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 78C4BC47258 for ; Thu, 25 Jan 2024 18:06:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=BaCLqh5nvWgou8y4heDLz9kALRt3vKbsyHlwi3xXfwA=; b=yEnj3UCubVmVaE Wq2vkM2QdGTg4myQyFgegAn3nvlTD0pPZgZoqanDetZByjuXqOUv2Xch9uYydMO/F/7g+2vmmIeTW SmdxHl/LtKE76jbK/s5QLZPuyTlvmkcBTZ3oExJoFYjjGC8ekWbJex55L7N197JhKgYPGzA5k/B45 yveSzSV2IUr/NQbhCiQXfuBqqFGS+t2WVTqWYl3RprEh9OkoP0WqAWT/59OoBxMEOpJfSN5FxhGGG GYQ3Q8MJKQV61PkTBOBh4W604qmh1eC5KOVwr67XkK4VkCPrzGQE9qtdcdeKbdBpSarBAkCCiQD1n xDM3kTVx3Pm3u6Xer60Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rT47R-00000001GNj-2ZGs; Thu, 25 Jan 2024 18:06:29 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rT47O-00000001GMJ-176z for linux-arm-kernel@lists.infradead.org; Thu, 25 Jan 2024 18:06:28 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id AAD3D61503; Thu, 25 Jan 2024 18:06:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 43125C433F1; Thu, 25 Jan 2024 18:06:23 +0000 (UTC) Date: Thu, 25 Jan 2024 18:06:20 +0000 From: Catalin Marinas To: Nanyong Sun Cc: will@kernel.org, mike.kravetz@oracle.com, muchun.song@linux.dev, akpm@linux-foundation.org, anshuman.khandual@arm.com, willy@infradead.org, wangkefeng.wang@huawei.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v3 0/3] A Solution to Re-enable hugetlb vmemmap optimize Message-ID: References: <20240113094436.2506396-1-sunnanyong@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240113094436.2506396-1-sunnanyong@huawei.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240125_100626_663291_042041C7 X-CRM114-Status: GOOD ( 13.14 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sat, Jan 13, 2024 at 05:44:33PM +0800, Nanyong Sun wrote: > HVO was previously disabled on arm64 [1] due to the lack of necessary > BBM(break-before-make) logic when changing page tables. > This set of patches fix this by adding necessary BBM sequence when > changing page table, and supporting vmemmap page fault handling to > fixup kernel address translation fault if vmemmap is concurrently accessed. I'm not keen on this approach. I'm not even sure it's safe. In the second patch, you take the init_mm.page_table_lock on the fault path but are we sure this is unlocked when the fault was taken? Basically you can get a fault anywhere something accesses a struct page. How often is this code path called? I wonder whether a stop_machine() approach would be simpler. Andrew, I'd suggest we drop these patches from the mm tree for the time being. They haven't received much review from the arm64 folk. Thanks. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel