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

From: Oscar Salvador
Date: Fri Feb 05 2021 - 04:00:38 EST


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@xxxxxxxxxxxxx/

>
> 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