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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 870AFC4360C for ; Thu, 10 Oct 2019 11:35:27 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 5A4DE2067B for ; Thu, 10 Oct 2019 11:35:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="jaARxR3F" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5A4DE2067B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject: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=JXFTFL5h+32oQOmF3Y/dQPXdZC4oCWguabljHeEl60M=; b=jaARxR3FWZzcKh xPElZ7niXBS5qa62ciNVq6aMUeU6wsw1XU8e5ibK4K1BPT6xCsT3S/i4+SmCefLtEMSF2u5PH5MuR RqYUVeRulE5/teiCLBvUOF58kmFLBdcr6rTUO1EWvIM4YfWj5YrwU9Fty+I54ug1T4wQ4F0PLOFMH CLZaXe8bk/F14ROCE/t4gzKSRf7G6AbxO0ARENwglmd868CFmUdD1B4JJQBHbaQMo5eLHSfJSEtKx qzJXgU+0DQICIANo+BPUYw3cvtl10lqLyoOe6oXrWVEDo9/xngdEwnuOJ7jrwF7OcabzTrwe6fQxW wDH3uiE9OJWhnTKWhfcg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iIWiz-0000gd-4Z; Thu, 10 Oct 2019 11:35:17 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iIWiw-0000fm-8V for linux-arm-kernel@lists.infradead.org; Thu, 10 Oct 2019 11:35:16 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5983E28; Thu, 10 Oct 2019 04:35:08 -0700 (PDT) Received: from mbp (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 776873F68E; Thu, 10 Oct 2019 04:35:05 -0700 (PDT) Date: Thu, 10 Oct 2019 12:34:59 +0100 From: Catalin Marinas To: Anshuman Khandual Subject: Re: [PATCH V9 2/2] arm64/mm: Enable memory hot remove Message-ID: <20191010113433.GI28269@mbp> References: <1570609308-15697-1-git-send-email-anshuman.khandual@arm.com> <1570609308-15697-3-git-send-email-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1570609308-15697-3-git-send-email-anshuman.khandual@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191010_043514_390124_D2EBF3B8 X-CRM114-Status: GOOD ( 13.16 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, david@redhat.com, linux-mm@kvack.org, arunks@codeaurora.org, cpandya@codeaurora.org, ira.weiny@intel.com, will@kernel.org, steven.price@arm.com, valentin.schneider@arm.com, suzuki.poulose@arm.com, Robin.Murphy@arm.com, broonie@kernel.org, cai@lca.pw, ard.biesheuvel@arm.com, dan.j.williams@intel.com, linux-arm-kernel@lists.infradead.org, osalvador@suse.de, steve.capper@arm.com, logang@deltatee.com, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, mgorman@techsingularity.net Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Anshuman, On Wed, Oct 09, 2019 at 01:51:48PM +0530, Anshuman Khandual wrote: > +static void unmap_hotplug_pmd_range(pud_t *pudp, unsigned long addr, > + unsigned long end, bool free_mapped) > +{ > + unsigned long next; > + pmd_t *pmdp, pmd; > + > + do { > + next = pmd_addr_end(addr, end); > + pmdp = pmd_offset(pudp, addr); > + pmd = READ_ONCE(*pmdp); > + if (pmd_none(pmd)) > + continue; > + > + WARN_ON(!pmd_present(pmd)); > + if (pmd_sect(pmd)) { > + pmd_clear(pmdp); > + flush_tlb_kernel_range(addr, next); The range here could be a whole PMD_SIZE. Since we are invalidating a single block entry, one TLBI should be sufficient: flush_tlb_kernel_range(addr, addr + PAGE_SIZE); > + if (free_mapped) > + free_hotplug_page_range(pmd_page(pmd), > + PMD_SIZE); > + continue; > + } > + WARN_ON(!pmd_table(pmd)); > + unmap_hotplug_pte_range(pmdp, addr, next, free_mapped); > + } while (addr = next, addr < end); > +} > + > +static void unmap_hotplug_pud_range(pgd_t *pgdp, unsigned long addr, > + unsigned long end, bool free_mapped) > +{ > + unsigned long next; > + pud_t *pudp, pud; > + > + do { > + next = pud_addr_end(addr, end); > + pudp = pud_offset(pgdp, addr); > + pud = READ_ONCE(*pudp); > + if (pud_none(pud)) > + continue; > + > + WARN_ON(!pud_present(pud)); > + if (pud_sect(pud)) { > + pud_clear(pudp); > + flush_tlb_kernel_range(addr, next); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ flush_tlb_kernel_range(addr, addr + PAGE_SIZE); [...] > +static void free_empty_pte_table(pmd_t *pmdp, unsigned long addr, > + unsigned long end, unsigned long floor, > + unsigned long ceiling) > +{ > + pte_t *ptep, pte; > + unsigned long i, start = addr; > + > + do { > + ptep = pte_offset_kernel(pmdp, addr); > + pte = READ_ONCE(*ptep); > + WARN_ON(!pte_none(pte)); > + } while (addr += PAGE_SIZE, addr < end); So this loop is just a sanity check (pte clearing having been done by the unmap loops). That's fine, maybe a comment for future reference. > + > + if (!pgtable_range_aligned(start, end, floor, ceiling, PMD_MASK)) > + return; > + > + ptep = pte_offset_kernel(pmdp, 0UL); > + for (i = 0; i < PTRS_PER_PTE; i++) { > + if (!pte_none(READ_ONCE(ptep[i]))) > + return; > + } We could do with a comment for this loop along the lines of: Check whether we can free the pte page if the rest of the entries are empty. Overlap with other regions have been handled by the floor/ceiling check. Apart from the comments above, the rest of the patch looks fine. Once fixed: Reviewed-by: Catalin Marinas Mark Rutland mentioned at some point that, as a preparatory patch to this series, we'd need to make sure we don't hot-remove memory already given to the kernel at boot. Any plans here? Thanks. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel