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 4AED8606A31A for ; Fri, 30 Oct 2026 03:42:20 +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=3PLYO5rf; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=nP21Y2MO 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=AiNk0l2rg2iXeiqwqVr+Pt9hVRxhcTvTMKbYUZzDWgA=; b=3PLYO5rfRLfxbSpOFOa1yY2LKI d7sVL3i2ShMZ7qceRc6D4ArLUbbVbfl32Op1SecHx0XTrmzLANn44lPC561IuAS12c+XkKM7l9Pp8 uz5axkDTjEBNWwdjK2ecB/Nrb1NhgOb7T+TtUeQvM/f52gCFBmPNwZBtPARHxkoCcJsaSi7CYvplw iz4xPP9ZrX9uhDHVe1ymdCTwRpPGl1m8v07z6e4hEyBVb/OEzHAdEzEP4bC14UjErdBRvMgxGGfkG 1t1OXt/kiWhUMFQXc2PMfd1aqn4+OeYBNzuA5ASl3uEnZvErkHE8FsPoMDd4i3qwYB3ZbYymxPVVM TloQD4sQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMdVT-0000000Al1W-3qAd; Fri, 30 Oct 2026 03:42:19 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMdVS-0000000Al0K-1SJg for kexec@lists.infradead.org; Fri, 30 Oct 2026 03:42:18 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id C5B97601EE; Fri, 30 Oct 2026 03:42:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AC88C1F0093A; Fri, 30 Oct 2026 03:42:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793331737; bh=AiNk0l2rg2iXeiqwqVr+Pt9hVRxhcTvTMKbYUZzDWgA=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=nP21Y2MOWKX5mNXosilZovGfoMu73QLkmpDaQu3AQc9yBLmIVwaajAnArjy8fdCCR tJzR9Dw5EQCc2Tjtx4OZXhdkfkVxjffLa1dL0GQobtvmbxX3tQxEZ4ByIduzu3rYPK inNZdP108nzRUpr6Twox8qw9FqhKtPRiPJpnkFqkhJrRMlZxhpDZqGj4wylHzFe046 98HI9LqMwVoOrxRHu3Nj2RXFtOH8dnmMvT4d81dHDmXSVnclqIPxOvQ4F/p2mvKTMx ykwfAvp7f79G1KxMJOJwYX2BL9Yaa1woK4+DRoumyJdwQ7jPdR0AJ2LTUX6Fc1JGKY M0lLt6hwsI1Nw== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH v2 38/47] 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: <20261029-fixes_core-v2-38-a64ce7f83abb@kernel.org> References: <20261029-fixes_core-v2-0-a64ce7f83abb@kernel.org> <20261029-fixes_core-v2-38-a64ce7f83abb@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Fri, 30 Oct 2026 03:42:14 +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=-10.9 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 > [ david: use new helpers consistently; simplify description and comments; > move_ptes() fixup ] >=20 > Fixes: 867a43a34ff8 ("userfaultfd: use per-vma locks in userfaultfd opera= tions") > Cc: stable@vger.kernel.org > Signed-off-by: Chris Mason > Reviewed-by: Lorenzo Stoakes (ARM) > Acked-by: Muchun Song > 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/20261029-fixes_core= -v2-0-a64ce7f83abb@kernel.org?part=3D38