In order to reduce the difficulty of code review in series[1]. We disable huge PMD mapping of vmemmap pages when that feature is enabled. In this series, we do not disable huge PMD mapping of vmemmap pages anymore. We will split huge PMD mapping when needed. [1] https://lore.kernel.org/linux-doc/20210510030027.56044-1-songmuchun@xxxxxxxxxxxxx/ Muchun Song (5): mm: hugetlb: introduce helpers to preallocate/free page tables mm: hugetlb: introduce helpers to preallocate page tables from bootmem allocator mm: sparsemem: split the huge PMD mapping of vmemmap pages mm: sparsemem: use huge PMD mapping for vmemmap pages mm: hugetlb: introduce CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON Documentation/admin-guide/kernel-parameters.txt | 10 +- arch/x86/mm/init_64.c | 8 +- fs/Kconfig | 10 ++ include/linux/hugetlb.h | 28 ++---- include/linux/mm.h | 2 +- mm/hugetlb.c | 42 +++++++- mm/hugetlb_vmemmap.c | 126 +++++++++++++++++++++++- mm/hugetlb_vmemmap.h | 25 +++++ mm/memory_hotplug.c | 2 +- mm/sparse-vmemmap.c | 61 ++++++++++-- 10 files changed, 267 insertions(+), 47 deletions(-) -- 2.11.0