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SubjectRe: [PATCH] hugetlb: allow to free gigantic pages regardless of the configuration
Date
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)

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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