[PATCH] proc: fix documentation and description of mmap

[PATCH] proc: fix documentation and description of mmap

[Yun Zhou]

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

Signed-off-by: Yun Zhou <yun.zhou@windriver.com>
---
 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..75511f78075f 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 (since 5.13) (see
+ * Bits 58-60 zero
  * Bit  61    page is file-page or shared-anon
  * Bit  62    page swapped
  * Bit  63    page present
-- 
2.27.0

Re: [PATCH] proc: fix documentation and description of mmap

[Peter Xu]

On Tue, Mar 01, 2022 at 11:21:15AM +0800, Yun Zhou wrote:
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 78125ef20255..75511f78075f 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 (since 5.13) (see
                                                ^^^^^^^^^^^^^^^^^ remove these?

Thanks,

-- 
Peter Xu

Re: [PATCH] proc: fix documentation and description of mmap

[Yun Zhou]

On 3/1/22 11:59 AM, Peter Xu wrote:
> [Please note: This e-mail is from an EXTERNAL e-mail address]
> 
> On Tue, Mar 01, 2022 at 11:21:15AM +0800, Yun Zhou wrote:
>> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
>> index 78125ef20255..75511f78075f 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 (since 5.13) (see
>                                                  ^^^^^^^^^^^^^^^^^ remove these?
Sorry for my mistake, I will follow your suggestion and send patch v2.

Thanks,
Yun