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Message-ID: <CAEVVKH_XRmPUEJmo7xXwuNV3mCA8=SHxLdY9EjC9XFZsuqAXJw@mail.gmail.com>
Date: Mon, 22 Jul 2024 22:16:54 +0800
From: Xiongwei Song <sxwjean@...il.com>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: "Paul E. McKenney" <paulmck@...nel.org>, Joel Fernandes <joel@...lfernandes.org>,
Josh Triplett <josh@...htriplett.org>, Boqun Feng <boqun.feng@...il.com>,
Christoph Lameter <cl@...ux.com>, David Rientjes <rientjes@...gle.com>, Steven Rostedt <rostedt@...dmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, Lai Jiangshan <jiangshanlai@...il.com>,
Zqiang <qiang.zhang1211@...il.com>, Julia Lawall <Julia.Lawall@...ia.fr>,
Jakub Kicinski <kuba@...nel.org>, "Jason A. Donenfeld" <Jason@...c4.com>,
"Uladzislau Rezki (Sony)" <urezki@...il.com>, Andrew Morton <akpm@...ux-foundation.org>,
Roman Gushchin <roman.gushchin@...ux.dev>, Hyeonggon Yoo <42.hyeyoo@...il.com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, rcu@...r.kernel.org
Subject: Re: [PATCH RFC 2/6] mm, slab: always maintain per-node slab and
object count
Don't we need the following changes for this patch?
diff --git a/mm/slub.c b/mm/slub.c
index c1222467c346..e6beb6743342 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4967,9 +4967,9 @@ init_kmem_cache_node(struct kmem_cache_node *n)
n->nr_partial = 0;
spin_lock_init(&n->list_lock);
INIT_LIST_HEAD(&n->partial);
-#ifdef CONFIG_SLUB_DEBUG
atomic_long_set(&n->nr_slabs, 0);
atomic_long_set(&n->total_objects, 0);
+#ifdef CONFIG_SLUB_DEBUG
INIT_LIST_HEAD(&n->full);
#endif
}
Thanks,
Xiongwei
On Tue, Jul 16, 2024 at 4:29 AM Vlastimil Babka <vbabka@...e.cz> wrote:
>
> Currently SLUB counts per-node slabs and total objects only with
> CONFIG_SLUB_DEBUG, in order to minimize overhead. However, the detection
> in __kmem_cache_shutdown() whether there are no outstanding object
> relies on the per-node slab count (node_nr_slabs()) so it may be
> unreliable without CONFIG_SLUB_DEBUG. Thus we might be failing to warn
> about such situations, and instead destroy a cache while leaving its
> slab(s) around (due to a buggy slab user creating such a scenario, not
> in normal operation).
>
> We will also need node_nr_slabs() to be reliable in the following work
> to gracefully handle kmem_cache_destroy() with kfree_rcu() objects in
> flight. Thus make the counting of per-node slabs and objects
> unconditional.
>
> Note that CONFIG_SLUB_DEBUG is the default anyway, and the counting is
> done only when allocating or freeing a slab page, so even in
> !CONFIG_SLUB_DEBUG configs the overhead should be negligible.
>
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
> ---
> mm/slub.c | 49 +++++++++++++++++++++----------------------------
> 1 file changed, 21 insertions(+), 28 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index 829a1f08e8a2..aa4d80109c49 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -426,9 +426,9 @@ struct kmem_cache_node {
> spinlock_t list_lock;
> unsigned long nr_partial;
> struct list_head partial;
> -#ifdef CONFIG_SLUB_DEBUG
> atomic_long_t nr_slabs;
> atomic_long_t total_objects;
> +#ifdef CONFIG_SLUB_DEBUG
> struct list_head full;
> #endif
> };
> @@ -438,6 +438,26 @@ static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
> return s->node[node];
> }
>
> +static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
> +{
> + return atomic_long_read(&n->nr_slabs);
> +}
> +
> +static inline void inc_slabs_node(struct kmem_cache *s, int node, int objects)
> +{
> + struct kmem_cache_node *n = get_node(s, node);
> +
> + atomic_long_inc(&n->nr_slabs);
> + atomic_long_add(objects, &n->total_objects);
> +}
> +static inline void dec_slabs_node(struct kmem_cache *s, int node, int objects)
> +{
> + struct kmem_cache_node *n = get_node(s, node);
> +
> + atomic_long_dec(&n->nr_slabs);
> + atomic_long_sub(objects, &n->total_objects);
> +}
> +
> /*
> * Iterator over all nodes. The body will be executed for each node that has
> * a kmem_cache_node structure allocated (which is true for all online nodes)
> @@ -1511,26 +1531,6 @@ static void remove_full(struct kmem_cache *s, struct kmem_cache_node *n, struct
> list_del(&slab->slab_list);
> }
>
> -static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
> -{
> - return atomic_long_read(&n->nr_slabs);
> -}
> -
> -static inline void inc_slabs_node(struct kmem_cache *s, int node, int objects)
> -{
> - struct kmem_cache_node *n = get_node(s, node);
> -
> - atomic_long_inc(&n->nr_slabs);
> - atomic_long_add(objects, &n->total_objects);
> -}
> -static inline void dec_slabs_node(struct kmem_cache *s, int node, int objects)
> -{
> - struct kmem_cache_node *n = get_node(s, node);
> -
> - atomic_long_dec(&n->nr_slabs);
> - atomic_long_sub(objects, &n->total_objects);
> -}
> -
> /* Object debug checks for alloc/free paths */
> static void setup_object_debug(struct kmem_cache *s, void *object)
> {
> @@ -1871,13 +1871,6 @@ slab_flags_t kmem_cache_flags(slab_flags_t flags, const char *name)
>
> #define disable_higher_order_debug 0
>
> -static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
> - { return 0; }
> -static inline void inc_slabs_node(struct kmem_cache *s, int node,
> - int objects) {}
> -static inline void dec_slabs_node(struct kmem_cache *s, int node,
> - int objects) {}
> -
> #ifndef CONFIG_SLUB_TINY
> static bool freelist_corrupted(struct kmem_cache *s, struct slab *slab,
> void **freelist, void *nextfree)
>
> --
> 2.45.2
>
>
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