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SubjectRe: [PATCH] hugetlb: allow to free gigantic pages regardless of the configuration
Date
On 2/5/19 6:23 AM, Michael Ellerman wrote:
> Alexandre Ghiti <aghiti@upmem.com> writes:
>
>> From: Alexandre Ghiti <alex@ghiti.fr>
>>
>> On systems without CMA or (MEMORY_ISOLATION && COMPACTION) activated but
>> that support gigantic pages, boottime reserved gigantic pages can not be
>> freed at all. This patchs simply enables the possibility to hand back
>> those pages to memory allocator.
>>
>> This commit then renames gigantic_page_supported and
>> ARCH_HAS_GIGANTIC_PAGE to make them more accurate. Indeed, those values
>> being false does not mean that the system cannot use gigantic pages: it
>> just means that runtime allocation of gigantic pages is not supported,
>> one can still allocate boottime gigantic pages if the architecture supports
>> it.
>>
>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
>> ---
>>
>> - Compiled on all architectures
>> - Tested on riscv architecture
>>
>> arch/arm64/Kconfig | 2 +-
>> arch/arm64/include/asm/hugetlb.h | 7 +++--
>> arch/powerpc/include/asm/book3s/64/hugetlb.h | 4 +--
>> arch/powerpc/platforms/Kconfig.cputype | 2 +-
> The powerpc parts look fine.
>
> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

Thank you Michael,

Alex

>
> cheers
>
>> arch/s390/Kconfig | 2 +-
>> arch/s390/include/asm/hugetlb.h | 7 +++--
>> arch/x86/Kconfig | 2 +-
>> arch/x86/include/asm/hugetlb.h | 7 +++--
>> fs/Kconfig | 2 +-
>> include/linux/gfp.h | 2 +-
>> mm/hugetlb.c | 43 +++++++++++++++-------------
>> mm/page_alloc.c | 4 +--
>> 12 files changed, 48 insertions(+), 36 deletions(-)
>>
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index a4168d366127..18239cbd7fcd 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -18,7 +18,7 @@ config ARM64
>> select ARCH_HAS_FAST_MULTIPLIER
>> select ARCH_HAS_FORTIFY_SOURCE
>> select ARCH_HAS_GCOV_PROFILE_ALL
>> - select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
>> + select ARCH_HAS_GIGANTIC_PAGE_RUNTIME_ALLOCATION if (MEMORY_ISOLATION && COMPACTION) || CMA
>> select ARCH_HAS_KCOV
>> select ARCH_HAS_MEMBARRIER_SYNC_CORE
>> select ARCH_HAS_PTE_SPECIAL
>> diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h
>> index fb6609875455..797fc77eabcd 100644
>> --- a/arch/arm64/include/asm/hugetlb.h
>> +++ b/arch/arm64/include/asm/hugetlb.h
>> @@ -65,8 +65,11 @@ extern void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr,
>>
>> #include <asm-generic/hugetlb.h>
>>
>> -#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
>> -static inline bool gigantic_page_supported(void) { return true; }
>> +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE_RUNTIME_ALLOCATION
>> +static inline bool gigantic_page_runtime_allocation_supported(void)
>> +{
>> + return true;
>> +}
>> #endif
>>
>> #endif /* __ASM_HUGETLB_H */
>> diff --git a/arch/powerpc/include/asm/book3s/64/hugetlb.h b/arch/powerpc/include/asm/book3s/64/hugetlb.h
>> index 5b0177733994..7711f0e2c7e5 100644
>> --- a/arch/powerpc/include/asm/book3s/64/hugetlb.h
>> +++ b/arch/powerpc/include/asm/book3s/64/hugetlb.h
>> @@ -32,8 +32,8 @@ static inline int hstate_get_psize(struct hstate *hstate)
>> }
>> }
>>
>> -#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
>> -static inline bool gigantic_page_supported(void)
>> +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE_RUNTIME_ALLOCATION
>> +static inline bool gigantic_page_runtime_allocation_supported(void)
>> {
>> return true;
>> }
>> diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
>> index 8c7464c3f27f..779e06bac697 100644
>> --- a/arch/powerpc/platforms/Kconfig.cputype
>> +++ b/arch/powerpc/platforms/Kconfig.cputype
>> @@ -319,7 +319,7 @@ config ARCH_ENABLE_SPLIT_PMD_PTLOCK
>> config PPC_RADIX_MMU
>> bool "Radix MMU Support"
>> depends on PPC_BOOK3S_64
>> - select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
>> + select ARCH_HAS_GIGANTIC_PAGE_RUNTIME_ALLOCATION if (MEMORY_ISOLATION && COMPACTION) || CMA
>> default y
>> help
>> Enable support for the Power ISA 3.0 Radix style MMU. Currently this
>> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
>> index ed554b09eb3f..6776eef6a9ae 100644
>> --- a/arch/s390/Kconfig
>> +++ b/arch/s390/Kconfig
>> @@ -69,7 +69,7 @@ config S390
>> select ARCH_HAS_ELF_RANDOMIZE
>> select ARCH_HAS_FORTIFY_SOURCE
>> select ARCH_HAS_GCOV_PROFILE_ALL
>> - select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
>> + select ARCH_HAS_GIGANTIC_PAGE_RUNTIME_ALLOCATION if (MEMORY_ISOLATION && COMPACTION) || CMA
>> select ARCH_HAS_KCOV
>> select ARCH_HAS_PTE_SPECIAL
>> select ARCH_HAS_SET_MEMORY
>> diff --git a/arch/s390/include/asm/hugetlb.h b/arch/s390/include/asm/hugetlb.h
>> index 2d1afa58a4b6..57c952f5388e 100644
>> --- a/arch/s390/include/asm/hugetlb.h
>> +++ b/arch/s390/include/asm/hugetlb.h
>> @@ -116,7 +116,10 @@ static inline pte_t huge_pte_modify(pte_t pte, pgprot_t newprot)
>> return pte_modify(pte, newprot);
>> }
>>
>> -#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
>> -static inline bool gigantic_page_supported(void) { return true; }
>> +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE_RUNTIME_ALLOCATION
>> +static inline bool gigantic_page_runtime_allocation_supported(void)
>> +{
>> + return true;
>> +}
>> #endif
>> #endif /* _ASM_S390_HUGETLB_H */
>> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
>> index 6185d4f33296..a88f5a4311c9 100644
>> --- a/arch/x86/Kconfig
>> +++ b/arch/x86/Kconfig
>> @@ -23,7 +23,7 @@ config X86_64
>> def_bool y
>> depends on 64BIT
>> # Options that are inherently 64-bit kernel only:
>> - select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA
>> + select ARCH_HAS_GIGANTIC_PAGE_RUNTIME_ALLOCATION if (MEMORY_ISOLATION && COMPACTION) || CMA
>> select ARCH_SUPPORTS_INT128
>> select ARCH_USE_CMPXCHG_LOCKREF
>> select HAVE_ARCH_SOFT_DIRTY
>> diff --git a/arch/x86/include/asm/hugetlb.h b/arch/x86/include/asm/hugetlb.h
>> index 7469d321f072..5a5e7119ced4 100644
>> --- a/arch/x86/include/asm/hugetlb.h
>> +++ b/arch/x86/include/asm/hugetlb.h
>> @@ -17,8 +17,11 @@ static inline void arch_clear_hugepage_flags(struct page *page)
>> {
>> }
>>
>> -#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
>> -static inline bool gigantic_page_supported(void) { return true; }
>> +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE_RUNTIME_ALLOCATION
>> +static inline bool gigantic_page_runtime_allocation_supported(void)
>> +{
>> + return true;
>> +}
>> #endif
>>
>> #endif /* _ASM_X86_HUGETLB_H */
>> diff --git a/fs/Kconfig b/fs/Kconfig
>> index ac474a61be37..4192d1fde0f0 100644
>> --- a/fs/Kconfig
>> +++ b/fs/Kconfig
>> @@ -207,7 +207,7 @@ config HUGETLB_PAGE
>> config MEMFD_CREATE
>> def_bool TMPFS || HUGETLBFS
>>
>> -config ARCH_HAS_GIGANTIC_PAGE
>> +config ARCH_HAS_GIGANTIC_PAGE_RUNTIME_ALLOCATION
>> bool
>>
>> source "fs/configfs/Kconfig"
>> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
>> index 5f5e25fd6149..79ff86fabd42 100644
>> --- a/include/linux/gfp.h
>> +++ b/include/linux/gfp.h
>> @@ -589,8 +589,8 @@ static inline bool pm_suspended_storage(void)
>> /* The below functions must be run on a range from a single zone. */
>> extern int alloc_contig_range(unsigned long start, unsigned long end,
>> unsigned migratetype, gfp_t gfp_mask);
>> -extern void free_contig_range(unsigned long pfn, unsigned nr_pages);
>> #endif
>> +extern void free_contig_range(unsigned long pfn, unsigned int nr_pages);
>>
>> #ifdef CONFIG_CMA
>> /* CMA stuff */
>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
>> index 745088810965..9893ba26b3b8 100644
>> --- a/mm/hugetlb.c
>> +++ b/mm/hugetlb.c
>> @@ -1035,7 +1035,6 @@ static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
>> ((node = hstate_next_node_to_free(hs, mask)) || 1); \
>> nr_nodes--)
>>
>> -#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
>> static void destroy_compound_gigantic_page(struct page *page,
>> unsigned int order)
>> {
>> @@ -1058,6 +1057,7 @@ static void free_gigantic_page(struct page *page, unsigned int order)
>> free_contig_range(page_to_pfn(page), 1 << order);
>> }
>>
>> +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE_RUNTIME_ALLOCATION
>> static int __alloc_gigantic_page(unsigned long start_pfn,
>> unsigned long nr_pages, gfp_t gfp_mask)
>> {
>> @@ -1143,22 +1143,19 @@ static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
>> static void prep_new_huge_page(struct hstate *h, struct page *page, int nid);
>> static void prep_compound_gigantic_page(struct page *page, unsigned int order);
>>
>> -#else /* !CONFIG_ARCH_HAS_GIGANTIC_PAGE */
>> -static inline bool gigantic_page_supported(void) { return false; }
>> +#else /* !CONFIG_ARCH_HAS_GIGANTIC_PAGE_RUNTIME_ALLOCATION */
>> +static inline bool gigantic_page_runtime_allocation_supported(void)
>> +{
>> + return false;
>> +}
>> static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
>> int nid, nodemask_t *nodemask) { return NULL; }
>> -static inline void free_gigantic_page(struct page *page, unsigned int order) { }
>> -static inline void destroy_compound_gigantic_page(struct page *page,
>> - unsigned int order) { }
>> #endif
>>
>> static void update_and_free_page(struct hstate *h, struct page *page)
>> {
>> int i;
>>
>> - if (hstate_is_gigantic(h) && !gigantic_page_supported())
>> - return;
>> -
>> h->nr_huge_pages--;
>> h->nr_huge_pages_node[page_to_nid(page)]--;
>> for (i = 0; i < pages_per_huge_page(h); i++) {
>> @@ -2276,13 +2273,20 @@ static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
>> }
>>
>> #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
>> -static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
>> +static int set_max_huge_pages(struct hstate *h, unsigned long count,
>> nodemask_t *nodes_allowed)
>> {
>> unsigned long min_count, ret;
>>
>> - if (hstate_is_gigantic(h) && !gigantic_page_supported())
>> - return h->max_huge_pages;
>> + if (hstate_is_gigantic(h) &&
>> + !gigantic_page_runtime_allocation_supported()) {
>> + spin_lock(&hugetlb_lock);
>> + if (count > persistent_huge_pages(h)) {
>> + spin_unlock(&hugetlb_lock);
>> + return -EINVAL;
>> + }
>> + goto decrease_pool;
>> + }
>>
>> /*
>> * Increase the pool size
>> @@ -2322,6 +2326,7 @@ static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
>> goto out;
>> }
>>
>> +decrease_pool:
>> /*
>> * Decrease the pool size
>> * First return free pages to the buddy allocator (being careful
>> @@ -2350,9 +2355,10 @@ static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
>> break;
>> }
>> out:
>> - ret = persistent_huge_pages(h);
>> + h->max_huge_pages = persistent_huge_pages(h);
>> spin_unlock(&hugetlb_lock);
>> - return ret;
>> +
>> + return 0;
>> }
>>
>> #define HSTATE_ATTR_RO(_name) \
>> @@ -2404,11 +2410,6 @@ static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
>> int err;
>> NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
>>
>> - if (hstate_is_gigantic(h) && !gigantic_page_supported()) {
>> - err = -EINVAL;
>> - goto out;
>> - }
>> -
>> if (nid == NUMA_NO_NODE) {
>> /*
>> * global hstate attribute
>> @@ -2428,7 +2429,9 @@ static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
>> } else
>> nodes_allowed = &node_states[N_MEMORY];
>>
>> - h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
>> + err = set_max_huge_pages(h, count, nodes_allowed);
>> + if (err)
>> + goto out;
>>
>> if (nodes_allowed != &node_states[N_MEMORY])
>> NODEMASK_FREE(nodes_allowed);
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index cde5dac6229a..81b931db85a1 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -8241,8 +8241,9 @@ int alloc_contig_range(unsigned long start, unsigned long end,
>> pfn_max_align_up(end), migratetype);
>> return ret;
>> }
>> +#endif
>>
>> -void free_contig_range(unsigned long pfn, unsigned nr_pages)
>> +void free_contig_range(unsigned long pfn, unsigned int nr_pages)
>> {
>> unsigned int count = 0;
>>
>> @@ -8254,7 +8255,6 @@ void free_contig_range(unsigned long pfn, unsigned nr_pages)
>> }
>> WARN(count != 0, "%d pages are still in use!\n", count);
>> }
>> -#endif
>>
>> #ifdef CONFIG_MEMORY_HOTPLUG
>> /*
>> --
>> 2.16.2

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