[PATCH 5.15 261/262] proc: fix documentation and description of pagemap

[Greg Kroah-Hartman]

From: Yun Zhou <yun.zhou@xxxxxxxxxxxxx>

commit dd21bfa425c098b95ca86845f8e7d1ec1ddf6e4a upstream.

Since bit 57 was exported for uffd-wp write-protected (commit
fb8e37f35a2f: "mm/pagemap: export uffd-wp protection information"),
fixing it can reduce some unnecessary confusion.

Link: https://lkml.kernel.org/r/20220301044538.3042713-1-yun.zhou@xxxxxxxxxxxxx
Fixes: fb8e37f35a2fe1 ("mm/pagemap: export uffd-wp protection information")
Signed-off-by: Yun Zhou <yun.zhou@xxxxxxxxxxxxx>
Reviewed-by: Peter Xu <peterx@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Tiberiu A Georgescu <tiberiu.georgescu@xxxxxxxxxxx>
Cc: Florian Schmidt <florian.schmidt@xxxxxxxxxxx>
Cc: Ivan Teterevkov <ivan.teterevkov@xxxxxxxxxxx>
Cc: SeongJae Park <sj@xxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Colin Cross <ccross@xxxxxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 Documentation/admin-guide/mm/pagemap.rst |    2 +-
 fs/proc/task_mmu.c                       |    3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

--- a/Documentation/admin-guide/mm/pagemap.rst
+++ b/Documentation/admin-guide/mm/pagemap.rst
@@ -23,7 +23,7 @@ There are four components to pagemap:
     * Bit  56    page exclusively mapped (since 4.2)
     * Bit  57    pte is uffd-wp write-protected (since 5.13) (see
       :ref:`Documentation/admin-guide/mm/userfaultfd.rst <userfaultfd>`)
-    * Bits 57-60 zero
+    * Bits 58-60 zero
     * Bit  61    page is file-page or shared-anon (since 3.5)
     * Bit  62    page swapped
     * Bit  63    page present
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1582,7 +1582,8 @@ static const struct mm_walk_ops pagemap_
  * Bits 5-54  swap offset if swapped
  * Bit  55    pte is soft-dirty (see Documentation/admin-guide/mm/soft-dirty.rst)
  * Bit  56    page exclusively mapped
- * Bits 57-60 zero
+ * Bit  57    pte is uffd-wp write-protected
+ * Bits 58-60 zero
  * Bit  61    page is file-page or shared-anon
  * Bit  62    page swapped
  * Bit  63    page present