Merge tag 'mm-stable-2022-08-09' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull remaining MM updates from Andrew Morton:
 "Three patch series - two that perform cleanups and one feature:

   - hugetlb_vmemmap cleanups from Muchun Song

   - hardware poisoning support for 1GB hugepages, from Naoya Horiguchi

   - highmem documentation fixups from Fabio De Francesco"

* tag 'mm-stable-2022-08-09' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (23 commits)
  Documentation/mm: add details about kmap_local_page() and preemption
  highmem: delete a sentence from kmap_local_page() kdocs
  Documentation/mm: rrefer kmap_local_page() and avoid kmap()
  Documentation/mm: avoid invalid use of addresses from kmap_local_page()
  Documentation/mm: don't kmap*() pages which can't come from HIGHMEM
  highmem: specify that kmap_local_page() is callable from interrupts
  highmem: remove unneeded spaces in kmap_local_page() kdocs
  mm, hwpoison: enable memory error handling on 1GB hugepage
  mm, hwpoison: skip raw hwpoison page in freeing 1GB hugepage
  mm, hwpoison: make __page_handle_poison returns int
  mm, hwpoison: set PG_hwpoison for busy hugetlb pages
  mm, hwpoison: make unpoison aware of raw error info in hwpoisoned hugepage
  mm, hwpoison, hugetlb: support saving mechanism of raw error pages
  mm/hugetlb: make pud_huge() and follow_huge_pud() aware of non-present pud entry
  mm/hugetlb: check gigantic_page_runtime_supported() in return_unused_surplus_pages()
  mm: hugetlb_vmemmap: use PTRS_PER_PTE instead of PMD_SIZE / PAGE_SIZE
  mm: hugetlb_vmemmap: move code comments to vmemmap_dedup.rst
  mm: hugetlb_vmemmap: improve hugetlb_vmemmap code readability
  mm: hugetlb_vmemmap: replace early_param() with core_param()
  mm: hugetlb_vmemmap: move vmemmap code related to HugeTLB to hugetlb_vmemmap.c
  ...

1 files changed, 4 insertions, 28 deletions

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index ea19528564d1..465ff35a8c00 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -205,34 +205,15 @@ enum pageflags {
 #ifndef __GENERATING_BOUNDS_H
 
 #ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
-DECLARE_STATIC_KEY_MAYBE(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON,
-			 hugetlb_optimize_vmemmap_key);
-
-static __always_inline bool hugetlb_optimize_vmemmap_enabled(void)
-{
-	return static_branch_maybe(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON,
-				   &hugetlb_optimize_vmemmap_key);
-}
+DECLARE_STATIC_KEY_FALSE(hugetlb_optimize_vmemmap_key);
 
 /*
- * If the feature of optimizing vmemmap pages associated with each HugeTLB
- * page is enabled, the head vmemmap page frame is reused and all of the tail
- * vmemmap addresses map to the head vmemmap page frame (furture details can
- * refer to the figure at the head of the mm/hugetlb_vmemmap.c).  In other
- * words, there are more than one page struct with PG_head associated with each
- * HugeTLB page.  We __know__ that there is only one head page struct, the tail
- * page structs with PG_head are fake head page structs.  We need an approach
- * to distinguish between those two different types of page structs so that
- * compound_head() can return the real head page struct when the parameter is
- * the tail page struct but with PG_head.
- *
- * The page_fixed_fake_head() returns the real head page struct if the @page is
- * fake page head, otherwise, returns @page which can either be a true page
- * head or tail.
+ * Return the real head page struct iff the @page is a fake head page, otherwise
+ * return the @page itself. See Documentation/mm/vmemmap_dedup.rst.
  */
 static __always_inline const struct page *page_fixed_fake_head(const struct page *page)
 {
-	if (!hugetlb_optimize_vmemmap_enabled())
+	if (!static_branch_unlikely(&hugetlb_optimize_vmemmap_key))
 		return page;
 
 	/*
@@ -260,11 +241,6 @@ static inline const struct page *page_fixed_fake_head(const struct page *page)
 {
 	return page;
 }
-
-static inline bool hugetlb_optimize_vmemmap_enabled(void)
-{
-	return false;
-}
 #endif
 
 static __always_inline int page_is_fake_head(struct page *page)