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=1793132726; b=SM+z3ykm19eE7QoaUYDMatqdUKg+SNx2anwaZac/vfv6W8vjqUFhiJt/eNpYiXSwyYZX +ShkHRpjL5+L5RWcnZoXDaqO4W3Dj+t1MrlxGKKiS9MaNJyWxCGIp0mdwSZS+SDr5xfKj zI674PJMPo94p4EA+hZWJyu36RJtHJYMV5JFDmSRMOVZQOqhC6AVDl7jyaD+NdBTVta8F 0BgHqMf/s4iIcfTi/7hIyH4w5NyQjpc9CumDjG7mr+uv/01kilZTTYxK1QEJGrdps2S8D 5CeBbFqdrkXM2PPWwT1Lr/bJSOCldGuucIa2DkBsmnH0XXz8J8yQIAkBgdcMDPLxlJQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793132726; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=FHMTsBnJMpXJNOaP415fipWiMQQwfvRW5x3lZ/lRcHU=; b=i6TIP+4TR/Ric3vsb/nFezb2EecfKAwbczaHflbPAcaF332hBEs9N8/A9U9xxZGqaALJ NaDfypSkyQad/iuoQUxVPpuk13Ily9QLjhVRLl8lmVlIYPn+OV0VlUbC9+OklJa5hwoBq MBv8U1V846DqDRm2bvYsgTCzE4dTMz0j5Xjsz2IJ7r5LX2GydVNVkGCht7Y+8Hr/EJyQi /XrPy3eC2Q9lLjZr4ZWZdSW5mKUFhRZ1NbjEb03Laa9exuuMBkWgrH5MsGtn29OzBrxY0 1oLpw0m06hzVu1Y3GR3pQdYM8IZofgXLqte2C2nTCpfRPVPDCWp2XViBOzPp+UwmQGw== 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=Mc83FUFA; 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 35684606A324; Tue, 27 Oct 2026 20:25:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Mc83FUFA Received: by smtp.kernel.org (Postfix) with ESMTPSA id 758541F01340; Tue, 27 Oct 2026 20:25:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793132726; bh=FHMTsBnJMpXJNOaP415fipWiMQQwfvRW5x3lZ/lRcHU=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=Mc83FUFATMQPouVzjUJeRj3mhiIcUvrA+Erhg5Hh0lTW3qwPysmiXYCN/sY2USdpd VQEeiyXwH3fAYJ+vI5Uk4lbY0OCURgOg/lZzGCGvnESQZo62rEREpGK+Ywua1pC7/p qLtQrl57LVvD3FOguw5Ccq1ddGp/nxRV2WelM6luaRwZ2gItpGPc55R3kKd/uEtYE3 F962dZ5NVZdLD83zdZJ57akrnRFkaxt1wSO3UiU8UVhqMNQKVzwdHfbh6D07tWcFW0 uvnXMmSet+gq+ZP42latzKtvPeBblPMlc6bL70NhuTjijHHpcfEiVBaUcHP26dtgTY lDs1oWuY01RLQ== Date: Tue, 27 Oct 2026 20:25:24 +0000 From: Harry Yoo To: "David Hildenbrand (Arm)" Cc: 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 , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , 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 , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, stable@vger.kernel.org, Josef Bacik Subject: Re: [PATCH 09/46] mm/rmap: handle device-exclusive entries in folio_referenced_one() Message-ID: References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-9-6f74bec9a5bb@kernel.org> X-Mailing-List: linux-cxl@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: <20261027-fixes_core-v1-9-6f74bec9a5bb@kernel.org> On Tue, Oct 27, 2026 at 12:17:29AM +0100, David Hildenbrand (Arm) wrote: > page_vma_mapped_walk() can return non-present device-exclusive entries, > but folio_referenced_one() passes them to PTE young-bit accessors that > require present PTEs. > > We must neither call clear_flush_young_ptes_notify() nor > folio_pte_batch() with non-present entries. For example, clearing the > young bit on non-present PTEs can corrupt the entry: on arm64 > PTE_AF overlaps the swap type, so clearing it turns a device-exclusive > entry into an ordinary swap entry. > > folio_pte_batch() will VM_WARN_ON_FOLIO. > > Apply the same approach as the previous fixes to e.g., damon_ptep_mkold(): > treat these entries as old from the CPU's perspective and obtain their > young state through the MMU notifier. > > Skip PTE batching and MGLRU look-around for non-present entries, and > don't modify non-present PTEs. > > Fixes: b756a3b5e7ea ("mm: device exclusive memory access") > Reviewed-by: Lorenzo Stoakes (ARM) > Cc: stable@vger.kernel.org > Reported-by: Josef Bacik > Signed-off-by: David Hildenbrand (Arm) > --- Looks good to me, Reviewed-by: Harry Yoo (Meta) -- Cheers, Harry / Hyeonggon