[PATCH 0/3] mm/damon: non-hotfix reviewed patches in damon/next tree

[PATCH 0/3] mm/damon: non-hotfix reviewed patches in damon/next tree

[SeongJae Park]

Re-posting non-hotfix DAMON patches that reviewed by DAMON maintainer
but not yet merged into mm.git.  Those are not urgent, so it should be
ok to be merged after the next rc1.  This is just a headsup.  I will
post these again after next rc1, if these are not merged into mm.git by
then.

The first patch from Liew Rui Yan add a minor performance optimization
using ilog2() instead of inefficient manual implementation of the
functionality.

The second patch from Cheng-Han Wu fixes a minor typo:
s/parametrs/parameters/.

The third patch from Liew Rui Yan make commit_inputs operation of
DAMON_RECLAIM and DAMON_LRU_SORT synchronous to improve the user
experience.

Cheng-Han Wu (1):
  Docs/admin-guide/mm/damon: fix 'parametrs' typo

Liew Rui Yan (2):
  mm/damon/ops-common: optimize damon_hot_score() using ilog2()
  mm/damon: add synchronous commit for commit_inputs

 .../admin-guide/mm/damon/lru_sort.rst         |  2 +-
 .../admin-guide/mm/damon/reclaim.rst          |  2 +-
 mm/damon/lru_sort.c                           | 46 ++++++++++++++++---
 mm/damon/ops-common.c                         |  9 ++--
 mm/damon/reclaim.c                            | 46 ++++++++++++++++---
 5 files changed, 86 insertions(+), 19 deletions(-)


base-commit: 2c5f83f56c4a5ec75db054510007baaa1fbe4ad5
-- 
2.47.3

[PATCH 1/3] mm/damon/ops-common: optimize damon_hot_score() using ilog2()

[SeongJae Park]

From: Liew Rui Yan <aethernet65535@gmail.com>

The current implementation of damon_hot_score() uses a manual for-loop
to calculate the value of 'age_in_log'. This can be efficiently replaced
by ilog2(), which is semantically more appropriate for calculating the
logarithmic value of age.

In a simulated-kernel-module performance test with 10,000,000 iterations,
this optimization showed a significant reduction in latency (average
latency reduced from ~12ns to ~1ns).

Test results from the simulated-kernel-module:
- ilog2:
    DAMON Perf Test: Starting 10000000 iterations
    =============================================
     Total Iterations : 10000000
     Average Latency  : 1 ns
     P95 Latency      : 41 ns
     P99 Latency      : 41 ns
    ---------------------------------------------
     Range (ns)      | Count        | Percent
    ---------------------------------------------
     0-19            | 0            |      0%
     20-39           | 2625000      |     26%
     40-59           | 7374000      |     73%
     60-79           | 0            |      0%
     80-99           | 0            |      0%
     100+            | 1000         |      0%
    =============================================

- for-loop:
    DAMON Perf Test: Starting 10000000 iterations
    =============================================
     Total Iterations : 10000000
     Average Latency  : 12 ns
     P95 Latency      : 51 ns
     P99 Latency      : 60 ns
    ---------------------------------------------
     Range (ns)      | Count        | Percent
    ---------------------------------------------
     0-19            | 0            |      0%
     20-39           | 0            |      0%
     40-59           | 9862000      |     98%
     60-79           | 135000       |      1%
     80-99           | 1000         |      0%
     100+            | 2000         |      0%
    =============================================

Full raw benchmark results can be found at [1].

[1] https://github.com/aethernet65535/damon-hot-score-fls-optimize/tree/master/result-raw

Signed-off-by: Liew Rui Yan <aethernet65535@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
---
Changes from v2
(https://lore.kernel.org/20260320192020.33004-1-aethernet65535@gmail.com)
- Rebased to latest mm-new.
Changes from v1 (actually it was RFC)
(https://lore.kernel.org/20260320072431.248235-1-aethernet65535@gmail.com)
- Replace fls() with ilog2() per SeongJae Park's suggestion for better
  semantic clarity.
- Move performance benchmark results into the commit message and add
  comparison between for-loop and ilog2.

 mm/damon/ops-common.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c
index 8c6d613425c1..3a0ddc3ac719 100644
--- a/mm/damon/ops-common.c
+++ b/mm/damon/ops-common.c
@@ -117,9 +117,12 @@ int damon_hot_score(struct damon_ctx *c, struct damon_region *r,
 		damon_max_nr_accesses(&c->attrs);
 
 	age_in_sec = (unsigned long)r->age * c->attrs.aggr_interval / 1000000;
-	for (age_in_log = 0; age_in_log < DAMON_MAX_AGE_IN_LOG && age_in_sec;
-			age_in_log++, age_in_sec >>= 1)
-		;
+	if (age_in_sec)
+		age_in_log = min_t(int, ilog2(age_in_sec) + 1,
+				DAMON_MAX_AGE_IN_LOG);
+	else
+		age_in_log = 0;
+
 
 	/* If frequency is 0, higher age means it's colder */
 	if (freq_subscore == 0)
-- 
2.47.3

Re: (sashiko review) [PATCH 1/3] mm/damon/ops-common: optimize damon_hot_score() using ilog2()

[SeongJae Park]

TL; DR: sashiko didn't find a blocker for this patch.

Forwarding Sashiko review in a review format with my inline comment, for
sharing more details of my view and doing more discussions via mails if needed.

> # review url: https://sashiko.dev/#/patchset/20260402155733.77050-2-sj@kernel.org
> # start of sashiko.dev inline review
> commit 3d1d9600685998aeba66926091d5a11897567bd0
> Author: Liew Rui Yan <aethernet65535@gmail.com>
> 
> mm/damon/ops-common: optimize damon_hot_score() using ilog2()
> 
> This commit replaces a manual for-loop with an ilog2() based calculation
> to optimize the derivation of age_in_log in damon_hot_score(), improving
> latency during performance tests.
> 
> > diff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c
> > --- a/mm/damon/ops-common.c
> > +++ b/mm/damon/ops-common.c
> [ ... ]
> > @@ -117,9 +117,12 @@ int damon_hot_score(struct damon_ctx *c, struct damon_region *r,
> >  		damon_max_nr_accesses(&c->attrs);
> >  
> >  	age_in_sec = (unsigned long)r->age * c->attrs.aggr_interval / 1000000;
> > -	for (age_in_log = 0; age_in_log < DAMON_MAX_AGE_IN_LOG && age_in_sec;
> > -			age_in_log++, age_in_sec >>= 1)
> > -		;
> > +	if (age_in_sec)
> > +		age_in_log = min_t(int, ilog2(age_in_sec) + 1,
> > +				DAMON_MAX_AGE_IN_LOG);
> > +	else
> > +		age_in_log = 0;
> 
> This isn't a bug, but could this logic be simplified and the branch avoided
> by using fls() instead of ilog2()?
> 
> For non-constant variable arguments, ilog2(x) internally resolves to
> fls(x) - 1. By evaluating ilog2(age_in_sec) + 1, this code essentially
> calculates fls(age_in_sec) - 1 + 1.
> 
> Since fls() natively returns 0 when the input is 0, using fls(age_in_sec)
> directly would remove the need for the conditional branch entirely and
> reduce the block to a single expression.

We decided to use ilog2() since it makes the code easier to read in my taste.
So, this is not a blocker for this patch.

> 
> 
> # end of sashiko.dev inline review
> # review url: https://sashiko.dev/#/patchset/20260402155733.77050-2-sj@kernel.org


Thanks,
SJ

[...]

[PATCH 2/3] Docs/admin-guide/mm/damon: fix 'parametrs' typo

[SeongJae Park]

From: Cheng-Han Wu <hank20010209@gmail.com>

Fix the misspelling of "parametrs" as "parameters" in
reclaim.rst and lru_sort.rst.

Signed-off-by: Cheng-Han Wu <hank20010209@gmail.com>
Signed-off-by: SeongJae Park <sj@kernel.org>
---
Changes from v1
(https://lore.kernel.org/20260324144851.12883-1-hank20010209@gmail.com)
- Rebase to latest mm-new.

 Documentation/admin-guide/mm/damon/lru_sort.rst | 2 +-
 Documentation/admin-guide/mm/damon/reclaim.rst  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/mm/damon/lru_sort.rst b/Documentation/admin-guide/mm/damon/lru_sort.rst
index 14cc6b2db897..25e2f042a383 100644
--- a/Documentation/admin-guide/mm/damon/lru_sort.rst
+++ b/Documentation/admin-guide/mm/damon/lru_sort.rst
@@ -75,7 +75,7 @@ Make DAMON_LRU_SORT reads the input parameters again, except ``enabled``.
 
 Input parameters that updated while DAMON_LRU_SORT is running are not applied
 by default.  Once this parameter is set as ``Y``, DAMON_LRU_SORT reads values
-of parametrs except ``enabled`` again.  Once the re-reading is done, this
+of parameters except ``enabled`` again.  Once the re-reading is done, this
 parameter is set as ``N``.  If invalid parameters are found while the
 re-reading, DAMON_LRU_SORT will be disabled.
 
diff --git a/Documentation/admin-guide/mm/damon/reclaim.rst b/Documentation/admin-guide/mm/damon/reclaim.rst
index 2068f1346b9c..17e938c319e3 100644
--- a/Documentation/admin-guide/mm/damon/reclaim.rst
+++ b/Documentation/admin-guide/mm/damon/reclaim.rst
@@ -67,7 +67,7 @@ Make DAMON_RECLAIM reads the input parameters again, except ``enabled``.
 
 Input parameters that updated while DAMON_RECLAIM is running are not applied
 by default.  Once this parameter is set as ``Y``, DAMON_RECLAIM reads values
-of parametrs except ``enabled`` again.  Once the re-reading is done, this
+of parameters except ``enabled`` again.  Once the re-reading is done, this
 parameter is set as ``N``.  If invalid parameters are found while the
 re-reading, DAMON_RECLAIM will be disabled.
 
-- 
2.47.3

[PATCH 3/3] mm/damon: add synchronous commit for commit_inputs

[SeongJae Park]

From: Liew Rui Yan <aethernet65535@gmail.com>

Problem
=======
Writing invalid parameters to sysfs followed by 'commit_inputs=Y' fails
silently (no error returned to shell), because the validation happens
asynchronously in the kdamond.

Solution
========
To fix this, the commit_inputs_store() callback now uses damon_call() to
synchronously commit parameters in the kdamond thread's safe context.
This ensures that validation errors are returned immediately to
userspace, following the pattern used by DAMON_SYSFS.

Changes
=======
1. Added commit_inputs_store() and commit_inputs_fn() to commit
   synchronously.
2. Removed handle_commit_inputs().

This change is motivated from another discussion [1].

[1] https://lore.kernel.org/20260318153731.97470-1-aethernet65535@gmail.com

Signed-off-by: Liew Rui Yan <aethernet65535@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
---
Changes from v2
(https://lore.kernelorg/20260329075415.36775-1-aethernet65535@gmail.com)
- Rebase to latest mm-new.
Changes from v1:
- Restore the KERNEL_PARAM_OPS_FL_NOARG flag to keep the compatibility.
- Link to V1: https://lore.kernel.org/20260328084524.5451-1-aethernet65535@gmail.com
Changes from RFC-v6
- Removed unnecessary assignment (repeat) in commit_inputs_store().
- Change the return value; if an error occurs, return the error code.
- Removed the RFC tag.
- Link to RFC-v6: https://lore.kernel.org/20260327062558.66392-1-aethernet65535@gmail.com
Changes from RFC-v5:
- Removed unnecessary assignment (data) in commit_inputs_store().
- Return -EINVAL instead of -EBUSY when 'commit_inputs' is triggered
  while kdamond is not running.
- Link to RFC-v5: https://lore.kernel.org/20260325013939.18167-1-aethernet65535@gmail.com
Changes from RFC-v4:
- Rename the 'yes' variable in commit_inputs_store() to the more
  understandable 'commit_inputs_request'.
- Return -EBUSY instead of -EINVAL when 'commit_inputs' is triggered
  while kdamond is not running.
- Link to RFC-v4: https://lore.kernel.org/20260323021648.6590-1-aethernet65535@gmail.com
Changes from RFC-v3:
- Added checks for 'ctx' and 'damon_is_running()' to prevent NULL
  pointer dereference during early boot. (Found by Sashiko.dev)
- Removed handle_commit_inputs() and its associated polling logic as
  they have become dead code after moving to the synchronous damon_call()
  approach.
- Ensure the 'commit_inputs' is properly updated.
Link to RFC-v3: https://lore.kernel.org/20260322231522.32700-1-aethernet65535@gmail.com
Changes from RFC-v2:
- Removed damon_validate_attrs(), now using damon_commit_ctx() for
  synchronous validation in the kdamond context.
- Following DAMON_SYSFS pattern for synchronous commit via damon_call().
- Link to RFC-v2: https://lore.kernel.org/20260321140926.22163-1-aethernet65535@gmail.com
Changes from RFC-v1:
- Remove question from commit message area.
- Added synchronous validation for DAMON_RECLAIM.
- Rename damon_valid_attrs() -> damon_validate_attrs().
- Exported a new function damon_validate_attrs() and declared it in
  damon.h.
- Link to RFC-v1: https://lore.kernel.org/20260321002642.22712-1-aethernet65535@gmail.com

 mm/damon/lru_sort.c | 46 ++++++++++++++++++++++++++++++++++++++-------
 mm/damon/reclaim.c  | 46 ++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 78 insertions(+), 14 deletions(-)

diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c
index 554559d72976..641af42cc2d1 100644
--- a/mm/damon/lru_sort.c
+++ b/mm/damon/lru_sort.c
@@ -39,7 +39,6 @@ static bool enabled __read_mostly;
  * the re-reading, DAMON_LRU_SORT will be disabled.
  */
 static bool commit_inputs __read_mostly;
-module_param(commit_inputs, bool, 0600);
 
 /*
  * Desired active to [in]active memory ratio in bp (1/10,000).
@@ -349,18 +348,51 @@ static int damon_lru_sort_apply_parameters(void)
 	return err;
 }
 
-static int damon_lru_sort_handle_commit_inputs(void)
+static int damon_lru_sort_commit_inputs_fn(void *arg)
 {
+	return damon_lru_sort_apply_parameters();
+}
+
+static int damon_lru_sort_commit_inputs_store(const char *val,
+					      const struct kernel_param *kp)
+{
+	bool commit_inputs_request;
 	int err;
+	struct damon_call_control control = {
+		.fn = damon_lru_sort_commit_inputs_fn,
+	};
+
+	if (!val) {
+		commit_inputs_request = true;
+	} else {
+		err = kstrtobool(val, &commit_inputs_request);
+		if (err)
+			return err;
+	}
 
-	if (!commit_inputs)
+	if (!commit_inputs_request)
 		return 0;
 
-	err = damon_lru_sort_apply_parameters();
-	commit_inputs = false;
-	return err;
+	/*
+	 * Skip damon_call() if ctx is not initialized to avoid
+	 * NULL pointer dereference.
+	 */
+	if (!ctx)
+		return -EINVAL;
+
+	err = damon_call(ctx, &control);
+
+	return err ? err : control.return_code;
 }
 
+static const struct kernel_param_ops commit_inputs_param_ops = {
+	.flags = KERNEL_PARAM_OPS_FL_NOARG,
+	.set = damon_lru_sort_commit_inputs_store,
+	.get = param_get_bool,
+};
+
+module_param_cb(commit_inputs, &commit_inputs_param_ops, &commit_inputs, 0600);
+
 static int damon_lru_sort_damon_call_fn(void *arg)
 {
 	struct damon_ctx *c = arg;
@@ -374,7 +406,7 @@ static int damon_lru_sort_damon_call_fn(void *arg)
 			damon_lru_sort_cold_stat = s->stat;
 	}
 
-	return damon_lru_sort_handle_commit_inputs();
+	return 0;
 }
 
 static struct damon_call_control call_control = {
diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
index 86da14778658..4fc4a54b5e54 100644
--- a/mm/damon/reclaim.c
+++ b/mm/damon/reclaim.c
@@ -39,7 +39,6 @@ static bool enabled __read_mostly;
  * re-reading, DAMON_RECLAIM will be disabled.
  */
 static bool commit_inputs __read_mostly;
-module_param(commit_inputs, bool, 0600);
 
 /*
  * Time threshold for cold memory regions identification in microseconds.
@@ -255,18 +254,51 @@ static int damon_reclaim_apply_parameters(void)
 	return err;
 }
 
-static int damon_reclaim_handle_commit_inputs(void)
+static int damon_reclaim_commit_inputs_fn(void *arg)
 {
+	return damon_reclaim_apply_parameters();
+}
+
+static int damon_reclaim_commit_inputs_store(const char *val,
+					     const struct kernel_param *kp)
+{
+	bool commit_inputs_request;
 	int err;
+	struct damon_call_control control = {
+		.fn = damon_reclaim_commit_inputs_fn,
+	};
 
-	if (!commit_inputs)
+	if (!val) {
+		commit_inputs_request = true;
+	} else {
+		err = kstrtobool(val, &commit_inputs_request);
+		if (err)
+			return err;
+	}
+
+	if (!commit_inputs_request)
 		return 0;
 
-	err = damon_reclaim_apply_parameters();
-	commit_inputs = false;
-	return err;
+	/*
+	 * Skip damon_call() if ctx is not initialized to avoid
+	 * NULL pointer dereference.
+	 */
+	if (!ctx)
+		return -EINVAL;
+
+	err = damon_call(ctx, &control);
+
+	return err ? err : control.return_code;
 }
 
+static const struct kernel_param_ops commit_inputs_param_ops = {
+	.flags = KERNEL_PARAM_OPS_FL_NOARG,
+	.set = damon_reclaim_commit_inputs_store,
+	.get = param_get_bool,
+};
+
+module_param_cb(commit_inputs, &commit_inputs_param_ops, &commit_inputs, 0600);
+
 static int damon_reclaim_damon_call_fn(void *arg)
 {
 	struct damon_ctx *c = arg;
@@ -276,7 +308,7 @@ static int damon_reclaim_damon_call_fn(void *arg)
 	damon_for_each_scheme(s, c)
 		damon_reclaim_stat = s->stat;
 
-	return damon_reclaim_handle_commit_inputs();
+	return 0;
 }
 
 static struct damon_call_control call_control = {
-- 
2.47.3

Re: [PATCH 3/3] mm/damon: add synchronous commit for commit_inputs

[SeongJae Park]

On Thu,  2 Apr 2026 08:57:30 -0700 SeongJae Park <sj@kernel.org> wrote:

> From: Liew Rui Yan <aethernet65535@gmail.com>
> 
> Problem
> =======
> Writing invalid parameters to sysfs followed by 'commit_inputs=Y' fails
> silently (no error returned to shell), because the validation happens
> asynchronously in the kdamond.
> 
> Solution
> ========
> To fix this, the commit_inputs_store() callback now uses damon_call() to
> synchronously commit parameters in the kdamond thread's safe context.
> This ensures that validation errors are returned immediately to
> userspace, following the pattern used by DAMON_SYSFS.
> 
> Changes
> =======
> 1. Added commit_inputs_store() and commit_inputs_fn() to commit
>    synchronously.
> 2. Removed handle_commit_inputs().
> 
> This change is motivated from another discussion [1].
> 
> [1] https://lore.kernel.org/20260318153731.97470-1-aethernet65535@gmail.com
> 
> Signed-off-by: Liew Rui Yan <aethernet65535@gmail.com>
> Reviewed-by: SeongJae Park <sj@kernel.org>
> Signed-off-by: SeongJae Park <sj@kernel.org>
> ---
> Changes from v2
> (https://lore.kernelorg/20260329075415.36775-1-aethernet65535@gmail.com)
> - Rebase to latest mm-new.
> Changes from v1:
> - Restore the KERNEL_PARAM_OPS_FL_NOARG flag to keep the compatibility.
> - Link to V1: https://lore.kernel.org/20260328084524.5451-1-aethernet65535@gmail.com
> Changes from RFC-v6
> - Removed unnecessary assignment (repeat) in commit_inputs_store().
> - Change the return value; if an error occurs, return the error code.
> - Removed the RFC tag.
> - Link to RFC-v6: https://lore.kernel.org/20260327062558.66392-1-aethernet65535@gmail.com
> Changes from RFC-v5:
> - Removed unnecessary assignment (data) in commit_inputs_store().
> - Return -EINVAL instead of -EBUSY when 'commit_inputs' is triggered
>   while kdamond is not running.
> - Link to RFC-v5: https://lore.kernel.org/20260325013939.18167-1-aethernet65535@gmail.com
> Changes from RFC-v4:
> - Rename the 'yes' variable in commit_inputs_store() to the more
>   understandable 'commit_inputs_request'.
> - Return -EBUSY instead of -EINVAL when 'commit_inputs' is triggered
>   while kdamond is not running.
> - Link to RFC-v4: https://lore.kernel.org/20260323021648.6590-1-aethernet65535@gmail.com
> Changes from RFC-v3:
> - Added checks for 'ctx' and 'damon_is_running()' to prevent NULL
>   pointer dereference during early boot. (Found by Sashiko.dev)
> - Removed handle_commit_inputs() and its associated polling logic as
>   they have become dead code after moving to the synchronous damon_call()
>   approach.
> - Ensure the 'commit_inputs' is properly updated.
> Link to RFC-v3: https://lore.kernel.org/20260322231522.32700-1-aethernet65535@gmail.com
> Changes from RFC-v2:
> - Removed damon_validate_attrs(), now using damon_commit_ctx() for
>   synchronous validation in the kdamond context.
> - Following DAMON_SYSFS pattern for synchronous commit via damon_call().
> - Link to RFC-v2: https://lore.kernel.org/20260321140926.22163-1-aethernet65535@gmail.com
> Changes from RFC-v1:
> - Remove question from commit message area.
> - Added synchronous validation for DAMON_RECLAIM.
> - Rename damon_valid_attrs() -> damon_validate_attrs().
> - Exported a new function damon_validate_attrs() and declared it in
>   damon.h.
> - Link to RFC-v1: https://lore.kernel.org/20260321002642.22712-1-aethernet65535@gmail.com
> 
>  mm/damon/lru_sort.c | 46 ++++++++++++++++++++++++++++++++++++++-------
>  mm/damon/reclaim.c  | 46 ++++++++++++++++++++++++++++++++++++++-------
>  2 files changed, 78 insertions(+), 14 deletions(-)
> 
> diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c
> index 554559d72976..641af42cc2d1 100644
> --- a/mm/damon/lru_sort.c
> +++ b/mm/damon/lru_sort.c
> @@ -39,7 +39,6 @@ static bool enabled __read_mostly;
>   * the re-reading, DAMON_LRU_SORT will be disabled.
>   */
>  static bool commit_inputs __read_mostly;
> -module_param(commit_inputs, bool, 0600);
>  
>  /*
>   * Desired active to [in]active memory ratio in bp (1/10,000).
> @@ -349,18 +348,51 @@ static int damon_lru_sort_apply_parameters(void)
>  	return err;
>  }
>  
> -static int damon_lru_sort_handle_commit_inputs(void)
> +static int damon_lru_sort_commit_inputs_fn(void *arg)
>  {
> +	return damon_lru_sort_apply_parameters();
> +}
> +
> +static int damon_lru_sort_commit_inputs_store(const char *val,
> +					      const struct kernel_param *kp)
> +{
> +	bool commit_inputs_request;
>  	int err;
> +	struct damon_call_control control = {
> +		.fn = damon_lru_sort_commit_inputs_fn,
> +	};
> +
> +	if (!val) {
> +		commit_inputs_request = true;
> +	} else {
> +		err = kstrtobool(val, &commit_inputs_request);
> +		if (err)
> +			return err;
> +	}
>  
> -	if (!commit_inputs)
> +	if (!commit_inputs_request)
>  		return 0;
>  
> -	err = damon_lru_sort_apply_parameters();
> -	commit_inputs = false;
> -	return err;
> +	/*
> +	 * Skip damon_call() if ctx is not initialized to avoid
> +	 * NULL pointer dereference.
> +	 */
> +	if (!ctx)
> +		return -EINVAL;
> +
> +	err = damon_call(ctx, &control);
> +
> +	return err ? err : control.return_code;
>  }
>  
> +static const struct kernel_param_ops commit_inputs_param_ops = {
> +	.flags = KERNEL_PARAM_OPS_FL_NOARG,
> +	.set = damon_lru_sort_commit_inputs_store,
> +	.get = param_get_bool,
> +};
> +
> +module_param_cb(commit_inputs, &commit_inputs_param_ops, &commit_inputs, 0600);
> +
>  static int damon_lru_sort_damon_call_fn(void *arg)
>  {
>  	struct damon_ctx *c = arg;
> @@ -374,7 +406,7 @@ static int damon_lru_sort_damon_call_fn(void *arg)
>  			damon_lru_sort_cold_stat = s->stat;
>  	}
>  
> -	return damon_lru_sort_handle_commit_inputs();
> +	return 0;
>  }
>  
>  static struct damon_call_control call_control = {
> diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
> index 86da14778658..4fc4a54b5e54 100644
> --- a/mm/damon/reclaim.c
> +++ b/mm/damon/reclaim.c
> @@ -39,7 +39,6 @@ static bool enabled __read_mostly;
>   * re-reading, DAMON_RECLAIM will be disabled.
>   */
>  static bool commit_inputs __read_mostly;
> -module_param(commit_inputs, bool, 0600);
>  
>  /*
>   * Time threshold for cold memory regions identification in microseconds.
> @@ -255,18 +254,51 @@ static int damon_reclaim_apply_parameters(void)
>  	return err;
>  }
>  
> -static int damon_reclaim_handle_commit_inputs(void)
> +static int damon_reclaim_commit_inputs_fn(void *arg)
>  {
> +	return damon_reclaim_apply_parameters();
> +}
> +
> +static int damon_reclaim_commit_inputs_store(const char *val,
> +					     const struct kernel_param *kp)
> +{
> +	bool commit_inputs_request;
>  	int err;
> +	struct damon_call_control control = {
> +		.fn = damon_reclaim_commit_inputs_fn,
> +	};
>  
> -	if (!commit_inputs)
> +	if (!val) {
> +		commit_inputs_request = true;
> +	} else {
> +		err = kstrtobool(val, &commit_inputs_request);
> +		if (err)
> +			return err;
> +	}
> +
> +	if (!commit_inputs_request)
>  		return 0;
>  
> -	err = damon_reclaim_apply_parameters();
> -	commit_inputs = false;
> -	return err;
> +	/*
> +	 * Skip damon_call() if ctx is not initialized to avoid
> +	 * NULL pointer dereference.
> +	 */
> +	if (!ctx)
> +		return -EINVAL;
> +
> +	err = damon_call(ctx, &control);
> +
> +	return err ? err : control.return_code;
>  }
>  
> +static const struct kernel_param_ops commit_inputs_param_ops = {
> +	.flags = KERNEL_PARAM_OPS_FL_NOARG,
> +	.set = damon_reclaim_commit_inputs_store,
> +	.get = param_get_bool,
> +};
> +
> +module_param_cb(commit_inputs, &commit_inputs_param_ops, &commit_inputs, 0600);
> +
>  static int damon_reclaim_damon_call_fn(void *arg)
>  {
>  	struct damon_ctx *c = arg;
> @@ -276,7 +308,7 @@ static int damon_reclaim_damon_call_fn(void *arg)
>  	damon_for_each_scheme(s, c)
>  		damon_reclaim_stat = s->stat;
>  
> -	return damon_reclaim_handle_commit_inputs();
> +	return 0;
>  }
>  
>  static struct damon_call_control call_control = {
> -- 
> 2.47.3

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Re: (sashiko status) [PATCH 0/3] mm/damon: non-hotfix reviewed patches in damon/next tree

[SeongJae Park]

Dropping recipients who are not 100% surely interested in the sashiko review.

TL; DR: no blocker for this series is found.

Forwarding sashiko.dev review status for this series in a reply format with my
inline comments for details of why I say the TL; DR.

> # review url: https://sashiko.dev/#/patchset/20260402155733.77050-1-sj@kernel.org
> 
> - [PATCH 1/3] mm/damon/ops-common: optimize damon_hot_score() using ilog2()
>   - status: Reviewed
>   - review: ISSUES MAY FOUND

No real issues here.  Read my reply to the patch for more details.

> - [PATCH 2/3] Docs/admin-guide/mm/damon: fix 'parametrs' typo
>   - status: Reviewed
>   - review: No issues found.

As the 'review' is saying.

> - [PATCH 3/3] mm/damon: add synchronous commit for commit_inputs
>   - status: Reviewed
>   - review: ISSUES MAY FOUND

No real issues here.  Read my reply to the patch for more details.


Thanks,
SJ