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authorRoman Gushchin <roman.gushchin@linux.dev>2022-05-31 20:22:24 -0700
committerakpm <akpm@linux-foundation.org>2022-07-03 18:08:40 -0700
commite33c267ab70de4249d22d7eab1cc7d68a889bac2 (patch)
tree625ae2ff52e80b8a602acd0d459e781893495bdb /mm/shrinker_debug.c
parent5035ebc644aec92d55d1bbfe042f35341e4bffb5 (diff)
downloadlwn-e33c267ab70de4249d22d7eab1cc7d68a889bac2.tar.gz
lwn-e33c267ab70de4249d22d7eab1cc7d68a889bac2.zip
mm: shrinkers: provide shrinkers with names
Currently shrinkers are anonymous objects. For debugging purposes they can be identified by count/scan function names, but it's not always useful: e.g. for superblock's shrinkers it's nice to have at least an idea of to which superblock the shrinker belongs. This commit adds names to shrinkers. register_shrinker() and prealloc_shrinker() functions are extended to take a format and arguments to master a name. In some cases it's not possible to determine a good name at the time when a shrinker is allocated. For such cases shrinker_debugfs_rename() is provided. The expected format is: <subsystem>-<shrinker_type>[:<instance>]-<id> For some shrinkers an instance can be encoded as (MAJOR:MINOR) pair. After this change the shrinker debugfs directory looks like: $ cd /sys/kernel/debug/shrinker/ $ ls dquota-cache-16 sb-devpts-28 sb-proc-47 sb-tmpfs-42 mm-shadow-18 sb-devtmpfs-5 sb-proc-48 sb-tmpfs-43 mm-zspool:zram0-34 sb-hugetlbfs-17 sb-pstore-31 sb-tmpfs-44 rcu-kfree-0 sb-hugetlbfs-33 sb-rootfs-2 sb-tmpfs-49 sb-aio-20 sb-iomem-12 sb-securityfs-6 sb-tracefs-13 sb-anon_inodefs-15 sb-mqueue-21 sb-selinuxfs-22 sb-xfs:vda1-36 sb-bdev-3 sb-nsfs-4 sb-sockfs-8 sb-zsmalloc-19 sb-bpf-32 sb-pipefs-14 sb-sysfs-26 thp-deferred_split-10 sb-btrfs:vda2-24 sb-proc-25 sb-tmpfs-1 thp-zero-9 sb-cgroup2-30 sb-proc-39 sb-tmpfs-27 xfs-buf:vda1-37 sb-configfs-23 sb-proc-41 sb-tmpfs-29 xfs-inodegc:vda1-38 sb-dax-11 sb-proc-45 sb-tmpfs-35 sb-debugfs-7 sb-proc-46 sb-tmpfs-40 [roman.gushchin@linux.dev: fix build warnings] Link: https://lkml.kernel.org/r/Yr+ZTnLb9lJk6fJO@castle Reported-by: kernel test robot <lkp@intel.com> Link: https://lkml.kernel.org/r/20220601032227.4076670-4-roman.gushchin@linux.dev Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Cc: Dave Chinner <dchinner@redhat.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Kent Overstreet <kent.overstreet@gmail.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/shrinker_debug.c')
-rw-r--r--mm/shrinker_debug.c47
1 files changed, 45 insertions, 2 deletions
diff --git a/mm/shrinker_debug.c b/mm/shrinker_debug.c
index 1a70556bd46c..781ecbd3d608 100644
--- a/mm/shrinker_debug.c
+++ b/mm/shrinker_debug.c
@@ -102,7 +102,7 @@ DEFINE_SHOW_ATTRIBUTE(shrinker_debugfs_count);
int shrinker_debugfs_add(struct shrinker *shrinker)
{
struct dentry *entry;
- char buf[16];
+ char buf[128];
int id;
lockdep_assert_held(&shrinker_rwsem);
@@ -116,7 +116,7 @@ int shrinker_debugfs_add(struct shrinker *shrinker)
return id;
shrinker->debugfs_id = id;
- snprintf(buf, sizeof(buf), "%d", id);
+ snprintf(buf, sizeof(buf), "%s-%d", shrinker->name, id);
/* create debugfs entry */
entry = debugfs_create_dir(buf, shrinker_debugfs_root);
@@ -131,10 +131,53 @@ int shrinker_debugfs_add(struct shrinker *shrinker)
return 0;
}
+int shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...)
+{
+ struct dentry *entry;
+ char buf[128];
+ const char *new, *old;
+ va_list ap;
+ int ret = 0;
+
+ va_start(ap, fmt);
+ new = kvasprintf_const(GFP_KERNEL, fmt, ap);
+ va_end(ap);
+
+ if (!new)
+ return -ENOMEM;
+
+ down_write(&shrinker_rwsem);
+
+ old = shrinker->name;
+ shrinker->name = new;
+
+ if (shrinker->debugfs_entry) {
+ snprintf(buf, sizeof(buf), "%s-%d", shrinker->name,
+ shrinker->debugfs_id);
+
+ entry = debugfs_rename(shrinker_debugfs_root,
+ shrinker->debugfs_entry,
+ shrinker_debugfs_root, buf);
+ if (IS_ERR(entry))
+ ret = PTR_ERR(entry);
+ else
+ shrinker->debugfs_entry = entry;
+ }
+
+ up_write(&shrinker_rwsem);
+
+ kfree_const(old);
+
+ return ret;
+}
+EXPORT_SYMBOL(shrinker_debugfs_rename);
+
void shrinker_debugfs_remove(struct shrinker *shrinker)
{
lockdep_assert_held(&shrinker_rwsem);
+ kfree_const(shrinker->name);
+
if (!shrinker->debugfs_entry)
return;