The patch titled
Subject: mm, page_alloc: use check_pages_enabled static key to check tail pages
has been added to the -mm mm-unstable branch. Its filename is
mm-page_alloc-use-check_pages_enabled-static-key-to-check-tail-pages.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_alloc-use-check_pages_enabled-static-key-to-check-tail-pages.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: mm, page_alloc: use check_pages_enabled static key to check tail pages
Date: Wed, 5 Apr 2023 16:28:40 +0200
Commit 700d2e9a36b9 ("mm, page_alloc: reduce page alloc/free sanity
checks") has introduced a new static key check_pages_enabled to control
when struct pages are sanity checked during allocation and freeing. Mel
Gorman suggested that free_tail_pages_check() could use this static key as
well, instead of relying on CONFIG_DEBUG_VM. That makes sense, so do
that. Also rename the function to free_tail_page_prepare() because it
works on a single tail page and has a struct page preparation component as
well as the optional checking component.
Also remove some unnecessary unlikely() within static_branch_unlikely()
statements that Mel pointed out for commit 700d2e9a36b9.
Link: https://lkml.kernel.org/r/20230405142840.11068-1-vbabka@xxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Suggested-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Alexander Halbuer <halbuer@xxxxxxxxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb_vmemmap.c | 2 +-
mm/page_alloc.c | 10 +++++-----
2 files changed, 6 insertions(+), 6 deletions(-)
--- a/mm/hugetlb_vmemmap.c~mm-page_alloc-use-check_pages_enabled-static-key-to-check-tail-pages
+++ a/mm/hugetlb_vmemmap.c
@@ -264,7 +264,7 @@ static void vmemmap_remap_pte(pte_t *pte
* How many struct page structs need to be reset. When we reuse the head
* struct page, the special metadata (e.g. page->flags or page->mapping)
* cannot copy to the tail struct page structs. The invalid value will be
- * checked in the free_tail_pages_check(). In order to avoid the message
+ * checked in the free_tail_page_prepare(). In order to avoid the message
* of "corrupted mapping in tail page". We need to reset at least 3 (one
* head struct page struct and two tail struct page structs) struct page
* structs.
--- a/mm/page_alloc.c~mm-page_alloc-use-check_pages_enabled-static-key-to-check-tail-pages
+++ a/mm/page_alloc.c
@@ -1131,7 +1131,7 @@ static inline bool free_page_is_bad(stru
return true;
}
-static int free_tail_pages_check(struct page *head_page, struct page *page)
+static int free_tail_page_prepare(struct page *head_page, struct page *page)
{
struct folio *folio = (struct folio *)head_page;
int ret = 1;
@@ -1142,7 +1142,7 @@ static int free_tail_pages_check(struct
*/
BUILD_BUG_ON((unsigned long)LIST_POISON1 & 1);
- if (!IS_ENABLED(CONFIG_DEBUG_VM)) {
+ if (!static_branch_unlikely(&check_pages_enabled)) {
ret = 0;
goto out;
}
@@ -1276,9 +1276,9 @@ static __always_inline bool free_pages_p
ClearPageHasHWPoisoned(page);
for (i = 1; i < (1 << order); i++) {
if (compound)
- bad += free_tail_pages_check(page, page + i);
+ bad += free_tail_pages_prepare(page, page + i);
if (is_check_pages_enabled()) {
- if (unlikely(free_page_is_bad(page + i))) {
+ if (free_page_is_bad(page + i)) {
bad++;
continue;
}
@@ -1627,7 +1627,7 @@ static inline bool check_new_pages(struc
for (int i = 0; i < (1 << order); i++) {
struct page *p = page + i;
- if (unlikely(check_new_page(p)))
+ if (check_new_page(p))
return true;
}
}
_
Patches currently in -mm which might be from vbabka@xxxxxxx are
mm-mmap-vma_merge-use-only-primary-pointers-for-preparing-merge.patch
mm-mmap-vma_merge-use-the-proper-vma-pointer-in-case-3.patch
mm-mmap-vma_merge-use-the-proper-vma-pointers-in-cases-1-and-6.patch
mm-mmap-vma_merge-use-the-proper-vma-pointer-in-case-4.patch
mm-mmap-vma_merge-initialize-mid-and-next-in-natural-order.patch
mm-mmap-vma_merge-set-mid-to-null-if-not-applicable.patch
mm-mmap-vma_merge-set-mid-to-null-if-not-applicable-fix.patch
mm-mmap-vma_merge-rename-adj_next-to-adj_start.patch
mm-mmap-vma_merge-convert-mergeability-checks-to-return-bool.patch
mm-mmap-start-distinguishing-if-vma-can-be-removed-in-mergeability-test.patch
mm-mmap-start-distinguishing-if-vma-can-be-removed-in-mergeability-test-fix.patch
mm-mremap-simplify-vma-expansion-again.patch
mm-page_alloc-use-check_pages_enabled-static-key-to-check-tail-pages.patch
