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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A9907C021A0 for ; Tue, 11 Feb 2025 06:59:26 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 9CAB310E222; Tue, 11 Feb 2025 06:59:24 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="TZpKpCGN"; dkim-atps=neutral Received: from nyc.source.kernel.org (nyc.source.kernel.org [147.75.193.91]) by gabe.freedesktop.org (Postfix) with ESMTPS id AD77E10E136; Tue, 11 Feb 2025 06:59:23 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id 1B5DEA40139; Tue, 11 Feb 2025 06:57:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 25880C4CEDD; Tue, 11 Feb 2025 06:59:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1739257162; bh=zn03NYUWlorjpWcW8rYMRK7iAV7p3dUDfxQ2kfLiz0c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TZpKpCGN/gwKCjVEwGWTHXWPnF82ODA84GaEvupijIwIXzW3AkFDN/jK0cyFFP+6p yblmsX65KhyykSwLqdx/Drtr7JJ51ONxH44nmmp7oyHdC7xwmO0Nnsne4z3T45HYEU D/6mhsZvjG2dJSX1W8swu8kYgxTCj98mnJ2m1qmV5tgBPi7aoKNx438wydZBYFFDib r1RaoQhdYNB1AgI7qkHrCB24Y4WF29++tUFVl/Qvh6gi6JVnMB8zgn7yBmE+8ujrn4 ym+s5bKOIAR3BCEpgH002IjRMToHrI8nNch8jwhFvVP4AKL5N8C2on/2w7PO+98ve9 xi/BqOGhF0a0A== From: SeongJae Park To: David Hildenbrand Cc: SeongJae Park , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-mm@kvack.org, nouveau@lists.freedesktop.org, linux-trace-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, damon@lists.linux.dev, Andrew Morton , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Jonathan Corbet , Alex Shi , Yanteng Si , Karol Herbst , Lyude Paul , Danilo Krummrich , David Airlie , Simona Vetter , Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , "Liam R. Howlett" , Lorenzo Stoakes , Vlastimil Babka , Jann Horn , Pasha Tatashin , Peter Xu , Alistair Popple , Jason Gunthorpe Subject: Re: [PATCH v2 14/17] mm/damon: handle device-exclusive entries correctly in damon_folio_young_one() Date: Mon, 10 Feb 2025 22:59:19 -0800 Message-Id: <20250211065919.5935-1-sj@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250210193801.781278-15-david@redhat.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Mon, 10 Feb 2025 20:37:56 +0100 David Hildenbrand wrote: > Ever since commit b756a3b5e7ea ("mm: device exclusive memory access") > we can return with a device-exclusive entry from page_vma_mapped_walk(). > > damon_folio_young_one() is not prepared for that, so teach it about these > PFN swap PTEs. Note that device-private entries are so far not applicable > on that path, as we expect ZONE_DEVICE pages so far only in migration code > when it comes to the RMAP. > > The impact is rather small: we'd be calling pte_young() on a > non-present PTE, which is not really defined to have semantic. > > Note that we could currently only run into this case with > device-exclusive entries on THPs. We still adjust the mapcount on > conversion to device-exclusive; this makes the rmap walk > abort early for small folios, because we'll always have > !folio_mapped() with a single device-exclusive entry. We'll adjust the > mapcount logic once all page_vma_mapped_walk() users can properly > handle device-exclusive entries. > > Fixes: b756a3b5e7ea ("mm: device exclusive memory access") > Signed-off-by: David Hildenbrand Reviewed-by: SeongJae Park Thanks, SJ [...]