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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 A9137C07542 for ; Mon, 27 May 2019 08:09:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 720EA21726 for ; Mon, 27 May 2019 08:09:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726300AbfE0IJH (ORCPT ); Mon, 27 May 2019 04:09:07 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:57822 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725869AbfE0IJH (ORCPT ); Mon, 27 May 2019 04:09:07 -0400 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 EFDD1374; Mon, 27 May 2019 01:09:05 -0700 (PDT) Received: from [10.162.40.17] (p8cg001049571a15.blr.arm.com [10.162.40.17]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9D8023F5AF; Mon, 27 May 2019 01:08:58 -0700 (PDT) Subject: Re: [PATCH V4 4/4] arm64/mm: Enable memory hot remove To: David Hildenbrand , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org, catalin.marinas@arm.com, will.deacon@arm.com Cc: mark.rutland@arm.com, mhocko@suse.com, ira.weiny@intel.com, cai@lca.pw, logang@deltatee.com, james.morse@arm.com, cpandya@codeaurora.org, arunks@codeaurora.org, dan.j.williams@intel.com, mgorman@techsingularity.net, osalvador@suse.de, ard.biesheuvel@arm.com References: <1558329516-10445-1-git-send-email-anshuman.khandual@arm.com> <1558329516-10445-5-git-send-email-anshuman.khandual@arm.com> From: Anshuman Khandual Message-ID: Date: Mon, 27 May 2019 13:39:11 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/21/2019 03:50 PM, David Hildenbrand wrote: > On 20.05.19 07:18, Anshuman Khandual wrote: >> 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 >> --- >> arch/arm64/Kconfig | 3 + >> arch/arm64/mm/mmu.c | 212 +++++++++++++++++++++++++++++++++++++++++++++++++++- >> 2 files changed, 213 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >> index 4780eb7..ce24427 100644 >> --- a/arch/arm64/Kconfig >> +++ b/arch/arm64/Kconfig >> @@ -267,6 +267,9 @@ 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..0cf0d41 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 +1271,25 @@ 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); > > Nit: Indentation of the parameters looks really weird. > >> + 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); > > Dito, indentation of the parameters. > > For these two changes (arch_*_memory) > > Acked-by: David Hildenbrand Thanks David. The following change on this patch should fix the indentation problem. If there are no other comments I will incorporate this and re-spin the series once more. diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 0cf0d41..a87ba18 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -1273,9 +1273,10 @@ int arch_add_memory(int nid, u64 start, u64 size, ret = __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT, restrictions); - if (ret) - __remove_pgd_mapping(swapper_pg_dir, - __phys_to_virt(start), size); + if (!ret) + return ret; + + __remove_pgd_mapping(swapper_pg_dir, __phys_to_virt(start), size); return ret; } @@ -1288,8 +1289,7 @@ void arch_remove_memory(int nid, u64 start, u64 size, 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); + __remove_pgd_mapping(swapper_pg_dir, __phys_to_virt(start), size); } #endif #endif