| Message ID | 20210204035043.36609-6-songmuchun@bytedance.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Free some vmemmap pages of HugeTLB page | expand |
Hi: On 2021/2/4 11:50, Muchun Song wrote: > Add a kernel parameter hugetlb_free_vmemmap to enable the feature of > freeing unused vmemmap pages associated with each hugetlb page on boot. > > We disables PMD mapping of vmemmap pages for x86-64 arch when this > feature is enabled. Because vmemmap_remap_free() depends on vmemmap > being base page mapped. > > Signed-off-by: Muchun Song <songmuchun@bytedance.com> > Reviewed-by: Oscar Salvador <osalvador@suse.de> > Reviewed-by: Barry Song <song.bao.hua@hisilicon.com> Looks good to me. Thanks. Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> > --- > 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 | 22 ++++++++++++++++++++++ > 5 files changed, 64 insertions(+), 2 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 5adf1e57e932..7db2591f3ad3 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -1577,6 +1577,20 @@ > Documentation/admin-guide/mm/hugetlbpage.rst. > Format: size[KMG] > > + hugetlb_free_vmemmap= > + [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= > [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 > > 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. > > 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..39f88c5faadc 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -34,6 +34,7 @@ > #include <linux/gfp.h> > #include <linux/kcore.h> > #include <linux/bootmem_info.h> > +#include <linux/hugetlb.h> > > #include <asm/processor.h> > #include <asm/bios_ebda.h> > @@ -1557,7 +1558,8 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, > { > int err; > > - if (end - start < PAGES_PER_SECTION * sizeof(struct page)) > + if ((is_hugetlb_free_vmemmap_enabled() && !altmap) || > + end - start < PAGES_PER_SECTION * sizeof(struct page)) > err = vmemmap_populate_basepages(start, end, node, NULL); > else if (boot_cpu_has(X86_FEATURE_PSE)) > err = vmemmap_populate_hugepages(start, end, node, altmap); > @@ -1585,6 +1587,8 @@ void register_page_bootmem_memmap(unsigned long section_nr, > pmd_t *pmd; > unsigned int nr_pmd_pages; > struct page *page; > + bool base_mapping = !boot_cpu_has(X86_FEATURE_PSE) || > + is_hugetlb_free_vmemmap_enabled(); > > for (; addr < end; addr = next) { > pte_t *pte = NULL; > @@ -1610,7 +1614,7 @@ void register_page_bootmem_memmap(unsigned long section_nr, > } > get_page_bootmem(section_nr, pud_page(*pud), MIX_SECTION_INFO); > > - if (!boot_cpu_has(X86_FEATURE_PSE)) { > + if (base_mapping) { > next = (addr + PAGE_SIZE) & PAGE_MASK; > pmd = pmd_offset(pud, addr); > if (pmd_none(*pmd)) > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index 37fd248ce271..ad249e56ac49 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -854,6 +854,20 @@ static inline void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, > > void set_page_huge_active(struct page *page); > > +#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 {}; > > @@ -1007,6 +1021,11 @@ static inline void set_huge_swap_pte_at(struct mm_struct *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 */ > > static inline spinlock_t *huge_pte_lock(struct hstate *h, > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c > index 0bd6b8d7282d..224a3cb69bf9 100644 > --- a/mm/hugetlb_vmemmap.c > +++ b/mm/hugetlb_vmemmap.c > @@ -183,6 +183,28 @@ > #define RESERVE_VMEMMAP_NR 2U > #define RESERVE_VMEMMAP_SIZE (RESERVE_VMEMMAP_NR << PAGE_SHIFT) > > +bool hugetlb_free_vmemmap_enabled; > + > +static int __init early_hugetlb_free_vmemmap_param(char *buf) > +{ > + /* We cannot optimize if a "struct page" crosses page boundaries. */ > + if ((!is_power_of_2(sizeof(struct page)))) { > + pr_warn("cannot free vmemmap pages because \"struct page\" crosses page boundaries\n"); > + return 0; > + } > + > + if (!buf) > + return -EINVAL; > + > + if (!strcmp(buf, "on")) > + hugetlb_free_vmemmap_enabled = true; > + else if (strcmp(buf, "off")) > + return -EINVAL; > + > + return 0; > +} > +early_param("hugetlb_free_vmemmap", early_hugetlb_free_vmemmap_param); > + > /* > * How many vmemmap pages associated with a HugeTLB page that can be freed > * to the buddy allocator. >
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 5adf1e57e932..7db2591f3ad3 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1577,6 +1577,20 @@ Documentation/admin-guide/mm/hugetlbpage.rst. Format: size[KMG] + hugetlb_free_vmemmap= + [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= [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 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. 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..39f88c5faadc 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -34,6 +34,7 @@ #include <linux/gfp.h> #include <linux/kcore.h> #include <linux/bootmem_info.h> +#include <linux/hugetlb.h> #include <asm/processor.h> #include <asm/bios_ebda.h> @@ -1557,7 +1558,8 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, { int err; - if (end - start < PAGES_PER_SECTION * sizeof(struct page)) + if ((is_hugetlb_free_vmemmap_enabled() && !altmap) || + end - start < PAGES_PER_SECTION * sizeof(struct page)) err = vmemmap_populate_basepages(start, end, node, NULL); else if (boot_cpu_has(X86_FEATURE_PSE)) err = vmemmap_populate_hugepages(start, end, node, altmap); @@ -1585,6 +1587,8 @@ void register_page_bootmem_memmap(unsigned long section_nr, pmd_t *pmd; unsigned int nr_pmd_pages; struct page *page; + bool base_mapping = !boot_cpu_has(X86_FEATURE_PSE) || + is_hugetlb_free_vmemmap_enabled(); for (; addr < end; addr = next) { pte_t *pte = NULL; @@ -1610,7 +1614,7 @@ void register_page_bootmem_memmap(unsigned long section_nr, } get_page_bootmem(section_nr, pud_page(*pud), MIX_SECTION_INFO); - if (!boot_cpu_has(X86_FEATURE_PSE)) { + if (base_mapping) { next = (addr + PAGE_SIZE) & PAGE_MASK; pmd = pmd_offset(pud, addr); if (pmd_none(*pmd)) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 37fd248ce271..ad249e56ac49 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -854,6 +854,20 @@ static inline void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, void set_page_huge_active(struct page *page); +#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 {}; @@ -1007,6 +1021,11 @@ static inline void set_huge_swap_pte_at(struct mm_struct *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 */ static inline spinlock_t *huge_pte_lock(struct hstate *h, diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index 0bd6b8d7282d..224a3cb69bf9 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -183,6 +183,28 @@ #define RESERVE_VMEMMAP_NR 2U #define RESERVE_VMEMMAP_SIZE (RESERVE_VMEMMAP_NR << PAGE_SHIFT) +bool hugetlb_free_vmemmap_enabled; + +static int __init early_hugetlb_free_vmemmap_param(char *buf) +{ + /* We cannot optimize if a "struct page" crosses page boundaries. */ + if ((!is_power_of_2(sizeof(struct page)))) { + pr_warn("cannot free vmemmap pages because \"struct page\" crosses page boundaries\n"); + return 0; + } + + if (!buf) + return -EINVAL; + + if (!strcmp(buf, "on")) + hugetlb_free_vmemmap_enabled = true; + else if (strcmp(buf, "off")) + return -EINVAL; + + return 0; +} +early_param("hugetlb_free_vmemmap", early_hugetlb_free_vmemmap_param); + /* * How many vmemmap pages associated with a HugeTLB page that can be freed * to the buddy allocator.