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-rw-r--r--Documentation/mm/vmemmap_dedup.rst22
1 files changed, 1 insertions, 21 deletions
diff --git a/Documentation/mm/vmemmap_dedup.rst b/Documentation/mm/vmemmap_dedup.rst
index 593ede6d314b..b4a55b6569fa 100644
--- a/Documentation/mm/vmemmap_dedup.rst
+++ b/Documentation/mm/vmemmap_dedup.rst
@@ -180,27 +180,7 @@ this correctly. There is only **one** head ``struct page``, the tail
``struct page`` with ``PG_head`` are fake head ``struct page``. We need an
approach to distinguish between those two different types of ``struct page`` so
that ``compound_head()`` can return the real head ``struct page`` when the
-parameter is the tail ``struct page`` but with ``PG_head``. The following code
-snippet describes how to distinguish between real and fake head ``struct page``.
-
-.. code-block:: c
-
- if (test_bit(PG_head, &page->flags)) {
- unsigned long head = READ_ONCE(page[1].compound_head);
-
- if (head & 1) {
- if (head == (unsigned long)page + 1)
- /* head struct page */
- else
- /* tail struct page */
- } else {
- /* head struct page */
- }
- }
-
-We can safely access the field of the **page[1]** with ``PG_head`` because the
-page is a compound page composed with at least two contiguous pages.
-The implementation refers to ``page_fixed_fake_head()``.
+parameter is the tail ``struct page`` but with ``PG_head``.
Device DAX
==========