mm/damon/sysfs: remove unused code for schemes tried regions update

DAMON sysfs interface was using damon_callback with its own complicated
synchronization logics to update DAMOS scheme applied regions directories
and files.  But it is replaced to use damos_walk(), and the additional
synchronization logics are no more being used.  Remove those.

Link: https://lkml.kernel.org/r/20250103174400.54890-11-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/sysfs-common.h b/mm/damon/sysfs-common.h
index 81f1c845118f0595413641171c845348d41d5b5f..b3f63bc658b7bf9a1dae1d5c0b9aaeb8e1f213e8 100644 (file)
--- a/mm/damon/sysfs-common.h
+++ b/mm/damon/sysfs-common.h
@@ -45,16 +45,6 @@ void damon_sysfs_schemes_update_stats(
                struct damon_sysfs_schemes *sysfs_schemes,
                struct damon_ctx *ctx);
 
-int damon_sysfs_schemes_update_regions_start(
-               struct damon_sysfs_schemes *sysfs_schemes,
-               struct damon_ctx *ctx, bool total_bytes_only);
-
-void damos_sysfs_mark_finished_regions_updates(struct damon_ctx *ctx);
-
-bool damos_sysfs_regions_upd_done(void);
-
-int damon_sysfs_schemes_update_regions_stop(struct damon_ctx *ctx);
-
 void damos_sysfs_populate_region_dir(struct damon_sysfs_schemes *sysfs_schemes,
                struct damon_ctx *ctx, struct damon_target *t,
                struct damon_region *r, struct damos *s,

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 1d8ad637051aa594646124f13a5404480cdc439f..5c4490b97258e46adf9fef9e9297db55630cc344 100644 (file)
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -114,55 +114,11 @@ static const struct kobj_type damon_sysfs_scheme_region_ktype = {
  * scheme regions directory
  */
 
-/*
- * enum damos_sysfs_regions_upd_status - Represent DAMOS tried regions update
- *                                      status
- * @DAMOS_TRIED_REGIONS_UPD_IDLE:              Waiting for next request.
- * @DAMOS_TRIED_REGIONS_UPD_STARTED:           Update started.
- * @DAMOS_TRIED_REGIONS_UPD_FINISHED:  Update finished.
- *
- * Each DAMON-based operation scheme (&struct damos) has its own apply
- * interval, and we need to expose the scheme tried regions based on only
- * single snapshot.  For this, we keep the tried regions update status for each
- * scheme.  The status becomes 'idle' at the beginning.
- *
- * Once the tried regions update request is received, the request handling
- * start function (damon_sysfs_scheme_update_regions_start()) sets the status
- * of all schemes as 'idle' again, and register ->before_damos_apply()
- * callback.
- *
- * Then, the first followup ->before_damos_apply() callback
- * (damon_sysfs_before_damos_apply()) sets the status 'started'.  The first
- * ->after_sampling() or ->after_aggregation() callback
- *  (damon_sysfs_cmd_request_callback()) after the call is called only after
- *  the scheme is completely applied to the given snapshot.  Hence the callback
- *  knows the situation by showing 'started' status, and sets the status as
- *  'finished'.  Then, damon_sysfs_before_damos_apply() understands the
- *  situation by showing the 'finished' status and do nothing.
- *
- * If DAMOS is not applied to any region due to any reasons including the
- * access pattern, the watermarks, the quotas, and the filters,
- * ->before_damos_apply() will not be called back.  Until the situation is
- * changed, the update will not be finished.  To avoid this,
- * damon_sysfs_after_sampling() set the status as 'finished' if more than two
- * apply intervals of the scheme is passed while the state is 'idle'.
- *
- *  Finally, the tried regions request handling finisher function
- *  (damon_sysfs_schemes_update_regions_stop()) unregisters the callbacks.
- */
-enum damos_sysfs_regions_upd_status {
-       DAMOS_TRIED_REGIONS_UPD_IDLE,
-       DAMOS_TRIED_REGIONS_UPD_STARTED,
-       DAMOS_TRIED_REGIONS_UPD_FINISHED,
-};
-
 struct damon_sysfs_scheme_regions {
        struct kobject kobj;
        struct list_head regions_list;
        int nr_regions;
        unsigned long total_bytes;
-       enum damos_sysfs_regions_upd_status upd_status;
-       unsigned long upd_timeout_jiffies;
 };
 
 static struct damon_sysfs_scheme_regions *
@@ -178,7 +134,6 @@ damon_sysfs_scheme_regions_alloc(void)
        INIT_LIST_HEAD(&regions->regions_list);
        regions->nr_regions = 0;
        regions->total_bytes = 0;
-       regions->upd_status = DAMOS_TRIED_REGIONS_UPD_IDLE;
        return regions;
 }
 
@@ -2126,63 +2081,6 @@ void damon_sysfs_schemes_update_stats(
        }
 }
 
-/*
- * damon_sysfs_schemes that need to update its schemes regions dir.  Protected
- * by damon_sysfs_lock
- */
-static struct damon_sysfs_schemes *damon_sysfs_schemes_for_damos_callback;
-static int damon_sysfs_schemes_region_idx;
-static bool damos_regions_upd_total_bytes_only;
-
-/*
- * DAMON callback that called before damos apply.  While this callback is
- * registered, damon_sysfs_lock should be held to ensure the regions
- * directories exist.
- */
-static int damon_sysfs_before_damos_apply(struct damon_ctx *ctx,
-               struct damon_target *t, struct damon_region *r,
-               struct damos *s)
-{
-       struct damos *scheme;
-       struct damon_sysfs_scheme_regions *sysfs_regions;
-       struct damon_sysfs_scheme_region *region;
-       struct damon_sysfs_schemes *sysfs_schemes =
-               damon_sysfs_schemes_for_damos_callback;
-       int schemes_idx = 0;
-
-       damon_for_each_scheme(scheme, ctx) {
-               if (scheme == s)
-                       break;
-               schemes_idx++;
-       }
-
-       /* user could have removed the scheme sysfs dir */
-       if (schemes_idx >= sysfs_schemes->nr)
-               return 0;
-
-       sysfs_regions = sysfs_schemes->schemes_arr[schemes_idx]->tried_regions;
-       if (sysfs_regions->upd_status == DAMOS_TRIED_REGIONS_UPD_FINISHED)
-               return 0;
-       if (sysfs_regions->upd_status == DAMOS_TRIED_REGIONS_UPD_IDLE)
-               sysfs_regions->upd_status = DAMOS_TRIED_REGIONS_UPD_STARTED;
-       sysfs_regions->total_bytes += r->ar.end - r->ar.start;
-       if (damos_regions_upd_total_bytes_only)
-               return 0;
-
-       region = damon_sysfs_scheme_region_alloc(r);
-       if (!region)
-               return 0;
-       list_add_tail(&region->list, &sysfs_regions->regions_list);
-       sysfs_regions->nr_regions++;
-       if (kobject_init_and_add(&region->kobj,
-                               &damon_sysfs_scheme_region_ktype,
-                               &sysfs_regions->kobj, "%d",
-                               damon_sysfs_schemes_region_idx++)) {
-               kobject_put(&region->kobj);
-       }
-       return 0;
-}
-
 /**
  * damos_sysfs_populate_region_dir() - Populate a schemes tried region dir.
  * @sysfs_schemes:     Schemes directory to populate regions directory.
@@ -2231,29 +2129,6 @@ void damos_sysfs_populate_region_dir(struct damon_sysfs_schemes *sysfs_schemes,
        }
 }
 
-/*
- * DAMON callback that called after each accesses sampling.  While this
- * callback is registered, damon_sysfs_lock should be held to ensure the
- * regions directories exist.
- */
-void damos_sysfs_mark_finished_regions_updates(struct damon_ctx *ctx)
-{
-       struct damon_sysfs_schemes *sysfs_schemes =
-               damon_sysfs_schemes_for_damos_callback;
-       struct damon_sysfs_scheme_regions *sysfs_regions;
-       int i;
-
-       for (i = 0; i < sysfs_schemes->nr; i++) {
-               sysfs_regions = sysfs_schemes->schemes_arr[i]->tried_regions;
-               if (sysfs_regions->upd_status ==
-                               DAMOS_TRIED_REGIONS_UPD_STARTED ||
-                               time_after(jiffies,
-                                       sysfs_regions->upd_timeout_jiffies))
-                       sysfs_regions->upd_status =
-                               DAMOS_TRIED_REGIONS_UPD_FINISHED;
-       }
-}
-
 /* Called from damon_sysfs_cmd_request_callback under damon_sysfs_lock */
 int damon_sysfs_schemes_clear_regions(
                struct damon_sysfs_schemes *sysfs_schemes)
@@ -2270,82 +2145,3 @@ int damon_sysfs_schemes_clear_regions(
        }
        return 0;
 }
-
-static struct damos *damos_sysfs_nth_scheme(int n, struct damon_ctx *ctx)
-{
-       struct damos *scheme;
-       int i = 0;
-
-       damon_for_each_scheme(scheme, ctx) {
-               if (i == n)
-                       return scheme;
-               i++;
-       }
-       return NULL;
-}
-
-static void damos_tried_regions_init_upd_status(
-               struct damon_sysfs_schemes *sysfs_schemes,
-               struct damon_ctx *ctx)
-{
-       int i;
-       struct damos *scheme;
-       struct damon_sysfs_scheme_regions *sysfs_regions;
-
-       for (i = 0; i < sysfs_schemes->nr; i++) {
-               sysfs_regions = sysfs_schemes->schemes_arr[i]->tried_regions;
-               scheme = damos_sysfs_nth_scheme(i, ctx);
-               if (!scheme) {
-                       sysfs_regions->upd_status =
-                               DAMOS_TRIED_REGIONS_UPD_FINISHED;
-                       continue;
-               }
-               sysfs_regions->upd_status = DAMOS_TRIED_REGIONS_UPD_IDLE;
-               sysfs_regions->upd_timeout_jiffies = jiffies +
-                       2 * usecs_to_jiffies(scheme->apply_interval_us ?
-                                       scheme->apply_interval_us :
-                                       ctx->attrs.aggr_interval);
-       }
-}
-
-/* Called while damon_sysfs_lock is hold */
-int damon_sysfs_schemes_update_regions_start(
-               struct damon_sysfs_schemes *sysfs_schemes,
-               struct damon_ctx *ctx, bool total_bytes_only)
-{
-       damon_sysfs_schemes_clear_regions(sysfs_schemes);
-       damon_sysfs_schemes_for_damos_callback = sysfs_schemes;
-       damos_tried_regions_init_upd_status(sysfs_schemes, ctx);
-       damos_regions_upd_total_bytes_only = total_bytes_only;
-       ctx->callback.before_damos_apply = damon_sysfs_before_damos_apply;
-       return 0;
-}
-
-bool damos_sysfs_regions_upd_done(void)
-{
-       struct damon_sysfs_schemes *sysfs_schemes =
-               damon_sysfs_schemes_for_damos_callback;
-       struct damon_sysfs_scheme_regions *sysfs_regions;
-       int i;
-
-       for (i = 0; i < sysfs_schemes->nr; i++) {
-               sysfs_regions = sysfs_schemes->schemes_arr[i]->tried_regions;
-               if (sysfs_regions->upd_status !=
-                               DAMOS_TRIED_REGIONS_UPD_FINISHED)
-                       return false;
-       }
-       return true;
-}
-
-/*
- * Called from damon_sysfs_cmd_request_callback under damon_sysfs_lock.  Caller
- * should unlock damon_sysfs_lock which held before
- * damon_sysfs_schemes_update_regions_start()
- */
-int damon_sysfs_schemes_update_regions_stop(struct damon_ctx *ctx)
-{
-       damon_sysfs_schemes_for_damos_callback = NULL;
-       ctx->callback.before_damos_apply = NULL;
-       damon_sysfs_schemes_region_idx = 0;
-       return 0;
-}

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 4ba44a314f2e90e6e156b8540a4d809152343d12..cf8fb5a963d6bada532e560dca8c3ae4e53a12c4 100644 (file)
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1181,25 +1181,9 @@ static int damon_sysfs_add_targets(struct damon_ctx *ctx,
        return 0;
 }
 
-static bool damon_sysfs_schemes_regions_updating;
-
 static void damon_sysfs_before_terminate(struct damon_ctx *ctx)
 {
        struct damon_target *t, *next;
-       struct damon_sysfs_kdamond *kdamond;
-       enum damon_sysfs_cmd cmd;
-
-       /* damon_sysfs_schemes_update_regions_stop() might not yet called */
-       kdamond = damon_sysfs_cmd_request.kdamond;
-       cmd = damon_sysfs_cmd_request.cmd;
-       if (kdamond && ctx == kdamond->damon_ctx &&
-                       (cmd == DAMON_SYSFS_CMD_UPDATE_SCHEMES_TRIED_REGIONS ||
-                        cmd == DAMON_SYSFS_CMD_UPDATE_SCHEMES_TRIED_BYTES) &&
-                       damon_sysfs_schemes_regions_updating) {
-               damon_sysfs_schemes_update_regions_stop(ctx);
-               damon_sysfs_schemes_regions_updating = false;
-               mutex_unlock(&damon_sysfs_lock);
-       }
 
        if (!damon_target_has_pid(ctx))
                return;
@@ -1232,28 +1216,6 @@ static int damon_sysfs_upd_schemes_stats(void *data)
        return 0;
 }
 
-static int damon_sysfs_upd_schemes_regions_start(
-               struct damon_sysfs_kdamond *kdamond, bool total_bytes_only)
-{
-       struct damon_ctx *ctx = kdamond->damon_ctx;
-
-       if (!ctx)
-               return -EINVAL;
-       return damon_sysfs_schemes_update_regions_start(
-                       kdamond->contexts->contexts_arr[0]->schemes, ctx,
-                       total_bytes_only);
-}
-
-static int damon_sysfs_upd_schemes_regions_stop(
-               struct damon_sysfs_kdamond *kdamond)
-{
-       struct damon_ctx *ctx = kdamond->damon_ctx;
-
-       if (!ctx)
-               return -EINVAL;
-       return damon_sysfs_schemes_update_regions_stop(ctx);
-}
-
 static inline bool damon_sysfs_kdamond_running(
                struct damon_sysfs_kdamond *kdamond)
 {
@@ -1358,12 +1320,10 @@ static int damon_sysfs_cmd_request_callback(struct damon_ctx *c, bool active,
                bool after_aggregation)
 {
        struct damon_sysfs_kdamond *kdamond;
-       bool total_bytes_only = false;
        int err = 0;
 
        /* avoid deadlock due to concurrent state_store('off') */
-       if (!damon_sysfs_schemes_regions_updating &&
-                       !mutex_trylock(&damon_sysfs_lock))
+       if (!mutex_trylock(&damon_sysfs_lock))
                return 0;
        kdamond = damon_sysfs_cmd_request.kdamond;
        if (!kdamond || kdamond->damon_ctx != c)
@@ -1374,39 +1334,13 @@ static int damon_sysfs_cmd_request_callback(struct damon_ctx *c, bool active,
                        goto out;
                err = damon_sysfs_commit_input(kdamond);
                break;
-       case DAMON_SYSFS_CMD_UPDATE_SCHEMES_TRIED_BYTES:
-               total_bytes_only = true;
-               fallthrough;
-       case DAMON_SYSFS_CMD_UPDATE_SCHEMES_TRIED_REGIONS:
-               if (!damon_sysfs_schemes_regions_updating) {
-                       err = damon_sysfs_upd_schemes_regions_start(kdamond,
-                                       total_bytes_only);
-                       if (!err) {
-                               damon_sysfs_schemes_regions_updating = true;
-                               goto keep_lock_out;
-                       }
-               } else {
-                       damos_sysfs_mark_finished_regions_updates(c);
-                       /*
-                        * Continue regions updating if DAMON is till
-                        * active and the update for all schemes is not
-                        * finished.
-                        */
-                       if (active && !damos_sysfs_regions_upd_done())
-                               goto keep_lock_out;
-                       err = damon_sysfs_upd_schemes_regions_stop(kdamond);
-                       damon_sysfs_schemes_regions_updating = false;
-               }
-               break;
        default:
                break;
        }
        /* Mark the request as invalid now. */
        damon_sysfs_cmd_request.kdamond = NULL;
 out:
-       if (!damon_sysfs_schemes_regions_updating)
-               mutex_unlock(&damon_sysfs_lock);
-keep_lock_out:
+       mutex_unlock(&damon_sysfs_lock);
        return err;
 }