[PATCH RESEND] slub: Remove userspace notifier for cache add/remove

[PATCH RESEND] slub: Remove userspace notifier for cache add/remove

[Michal Koutný]

From: Christoph Lameter <cl@linux.com>

I came across some unnecessary uevents once again which reminded me
this. The patch seems to be lost in the leaves of the original
discussion [1], so resending.

[1] https://lore.kernel.org/r/alpine.DEB.2.21.2001281813130.745@www.lameter.com

8<---
Kmem caches are internal kernel structures so it is strange that
userspace notifiers would be needed. And I am not aware of any use
of these notifiers. These notifiers may just exist because in the
initial slub release the sysfs code was copied from another
subsystem.

Signed-off-by: Christoph Lameter <cl@linux.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Koutný <mkoutny@suse.com>
---
 mm/slub.c | 17 +----------------
 1 file changed, 1 insertion(+), 16 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 332d4b459a90..ae6116adf875 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5665,19 +5665,6 @@ static struct kobj_type slab_ktype = {
 	.release = kmem_cache_release,
 };
 
-static int uevent_filter(struct kset *kset, struct kobject *kobj)
-{
-	struct kobj_type *ktype = get_ktype(kobj);
-
-	if (ktype == &slab_ktype)
-		return 1;
-	return 0;
-}
-
-static const struct kset_uevent_ops slab_uevent_ops = {
-	.filter = uevent_filter,
-};
-
 static struct kset *slab_kset;
 
 static inline struct kset *cache_kset(struct kmem_cache *s)
@@ -5745,7 +5732,6 @@ static void sysfs_slab_remove_workfn(struct work_struct *work)
 #ifdef CONFIG_MEMCG
 	kset_unregister(s->memcg_kset);
 #endif
-	kobject_uevent(&s->kobj, KOBJ_REMOVE);
 out:
 	kobject_put(&s->kobj);
 }
@@ -5803,7 +5789,6 @@ static int sysfs_slab_add(struct kmem_cache *s)
 	}
 #endif
 
-	kobject_uevent(&s->kobj, KOBJ_ADD);
 	if (!unmergeable) {
 		/* Setup first alias */
 		sysfs_slab_alias(s, s->name);
@@ -5884,7 +5869,7 @@ static int __init slab_sysfs_init(void)
 
 	mutex_lock(&slab_mutex);
 
-	slab_kset = kset_create_and_add("slab", &slab_uevent_ops, kernel_kobj);
+	slab_kset = kset_create_and_add("slab", NULL, kernel_kobj);
 	if (!slab_kset) {
 		mutex_unlock(&slab_mutex);
 		pr_err("Cannot register slab subsystem.\n");
-- 
2.26.0

Re: [PATCH RESEND] slub: Remove userspace notifier for cache add/remove

[David Rientjes]

[-- Attachment #1: Type: text/plain, Size: 842 bytes --]

On Thu, 23 Apr 2020, Michal Koutný wrote:

> From: Christoph Lameter <cl@linux.com>
> 
> I came across some unnecessary uevents once again which reminded me
> this. The patch seems to be lost in the leaves of the original
> discussion [1], so resending.
> 
> [1] https://lore.kernel.org/r/alpine.DEB.2.21.2001281813130.745@www.lameter.com
> 
> 8<---
> Kmem caches are internal kernel structures so it is strange that
> userspace notifiers would be needed. And I am not aware of any use
> of these notifiers. These notifiers may just exist because in the
> initial slub release the sysfs code was copied from another
> subsystem.
> 
> Signed-off-by: Christoph Lameter <cl@linux.com>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
> Acked-by: Michal Koutný <mkoutny@suse.com>

Acked-by: David Rientjes <rientjes@google.com>