Re: [PATCH v14 0/8] Free some vmemmap pages of HugeTLB page

On Thu, Feb 04, 2021 at 11:50:35AM +0800, Muchun Song wrote:

Changelog in v13 -> v14:
  - Refuse to free the HugeTLB page when the system is under memory pressure.
  - Use GFP_ATOMIC to allocate vmemmap pages instead of GFP_KERNEL.
  - Rebase to linux-next 20210202.
  - Fix and add some comments for vmemmap_remap_free().

What has happened to [1] ? AFAIK we still need it, right?
If not, could you explain why?

[1] https://patchwork.kernel.org/project/linux-mm/patch/20210117151053.24600-7-songmuchun@bytedance.com/

  Thanks to Oscar, Mike, David H and David R's suggestions and review.

Changelog in v12 -> v13:
  - Remove VM_WARN_ON_PAGE macro.
  - Add more comments in vmemmap_pte_range() and vmemmap_remap_free().

  Thanks to Oscar and Mike's suggestions and review.

Changelog in v11 -> v12:
  - Move VM_WARN_ON_PAGE to a separate patch.
  - Call __free_hugepage() with hugetlb_lock (See patch #5.) to serialize
    with dissolve_free_huge_page(). It is to prepare for patch #9.
  - Introduce PageHugeInflight. See patch #9.

Changelog in v10 -> v11:
  - Fix compiler error when !CONFIG_HUGETLB_PAGE_FREE_VMEMMAP.
  - Rework some comments and commit changes.
  - Rework vmemmap_remap_free() to 3 parameters.

  Thanks to Oscar and Mike's suggestions and review.

Changelog in v9 -> v10:
  - Fix a bug in patch #11. Thanks to Oscar for pointing that out.
  - Rework some commit log or comments. Thanks Mike and Oscar for the suggestions.
  - Drop VMEMMAP_TAIL_PAGE_REUSE in the patch #3.

  Thank you very much Mike and Oscar for reviewing the code.

Changelog in v8 -> v9:
  - Rework some code. Very thanks to Oscar.
  - Put all the non-hugetlb vmemmap functions under sparsemem-vmemmap.c.

Changelog in v7 -> v8:
  - Adjust the order of patches.

  Very thanks to David and Oscar. Your suggestions are very valuable.

Changelog in v6 -> v7:
  - Rebase to linux-next 20201130
  - Do not use basepage mapping for vmemmap when this feature is disabled.
  - Rework some patchs.
    [PATCH v6 08/16] mm/hugetlb: Free the vmemmap pages associated with each hugetlb page
    [PATCH v6 10/16] mm/hugetlb: Allocate the vmemmap pages associated with each hugetlb page

  Thanks to Oscar and Barry.

Changelog in v5 -> v6:
  - Disable PMD/huge page mapping of vmemmap if this feature was enabled.
  - Simplify the first version code.

Changelog in v4 -> v5:
  - Rework somme comments and code in the [PATCH v4 04/21] and [PATCH v4 05/21].

  Thanks to Mike and Oscar's suggestions.

Changelog in v3 -> v4:
  - Move all the vmemmap functions to hugetlb_vmemmap.c.
  - Make the CONFIG_HUGETLB_PAGE_FREE_VMEMMAP default to y, if we want to
    disable this feature, we should disable it by a boot/kernel command line.
  - Remove vmemmap_pgtable_{init, deposit, withdraw}() helper functions.
  - Initialize page table lock for vmemmap through core_initcall mechanism.

  Thanks for Mike and Oscar's suggestions.

Changelog in v2 -> v3:
  - Rename some helps function name. Thanks Mike.
  - Rework some code. Thanks Mike and Oscar.
  - Remap the tail vmemmap page with PAGE_KERNEL_RO instead of PAGE_KERNEL.
    Thanks Matthew.
  - Add some overhead analysis in the cover letter.
  - Use vmemap pmd table lock instead of a hugetlb specific global lock.

Changelog in v1 -> v2:
  - Fix do not call dissolve_compound_page in alloc_huge_page_vmemmap().
  - Fix some typo and code style problems.
  - Remove unused handle_vmemmap_fault().
  - Merge some commits to one commit suggested by Mike.

Muchun Song (8):
  mm: memory_hotplug: factor out bootmem core functions to
    bootmem_info.c
  mm: hugetlb: introduce a new config HUGETLB_PAGE_FREE_VMEMMAP
  mm: hugetlb: free the vmemmap pages associated with each HugeTLB page
  mm: hugetlb: alloc the vmemmap pages associated with each HugeTLB page
  mm: hugetlb: add a kernel parameter hugetlb_free_vmemmap
  mm: hugetlb: introduce nr_free_vmemmap_pages in the struct hstate
  mm: hugetlb: gather discrete indexes of tail page
  mm: hugetlb: optimize the code with the help of the compiler

 Documentation/admin-guide/kernel-parameters.txt |  14 ++
 Documentation/admin-guide/mm/hugetlbpage.rst    |   3 +
 arch/x86/mm/init_64.c                           |  13 +-
 fs/Kconfig                                      |   6 +
 include/linux/bootmem_info.h                    |  65 +++++
 include/linux/hugetlb.h                         |  43 +++-
 include/linux/hugetlb_cgroup.h                  |  19 +-
 include/linux/memory_hotplug.h                  |  27 --
 include/linux/mm.h                              |   5 +
 mm/Makefile                                     |   2 +
 mm/bootmem_info.c                               | 124 ++++++++++
 mm/hugetlb.c                                    |  23 +-
 mm/hugetlb_vmemmap.c                            | 314 ++++++++++++++++++++++++
 mm/hugetlb_vmemmap.h                            |  33 +++
 mm/memory_hotplug.c                             | 116 ---------
 mm/sparse-vmemmap.c                             | 280 +++++++++++++++++++++
 mm/sparse.c                                     |   1 +
 17 files changed, 930 insertions(+), 158 deletions(-)
 create mode 100644 include/linux/bootmem_info.h
 create mode 100644 mm/bootmem_info.c
 create mode 100644 mm/hugetlb_vmemmap.c
 create mode 100644 mm/hugetlb_vmemmap.h

-- 
2.11.0

-- 
Oscar Salvador
SUSE L3