mm/damon/sysfs: handle commit command using damon_call()

DAMON sysfs interface is using damon_callback->after_aggregation hook with
its self-implemented synchronization mechanism for the hook.  It is
inefficient, complicated, and take up to one aggregation interval to
complete, which can be long on some configs.

Use damon_call() instead.  It provides a synchronization mechanism that
built inside DAMON's core layer, so more efficient than DAMON sysfs
interface's own one.  Also it isolates the implementation inside the core
layer, and hence it makes the code easier to maintain.  Finally, it takes
up to one sampling interval, which is much shorter than the aggregation
interval in common setups.

Link: https://lkml.kernel.org/r/20250306175908.66300-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 87e4c6e3614e774734faf145c06b3766a60e3c33..c55a2cee4b749df4916eb40ee221ac4cf8f00beb 100644 (file)
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1451,8 +1451,9 @@ static struct damon_ctx *damon_sysfs_build_ctx(
  *
  * Returns error if the sysfs input is wrong.
  */
-static int damon_sysfs_commit_input(struct damon_sysfs_kdamond *kdamond)
+static int damon_sysfs_commit_input(void *data)
 {
+       struct damon_sysfs_kdamond *kdamond = data;
        struct damon_ctx *param_ctx, *test_ctx;
        int err;
 
@@ -1550,11 +1551,6 @@ static int damon_sysfs_cmd_request_callback(struct damon_ctx *c, bool active,
        if (!kdamond || kdamond->damon_ctx != c)
                goto out;
        switch (damon_sysfs_cmd_request.cmd) {
-       case DAMON_SYSFS_CMD_COMMIT:
-               if (!after_aggregation)
-                       goto out;
-               err = damon_sysfs_commit_input(kdamond);
-               break;
        default:
                break;
        }
@@ -1712,11 +1708,7 @@ static int damon_sysfs_update_schemes_tried_regions(
  * @cmd:       The command to handle.
  * @kdamond:   The kobject wrapper for the associated kdamond.
  *
- * This function handles a DAMON sysfs command for a kdamond.  For commands
- * that need to access running DAMON context-internal data, it requests
- * handling of the command to the DAMON callback
- * (@damon_sysfs_cmd_request_callback()) and wait until it is properly handled,
- * or the context is completed.
+ * This function handles a DAMON sysfs command for a kdamond.
  *
  * Return: 0 on success, negative error code otherwise.
  */
@@ -1730,6 +1722,9 @@ static int damon_sysfs_handle_cmd(enum damon_sysfs_cmd cmd,
                return damon_sysfs_turn_damon_on(kdamond);
        case DAMON_SYSFS_CMD_OFF:
                return damon_sysfs_turn_damon_off(kdamond);
+       case DAMON_SYSFS_CMD_COMMIT:
+               return damon_sysfs_damon_call(
+                               damon_sysfs_commit_input, kdamond);
        case DAMON_SYSFS_CMD_COMMIT_SCHEMES_QUOTA_GOALS:
                return damon_sysfs_damon_call(
                                damon_sysfs_commit_schemes_quota_goals,