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().

[willy@infradead.org: fix assertions]
Link: https://lkml.kernel.org/r/ZwApWPER7caIA_N3@casper.infradead.org
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 cc839e4365c18223e68c35efd0f67e7650708e8b..1fcef06a2d3164bfccca4618a7f7115a0eeada07 100644 (file)
--- 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);
 }