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Subject[PATCH 1/2] mm, slab: Revert "extend slab/shrink to shrink all memcg caches"
Date
When the slub shrink sysfs file is written into, the function call
sequence is as follows:

kernfs_fop_write
=> slab_attr_store
=> shrink_store
=> kmem_cache_shrink_all

It turns out that doing a memcg cache scan in kmem_cache_shrink_all()
is redundant as the same memcg cache scan is being done in
slab_attr_store(). So revert the commit 04f768a39d55 ("mm, slab: extend
slab/shrink to shrink all memcg caches") except the documentation change
which is still valid.

Signed-off-by: Waiman Long <longman@redhat.com>
---
mm/slab.h | 1 -
mm/slab_common.c | 37 -------------------------------------
mm/slub.c | 2 +-
3 files changed, 1 insertion(+), 39 deletions(-)

diff --git a/mm/slab.h b/mm/slab.h
index 207c83ef6e06..0937cb2ae8aa 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -237,7 +237,6 @@ int __kmem_cache_shrink(struct kmem_cache *);
void __kmemcg_cache_deactivate(struct kmem_cache *s);
void __kmemcg_cache_deactivate_after_rcu(struct kmem_cache *s);
void slab_kmem_cache_release(struct kmem_cache *);
-void kmem_cache_shrink_all(struct kmem_cache *s);

struct seq_file;
struct file;
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 23c7500eea7d..2e367ab8c15c 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -995,43 +995,6 @@ int kmem_cache_shrink(struct kmem_cache *cachep)
}
EXPORT_SYMBOL(kmem_cache_shrink);

-/**
- * kmem_cache_shrink_all - shrink a cache and all memcg caches for root cache
- * @s: The cache pointer
- */
-void kmem_cache_shrink_all(struct kmem_cache *s)
-{
- struct kmem_cache *c;
-
- if (!IS_ENABLED(CONFIG_MEMCG_KMEM) || !is_root_cache(s)) {
- kmem_cache_shrink(s);
- return;
- }
-
- get_online_cpus();
- get_online_mems();
- kasan_cache_shrink(s);
- __kmem_cache_shrink(s);
-
- /*
- * We have to take the slab_mutex to protect from the memcg list
- * modification.
- */
- mutex_lock(&slab_mutex);
- for_each_memcg_cache(c, s) {
- /*
- * Don't need to shrink deactivated memcg caches.
- */
- if (s->flags & SLAB_DEACTIVATED)
- continue;
- kasan_cache_shrink(c);
- __kmem_cache_shrink(c);
- }
- mutex_unlock(&slab_mutex);
- put_online_mems();
- put_online_cpus();
-}
-
bool slab_is_available(void)
{
return slab_state >= UP;
diff --git a/mm/slub.c b/mm/slub.c
index 9bf44955c4f1..183ccc364ccf 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5343,7 +5343,7 @@ static ssize_t shrink_store(struct kmem_cache *s,
const char *buf, size_t length)
{
if (buf[0] == '1')
- kmem_cache_shrink_all(s);
+ kmem_cache_shrink(s);
else
return -EINVAL;
return length;
--
2.18.1
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