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authorRoman Gushchin <roman.gushchin@linux.dev>2022-06-01 06:22:23 +0300
committerakpm <akpm@linux-foundation.org>2022-07-04 04:08:40 +0300
commit5035ebc644aec92d55d1bbfe042f35341e4bffb5 (patch)
treeb6b76cac588da2cb4f7e17761fc8f508bef80051 /mm/vmscan.c
parentc15187a4a2d660bf490f7873afd0de5288f65c8f (diff)
downloadlinux-5035ebc644aec92d55d1bbfe042f35341e4bffb5.tar.xz
mm: shrinkers: introduce debugfs interface for memory shrinkers
This commit introduces the /sys/kernel/debug/shrinker debugfs interface which provides an ability to observe the state of individual kernel memory shrinkers. Because the feature adds some memory overhead (which shouldn't be large unless there is a huge amount of registered shrinkers), it's guarded by a config option (enabled by default). This commit introduces the "count" interface for each shrinker registered in the system. The output is in the following format: <cgroup inode id> <nr of objects on node 0> <nr of objects on node 1>... <cgroup inode id> <nr of objects on node 0> <nr of objects on node 1>... ... To reduce the size of output on machines with many thousands cgroups, if the total number of objects on all nodes is 0, the line is omitted. If the shrinker is not memcg-aware or CONFIG_MEMCG is off, 0 is printed as cgroup inode id. If the shrinker is not numa-aware, 0's are printed for all nodes except the first one. This commit gives debugfs entries simple numeric names, which are not very convenient. The following commit in the series will provide shrinkers with more meaningful names. [akpm@linux-foundation.org: remove WARN_ON_ONCE(), per Roman] Reported-by: syzbot+300d27c79fe6d4cbcc39@syzkaller.appspotmail.com Link: https://lkml.kernel.org/r/20220601032227.4076670-3-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Reviewed-by: Kent Overstreet <kent.overstreet@gmail.com> Acked-by: Muchun Song <songmuchun@bytedance.com> Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Cc: Dave Chinner <dchinner@redhat.com> Cc: Hillf Danton <hdanton@sina.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index f7d9a683e3a7..35dedff79eb4 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -190,8 +190,8 @@ static void set_task_reclaim_state(struct task_struct *task,
task->reclaim_state = rs;
}
-static LIST_HEAD(shrinker_list);
-static DECLARE_RWSEM(shrinker_rwsem);
+LIST_HEAD(shrinker_list);
+DECLARE_RWSEM(shrinker_rwsem);
#ifdef CONFIG_MEMCG
static int shrinker_nr_max;
@@ -650,6 +650,7 @@ void register_shrinker_prepared(struct shrinker *shrinker)
down_write(&shrinker_rwsem);
list_add_tail(&shrinker->list, &shrinker_list);
shrinker->flags |= SHRINKER_REGISTERED;
+ shrinker_debugfs_add(shrinker);
up_write(&shrinker_rwsem);
}
@@ -677,6 +678,7 @@ void unregister_shrinker(struct shrinker *shrinker)
shrinker->flags &= ~SHRINKER_REGISTERED;
if (shrinker->flags & SHRINKER_MEMCG_AWARE)
unregister_memcg_shrinker(shrinker);
+ shrinker_debugfs_remove(shrinker);
up_write(&shrinker_rwsem);
kfree(shrinker->nr_deferred);