From patchwork Mon Sep 23 05:43:45 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anshuman Khandual X-Patchwork-Id: 11156061 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 0966A14ED for ; Mon, 23 Sep 2019 05:43:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B90082089F for ; Mon, 23 Sep 2019 05:43:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B90082089F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D7D856B0010; Mon, 23 Sep 2019 01:43:56 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id D2F666B0266; Mon, 23 Sep 2019 01:43:56 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C1D616B0269; Mon, 23 Sep 2019 01:43:56 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0216.hostedemail.com [216.40.44.216]) by kanga.kvack.org (Postfix) with ESMTP id 995916B0010 for ; Mon, 23 Sep 2019 01:43:56 -0400 (EDT) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 3F32A4853 for ; Mon, 23 Sep 2019 05:43:56 +0000 (UTC) X-FDA: 75965094072.13.game04_3f69f1e996926 X-Spam-Summary: 2,0,0,9226e987a5da5981,d41d8cd98f00b204,anshuman.khandual@arm.com,::linux-kernel@vger.kernel.org:linux-arm-kernel@lists.infradead.org:akpm@linux-foundation.org:catalin.marinas@arm.com:will@kernel.org:mark.rutland@arm.com:mhocko@suse.com:david@redhat.com:cai@lca.pw:logang@deltatee.com:cpandya@codeaurora.org:arunks@codeaurora.org:dan.j.williams@intel.com:mgorman@techsingularity.net:osalvador@suse.de:ard.biesheuvel@arm.com:steve.capper@arm.com:broonie@kernel.org:valentin.schneider@arm.com:robin.murphy@arm.com:steven.price@arm.com:suzuki.poulose@arm.com:ira.weiny@intel.com,RULES_HIT:1:41:355:379:541:800:960:966:968:973:988:989:1260:1261:1345:1359:1431:1437:1605:1730:1747:1777:1792:1963:2196:2198:2199:2200:2393:2553:2559:2562:2638:2693:2895:2898:3138:3139:3140:3141:3142:3865:3866:3867:3868:3870:3871:3872:4250:4321:4385:4419:4605:5007:6117:6119:6261:6742:7903:8603:8634:8957:9036:10004:10128:11026:11473:11657:11658:11914:12043:12048:12291:12296:12297:12438:12555:1268 3:12895: X-HE-Tag: game04_3f69f1e996926 X-Filterd-Recvd-Size: 14579 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf16.hostedemail.com (Postfix) with ESMTP for ; Mon, 23 Sep 2019 05:43:55 +0000 (UTC) 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 AE7451570; Sun, 22 Sep 2019 22:43:54 -0700 (PDT) Received: from p8cg001049571a15.blr.arm.com (p8cg001049571a15.blr.arm.com [10.162.40.137]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id F12583F59C; Sun, 22 Sep 2019 22:43:46 -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 Cc: mark.rutland@arm.com, mhocko@suse.com, david@redhat.com, cai@lca.pw, logang@deltatee.com, cpandya@codeaurora.org, arunks@codeaurora.org, dan.j.williams@intel.com, mgorman@techsingularity.net, osalvador@suse.de, ard.biesheuvel@arm.com, steve.capper@arm.com, broonie@kernel.org, valentin.schneider@arm.com, Robin.Murphy@arm.com, steven.price@arm.com, suzuki.poulose@arm.com, ira.weiny@intel.com Subject: [PATCH V8 2/2] arm64/mm: Enable memory hot remove Date: Mon, 23 Sep 2019 11:13:45 +0530 Message-Id: <1569217425-23777-3-git-send-email-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1569217425-23777-1-git-send-email-anshuman.khandual@arm.com> References: <1569217425-23777-1-git-send-email-anshuman.khandual@arm.com> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 sparse_vmap 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. Acked-by: Steve Capper Acked-by: David Hildenbrand Signed-off-by: Anshuman Khandual --- arch/arm64/Kconfig | 3 + arch/arm64/include/asm/memory.h | 1 + arch/arm64/mm/mmu.c | 305 ++++++++++++++++++++++++++++++++++++++-- 3 files changed, 300 insertions(+), 9 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 41a9b42..511249f 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -274,6 +274,9 @@ 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 60c929f..6178837 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -725,6 +725,277 @@ 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(!page || 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 free_pte_table(pmd_t *pmdp, unsigned long addr, unsigned long end, + unsigned long floor, unsigned long ceiling) +{ + struct page *page; + pte_t *ptep; + int i; + + if (!pgtable_range_aligned(addr, 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; + } + + page = pmd_page(READ_ONCE(*pmdp)); + pmd_clear(pmdp); + __flush_tlb_kernel_pgtable(addr); + free_hotplug_pgtable_page(page); +} + +static void free_pmd_table(pud_t *pudp, unsigned long addr, unsigned long end, + unsigned long floor, unsigned long ceiling) +{ + struct page *page; + pmd_t *pmdp; + int i; + + if (CONFIG_PGTABLE_LEVELS <= 2) + return; + + if (!pgtable_range_aligned(addr, end, floor, ceiling, PUD_MASK)) + return; + + pmdp = pmd_offset(pudp, 0UL); + for (i = 0; i < PTRS_PER_PMD; i++) { + if (!pmd_none(READ_ONCE(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(pgd_t *pgdp, unsigned long addr, unsigned long end, + unsigned long floor, unsigned long ceiling) +{ + struct page *page; + pud_t *pudp; + int i; + + if (CONFIG_PGTABLE_LEVELS <= 3) + return; + + if (!pgtable_range_aligned(addr, end, floor, ceiling, PGDIR_MASK)) + return; + + pudp = pud_offset(pgdp, 0UL); + for (i = 0; i < PTRS_PER_PUD; i++) { + if (!pud_none(READ_ONCE(pudp[i]))) + return; + } + + page = pgd_page(READ_ONCE(*pgdp)); + pgd_clear(pgdp); + __flush_tlb_kernel_pgtable(addr); + free_hotplug_pgtable_page(page); +} + +static void unmap_hotplug_pte_range(pmd_t *pmdp, unsigned long addr, + unsigned long end, bool sparse_vmap) +{ + struct page *page; + 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)); + page = sparse_vmap ? pte_page(pte) : NULL; + pte_clear(&init_mm, addr, ptep); + flush_tlb_kernel_range(addr, addr + PAGE_SIZE); + if (sparse_vmap) + free_hotplug_page_range(page, PAGE_SIZE); + } while (addr += PAGE_SIZE, addr < end); +} + +static void unmap_hotplug_pmd_range(pud_t *pudp, unsigned long addr, + unsigned long end, bool sparse_vmap) +{ + unsigned long next; + struct page *page; + 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)) { + page = sparse_vmap ? pmd_page(pmd) : NULL; + pmd_clear(pmdp); + flush_tlb_kernel_range(addr, next); + if (sparse_vmap) + free_hotplug_page_range(page, PMD_SIZE); + continue; + } + WARN_ON(!pmd_table(pmd)); + unmap_hotplug_pte_range(pmdp, addr, next, sparse_vmap); + } while (addr = next, addr < end); +} + +static void unmap_hotplug_pud_range(pgd_t *pgdp, unsigned long addr, + unsigned long end, bool sparse_vmap) +{ + unsigned long next; + struct page *page; + 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)) { + page = sparse_vmap ? pud_page(pud) : NULL; + pud_clear(pudp); + flush_tlb_kernel_range(addr, next); + if (sparse_vmap) + free_hotplug_page_range(page, PUD_SIZE); + continue; + } + WARN_ON(!pud_table(pud)); + unmap_hotplug_pmd_range(pudp, addr, next, sparse_vmap); + } while (addr = next, addr < end); +} + +static void unmap_hotplug_range(unsigned long addr, unsigned long end, + bool sparse_vmap) +{ + 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, sparse_vmap); + } while (addr = next, addr < end); +} + +static void free_empty_pte_table(pmd_t *pmdp, unsigned long addr, + unsigned long end) +{ + pte_t *ptep, pte; + + do { + ptep = pte_offset_kernel(pmdp, addr); + pte = READ_ONCE(*ptep); + WARN_ON(!pte_none(pte)); + } while (addr += PAGE_SIZE, addr < end); +} + +static void free_empty_pmd_table(pud_t *pudp, unsigned long addr, + unsigned long end, unsigned long floor, + unsigned long ceiling) +{ + 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) || !pmd_table(pmd) || pmd_sect(pmd)); + free_empty_pte_table(pmdp, addr, next); + free_pte_table(pmdp, addr, next, floor, ceiling); + } while (addr = next, addr < end); +} + +static void free_empty_pud_table(pgd_t *pgdp, unsigned long addr, + unsigned long end, unsigned long floor, + unsigned long ceiling) +{ + 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) || !pud_table(pud) || pud_sect(pud)); + free_empty_pmd_table(pudp, addr, next, floor, ceiling); + free_pmd_table(pudp, addr, next, floor, ceiling); + } while (addr = next, addr < end); +} + +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); + free_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 +1043,12 @@ 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 +1327,21 @@ 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; @@ -1061,9 +1349,14 @@ 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) { @@ -1071,14 +1364,8 @@ void arch_remove_memory(int nid, u64 start, u64 size, unsigned long nr_pages = size >> PAGE_SHIFT; struct zone *zone; - /* - * 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. - */ 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