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SubjectRe: [PATCH v7 4/4] hugetlb: allow to free gigantic pages regardless of the configuration
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Le 17/03/2019 à 17:28, Alexandre Ghiti a écrit :
> On systems without CONTIG_ALLOC activated but that support gigantic pages,
> boottime reserved gigantic pages can not be freed at all. This patch
> simply enables the possibility to hand back those pages to memory
> allocator.
>
> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
> Acked-by: David S. Miller <davem@davemloft.net> [sparc]
> ---
> arch/arm64/Kconfig | 2 +-
> arch/arm64/include/asm/hugetlb.h | 4 --
> arch/powerpc/include/asm/book3s/64/hugetlb.h | 7 ---
> arch/powerpc/platforms/Kconfig.cputype | 2 +-
> arch/s390/Kconfig | 2 +-
> arch/s390/include/asm/hugetlb.h | 3 --
> arch/sh/Kconfig | 2 +-
> arch/sparc/Kconfig | 2 +-
> arch/x86/Kconfig | 2 +-
> arch/x86/include/asm/hugetlb.h | 4 --
> include/asm-generic/hugetlb.h | 14 +++++
> include/linux/gfp.h | 2 +-
> mm/hugetlb.c | 54 ++++++++++++++------
> mm/page_alloc.c | 4 +-
> 14 files changed, 61 insertions(+), 43 deletions(-)
>

[...]

> diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h
> index 71d7b77eea50..aaf14974ee5f 100644
> --- a/include/asm-generic/hugetlb.h
> +++ b/include/asm-generic/hugetlb.h
> @@ -126,4 +126,18 @@ static inline pte_t huge_ptep_get(pte_t *ptep)
> }
> #endif
>
> +#ifndef __HAVE_ARCH_GIGANTIC_PAGE_RUNTIME_SUPPORTED
> +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE
> +static inline bool gigantic_page_runtime_supported(void)
> +{
> + return true;
> +}
> +#else
> +static inline bool gigantic_page_runtime_supported(void)
> +{
> + return false;
> +}
> +#endif /* CONFIG_ARCH_HAS_GIGANTIC_PAGE */

What about the following instead:

static inline bool gigantic_page_runtime_supported(void)
{
return IS_ENABLED(CONFIG_ARCH_HAS_GIGANTIC_PAGE);
}


> +#endif /* __HAVE_ARCH_GIGANTIC_PAGE_RUNTIME_SUPPORTED */
> +
> #endif /* _ASM_GENERIC_HUGETLB_H */
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index 1f1ad9aeebb9..58ea44bf75de 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);

'extern' is unneeded and should be avoided (iaw checkpatch)

Christophe

>
> #ifdef CONFIG_CMA
> /* CMA stuff */
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index afef61656c1e..4e55aa38704f 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1058,6 +1058,7 @@ static void free_gigantic_page(struct page *page, unsigned int order)
> free_contig_range(page_to_pfn(page), 1 << order);
> }
>
> +#ifdef CONFIG_CONTIG_ALLOC
> static int __alloc_gigantic_page(unsigned long start_pfn,
> unsigned long nr_pages, gfp_t gfp_mask)
> {
> @@ -1142,11 +1143,20 @@ 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_CONTIG_ALLOC */
> +static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
> + int nid, nodemask_t *nodemask)
> +{
> + return NULL;
> +}
> +#endif /* CONFIG_CONTIG_ALLOC */
>
> #else /* !CONFIG_ARCH_HAS_GIGANTIC_PAGE */
> -static inline bool gigantic_page_supported(void) { return false; }
> static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
> - int nid, nodemask_t *nodemask) { return NULL; }
> + 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) { }
> @@ -1156,7 +1166,7 @@ static void update_and_free_page(struct hstate *h, struct page *page)
> {
> int i;
>
> - if (hstate_is_gigantic(h) && !gigantic_page_supported())
> + if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
> return;
>
> h->nr_huge_pages--;
> @@ -2276,13 +2286,27 @@ 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,
> - nodemask_t *nodes_allowed)
> +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;
> + spin_lock(&hugetlb_lock);
> +
> + /*
> + * Gigantic pages runtime allocation depend on the capability for large
> + * page range allocation.
> + * If the system does not provide this feature, return an error when
> + * the user tries to allocate gigantic pages but let the user free the
> + * boottime allocated gigantic pages.
> + */
> + if (hstate_is_gigantic(h) && !IS_ENABLED(CONFIG_CONTIG_ALLOC)) {
> + if (count > persistent_huge_pages(h)) {
> + spin_unlock(&hugetlb_lock);
> + return -EINVAL;
> + }
> + /* Fall through to decrease pool */
> + }
>
> /*
> * Increase the pool size
> @@ -2295,7 +2319,6 @@ static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
> * pool might be one hugepage larger than it needs to be, but
> * within all the constraints specified by the sysctls.
> */
> - spin_lock(&hugetlb_lock);
> while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
> if (!adjust_pool_surplus(h, nodes_allowed, -1))
> break;
> @@ -2350,9 +2373,10 @@ 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) \
> @@ -2404,7 +2428,7 @@ 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()) {
> + if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported()) {
> err = -EINVAL;
> goto out;
> }
> @@ -2428,15 +2452,13 @@ 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);
>
> +out:
> if (nodes_allowed != &node_states[N_MEMORY])
> NODEMASK_FREE(nodes_allowed);
>
> - return len;
> -out:
> - NODEMASK_FREE(nodes_allowed);
> - return err;
> + return err ? err : len;
> }
>
> static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index ac9c45ffb344..a4547d90fa7a 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -8234,8 +8234,9 @@ int alloc_contig_range(unsigned long start, unsigned long end,
> pfn_max_align_up(end), migratetype);
> return ret;
> }
> +#endif /* CONFIG_CONTIG_ALLOC */
>
> -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;
>
> @@ -8247,7 +8248,6 @@ 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
> /*
>

---
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