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Signed-off-by: Muchun Song Reviewed-by: Oscar Salvador Reviewed-by: Barry Song --- Documentation/admin-guide/kernel-parameters.txt | 14 ++++++++++++++ Documentation/admin-guide/mm/hugetlbpage.rst | 3 +++ arch/x86/mm/init_64.c | 8 ++++++-- include/linux/hugetlb.h | 19 +++++++++++++++++++ mm/hugetlb_vmemmap.c | 16 ++++++++++++++++ 5 files changed, 58 insertions(+), 2 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentat= ion/admin-guide/kernel-parameters.txt index 3ae25630a223..44dde9be7e00 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1551,6 +1551,20 @@ Documentation/admin-guide/mm/hugetlbpage.rst. Format: size[KMG] =20 + hugetlb_free_vmemmap=3D + [KNL] When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, + this controls freeing unused vmemmap pages associated + with each HugeTLB page. When this option is enabled, + we disable PMD/huge page mapping of vmemmap pages which + increase page table pages. So if a user/sysadmin only + uses a small number of HugeTLB pages (as a percentage + of system memory), they could end up using more memory + with hugetlb_free_vmemmap on as opposed to off. + Format: { on | off (default) } + + on: enable the feature + off: disable the feature + hung_task_panic=3D [KNL] Should the hung task detector generate panics. Format: 0 | 1 diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst b/Documentation= /admin-guide/mm/hugetlbpage.rst index f7b1c7462991..3a23c2377acc 100644 --- a/Documentation/admin-guide/mm/hugetlbpage.rst +++ b/Documentation/admin-guide/mm/hugetlbpage.rst @@ -145,6 +145,9 @@ default_hugepagesz =20 will all result in 256 2M huge pages being allocated. Valid default huge page size is architecture dependent. +hugetlb_free_vmemmap + When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this enables freeing + unused vmemmap pages associated with each HugeTLB page. =20 When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages= `` indicates the current number of pre-allocated huge pages of the default = size. diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 0435bee2e172..1bce5f20e6ca 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -34,6 +34,7 @@ #include #include #include +#include =20 #include #include @@ -1557,7 +1558,8 @@ int __meminit vmemmap_populate(unsigned long start,= unsigned long end, int node, { int err; =20 - if (end - start < PAGES_PER_SECTION * sizeof(struct page)) + if (is_hugetlb_free_vmemmap_enabled() || + end - start < PAGES_PER_SECTION * sizeof(struct page)) err =3D vmemmap_populate_basepages(start, end, node, NULL); else if (boot_cpu_has(X86_FEATURE_PSE)) err =3D vmemmap_populate_hugepages(start, end, node, altmap); @@ -1585,6 +1587,8 @@ void register_page_bootmem_memmap(unsigned long sec= tion_nr, pmd_t *pmd; unsigned int nr_pmd_pages; struct page *page; + bool base_mapping =3D !boot_cpu_has(X86_FEATURE_PSE) || + is_hugetlb_free_vmemmap_enabled(); =20 for (; addr < end; addr =3D next) { pte_t *pte =3D NULL; @@ -1610,7 +1614,7 @@ void register_page_bootmem_memmap(unsigned long sec= tion_nr, } get_page_bootmem(section_nr, pud_page(*pud), MIX_SECTION_INFO); =20 - if (!boot_cpu_has(X86_FEATURE_PSE)) { + if (base_mapping) { next =3D (addr + PAGE_SIZE) & PAGE_MASK; pmd =3D pmd_offset(pud, addr); if (pmd_none(*pmd)) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index ebca2ef02212..7f47f0eeca3b 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -770,6 +770,20 @@ static inline void huge_ptep_modify_prot_commit(stru= ct vm_area_struct *vma, } #endif =20 +#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP +extern bool hugetlb_free_vmemmap_enabled; + +static inline bool is_hugetlb_free_vmemmap_enabled(void) +{ + return hugetlb_free_vmemmap_enabled; +} +#else +static inline bool is_hugetlb_free_vmemmap_enabled(void) +{ + return false; +} +#endif + #else /* CONFIG_HUGETLB_PAGE */ struct hstate {}; =20 @@ -923,6 +937,11 @@ static inline void set_huge_swap_pte_at(struct mm_st= ruct *mm, unsigned long addr pte_t *ptep, pte_t pte, unsigned long sz) { } + +static inline bool is_hugetlb_free_vmemmap_enabled(void) +{ + return false; +} #endif /* CONFIG_HUGETLB_PAGE */ =20 static inline spinlock_t *huge_pte_lock(struct hstate *h, diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index 273816dd95b6..9e9bd458a3f5 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -178,6 +178,22 @@ #define RESERVE_VMEMMAP_NR 2U #define RESERVE_VMEMMAP_SIZE (RESERVE_VMEMMAP_NR << PAGE_SHIFT) =20 +bool hugetlb_free_vmemmap_enabled; + +static int __init early_hugetlb_free_vmemmap_param(char *buf) +{ + if (!buf) + return -EINVAL; + + if (!strcmp(buf, "on")) + hugetlb_free_vmemmap_enabled =3D true; + else if (strcmp(buf, "off")) + return -EINVAL; + + return 0; +} +early_param("hugetlb_free_vmemmap", early_hugetlb_free_vmemmap_param); + static inline unsigned long free_vmemmap_pages_size_per_hpage(struct hst= ate *h) { return (unsigned long)free_vmemmap_pages_per_hpage(h) << PAGE_SHIFT; --=20 2.11.0