linux-kernel - Re: [PATCH] slab/mempolicy: always use local policy from interrupt context v3

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Message-ID: <CAHGf_=p7JbWW8jgzWGHX+xwU8JWzpSMZS0kn-rmP=eg_Uqrgow@mail.gmail.com>
Date:	Mon, 7 May 2012 19:47:13 -0400
From:	KOSAKI Motohiro <kosaki.motohiro@...il.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
	penberg@...nel.org, cl@...ux.com
Subject: Re: [PATCH] slab/mempolicy: always use local policy from interrupt
 context v3

> diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
> index 7c727a9..7106786 100644
> --- a/include/linux/mempolicy.h
> +++ b/include/linux/mempolicy.h
> @@ -215,7 +215,7 @@ extern struct zonelist *huge_zonelist(struct vm_area_struct *vma,
>  extern bool init_nodemask_of_mempolicy(nodemask_t *mask);
>  extern bool mempolicy_nodemask_intersects(struct task_struct *tsk,
>                                const nodemask_t *mask);
> -extern unsigned slab_node(struct mempolicy *policy);
> +extern unsigned slab_node(void);
>
>  extern enum zone_type policy_zone;
>
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index cfb6c86..e05e007 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -1586,9 +1586,11 @@ static unsigned interleave_nodes(struct mempolicy *policy)
>  * task can change it's policy.  The system default policy requires no
>  * such protection.
>  */
> -unsigned slab_node(struct mempolicy *policy)
> +unsigned slab_node(void)
>  {
> -       if (!policy || policy->flags & MPOL_F_LOCAL)
> +       struct mempolicy *policy = current->mempolicy;
> +
> +       if (!in_interrupt() || !policy || policy->flags & MPOL_F_LOCAL)
>                return numa_node_id();

I think your patch is correct. but I don't like interrupt context
dereference current task.
It would be nice if we only see current->mempolicy when !in_interrupt.

But this doesn't mean NAK anyway.

 Acked-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
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