mm/damon/sysfs-schemes: implement DAMOS-tried regions clear command

When there are huge number of DAMON regions that specific scheme actions
are tried to be applied, directories and files under 'tried_regions'
scheme directory could waste some memory.  Add another special input
keyword ('clear_schemes_tried_regions') for 'state' file of each kdamond
sysfs directory that can be used for cleanup of the 'tried_regions'
sub-directories.

[sj@kernel.org: skip regions clearing if the scheme directory was removed]
Link: https://lkml.kernel.org/r/20221114182954.4745-3-sj@kernel.org
Link: https://lkml.kernel.org/r/20221101220328.95765-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/sysfs-common.h b/mm/damon/sysfs-common.h
index 634a6e7fca78a5ff1bb96f8d3a960ab3918c2e52..604a6cbc3edeab2e019a0dadd92282f147eafdf9 100644 (file)
--- a/mm/damon/sysfs-common.h
+++ b/mm/damon/sysfs-common.h
@@ -50,3 +50,7 @@ int damon_sysfs_schemes_update_regions_start(
                struct damon_ctx *ctx);
 
 int damon_sysfs_schemes_update_regions_stop(struct damon_ctx *ctx);
+
+int damon_sysfs_schemes_clear_regions(
+               struct damon_sysfs_schemes *sysfs_schemes,
+               struct damon_ctx *ctx);

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 5f14f18bcc49c9e598575b57ab160dbd44df381b..81fc4d27f4e45d9789b6752f6f47ab14235d7a12 100644 (file)
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1292,7 +1292,7 @@ static int damon_sysfs_before_damos_apply(struct damon_ctx *ctx,
 }
 
 /* Called from damon_sysfs_cmd_request_callback under damon_sysfs_lock */
-int damon_sysfs_schemes_update_regions_start(
+int damon_sysfs_schemes_clear_regions(
                struct damon_sysfs_schemes *sysfs_schemes,
                struct damon_ctx *ctx)
 {
@@ -1302,11 +1302,23 @@ int damon_sysfs_schemes_update_regions_start(
        damon_for_each_scheme(scheme, ctx) {
                struct damon_sysfs_scheme *sysfs_scheme;
 
+               /* user could have removed the scheme sysfs dir */
+               if (schemes_idx >= sysfs_schemes->nr)
+                       break;
+
                sysfs_scheme = sysfs_schemes->schemes_arr[schemes_idx++];
                damon_sysfs_scheme_regions_rm_dirs(
                                sysfs_scheme->tried_regions);
        }
+       return 0;
+}
 
+/* Called from damon_sysfs_cmd_request_callback under damon_sysfs_lock */
+int damon_sysfs_schemes_update_regions_start(
+               struct damon_sysfs_schemes *sysfs_schemes,
+               struct damon_ctx *ctx)
+{
+       damon_sysfs_schemes_clear_regions(sysfs_schemes, ctx);
        damon_sysfs_schemes_for_damos_callback = sysfs_schemes;
        ctx->callback.before_damos_apply = damon_sysfs_before_damos_apply;
        return 0;

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index ffb5a84059d7c38725b142d11449171a860363d7..aeb0beb1da913a350c94749c00fa5d1066e5e10e 100644 (file)
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1004,6 +1004,11 @@ enum damon_sysfs_cmd {
         * regions
         */
        DAMON_SYSFS_CMD_UPDATE_SCHEMES_TRIED_REGIONS,
+       /*
+        * @DAMON_SYSFS_CMD_CLEAR_SCHEMES_TRIED_REGIONS: Clear schemes tried
+        * regions
+        */
+       DAMON_SYSFS_CMD_CLEAR_SCHEMES_TRIED_REGIONS,
        /*
         * @NR_DAMON_SYSFS_CMDS: Total number of DAMON sysfs commands.
         */
@@ -1017,6 +1022,7 @@ static const char * const damon_sysfs_cmd_strs[] = {
        "commit",
        "update_schemes_stats",
        "update_schemes_tried_regions",
+       "clear_schemes_tried_regions",
 };
 
 /*
@@ -1262,6 +1268,17 @@ static int damon_sysfs_upd_schemes_regions_stop(
        return damon_sysfs_schemes_update_regions_stop(ctx);
 }
 
+static int damon_sysfs_clear_schemes_regions(
+               struct damon_sysfs_kdamond *kdamond)
+{
+       struct damon_ctx *ctx = kdamond->damon_ctx;
+
+       if (!ctx)
+               return -EINVAL;
+       return damon_sysfs_schemes_clear_regions(
+                       kdamond->contexts->contexts_arr[0]->schemes, ctx);
+}
+
 static inline bool damon_sysfs_kdamond_running(
                struct damon_sysfs_kdamond *kdamond)
 {
@@ -1343,6 +1360,9 @@ static int damon_sysfs_cmd_request_callback(struct damon_ctx *c)
                        damon_sysfs_schemes_regions_updating = false;
                }
                break;
+       case DAMON_SYSFS_CMD_CLEAR_SCHEMES_TRIED_REGIONS:
+               err = damon_sysfs_clear_schemes_regions(kdamond);
+               break;
        default:
                break;
        }