linux-kernel - Re: [RFC][PATCH v2] slub: Keep page and object in sync in slab_alloc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1358522992.7383.13.camel@gandalf.local.home>
Date:	Fri, 18 Jan 2013 10:29:52 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Joonsoo Kim <iamjoonsoo.kim@....com>
Cc:	Christoph Lameter <cl@...ux.com>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Pekka Enberg <penberg@...nel.org>,
	Matt Mackall <mpm@...enic.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	RT <linux-rt-users@...r.kernel.org>,
	Clark Williams <clark@...hat.com>,
	John Kacur <jkacur@...il.com>,
	"Luis Claudio R. Goncalves" <lgoncalv@...hat.com>
Subject: Re: [RFC][PATCH v2] slub: Keep page and object in sync in
 slab_alloc_node()

On Fri, 2013-01-18 at 13:42 +0900, Joonsoo Kim wrote:

> diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
> index 9db4825..b54dffa 100644
> --- a/include/linux/slub_def.h
> +++ b/include/linux/slub_def.h
> @@ -46,6 +46,9 @@ enum stat_item {
>  struct kmem_cache_cpu {
>  	void **freelist;	/* Pointer to next available object */
>  	unsigned long tid;	/* Globally unique transaction id */
> +#ifdef CONFIG_NUMA
> +	int node;

Note, you put an int between a long and a pointer, which will waste 4
bytes on 64bit machines.

> +#endif
>  	struct page *page;	/* The slab from which we are allocating */
>  	struct page *partial;	/* Partially allocated frozen slabs */
>  #ifdef CONFIG_SLUB_STATS



> @@ -2038,10 +2049,10 @@ static void flush_all(struct kmem_cache *s)
>   * Check if the objects in a per cpu structure fit numa
>   * locality expectations.
>   */
> -static inline int node_match(struct page *page, int node)
> +static inline int node_match(struct kmem_cache_cpu *c, int node)
>  {
>  #ifdef CONFIG_NUMA
> -	if (node != NUMA_NO_NODE && page_to_nid(page) != node)
> +	if (node != NUMA_NO_NODE && c->node != node)

We still have the issue of cpu fetching c->node before c->tid and
c->freelist.

I still believe the only solution is to prevent the task from migrating
via a preempt disable.

-- Steve


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/