2022-03-01 05:06:54

by Yun Zhou

[permalink] [raw]
Subject: [v2][PATCH] proc: fix documentation and description of pagemap

Since bit 57 was exported for uffd-wp write-protected(commit fb8e37f35a2f),
fixing it can reduce some unnecessary confusion.

Signed-off-by: Yun Zhou <[email protected]>
---
Documentation/admin-guide/mm/pagemap.rst | 2 +-
fs/proc/task_mmu.c | 3 ++-
2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst
index bfc28704856c..6e2e416af783 100644
--- 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
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 78125ef20255..2f110089d50e 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1596,7 +1596,8 @@ static const struct mm_walk_ops pagemap_ops = {
* 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
--
2.27.0


2022-03-01 08:06:09

by Peter Xu

[permalink] [raw]
Subject: Re: [v2][PATCH] proc: fix documentation and description of pagemap

On Tue, Mar 01, 2022 at 12:45:38PM +0800, Yun Zhou wrote:
> Since bit 57 was exported for uffd-wp write-protected(commit fb8e37f35a2f),
> fixing it can reduce some unnecessary confusion.
>
> Signed-off-by: Yun Zhou <[email protected]>

Reviewed-by: Peter Xu <[email protected]>

Thanks,

--
Peter Xu