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>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 35dedff..97ac6c6 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -608,7 +608,7 @@ static unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru,
/*
* Add a shrinker callback to be called from the vm.
*/
-int prealloc_shrinker(struct shrinker *shrinker)
+static int __prealloc_shrinker(struct shrinker *shrinker)
{
unsigned int size;
int err;
@@ -632,8 +632,36 @@ int prealloc_shrinker(struct shrinker *shrinker)
return 0;
}
+#ifdef CONFIG_SHRINKER_DEBUG
+int prealloc_shrinker(struct shrinker *shrinker, const char *fmt, ...)
+{
+ va_list ap;
+ int err;
+
+ va_start(ap, fmt);
+ shrinker->name = kvasprintf_const(GFP_KERNEL, fmt, ap);
+ va_end(ap);
+ if (!shrinker->name)
+ return -ENOMEM;
+
+ err = __prealloc_shrinker(shrinker);
+ if (err)
+ kfree_const(shrinker->name);
+
+ return err;
+}
+#else
+int prealloc_shrinker(struct shrinker *shrinker, const char *fmt, ...)
+{
+ return __prealloc_shrinker(shrinker);
+}
+#endif
+
void free_prealloced_shrinker(struct shrinker *shrinker)
{
+#ifdef CONFIG_SHRINKER_DEBUG
+ kfree_const(shrinker->name);
+#endif
if (shrinker->flags & SHRINKER_MEMCG_AWARE) {
down_write(&shrinker_rwsem);
unregister_memcg_shrinker(shrinker);
@@ -654,15 +682,39 @@ void register_shrinker_prepared(struct shrinker *shrinker)
up_write(&shrinker_rwsem);
}
-int register_shrinker(struct shrinker *shrinker)
+static int __register_shrinker(struct shrinker *shrinker)
{
- int err = prealloc_shrinker(shrinker);
+ int err = __prealloc_shrinker(shrinker);
if (err)
return err;
register_shrinker_prepared(shrinker);
return 0;
}
+
+#ifdef CONFIG_SHRINKER_DEBUG
+int register_shrinker(struct shrinker *shrinker, const char *fmt, ...)
+{
+ va_list ap;
+ int err;
+
+ va_start(ap, fmt);
+ shrinker->name = kvasprintf_const(GFP_KERNEL, fmt, ap);
+ va_end(ap);
+ if (!shrinker->name)
+ return -ENOMEM;
+
+ err = __register_shrinker(shrinker);
+ if (err)
+ kfree_const(shrinker->name);
+ return err;
+}
+#else
+int register_shrinker(struct shrinker *shrinker, const char *fmt, ...)
+{
+ return __register_shrinker(shrinker);
+}
+#endif
EXPORT_SYMBOL(register_shrinker);
/*
