[V4,4/4] arm64/mm: Enable memory hot remove
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Message ID 1558329516-10445-5-git-send-email-anshuman.khandual@arm.com
State New
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Series
  • arm64/mm: Enable memory hot remove
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Commit Message

Anshuman Khandual May 20, 2019, 5:18 a.m. UTC
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 <anshuman.khandual@arm.com>
---
 arch/arm64/Kconfig  |   3 +
 arch/arm64/mm/mmu.c | 212 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 213 insertions(+), 2 deletions(-)

Comments

David Hildenbrand May 21, 2019, 10:20 a.m. UTC | #1
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 <anshuman.khandual@arm.com>
> ---
>  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 <david@redhat.com>
Anshuman Khandual May 27, 2019, 8:09 a.m. UTC | #2
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 <anshuman.khandual@arm.com>
>> ---
>>  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 <david@redhat.com>

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
David Hildenbrand May 27, 2019, 10:21 a.m. UTC | #3
On 27.05.19 10:09, Anshuman Khandual wrote:
> 
> 
> 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 <anshuman.khandual@arm.com>
>>> ---
>>>  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 <david@redhat.com>
> 
> 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);


you can leave the old code, just make sure the start of all parameters
on new lines are aligned, that seemed to be not the case

if (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
>
David Hildenbrand May 27, 2019, 10:21 a.m. UTC | #4
On 27.05.19 10:09, Anshuman Khandual wrote:
> 
> 
> 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 <anshuman.khandual@arm.com>
>>> ---
>>>  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 <david@redhat.com>
> 
> 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);


you can leave the old code, just make sure the start of all parameters
on new lines are aligned, that seemed to be not the case

if (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
>

Patch
diff mbox series

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);
+	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