Re: [PATCH] Docs/mm/damon: document exclusivity of special-purpose modules

[SeongJae Park <sj@kernel.org>]

Hello Liew,

On Sat, 14 Mar 2026 17:20:22 +0800 Liew Rui Yan <aethernet65535@gmail.com> wrote:

> Add a section in design.rst to explain that DAMON special-purpose kernel
> modules (LRU_SORT, RECLAIM, STAT) run in an exclusive manner and return
> -EBUSY if another is already running.
> 
> Update lru_sort.rst, reclaim.rst and stat.rst by adding cross-references
> to this exclusivity rule at the end of their respective Example
> sections.

Thank you for doing this!

> 
> While at it, fix a Sphinx syntax error in the "contents" directive in
> design.rst (missing space after :depth:) that prevents the table of
> contents from being rendered on docs.kernel.org.

And thank you for fixing this!  But, the broken "contents" directive is added
by a commit on damon/next tree [1] that not yet planned to be upstreamed.  That
is, seems this patch is based on damon/next tree.  As a result, this patch
cannot be cleanly applied on mm-new.  We prefer making patches based on mm-new
unless there is a reason.

> 
> Signed-off-by: Liew Rui Yan <aethernet65535@gmail.com>
> Link: https://lore.kernel.org/damon/20260314002119.79742-1-sj@kernel.org/T/#t

I think it would be nice to give a context about the link.

Other than that,

Reviewed-by: SeongJae Park <sj@kernel.org>

Assuming you agree to my above suggestions, I added this patch to the top area
of damon/next after dropping the "contents" directive fix and adding a simple
sentence describing the context of the link.  The change made to this patch for
that is as below.  If you don't mind, I will post it as v2 of this patch by
tomorrow morning in Pacific Time.  Please let me know if you have any comments
about the plan.

'''
diff --git a/Docs-mm-damon-document-exclusivity-of-special-purpos.patch b/Docs-mm-damon-document-exclusivity-of-special-purpos.patch
index 9e74de3b..db466405 100644
--- a/Docs-mm-damon-document-exclusivity-of-special-purpos.patch
+++ b/Docs-mm-damon-document-exclusivity-of-special-purpos.patch
@@ -11,26 +11,31 @@ Update lru_sort.rst, reclaim.rst and stat.rst by adding cross-references
 to this exclusivity rule at the end of their respective Example
 sections.
 
-While at it, fix a Sphinx syntax error in the "contents" directive in
-design.rst (missing space after :depth:) that prevents the table of
-contents from being rendered on docs.kernel.org.
+This change is motivated from another discussion [1].
+
+[1] https://lore.kernel.org/damon/20260314002119.79742-1-sj@kernel.org/T/#t
+
+TODO: move below changelog to the comment section when posting
+Change from v1
+(https://lore.kernel.org/20260314092145.7496-1-aethernet65535@gmail.com)
+- Drop contents directive fix
+- Reword description
 
-Link: https://patch.msgid.link/20260314092145.7496-1-aethernet65535@gmail.com
 Signed-off-by: Liew Rui Yan <aethernet65535@gmail.com>
-Link: https://lore.kernel.org/damon/20260314002119.79742-1-sj@kernel.org/T/#t
+Reviewed-by: SeongJae Park <sj@kernel.org>
 Signed-off-by: SeongJae Park <sj@kernel.org>
 ---
  Documentation/admin-guide/mm/damon/lru_sort.rst | 5 +++++
  Documentation/admin-guide/mm/damon/reclaim.rst  | 5 +++++
  Documentation/admin-guide/mm/damon/stat.rst     | 5 +++++
- Documentation/mm/damon/design.rst               | 6 +++++-
- 4 files changed, 20 insertions(+), 1 deletion(-)
+ Documentation/mm/damon/design.rst               | 4 ++++
+ 4 files changed, 19 insertions(+)
 
 diff --git a/Documentation/admin-guide/mm/damon/lru_sort.rst b/Documentation/admin-guide/mm/damon/lru_sort.rst
-index 06a46812a728c..0198dfe87f4d5 100644
+index 73980bacc3a02..56690646cf398 100644
 --- a/Documentation/admin-guide/mm/damon/lru_sort.rst
 +++ b/Documentation/admin-guide/mm/damon/lru_sort.rst
-@@ -353,3 +353,8 @@ the LRU-list based page granularity reclamation. ::
+@@ -351,3 +351,8 @@ the LRU-list based page granularity reclamation. ::
      # echo 400 > wmarks_mid
      # echo 200 > wmarks_low
      # echo Y > enabled
@@ -40,10 +45,10 @@ index 06a46812a728c..0198dfe87f4d5 100644
 +purpose modules exclusivity <damon_design_special_purpose_modules_exclusivity>`
 +for more details.
 diff --git a/Documentation/admin-guide/mm/damon/reclaim.rst b/Documentation/admin-guide/mm/damon/reclaim.rst
-index c5b4d8a1b0014..a37ce6fdff050 100644
+index 552a7786b0829..6f580f637134a 100644
 --- a/Documentation/admin-guide/mm/damon/reclaim.rst
 +++ b/Documentation/admin-guide/mm/damon/reclaim.rst
-@@ -331,6 +331,11 @@ granularity reclamation. ::
+@@ -318,6 +318,11 @@ granularity reclamation. ::
      # echo 200 > wmarks_low
      # echo Y > enabled
  
@@ -56,7 +61,7 @@ index c5b4d8a1b0014..a37ce6fdff050 100644
  .. [2] https://lwn.net/Articles/787611/
  .. [3] Documentation/mm/free_page_reporting.rst
 diff --git a/Documentation/admin-guide/mm/damon/stat.rst b/Documentation/admin-guide/mm/damon/stat.rst
-index 468c122c42594..46c5dd96aa2ed 100644
+index e5a5a2c4f803a..c4b14daeb2dd6 100644
 --- a/Documentation/admin-guide/mm/damon/stat.rst
 +++ b/Documentation/admin-guide/mm/damon/stat.rst
 @@ -45,6 +45,11 @@ You can enable DAMON_STAT by setting the value of this parameter as ``Y``.
@@ -72,19 +77,10 @@ index 468c122c42594..46c5dd96aa2ed 100644
  
  aggr_interval_us
 diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
-index 0a3b77ec458fe..3694c541e65aa 100644
+index 29fff20b3c2a9..dc37402c0fee9 100644
 --- a/Documentation/mm/damon/design.rst
 +++ b/Documentation/mm/damon/design.rst
-@@ -5,7 +5,7 @@ Design
- ======
- 
- .. contents:: :local:
--   :depth:2
-+   :depth: 2
- 
- .. _damon_design_execution_model_and_data_structures:
- 
-@@ -960,6 +960,10 @@ more detail, please read the usage documents for those
+@@ -853,6 +853,10 @@ more detail, please read the usage documents for those
  (:doc:`/admin-guide/mm/damon/stat`, :doc:`/admin-guide/mm/damon/reclaim` and
  :doc:`/admin-guide/mm/damon/lru_sort`).
'''  

[1] https://origin.kernel.org/doc/html/latest/mm/damon/maintainer-profile.html#scm-trees


Thanks,
SJ

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