mm: Don't pin ZERO_PAGE in pin_user_pages()

[linux-block.git] / include / linux / mm.h

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 3731999cd9f09a0e873d5987e030f8b3cde7987a..3c2f6b452586f233dfdbe1f0ce1580733430f2ee 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -98,17 +98,6 @@ extern int mmap_rnd_compat_bits __read_mostly;
 #include <asm/page.h>
 #include <asm/processor.h>
 
-/*
- * Architectures that support memory tagging (assigning tags to memory regions,
- * embedding these tags into addresses that point to these memory regions, and
- * checking that the memory and the pointer tags match on memory accesses)
- * redefine this macro to strip tags from pointers.
- * It's defined as noop for architectures that don't support memory tagging.
- */
-#ifndef untagged_addr
-#define untagged_addr(addr) (addr)
-#endif
-
 #ifndef __pa_symbol
 #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
 #endif
@@ -1921,6 +1910,28 @@ static inline bool page_needs_cow_for_dma(struct vm_area_struct *vma,
        return page_maybe_dma_pinned(page);
 }
 
+/**
+ * is_zero_page - Query if a page is a zero page
+ * @page: The page to query
+ *
+ * This returns true if @page is one of the permanent zero pages.
+ */
+static inline bool is_zero_page(const struct page *page)
+{
+       return is_zero_pfn(page_to_pfn(page));
+}
+
+/**
+ * is_zero_folio - Query if a folio is a zero page
+ * @folio: The folio to query
+ *
+ * This returns true if @folio is one of the permanent zero pages.
+ */
+static inline bool is_zero_folio(const struct folio *folio)
+{
+       return is_zero_page(&folio->page);
+}
+
 /* MIGRATE_CMA and ZONE_MOVABLE do not allow pin pages */
 #ifdef CONFIG_MIGRATION
 static inline bool is_longterm_pinnable_page(struct page *page)
@@ -1931,8 +1942,8 @@ static inline bool is_longterm_pinnable_page(struct page *page)
        if (mt == MIGRATE_CMA || mt == MIGRATE_ISOLATE)
                return false;
 #endif
-       /* The zero page may always be pinned */
-       if (is_zero_pfn(page_to_pfn(page)))
+       /* The zero page can be "pinned" but gets special handling. */
+       if (is_zero_page(page))
                return true;
 
        /* Coherent device memory must always allow eviction. */