Merge tag 'mm-stable-2022-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:
 "Most of the MM queue. A few things are still pending.

  Liam's maple tree rework didn't make it. This has resulted in a few
  other minor patch series being held over for next time.

  Multi-gen LRU still isn't merged as we were waiting for mapletree to
  stabilize. The current plan is to merge MGLRU into -mm soon and to
  later reintroduce mapletree, with a view to hopefully getting both
  into 6.1-rc1.

  Summary:

   - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe
     Lin, Yang Shi, Anshuman Khandual and Mike Rapoport

   - Some kmemleak fixes from Patrick Wang and Waiman Long

   - DAMON updates from SeongJae Park

   - memcg debug/visibility work from Roman Gushchin

   - vmalloc speedup from Uladzislau Rezki

   - more folio conversion work from Matthew Wilcox

   - enhancements for coherent device memory mapping from Alex Sierra

   - addition of shared pages tracking and CoW support for fsdax, from
     Shiyang Ruan

   - hugetlb optimizations from Mike Kravetz

   - Mel Gorman has contributed some pagealloc changes to improve
     latency and realtime behaviour.

   - mprotect soft-dirty checking has been improved by Peter Xu

   - Many other singleton patches all over the place"

 [ XFS merge from hell as per Darrick Wong in

   https://lore.kernel.org/all/YshKnxb4VwXycPO8@magnolia/ ]

* tag 'mm-stable-2022-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (282 commits)
  tools/testing/selftests/vm/hmm-tests.c: fix build
  mm: Kconfig: fix typo
  mm: memory-failure: convert to pr_fmt()
  mm: use is_zone_movable_page() helper
  hugetlbfs: fix inaccurate comment in hugetlbfs_statfs()
  hugetlbfs: cleanup some comments in inode.c
  hugetlbfs: remove unneeded header file
  hugetlbfs: remove unneeded hugetlbfs_ops forward declaration
  hugetlbfs: use helper macro SZ_1{K,M}
  mm: cleanup is_highmem()
  mm/hmm: add a test for cross device private faults
  selftests: add soft-dirty into run_vmtests.sh
  selftests: soft-dirty: add test for mprotect
  mm/mprotect: fix soft-dirty check in can_change_pte_writable()
  mm: memcontrol: fix potential oom_lock recursion deadlock
  mm/gup.c: fix formatting in check_and_migrate_movable_page()
  xfs: fail dax mount if reflink is enabled on a partition
  mm/memcontrol.c: remove the redundant updating of stats_flush_threshold
  userfaultfd: don't fail on unrecognized features
  hugetlb_cgroup: fix wrong hugetlb cgroup numa stat
  ...

1 files changed, 96 insertions, 0 deletions

diff --git a/Documentation/translations/zh_CN/mm/split_page_table_lock.rst b/Documentation/translations/zh_CN/mm/split_page_table_lock.rst
new file mode 100644
index 000000000000..4fb7aa666037
--- /dev/null
+++ b/Documentation/translations/zh_CN/mm/split_page_table_lock.rst
@@ -0,0 +1,96 @@
+:Original: Documentation/mm/split_page_table_lock.rst
+
+:翻译:
+
+ 司延腾 Yanteng Si <siyanteng@loongson.cn>
+
+:校译:
+
+
+=================================
+分页表锁（split page table lock）
+=================================
+
+最初，mm->page_table_lock spinlock保护了mm_struct的所有页表。但是这种方
+法导致了多线程应用程序的缺页异常可扩展性差，因为对锁的争夺很激烈。为了提高可扩
+展性，我们引入了分页表锁。
+
+有了分页表锁，我们就有了单独的每张表锁来顺序化对表的访问。目前，我们对PTE和
+PMD表使用分页锁。对高层表的访问由mm->page_table_lock保护。
+
+有一些辅助工具来锁定/解锁一个表和其他访问器函数:
+
+ - pte_offset_map_lock()
+	映射pte并获取PTE表锁，返回所取锁的指针；
+ - pte_unmap_unlock()
+	解锁和解映射PTE表；
+ - pte_alloc_map_lock()
+	如果需要的话，分配PTE表并获取锁，如果分配失败，返回已获取的锁的指针
+	或NULL；
+ - pte_lockptr()
+	返回指向PTE表锁的指针；
+ - pmd_lock()
+	取得PMD表锁，返回所取锁的指针。
+ - pmd_lockptr()
+	返回指向PMD表锁的指针；
+
+如果CONFIG_SPLIT_PTLOCK_CPUS（通常为4）小于或等于NR_CPUS，则在编译
+时启用PTE表的分页表锁。如果分页锁被禁用，所有的表都由mm->page_table_lock
+来保护。
+
+如果PMD表启用了分页锁，并且架构支持它，那么PMD表的分页锁就会被启用（见
+下文）。
+
+Hugetlb 和分页表锁
+==================
+
+Hugetlb可以支持多种页面大小。我们只对PMD级别使用分页锁，但不对PUD使用。
+
+Hugetlb特定的辅助函数:
+
+ - huge_pte_lock()
+	对PMD_SIZE页面采取pmd分割锁，否则mm->page_table_lock；
+ - huge_pte_lockptr()
+	返回指向表锁的指针。
+
+架构对分页表锁的支持
+====================
+
+没有必要特别启用PTE分页表锁：所有需要的东西都由pgtable_pte_page_ctor()
+和pgtable_pte_page_dtor()完成，它们必须在PTE表分配/释放时被调用。
+
+确保架构不使用slab分配器来分配页表：slab使用page->slab_cache来分配其页
+面。这个区域与page->ptl共享存储。
+
+PMD分页锁只有在你有两个以上的页表级别时才有意义。
+
+启用PMD分页锁需要在PMD表分配时调用pgtable_pmd_page_ctor()，在释放时调
+用pgtable_pmd_page_dtor()。
+
+分配通常发生在pmd_alloc_one()中，释放发生在pmd_free()和pmd_free_tlb()
+中，但要确保覆盖所有的PMD表分配/释放路径：即X86_PAE在pgd_alloc()中预先
+分配一些PMD。
+
+一切就绪后，你可以设置CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK。
+
+注意：pgtable_pte_page_ctor()和pgtable_pmd_page_ctor()可能失败--必
+须正确处理。
+
+page->ptl
+=========
+
+page->ptl用于访问分割页表锁，其中'page'是包含该表的页面struct page。它
+与page->private（以及union中的其他几个字段）共享存储。
+
+为了避免增加struct page的大小并获得最佳性能，我们使用了一个技巧:
+
+ - 如果spinlock_t适合于long，我们使用page->ptr作为spinlock，这样我们
+   就可以避免间接访问并节省一个缓存行。
+ - 如果spinlock_t的大小大于long的大小，我们使用page->ptl作为spinlock_t
+   的指针并动态分配它。这允许在启用DEBUG_SPINLOCK或DEBUG_LOCK_ALLOC的
+   情况下使用分页锁，但由于间接访问而多花了一个缓存行。
+
+PTE表的spinlock_t分配在pgtable_pte_page_ctor()中，PMD表的spinlock_t
+分配在pgtable_pmd_page_ctor()中。
+
+请不要直接访问page->ptl - -使用适当的辅助函数。