From patchwork Fri Oct 11 10:14:12 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anshuman Khandual X-Patchwork-Id: 11185179 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B58F314ED for ; Fri, 11 Oct 2019 10:14:27 +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 8B0572190F for ; Fri, 11 Oct 2019 10:14:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Hux/ie//" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8B0572190F 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+patchwork-linux-arm=patchwork.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: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=APBujpTz/DHhcIUzKBXmiyx4U0tqZQfn46gae5ggxSU=; b=Hux/ie//x2Y7H0QkGMvVoPYM2H AcmTxbsVv6xzobrUX5cJm9JWAtRN4KkliC28IaaJebJfdgUyXq2ZxGPafGOjAkT9R1fFAHWW87lXX VgB2hnIZQOK/bHovbJRl+vdsv6+7n76stCYc6UG0yWlj6QFruFP42JKoSTSU19a9TkZefJj5JGmvM mGkjkuWqOR5nWJU9ZdBVOi20zMX02LGevcyiU1fWPmqi0cREBB+LekpaJ6FdIeHj+x1IiN3JK2j8i ohnx2ghgOBrgF/Sm5cVhGKc3kSR00XFuz7RMj3OYGXAyINlDynXZgMgktWaEMvtesAKCSDkEpz1hK hmUjIwWw==; 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 1iIrwH-0001Sg-Td; Fri, 11 Oct 2019 10:14:26 +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 1iIrw6-0001Hs-N0 for linux-arm-kernel@lists.infradead.org; Fri, 11 Oct 2019 10:14:17 +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 E5D591570; Fri, 11 Oct 2019 03:14:13 -0700 (PDT) Received: from p8cg001049571a15.blr.arm.com (p8cg001049571a15.blr.arm.com [10.162.41.129]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 7A1933F703; Fri, 11 Oct 2019 03:14:07 -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@kernel.org Subject: [PATCH V10 2/2] arm64/mm: Enable memory hot remove Date: Fri, 11 Oct 2019 15:44:12 +0530 Message-Id: <1570788852-12402-3-git-send-email-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1570788852-12402-1-git-send-email-anshuman.khandual@arm.com> References: <1570788852-12402-1-git-send-email-anshuman.khandual@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191011_031414_898350_ECF110A2 X-CRM114-Status: GOOD ( 20.59 ) X-Spam-Score: 0.0 (/) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (0.0 points) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record 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, ira.weiny@intel.com, david@redhat.com, mgorman@techsingularity.net, steve.capper@arm.com, Robin.Murphy@arm.com, steven.price@arm.com, broonie@kernel.org, cai@lca.pw, ard.biesheuvel@arm.com, cpandya@codeaurora.org, arunks@codeaurora.org, dan.j.williams@intel.com, logang@deltatee.com, valentin.schneider@arm.com, suzuki.poulose@arm.com, 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 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 unmap_hotplug_range() and free_empty_tables() helpers which can be used to tear down either region and calls it from vmemmap_free() and ___remove_pgd_mapping(). The free_mapped argument determines whether the backing memory will be freed. It makes two distinct passes over the kernel page table. In the first pass with unmap_hotplug_range() it unmaps, invalidates applicable TLB cache and frees backing memory if required (vmemmap) for each mapped leaf entry. In the second pass with free_empty_tables() it looks for empty page table sections whose page table page can be unmapped, TLB invalidated and freed. While freeing intermediate level page table pages bail out if any of its 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. There can be conflicts between hot remove freeing page table pages with a concurrent vmalloc() walking the kernel page table. This conflict can not just be solved by taking the init_mm ptl because of existing locking scheme in vmalloc(). So free_empty_tables() implements a floor and ceiling method which is borrowed from user page table tear with free_pgd_range() which skips freeing page table pages if intermediate address range is not aligned or maximum floor-ceiling might not own the entire page table page. 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 and user page table tear down method. Signed-off-by: Anshuman Khandual Reviewed-by: Catalin Marinas --- arch/arm64/Kconfig | 3 + arch/arm64/include/asm/memory.h | 1 + arch/arm64/mm/mmu.c | 303 ++++++++++++++++++++++++++++++++++++++-- 3 files changed, 298 insertions(+), 9 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 950a56b..c9a3c02 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -273,6 +273,9 @@ config ZONE_DMA32 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/include/asm/memory.h b/arch/arm64/include/asm/memory.h index b61b50b..615dcd0 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -54,6 +54,7 @@ #define MODULES_VADDR (BPF_JIT_REGION_END) #define MODULES_VSIZE (SZ_128M) #define VMEMMAP_START (-VMEMMAP_SIZE - SZ_2M) +#define VMEMMAP_END (VMEMMAP_START + VMEMMAP_SIZE) #define PCI_IO_END (VMEMMAP_START - SZ_2M) #define PCI_IO_START (PCI_IO_END - PCI_IO_SIZE) #define FIXADDR_TOP (PCI_IO_START - SZ_2M) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index d10247f..66ef63e 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -725,6 +725,275 @@ 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, size_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 bool pgtable_range_aligned(unsigned long start, unsigned long end, + unsigned long floor, unsigned long ceiling, + unsigned long mask) +{ + start &= mask; + if (start < floor) + return false; + + if (ceiling) { + ceiling &= mask; + if (!ceiling) + return false; + } + + if (end - 1 > ceiling - 1) + return false; + return true; +} + +static void unmap_hotplug_pte_range(pmd_t *pmdp, unsigned long addr, + unsigned long end, bool free_mapped) +{ + pte_t *ptep, pte; + + do { + ptep = pte_offset_kernel(pmdp, addr); + pte = READ_ONCE(*ptep); + if (pte_none(pte)) + continue; + + WARN_ON(!pte_present(pte)); + pte_clear(&init_mm, addr, ptep); + flush_tlb_kernel_range(addr, addr + PAGE_SIZE); + if (free_mapped) + free_hotplug_page_range(pte_page(pte), PAGE_SIZE); + } while (addr += PAGE_SIZE, addr < end); +} + +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); + + /* + * One TLBI should be sufficient here as the PMD_SIZE + * range is mapped with a single block entry. + */ + 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); + + /* + * One TLBI should be sufficient here as the PUD_SIZE + * range is mapped with a single block entry. + */ + flush_tlb_kernel_range(addr, addr + PAGE_SIZE); + if (free_mapped) + free_hotplug_page_range(pud_page(pud), + PUD_SIZE); + continue; + } + WARN_ON(!pud_table(pud)); + unmap_hotplug_pmd_range(pudp, addr, next, free_mapped); + } while (addr = next, addr < end); +} + +static void unmap_hotplug_range(unsigned long addr, unsigned long end, + bool free_mapped) +{ + unsigned long next; + pgd_t *pgdp, pgd; + + do { + 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)); + unmap_hotplug_pud_range(pgdp, addr, next, free_mapped); + } while (addr = next, addr < end); +} + +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); + + /* + * This is just a sanity check here which verifies that + * pte clearing has been done by earlier unmap loops. + */ + WARN_ON(!pte_none(pte)); + } while (addr += PAGE_SIZE, addr < end); + + if (!pgtable_range_aligned(start, end, floor, ceiling, PMD_MASK)) + return; + + /* + * 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. + */ + ptep = pte_offset_kernel(pmdp, 0UL); + for (i = 0; i < PTRS_PER_PTE; i++) { + if (!pte_none(READ_ONCE(ptep[i]))) + return; + } + + pmd_clear(pmdp); + __flush_tlb_kernel_pgtable(start); + free_hotplug_pgtable_page(virt_to_page(ptep)); +} + +static void free_empty_pmd_table(pud_t *pudp, unsigned long addr, + unsigned long end, unsigned long floor, + unsigned long ceiling) +{ + pmd_t *pmdp, pmd; + unsigned long i, next, start = addr; + + 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) || !pmd_table(pmd) || pmd_sect(pmd)); + free_empty_pte_table(pmdp, addr, next, floor, ceiling); + } while (addr = next, addr < end); + + if (CONFIG_PGTABLE_LEVELS <= 2) + return; + + if (!pgtable_range_aligned(start, end, floor, ceiling, PUD_MASK)) + return; + + /* + * Check whether we can free the pmd page if the rest of the + * entries are empty. Overlap with other regions have been + * handled by the floor/ceiling check. + */ + pmdp = pmd_offset(pudp, 0UL); + for (i = 0; i < PTRS_PER_PMD; i++) { + if (!pmd_none(READ_ONCE(pmdp[i]))) + return; + } + + pud_clear(pudp); + __flush_tlb_kernel_pgtable(start); + free_hotplug_pgtable_page(virt_to_page(pmdp)); +} + +static void free_empty_pud_table(pgd_t *pgdp, unsigned long addr, + unsigned long end, unsigned long floor, + unsigned long ceiling) +{ + pud_t *pudp, pud; + unsigned long i, next, start = addr; + + 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) || !pud_table(pud) || pud_sect(pud)); + free_empty_pmd_table(pudp, addr, next, floor, ceiling); + } while (addr = next, addr < end); + + if (CONFIG_PGTABLE_LEVELS <= 3) + return; + + if (!pgtable_range_aligned(start, end, floor, ceiling, PGDIR_MASK)) + return; + + /* + * Check whether we can free the pud page if the rest of the + * entries are empty. Overlap with other regions have been + * handled by the floor/ceiling check. + */ + pudp = pud_offset(pgdp, 0UL); + for (i = 0; i < PTRS_PER_PUD; i++) { + if (!pud_none(READ_ONCE(pudp[i]))) + return; + } + + pgd_clear(pgdp); + __flush_tlb_kernel_pgtable(start); + free_hotplug_pgtable_page(virt_to_page(pudp)); +} + +static void free_empty_tables(unsigned long addr, unsigned long end, + unsigned long floor, unsigned long ceiling) +{ + unsigned long next; + pgd_t *pgdp, pgd; + + do { + 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)); + free_empty_pud_table(pgdp, addr, next, floor, ceiling); + } while (addr = next, addr < end); +} +#endif + #ifdef CONFIG_SPARSEMEM_VMEMMAP #if !ARM64_SWAPPER_USES_SECTION_MAPS int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, @@ -772,6 +1041,12 @@ 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 + WARN_ON((start < VMEMMAP_START) || (end > VMEMMAP_END)); + + unmap_hotplug_range(start, end, true); + free_empty_tables(start, end, VMEMMAP_START, VMEMMAP_END); +#endif } #endif /* CONFIG_SPARSEMEM_VMEMMAP */ @@ -1050,10 +1325,21 @@ 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) +{ + unsigned long end = start + size; + + WARN_ON(pgdir != init_mm.pgd); + WARN_ON((start < PAGE_OFFSET) || (end > PAGE_END)); + + unmap_hotplug_range(start, end, false); + free_empty_tables(start, end, PAGE_OFFSET, PAGE_END); +} + 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; @@ -1061,22 +1347,21 @@ 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; } + 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; - /* - * FIXME: Cleanup page tables (also in arch_add_memory() in case - * adding fails). Until then, this function should only be used - * during memory hotplug (adding memory), not for memory - * unplug. ARCH_ENABLE_MEMORY_HOTREMOVE must not be - * unlocked yet. - */ __remove_pages(start_pfn, nr_pages, altmap); + __remove_pgd_mapping(swapper_pg_dir, __phys_to_virt(start), size); } #endif