Hi,
Le 22/04/2022 à 22:26, Roman Gushchin a écrit :
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. If CONFIG_SHRINKER_DEBUG is on,
the name is saved until the corresponding debugfs object is created,
otherwise it's simple ignored.
After this change the shrinker debugfs directory looks like:
$ cd /sys/kernel/debug/shrinker/
$ ls
dqcache-16 sb-cgroup2-30 sb-hugetlbfs-33 sb-proc-41 sb-selinuxfs-22 sb-tmpfs-40 sb-zsmalloc-19
kfree_rcu-0 sb-configfs-23 sb-iomem-12 sb-proc-44 sb-sockfs-8 sb-tmpfs-42 shadow-18
sb-aio-20 sb-dax-11 sb-mqueue-21 sb-proc-45 sb-sysfs-26 sb-tmpfs-43 thp_deferred_split-10
sb-anon_inodefs-15 sb-debugfs-7 sb-nsfs-4 sb-proc-47 sb-tmpfs-1 sb-tmpfs-46 thp_zero-9
sb-bdev-3 sb-devpts-28 sb-pipefs-14 sb-pstore-31 sb-tmpfs-27 sb-tmpfs-49 xfs_buf-37
sb-bpf-32 sb-devtmpfs-5 sb-proc-25 sb-rootfs-2 sb-tmpfs-29 sb-tracefs-13 xfs_inodegc-38
sb-btrfs-24 sb-hugetlbfs-17 sb-proc-39 sb-securityfs-6 sb-tmpfs-35 sb-xfs-36 zspool-34
Signed-off-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
---
[...]
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 59f91e392a2a..1b326b93155c 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7383,7 +7383,7 @@ static struct r5conf *setup_conf(struct mddev *mddev)
conf->shrinker.count_objects = raid5_cache_count;
conf->shrinker.batch = 128;
conf->shrinker.flags = 0;
- if (register_shrinker(&conf->shrinker)) {
+ if (register_shrinker(&conf->shrinker, "md")) {
Based on pr_warn below, does it make sense to have something like:
register_shrinker(&conf->shrinker, "md-%s", mdname(mddev))
pr_warn("md/raid:%s: couldn't register shrinker.\n",
mdname(mddev));
goto abort;
[...]
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 121a54a1602b..6025cfda4932 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -613,7 +613,7 @@ 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;
@@ -637,6 +637,34 @@ int prealloc_shrinker(struct shrinker *shrinker)
return 0;
}
+#ifdef CONFIG_SHRINKER_DEBUG
+int prealloc_shrinker(struct shrinker *shrinker, const char *fmt, ...)
+{
+ int err;
+ char buf[64];
+ va_list ap;
+
+ va_start(ap, fmt);
+ vscnprintf(buf, sizeof(buf), fmt, ap);
+ va_end(ap);
+
+ shrinker->name = kstrdup(buf, GFP_KERNEL);
+ if (!shrinker->name)
+ return -ENOMEM;
use kvasprintf_const() (and kfree_const() elsewhere) to simplify code
and take advantage of kstrdup_const() in most cases?
+
+ err = __prealloc_shrinker(shrinker);
+ if (err)
+ kfree(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)
{
if (shrinker->flags & SHRINKER_MEMCG_AWARE) {
@@ -648,6 +676,9 @@ void free_prealloced_shrinker(struct shrinker *shrinker)
kfree(shrinker->nr_deferred);
shrinker->nr_deferred = NULL;
+#ifdef CONFIG_SHRINKER_DEBUG
+ kfree(shrinker->name);
+#endif
}
void register_shrinker_prepared(struct shrinker *shrinker)
@@ -659,15 +690,38 @@ 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, ...)
+{
+ char buf[64];
+ va_list ap;
+
+ va_start(ap, fmt);
+ vscnprintf(buf, sizeof(buf), fmt, ap);
+ va_end(ap);
+
+ shrinker->name = kstrdup(buf, GFP_KERNEL);
+ if (!shrinker->name)
+ return -ENOMEM;
+
same as above.
+ return __register_shrinker(shrinker);
Missing error handling and freeing of shrinker->name as done in
prealloc_shrinker()?
CJ
+}
+#else
+int register_shrinker(struct shrinker *shrinker, const char *fmt, ...)
+{
+ return __register_shrinker(shrinker);
+}
+#endif
EXPORT_SYMBOL(register_shrinker);
/*
[...]
