedro Falcato" , "Hugh Dickins" , "Pasha Tatashin" , "Pratyush Yadav" , =?utf-8?b?TWF0dGhldyBXaWxjb3ggKE9yYWNsZSk=?= , "Jan Kara" , "Zi Yan" , "Lance Yang" , "Rik van Riel" , "Harry Yoo" , "Alistair Popple" , "Nico Pache" , "Ryan Roberts" , "Dev Jain" , "Usama Arif" , "Kiryl Shutsemau" , "Matthew Brost" , "John Hubbard" , "Peter Xu" , "Will Deacon" , "Aneesh Kumar K.V" , "Nick Piggin" , "Oscar Salvador" , "Minchan Kim" , "Muchun Song" , "Xu Xin" , "Chengming Zhou" , "Chris Li" , "Kemeng Shi" , "Nhat Pham" , "Youngjun Park" , "Gregory Price" , "Joshua Hahn" , "Rakie Kim" , "Ying Huang" , "Jason Gunthorpe" Cc: kexec@lists.infradead.org, "Chris Mason" In-Reply-To: <20261027-fixes_core-v1-37-6f74bec9a5bb@kernel.org> References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-37-6f74bec9a5bb@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 27 Oct 2026 00:14:00 +0000 X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: sashiko-reviews@lists.linux.dev Sender: "kexec" X-Spam-Status: No, score=-11.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 X-Archived-By: > From: Chris Mason >=20 > With per-VMA locks, UFFDIO_MOVE can run concurrently with mremap() > on different VMAs in the same mm. Those VMAs can share page tables, so > both operations can acquire the same pair of page-table locks. >=20 > UFFDIO_MOVE orders the locks by address, while mremap() takes the source > lock first. These conflicting orders can deadlock; mremap() holding > mmap_lock for writing no longer helps. >=20 > Move double_pt_lock() and double_pt_unlock() to mm/internal.h and use > them for all page-table moves in mremap(). Preserve the source entry > checks after acquiring both locks. Remove the comments claiming that > exclusive mmap_lock makes lock ordering irrelevant. >=20 > In move_ptes(), make sure to just recheck source and destination PMD > after taking the locks and drop the overly-long comment. >=20 > Fix generated by an LLM and sent by Chris Mason in private. >=20 > Fixes: 867a43a34ff8 ("userfaultfd: use per-vma locks in userfaultfd opera= tions") > Cc: stable@vger.kernel.org > Signed-off-by: Chris Mason > [ david: use new helpers consistently; simplify description and comments; > move_ptes() fixup ] > Signed-off-by: David Hildenbrand (Arm) Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261027-fixes_core= -v1-0-6f74bec9a5bb@kernel.org?part=3D37