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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 02B4AF417E7 for ; Mon, 9 Mar 2026 14:39:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=ax2e3nDwsvw9ILVHvWERWqTLhgIowHpeGr3SQn+CkPI=; b=E/9ObsTcHqrd0e61yNCkYzjt9J 9CkZnD1pxaS5c9VcIQH9b5vJP4gR5hVHhNsvUI4sf97TIStFviVHyy+MgmeRCBfDzN+8iwOey860L whtCvLOE6EURpDhc1iAxVXX2zGi1+8YpOqohlQOXvydPP3JLNjgtCFbVDZ/of+B1EIe8livT9/aMK GWJnVnEoPtMW2ZWpJEXkzVGEZWw+LL26iOC7srtEFbzJh7+4xbCiX7DndtquIJRV0/NgXekOVJ/ZI veXJ6hw4fKt1N9LimcfLzrF9oCDMPF/LCqa2Twvvdu9L2OlkI3nu8AvF7SH4ZmCXe3711r8jaVjQ5 VuU+rDjQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vzble-00000007UXP-3B2w; Mon, 09 Mar 2026 14:39:34 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vzblc-00000007UVz-2JKc for linux-arm-kernel@lists.infradead.org; Mon, 09 Mar 2026 14:39:33 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id EEF0D443B2; Mon, 9 Mar 2026 14:39:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 54697C2BCB4; Mon, 9 Mar 2026 14:39:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773067171; bh=9PukcKOFazN0dG+ZH11NZrXPlcPN2/bdDpO63eNNTeM=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=J1RRaJsjFoPPzLLr+uhbPsnz4s6HEiGtDUliOig0I6SGfRKOs6wSvlzLJb4/GiJhD O87gKny2z+59fQSrPq0OpUbuXNOz2YjE+3mJ8tXxiuvSKRaG9x4hYFcAjcX8aKOq8W +KOuL/Lnlo6fJKFqOw5ouWYPRW1vccwAW9VyGXFoFV+PF98W9TEHARAXUiTcqhiaJp 2eynJFn5+FPYRGCrD3lTK2oWYT1Lb6D2CjwpquUhL7AYCnK52bv49oSzW/pzMXI0j8 t2k414mb6oDPC8cJb/Ivs5I8kOhx+bHIC8miqqFrQJUOTr8l9DuiaI/FzvE+dgtkH+ kXI+vX0aZe5Tg== Message-ID: <92376758-5bb5-4391-8904-cd0e2f72acf8@kernel.org> Date: Mon, 9 Mar 2026 15:39:22 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 6/6] arm64: mm: implement the architecture-specific test_and_clear_young_ptes() To: Baolin Wang , akpm@linux-foundation.org Cc: catalin.marinas@arm.com, will@kernel.org, lorenzo.stoakes@oracle.com, ryan.roberts@arm.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, riel@surriel.com, harry.yoo@oracle.com, jannh@google.com, willy@infradead.org, baohua@kernel.org, dev.jain@arm.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, hannes@cmpxchg.org, zhengqi.arch@bytedance.com, shakeel.butt@linux.dev, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <7f891d42a720cc2e57862f3b79e4f774404f313c.1772778858.git.baolin.wang@linux.alibaba.com> <6305e05e-2911-42b0-b6f5-7fdde787b778@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260309_073932_632975_E71EC22F X-CRM114-Status: GOOD ( 10.04 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org >> >> (b) The first pte is !pte_cont(), but some others in there are? > > IMO they can’t be handled in a single batch. Since the folio_pte_batch() > will group consecutive !cont PTEs into one batch and consecutive cont > PTEs into another (assume all PTEs belong to a single large folio), > because their PTE entries have different CONT bits. Interesting, thanks. I thought that folio_pte_batch() would be able to batch that. But yes, pte_batch_hint() relies on the CONT bit still being set after a ptep_get(). I wonder whether we should document somewhere that the arm implementation depends on that. This might be something to look into in the future. (make folio_pte_batch() ignore cont information when comparing and make the arm implementation be able to deal with that). Assume we unmapped the last page of a large folio. Ideally, we'd be able to process the remaining THP pieces (all ptes) in a single operation. I guess right now it would be two. -- Cheers, David