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 C0FDD109E52B for ; Thu, 26 Mar 2026 01:48:11 +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=H8uD3fXoJUVKVQlQPb1UgplQm2Umx6AyBtREGpInkaM=; b=Pi99fKp8zrNxFb/2vJpDadE4sT DEbxLHMXb4E49pNsvebwTpM2r3NCA3wPMaHHuDabDax4dA+lg+FDJFavr0jHI82+HsdLoum7Qe5ps 4DFuH4szFFbpBfv6sAdd2i19eJwc7hoKIHOKaJikY3B/skpNwcgg2sI1Lp0WLGtLbBgy241fQv95l qRZcOP7PnjXJTqJ8J38vw7vVgaNQaqdjyJYoxizGDx/WChHYUtQ0GTvL/ZPyrlc0rJ0X8eDFbKNFj qeA0Bf8euGA8PtE6lWoByqdxznS2DhIMnKrMbLo+NLXelAgLOLeiiyAd6mIwaZMZgrrHu3/yuo/Mf RXdok4Tg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1w5ZpN-00000004Xex-3wEk; Thu, 26 Mar 2026 01:48:05 +0000 Received: from out30-132.freemail.mail.aliyun.com ([115.124.30.132]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1w5ZpK-00000004Xe2-001H for linux-arm-kernel@lists.infradead.org; Thu, 26 Mar 2026 01:48:04 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1774489674; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=H8uD3fXoJUVKVQlQPb1UgplQm2Umx6AyBtREGpInkaM=; b=EF3koCnKfebTyiOrU7IFleaG4W9jjVjbGQmJDFXmKOkOzcWNcRTOlbdk9tP4DejgcWMD3/aIJnpTjElLxoEF4wTDGQFxaaF5SJUL2q1qPVo+kQRnHpcFnYVNtryhjDA64kQIc8ot3HDG5cGERsupr2Lsex7yJNg24mT+JuBf95o= X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R181e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037026112;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=21;SR=0;TI=SMTPD_---0X.jfTBI_1774489671; Received: from 30.74.144.123(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0X.jfTBI_1774489671 cluster:ay36) by smtp.aliyun-inc.com; Thu, 26 Mar 2026 09:47:52 +0800 Message-ID: Date: Thu, 26 Mar 2026 09:47:51 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 1/5] mm: rmap: support batched checks of the references for large folios To: "Lorenzo Stoakes (Oracle)" , "David Hildenbrand (Arm)" Cc: Barry Song <21cnbao@gmail.com>, akpm@linux-foundation.org, 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, dev.jain@arm.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <12132694536834262062d1fb304f8f8a064b6750.1770645603.git.baolin.wang@linux.alibaba.com> <43831628-a00f-4292-9797-cb96a029bb00@kernel.org> <86f611cb-1292-44e4-b629-6503135d33ca@kernel.org> From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260325_184802_747031_4BC03556 X-CRM114-Status: GOOD ( 13.22 ) 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 On 3/25/26 11:06 PM, Lorenzo Stoakes (Oracle) wrote: > On Wed, Mar 25, 2026 at 03:58:36PM +0100, David Hildenbrand (Arm) wrote: >> On 3/25/26 15:36, Lorenzo Stoakes (Oracle) wrote: >>> On Mon, Mar 16, 2026 at 03:15:18PM +0100, David Hildenbrand (Arm) wrote: >>>> On 3/16/26 07:25, Baolin Wang wrote: >>>>> >>>>> >>>>> >>>>> Sure. However, after investigating RISC‑V and x86, I found that >>>>> ptep_clear_flush_young() does not flush the TLB on these architectures: >>>>> >>>>> int ptep_clear_flush_young(struct vm_area_struct *vma, >>>>>                unsigned long address, pte_t *ptep) >>>>> { >>>>>     /* >>>>>      * On x86 CPUs, clearing the accessed bit without a TLB flush >>>>>      * doesn't cause data corruption. [ It could cause incorrect >>>>>      * page aging and the (mistaken) reclaim of hot pages, but the >>>>>      * chance of that should be relatively low. ] >>>>>      * >>>>>      * So as a performance optimization don't flush the TLB when >>>>>      * clearing the accessed bit, it will eventually be flushed by >>>>>      * a context switch or a VM operation anyway. [ In the rare >>>>>      * event of it not getting flushed for a long time the delay >>>>>      * shouldn't really matter because there's no real memory >>>>>      * pressure for swapout to react to. ] >>>>>      */ >>>>>     return ptep_test_and_clear_young(vma, address, ptep); >>>>> } >>>> >>>> You'd probably want an arch helper then, that tells you whether >>>> a flush_tlb_range() after ptep_test_and_clear_young() is required. >>>> >>>> Or some special flush_tlb_range() helper. >>>> >>>> I agree that it requires more work. (Sorry, David. I forgot to reply to your email because I've had a lot to sort out recently.) Rather than adding more arch helpers (we already have plenty for the young flag check), I think we should try removing the TLB flush, as I mentioned to Barry[1]. MGLRU reclaim already skips the TLB flush, and it seems to work fine. What do you think? Here are our previous attempts to remove the TLB flush: My patch: https://lkml.org/lkml/2023/10/24/533 Barry's patch: https://lore.kernel.org/lkml/20220617070555.344368-1-21cnbao@gmail.com/ [1] https://lore.kernel.org/all/6bdc4b03-9631-4717-a3fa-2785a7930aba@linux.alibaba.com/ >>> Sorry unclear here - does the series need more work or does a follow up patch >>> need more work? >> >> Follow up! > > Ok good as in mm-stable now. Sadly means I don't get to review it but there we > go. Actually this patchset has already been merged upstream:)