This series is based on next-20220428. This series amis to add hugetlb_optimize_vmemmap sysctl to enable or disable the feature of optimizing vmemmap pages associated with HugeTLB pages. v11: - Collect Reviewed-by from Mike. - Remove hugetlb_optimize_vmemmap_enabled() check from flush_free_hpage_work(). v10: - Collect Reviewed-by from Mike. - Remove hugetlb_optimize_vmemmap_enabled() check from hugetlb_optimize_vmemmap_pages() (Mike). - Add more explanation to Documentation/admin-guide/sysctl/vm.rst. - Fix cannot disable the feature via hugetlb_optimize_vmemmap sysctl (Mike). - Update patch 2's commit log (Mike). v9: - Go back to v3 since checking the size of struct page at config time is very complex. v8: - Fix compilation (scripts/selinux/mdp/mdp.c) error when CONFIG_SECURITY_SELINUX is selected. v7: - Fix circular dependency issue reported by kernel test robot. - Introduce CONFIG_HUGETLB_PAGE_HAS_OPTIMIZE_VMEMMAP instead of STRUCT_PAGE_SIZE_IS_POWER_OF_2. - Add more comments into vm.rst to explain hugetlb_optimize_vmemmap (Andrew). - Drop the patch "sysctl: allow to set extra1 to SYSCTL_ONE". - Add a new patch "use kstrtobool for hugetlb_vmemmap param parsing". - Reuse static_key's refcount to count the number of HugeTLB pages with vmemmap pages optimized to simplify the lock scheme. v6: - Remove "make syncconfig" from Kbuild. v5: - Fix not working properly if one is workig off of a very clean build reported by Luis Chamberlain. - Add Suggested-by for Luis Chamberlain. v4: - Introduce STRUCT_PAGE_SIZE_IS_POWER_OF_2 inspired by Luis. v3: - Add pr_warn_once() (Mike). - Handle the transition from enabling to disabling (Luis) v2: - Fix compilation when !CONFIG_MHP_MEMMAP_ON_MEMORY reported by kernel test robot <lkp@xxxxxxxxx>. - Move sysctl code from kernel/sysctl.c to mm/hugetlb_vmemmap.c. Muchun Song (4): mm: hugetlb_vmemmap: disable hugetlb_optimize_vmemmap when struct page crosses page boundaries mm: memory_hotplug: override memmap_on_memory when hugetlb_free_vmemmap=on mm: hugetlb_vmemmap: use kstrtobool for hugetlb_vmemmap param parsing mm: hugetlb_vmemmap: add hugetlb_optimize_vmemmap sysctl Documentation/admin-guide/kernel-parameters.txt | 6 +- Documentation/admin-guide/sysctl/vm.rst | 39 +++++++++ include/linux/memory_hotplug.h | 9 ++ mm/hugetlb_vmemmap.c | 105 ++++++++++++++++++++---- mm/memory_hotplug.c | 27 ++++-- 5 files changed, 162 insertions(+), 24 deletions(-) -- 2.11.0