From: Muchun Song <songmuchun@xxxxxxxxxxxxx> Subject: mm: hugetlb: introduce a new config HUGETLB_PAGE_FREE_VMEMMAP The option HUGETLB_PAGE_FREE_VMEMMAP allows for the freeing of some vmemmap pages associated with pre-allocated HugeTLB pages. For example, on X86_64 6 vmemmap pages of size 4KB each can be saved for each 2MB HugeTLB page. 4094 vmemmap pages of size 4KB each can be saved for each 1GB HugeTLB page. When a HugeTLB page is allocated or freed, the vmemmap array representing the range associated with the page will need to be remapped. When a page is allocated, vmemmap pages are freed after remapping. When a page is freed, previously discarded vmemmap pages must be allocated before remapping. The config option is introduced early so that supporting code can be written to depend on the option. The initial version of the code only provides support for x86-64. If config HAVE_BOOTMEM_INFO_NODE is enabled, the freeing vmemmap page code denpend on it to free vmemmap pages. Otherwise, just use free_reserved_page() to free vmemmmap pages. The routine register_page_bootmem_info() is used to register bootmem info. Therefore, make sure register_page_bootmem_info is enabled if HUGETLB_PAGE_FREE_VMEMMAP is defined. Link: https://lkml.kernel.org/r/20210510030027.56044-3-songmuchun@xxxxxxxxxxxxx Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> Reviewed-by: Oscar Salvador <osalvador@xxxxxxx> Acked-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Reviewed-by: Miaohe Lin <linmiaohe@xxxxxxxxxx> Tested-by: Chen Huang <chenhuang5@xxxxxxxxxx> Tested-by: Bodeddula Balasubramaniam <bodeddub@xxxxxxxxxx> Reviewed-by: Balbir Singh <bsingharora@xxxxxxxxx> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx> Cc: Barry Song <song.bao.hua@xxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: David Hildenbrand <david@xxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: HORIGUCHI NAOYA <naoya.horiguchi@xxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Joao Martins <joao.m.martins@xxxxxxxxxx> Cc: Joerg Roedel <jroedel@xxxxxxx> Cc: Jonathan Corbet <corbet@xxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Mina Almasry <almasrymina@xxxxxxxxxx> Cc: Oliver Neukum <oneukum@xxxxxxxx> Cc: Paul E. McKenney <paulmck@xxxxxxxxxx> Cc: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Xiongchun Duan <duanxiongchun@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/x86/mm/init_64.c | 2 +- fs/Kconfig | 5 +++++ 2 files changed, 6 insertions(+), 1 deletion(-) --- a/arch/x86/mm/init_64.c~mm-hugetlb-introduce-a-new-config-hugetlb_page_free_vmemmap +++ a/arch/x86/mm/init_64.c @@ -1270,7 +1270,7 @@ static struct kcore_list kcore_vsyscall; static void __init register_page_bootmem_info(void) { -#ifdef CONFIG_NUMA +#if defined(CONFIG_NUMA) || defined(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP) int i; for_each_online_node(i) --- a/fs/Kconfig~mm-hugetlb-introduce-a-new-config-hugetlb_page_free_vmemmap +++ a/fs/Kconfig @@ -240,6 +240,11 @@ config HUGETLBFS config HUGETLB_PAGE def_bool HUGETLBFS +config HUGETLB_PAGE_FREE_VMEMMAP + def_bool HUGETLB_PAGE + depends on X86_64 + depends on SPARSEMEM_VMEMMAP + config MEMFD_CREATE def_bool TMPFS || HUGETLBFS _
