Messages in this thread Patch in this message | | | Subject | Re: [PATCH v6 4/4] hugetlb: allow to free gigantic pages regardless of the configuration | From | Alexandre Ghiti <> | Date | Thu, 14 Mar 2019 12:43:51 +0100 |
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On 03/14/2019 06:52 AM, Aneesh Kumar K.V wrote: > Alexandre Ghiti <alex@ghiti.fr> writes: > >> 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/linux/gfp.h | 2 +- >> mm/hugetlb.c | 57 ++++++++++++-------- >> mm/page_alloc.c | 4 +- >> 13 files changed, 44 insertions(+), 49 deletions(-) >> >> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >> index 091a513b93e9..af687eff884a 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 CONTIG_ALLOC >> + select ARCH_HAS_GIGANTIC_PAGE >> 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..59893e766824 100644 >> --- a/arch/arm64/include/asm/hugetlb.h >> +++ b/arch/arm64/include/asm/hugetlb.h >> @@ -65,8 +65,4 @@ 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; } >> -#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..d04a0bcc2f1c 100644 >> --- a/arch/powerpc/include/asm/book3s/64/hugetlb.h >> +++ b/arch/powerpc/include/asm/book3s/64/hugetlb.h >> @@ -32,13 +32,6 @@ static inline int hstate_get_psize(struct hstate *hstate) >> } >> } >> >> -#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE >> -static inline bool gigantic_page_supported(void) >> -{ >> - return true; >> -} >> -#endif >> - >> /* hugepd entry valid bit */ >> #define HUGEPD_VAL_BITS (0x8000000000000000UL) >> > As explained in https://patchwork.ozlabs.org/patch/1047003/ > architectures like ppc64 have a hypervisor assisted mechanism to indicate > where to find gigantic huge pages(16G pages). At this point, we don't use this > reserved pages for anything other than hugetlb backing and hence there > is no runtime free of this pages needed ( Also we don't do > runtime allocation of them). > > I guess you can still achieve what you want to do in this patch by > keeping gigantic_page_supported()? > > NOTE: We should rename gigantic_page_supported to be more specific to > support for runtime_alloc/free of gigantic pages > > -aneesh > Thanks for noticing Aneesh.
I can't find a better solution than bringing back gigantic_page_supported check, since it is must be done at runtime in your case. I'm not sure of one thing though: you say that freeing boottime gigantic pages is not needed, but is it forbidden ? Just to know where the check and what its new name should be. Is something like that (on top of this series) ok for you (and everyone else) before I send a v7:
diff --git a/arch/powerpc/include/asm/book3s/64/hugetlb.h b/arch/powerpc/include/asm/book3s/64/hugetlb.h index d04a0bc..d121559 100644 --- a/arch/powerpc/include/asm/book3s/64/hugetlb.h +++ b/arch/powerpc/include/asm/book3s/64/hugetlb.h @@ -35,4 +35,20 @@ static inline int hstate_get_psize(struct hstate *hstate) /* hugepd entry valid bit */ #define HUGEPD_VAL_BITS (0x8000000000000000UL)
+#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE +#define __HAVE_ARCH_GIGANTIC_PAGE_SUPPORTED +static inline bool gigantic_page_supported(void) +{ + /* + * We used gigantic page reservation with hypervisor assist in some case. + * We cannot use runtime allocation of gigantic pages in those platforms + * This is hash translation mode LPARs. + */ + if (firmware_has_feature(FW_FEATURE_LPAR) && !radix_enabled()) + return false; + + return true; +} +#endif + #endif diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h index 71d7b77..7d12e73 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_SUPPORTED +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE +static inline bool gigantic_page_supported(void) +{ + return true; +} +#else +static inline bool gigantic_page_supported(void) +{ + return false; +} +#endif /* CONFIG_ARCH_HAS_GIGANTIC_PAGE */ +#endif /* __HAVE_ARCH_GIGANTIC_PAGE_SUPPORTED */ + #endif /* _ASM_GENERIC_HUGETLB_H */ diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 9fc96ef..cfbbafe 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2425,6 +2425,11 @@ 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 @@ -2446,6 +2451,7 @@ static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
err = set_max_huge_pages(h, count, nodes_allowed);
+out: if (nodes_allowed != &node_states[N_MEMORY]) NODEMASK_FREE(nodes_allowed);
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