From: Matthew Wilcox (Oracle) <willy@infradead.org>
Date: Wed, 2 Oct 2024 15:25:30 +0000 (+0100)
Subject: mm: add PageAnonNotKsm()
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=c40737c80f77af3a43e02fabae6e3e2222262aac;p=users%2Fjedix%2Flinux-maple.git

mm: add PageAnonNotKsm()

Check that this anonymous page is really anonymous, not anonymous-or-KSM.
This optimises the debug check, but its real purpose is to remove the last
two users of PageKsm().

Link: https://lkml.kernel.org/r/20241002152533.1350629-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Alex Shi <alexs@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index cc839e4365c18..dbca42c9c53ca 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -689,6 +689,13 @@ static __always_inline bool folio_test_anon(const struct folio *folio)
 	return ((unsigned long)folio->mapping & PAGE_MAPPING_ANON) != 0;
 }
 
+static __always_inline bool PageAnonNotKsm(const struct page *page)
+{
+	unsigned long flags = (unsigned long)page_folio(page)->mapping;
+
+	return (flags & PAGE_MAPPING_FLAGS) == PAGE_MAPPING_ANON;
+}
+
 static __always_inline bool PageAnon(const struct page *page)
 {
 	return folio_test_anon(page_folio(page));
@@ -1137,14 +1144,14 @@ static __always_inline int PageAnonExclusive(const struct page *page)
 
 static __always_inline void SetPageAnonExclusive(struct page *page)
 {
-	VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
+	VM_BUG_ON_PGFLAGS(PageAnonNotKsm(page), page);
 	VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
 	set_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
 }
 
 static __always_inline void ClearPageAnonExclusive(struct page *page)
 {
-	VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
+	VM_BUG_ON_PGFLAGS(PageAnonNotKsm(page), page);
 	VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
 	clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
 }