linux-kernel - [PATCH v1 22/39] mm/rmap: remove RMAP

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Date:   Mon, 11 Dec 2023 16:56:35 +0100
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-mm@...ck.org, David Hildenbrand <david@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Hugh Dickins <hughd@...gle.com>,
        Ryan Roberts <ryan.roberts@....com>,
        Yin Fengwei <fengwei.yin@...el.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Muchun Song <muchun.song@...ux.dev>,
        Peter Xu <peterx@...hat.com>
Subject: [PATCH v1 22/39] mm/rmap: remove RMAP_COMPOUND

No longer used, let's remove it and clarify RMAP_NONE/RMAP_EXCLUSIVE a
bit.

Signed-off-by: David Hildenbrand <david@...hat.com>
---
 include/linux/rmap.h | 12 +++---------
 mm/rmap.c            |  2 --
 2 files changed, 3 insertions(+), 11 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index bd4edae4dbe7..0acebe41ab8e 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -177,20 +177,14 @@ struct anon_vma *folio_get_anon_vma(struct folio *folio);
 typedef int __bitwise rmap_t;
 
 /*
- * No special request: if the page is a subpage of a compound page, it is
- * mapped via a PTE. The mapped (sub)page is possibly shared between processes.
+ * No special request: A mapped anonymous (sub)page is possibly shared between
+ * processes.
  */
 #define RMAP_NONE		((__force rmap_t)0)
 
-/* The (sub)page is exclusive to a single process. */
+/* The anonymous (sub)page is exclusive to a single process. */
 #define RMAP_EXCLUSIVE		((__force rmap_t)BIT(0))
 
-/*
- * The compound page is not mapped via PTEs, but instead via a single PMD and
- * should be accounted accordingly.
- */
-#define RMAP_COMPOUND		((__force rmap_t)BIT(1))
-
 /*
  * Internally, we're using an enum to specify the granularity. Usually,
  * we make the compiler create specialized variants for the different
diff --git a/mm/rmap.c b/mm/rmap.c
index 83cba8909848..9212726268ba 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -2663,8 +2663,6 @@ void rmap_walk_locked(struct folio *folio, struct rmap_walk_control *rwc)
  * The following two functions are for anonymous (private mapped) hugepages.
  * Unlike common anonymous pages, anonymous hugepages have no accounting code
  * and no lru code, because we handle hugepages differently from common pages.
- *
- * RMAP_COMPOUND is ignored.
  */
 void hugetlb_add_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
 		unsigned long address, rmap_t flags)
-- 
2.43.0