linux-kernel - Re: [PATCH v3] cgroup/kmemcheck: Annotate alloc

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Message-ID: <20110812095827.GB1639@e102109-lin.cambridge.arm.com>
Date:	Fri, 12 Aug 2011 10:58:28 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Michal Hocko <mhocko@...e.cz>, LKML <linux-kernel@...r.kernel.org>,
	Johannes Weiner <hannes@...xchg.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Daisuke Nishimura <nishimura@....nes.nec.co.jp>,
	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	Minchan Kim <minchan.kim@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dave Hansen <dave@...ux.vnet.ibm.com>,
	Randy Dunlap <rdunlap@...otime.net>
Subject: Re: [PATCH v3] cgroup/kmemcheck: Annotate alloc_page() for cgroup
 allocations

On Tue, Jul 26, 2011 at 08:19:16PM +0100, Steven Rostedt wrote:
> When the cgroup base was allocated with kmalloc, it was necessary to
> annotate the variable with kmemcheck_not_leak(). But because it has
> recently been changed to be allocated with alloc_page() (which skips
> kmemleak checks) causes a warning on boot up.

Sorry for the delay, too much holiday over here :)

> diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
> index 53bffc6..1eb534a 100644
> --- a/mm/page_cgroup.c
> +++ b/mm/page_cgroup.c
> @@ -133,10 +133,13 @@ struct page *lookup_cgroup_page(struct page_cgroup *pc)
>  static void *__meminit alloc_page_cgroup(size_t size, int nid)
>  {
>  	void *addr = NULL;
> +	gfp_t flags = GFP_KERNEL | __GFP_NOWARN;
>  
> -	addr = alloc_pages_exact_nid(nid, size, GFP_KERNEL | __GFP_NOWARN);
> -	if (addr)
> +	addr = alloc_pages_exact_nid(nid, size, flags);
> +	if (addr) {
> +		kmemleak_alloc(addr, size, 1, flags);
>  		return addr;
> +	}
>  
>  	if (node_state(nid, N_HIGH_MEMORY))
>  		addr = vmalloc_node(size, nid);

The __GFP_NOWARN is already added by kmemleak_alloc but there is no harm
in leaving it.

One minor thing with the subject, unless you already submitted the
patch - it's kmemleak rather than kmemcheck (different things,
confusingly).

Acked-by: Catalin Marinas <catalin.marinas@....com>
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