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

[Muchun Song <songmuchun@bytedance.com>]

On Fri, Feb 5, 2021 at 4:59 PM Oscar Salvador <osalvador@suse.de> wrote:
>
> 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/

Hi Oscar,

I reply to you in another thread (in the patch #4).

Thanks. :-)

>
> >
> >   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