Re: [PATCH v2 04/11] mm/slab: factor out kmem_cache_node initialization code

[Joonsoo Kim]

On Tue, Apr 12, 2016 at 01:50:59PM +0900, js1...@gmail.com wrote:
> From: Joonsoo Kim <iamjoonsoo....@lge.com>
> 
> It can be reused on other place, so factor out it.  Following patch will
> use it.
> 
> Signed-off-by: Joonsoo Kim <iamjoonsoo....@lge.com>
> ---
>  mm/slab.c | 68 
> ++++++++++++++++++++++++++++++++++++---------------------------
>  1 file changed, 39 insertions(+), 29 deletions(-)
> 
> diff --git a/mm/slab.c b/mm/slab.c
> index 5451929..49af685 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -841,6 +841,40 @@ static inline gfp_t gfp_exact_node(gfp_t flags)
>  }
>  #endif
>  
> +static int init_cache_node(struct kmem_cache *cachep, int node, gfp_t gfp)
> +{
> +     struct kmem_cache_node *n;
> +
> +     /*
> +      * Set up the kmem_cache_node for cpu before we can
> +      * begin anything. Make sure some other cpu on this
> +      * node has not already allocated this
> +      */
> +     n = get_node(cachep, node);
> +     if (n)
> +             return 0;
> +
> +     n = kmalloc_node(sizeof(struct kmem_cache_node), gfp, node);
> +     if (!n)
> +             return -ENOMEM;
> +
> +     kmem_cache_node_init(n);
> +     n->next_reap = jiffies + REAPTIMEOUT_NODE +
> +                 ((unsigned long)cachep) % REAPTIMEOUT_NODE;
> +
> +     n->free_limit =
> +             (1 + nr_cpus_node(node)) * cachep->batchcount + cachep->num;
> +
> +     /*
> +      * The kmem_cache_nodes don't come and go as CPUs
> +      * come and go.  slab_mutex is sufficient
> +      * protection here.
> +      */
> +     cachep->node[node] = n;
> +
> +     return 0;
> +}
> +

Hello, Andrew.

Could you apply following fix for this patch to mmotm?

Thanks.

------>8-----------
Date: Thu, 14 Apr 2016 10:28:11 +0900
Subject: [PATCH] mm/slab: fix bug

n->free_limit is once set in boot-up process without enabling multiple
cpu so it could be very low value. If we don't re-set when another cpu
is up, it will stay too low. Fix it.

Signed-off-by: Joonsoo Kim <iamjoonsoo....@lge.com>

---
 mm/slab.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/mm/slab.c b/mm/slab.c
index 13e74aa..59dd94a 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -856,8 +856,14 @@ static int init_cache_node(struct kmem_cache *cachep, int 
node, gfp_t gfp)
         * node has not already allocated this
         */
        n = get_node(cachep, node);
-       if (n)
+       if (n) {
+               spin_lock_irq(&n->list_lock);
+               n->free_limit = (1 + nr_cpus_node(node)) * cachep->batchcount +
+                               cachep->num;
+               spin_unlock_irq(&n->list_lock);
+
                return 0;
+       }
 
        n = kmalloc_node(sizeof(struct kmem_cache_node), gfp, node);
        if (!n)
-- 
1.9.1