From patchwork Wed May 29 09:16:27 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anshuman Khandual X-Patchwork-Id: 10966585 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 16D5F1398 for ; Wed, 29 May 2019 09:17:19 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 07CCC28894 for ; Wed, 29 May 2019 09:17:19 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EF67B288E5; Wed, 29 May 2019 09:17:18 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 5EE7728894 for ; Wed, 29 May 2019 09:17:18 +0000 (UTC) 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:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=D6610cqhJR9LaiOk/N/NjV1zSobLokHIp1Xus0B8Bo8=; b=Z8GzsxXs6IyAdeT1p80pPB1NGD OqG/4k0igmGGUuOIeGe/cxREhsm1GATSCTkg0iy9INncs1rDDJFSxMsU9ATp4D2hcJdX3UF6VB8HX aoztjyZjoX9TBYuTBpW8EyfNuXVugPxr64RdYIg3GphW//KqK+nRYxI746XIhV/CpLJyGfCFcmW4i +LUJiW+iG7/8Bk3gBcdrkr/Q7p0WIcQEeMv/CkA2RzxaPGdS3boe4Y1bZSrpX7K0fbWNg6URmtohf cKyMZlVGwII+HN6Yuz5z1MTPvKHrvUH45Uuuj79JqkTixljFNQjjbJZJKDA2FbLdx8Jho2eWGN1L7 FEvNtVGg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hVuhr-0000AL-3f; Wed, 29 May 2019 09:17:11 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hVuhN-0007z0-54 for linux-arm-kernel@lists.infradead.org; Wed, 29 May 2019 09:16:44 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2D180165C; Wed, 29 May 2019 02:16:40 -0700 (PDT) Received: from p8cg001049571a15.blr.arm.com (p8cg001049571a15.blr.arm.com [10.162.41.181]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id E0E943F5AF; Wed, 29 May 2019 02:16:34 -0700 (PDT) From: Anshuman Khandual To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org, catalin.marinas@arm.com, will.deacon@arm.com Subject: [PATCH V5 3/3] arm64/mm: Enable memory hot remove Date: Wed, 29 May 2019 14:46:27 +0530 Message-Id: <1559121387-674-4-git-send-email-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1559121387-674-1-git-send-email-anshuman.khandual@arm.com> References: <1559121387-674-1-git-send-email-anshuman.khandual@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190529_021641_572621_69A4147B X-CRM114-Status: GOOD ( 17.91 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, mhocko@suse.com, david@redhat.com, ira.weiny@intel.com, mgorman@techsingularity.net, cai@lca.pw, ard.biesheuvel@arm.com, cpandya@codeaurora.org, james.morse@arm.com, dan.j.williams@intel.com, logang@deltatee.com, arunks@codeaurora.org, osalvador@suse.de MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP The arch code for hot-remove must tear down portions of the linear map and vmemmap corresponding to memory being removed. In both cases the page tables mapping these regions must be freed, and when sparse vmemmap is in use the memory backing the vmemmap must also be freed. This patch adds a new remove_pagetable() helper which can be used to tear down either region, and calls it from vmemmap_free() and ___remove_pgd_mapping(). The sparse_vmap argument determines whether the backing memory will be freed. While freeing intermediate level page table pages bail out if any of it's entries are still valid. This can happen for partially filled kernel page table either from a previously attempted failed memory hot add or while removing an address range which does not span the entire page table page range. The vmemmap region may share levels of table with the vmalloc region. Take the kernel ptl so that we can safely free potentially-shared tables. While here update arch_add_memory() to handle __add_pages() failures by just unmapping recently added kernel linear mapping. Now enable memory hot remove on arm64 platforms by default with ARCH_ENABLE_MEMORY_HOTREMOVE. This implementation is overall inspired from kernel page table tear down procedure on X86 architecture. Signed-off-by: Anshuman Khandual Acked-by: David Hildenbrand --- arch/arm64/Kconfig | 3 + arch/arm64/mm/mmu.c | 211 +++++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 212 insertions(+), 2 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 697ea05..7f917fe 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -268,6 +268,9 @@ config HAVE_GENERIC_GUP config ARCH_ENABLE_MEMORY_HOTPLUG def_bool y +config ARCH_ENABLE_MEMORY_HOTREMOVE + def_bool y + config SMP def_bool y diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index a1bfc44..4803624 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -733,6 +733,187 @@ int kern_addr_valid(unsigned long addr) return pfn_valid(pte_pfn(pte)); } + +#ifdef CONFIG_MEMORY_HOTPLUG +static void free_hotplug_page_range(struct page *page, ssize_t size) +{ + WARN_ON(PageReserved(page)); + free_pages((unsigned long)page_address(page), get_order(size)); +} + +static void free_hotplug_pgtable_page(struct page *page) +{ + free_hotplug_page_range(page, PAGE_SIZE); +} + +static void free_pte_table(pte_t *ptep, pmd_t *pmdp, unsigned long addr) +{ + struct page *page; + int i; + + for (i = 0; i < PTRS_PER_PTE; i++) { + if (!pte_none(ptep[i])) + return; + } + + page = pmd_page(READ_ONCE(*pmdp)); + pmd_clear(pmdp); + __flush_tlb_kernel_pgtable(addr); + free_hotplug_pgtable_page(page); +} + +static void free_pmd_table(pmd_t *pmdp, pud_t *pudp, unsigned long addr) +{ + struct page *page; + int i; + + if (CONFIG_PGTABLE_LEVELS <= 2) + return; + + for (i = 0; i < PTRS_PER_PMD; i++) { + if (!pmd_none(pmdp[i])) + return; + } + + page = pud_page(READ_ONCE(*pudp)); + pud_clear(pudp); + __flush_tlb_kernel_pgtable(addr); + free_hotplug_pgtable_page(page); +} + +static void free_pud_table(pud_t *pudp, pgd_t *pgdp, unsigned long addr) +{ + struct page *page; + int i; + + if (CONFIG_PGTABLE_LEVELS <= 3) + return; + + for (i = 0; i < PTRS_PER_PUD; i++) { + if (!pud_none(pudp[i])) + return; + } + + page = pgd_page(READ_ONCE(*pgdp)); + pgd_clear(pgdp); + __flush_tlb_kernel_pgtable(addr); + free_hotplug_pgtable_page(page); +} + +static void +remove_pte_table(pmd_t *pmdp, unsigned long addr, + unsigned long end, bool sparse_vmap) +{ + struct page *page; + pte_t *ptep, pte; + unsigned long start = addr; + + for (; addr < end; addr += PAGE_SIZE) { + ptep = pte_offset_kernel(pmdp, addr); + pte = READ_ONCE(*ptep); + + if (pte_none(pte)) + continue; + + WARN_ON(!pte_present(pte)); + if (sparse_vmap) { + page = pte_page(pte); + free_hotplug_page_range(page, PAGE_SIZE); + } + pte_clear(&init_mm, addr, ptep); + } + flush_tlb_kernel_range(start, end); +} + +static void +remove_pmd_table(pud_t *pudp, unsigned long addr, + unsigned long end, bool sparse_vmap) +{ + unsigned long next; + struct page *page; + pte_t *ptep_base; + pmd_t *pmdp, pmd; + + for (; addr < end; addr = next) { + 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)) { + if (sparse_vmap) { + page = pmd_page(pmd); + free_hotplug_page_range(page, PMD_SIZE); + } + pmd_clear(pmdp); + continue; + } + ptep_base = pte_offset_kernel(pmdp, 0UL); + remove_pte_table(pmdp, addr, next, sparse_vmap); + free_pte_table(ptep_base, pmdp, addr); + } +} + +static void +remove_pud_table(pgd_t *pgdp, unsigned long addr, + unsigned long end, bool sparse_vmap) +{ + unsigned long next; + struct page *page; + pmd_t *pmdp_base; + pud_t *pudp, pud; + + for (; addr < end; addr = next) { + 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)) { + if (sparse_vmap) { + page = pud_page(pud); + free_hotplug_page_range(page, PUD_SIZE); + } + pud_clear(pudp); + continue; + } + pmdp_base = pmd_offset(pudp, 0UL); + remove_pmd_table(pudp, addr, next, sparse_vmap); + free_pmd_table(pmdp_base, pudp, addr); + } +} + +static void +remove_pagetable(unsigned long start, unsigned long end, bool sparse_vmap) +{ + unsigned long addr, next; + pud_t *pudp_base; + pgd_t *pgdp, pgd; + + spin_lock(&init_mm.page_table_lock); + for (addr = start; addr < end; addr = next) { + next = pgd_addr_end(addr, end); + pgdp = pgd_offset_k(addr); + pgd = READ_ONCE(*pgdp); + + if (pgd_none(pgd)) + continue; + + WARN_ON(!pgd_present(pgd)); + pudp_base = pud_offset(pgdp, 0UL); + remove_pud_table(pgdp, addr, next, sparse_vmap); + free_pud_table(pudp_base, pgdp, addr); + } + spin_unlock(&init_mm.page_table_lock); +} +#endif + #ifdef CONFIG_SPARSEMEM_VMEMMAP #if !ARM64_SWAPPER_USES_SECTION_MAPS int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, @@ -780,6 +961,9 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, void vmemmap_free(unsigned long start, unsigned long end, struct vmem_altmap *altmap) { +#ifdef CONFIG_MEMORY_HOTPLUG + remove_pagetable(start, end, true); +#endif } #endif /* CONFIG_SPARSEMEM_VMEMMAP */ @@ -1070,10 +1254,16 @@ int p4d_free_pud_page(p4d_t *p4d, unsigned long addr) } #ifdef CONFIG_MEMORY_HOTPLUG +static void __remove_pgd_mapping(pgd_t *pgdir, unsigned long start, u64 size) +{ + WARN_ON(pgdir != init_mm.pgd); + remove_pagetable(start, start + size, false); +} + int arch_add_memory(int nid, u64 start, u64 size, struct mhp_restrictions *restrictions) { - int flags = 0; + int ret, flags = 0; if (rodata_full || debug_pagealloc_enabled()) flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; @@ -1081,7 +1271,24 @@ int arch_add_memory(int nid, u64 start, u64 size, __create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start), size, PAGE_KERNEL, __pgd_pgtable_alloc, flags); - return __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT, + ret = __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT, restrictions); + if (ret) + __remove_pgd_mapping(swapper_pg_dir, + __phys_to_virt(start), size); + return ret; +} + +#ifdef CONFIG_MEMORY_HOTREMOVE +void arch_remove_memory(int nid, u64 start, u64 size, + struct vmem_altmap *altmap) +{ + unsigned long start_pfn = start >> PAGE_SHIFT; + unsigned long nr_pages = size >> PAGE_SHIFT; + struct zone *zone = page_zone(pfn_to_page(start_pfn)); + + __remove_pages(zone, start_pfn, nr_pages, altmap); + __remove_pgd_mapping(swapper_pg_dir, __phys_to_virt(start), size); } #endif +#endif